Concorde question

[howiehowie93]

Ideally I'd like a sectioned 593 on display, as there's not a lot to see on the outside of a turbojet engine except the ancilliaries - and you can see those by opening the engine bay doors. There used to be one of those hanging from the Foyer roof of the Engineering Department of Leeds University. AFAIR is was motorised and the HP & LP Spools used to rotate at a fraction of an RPM. I think there were internal lights too and/or the spools were painted as well. I think it was also in a Concorde type nacelle. This must have been in the 70's as I used to go to the annual Open Days with my Grandad who worked there.

I can't seem to find any reference to it as to whether it is still there, disposed of or in storeage ??? Perhaps someone has contacts ???

regards
Howie

[twochai]

A more practical issue was that the engines were "handed", so that if a "left-handed" engine failed and you had only "right-handed" engines in stock, you had a problem.....


Now that raises an interesting question - "why?". Why would turbojet engines need to be handed? Was it to eliminate the need for slightly offset trims required to cancel the gyroscopic forces of symmetrical rotation of the engines in cruise??

[BN2A]

Storage space for pipes/gearboxes/ancillaries in the nacelle??

See, Concorde Engineers CAN make it happen and fit a round peg in a square hole!!!

:ok:

[911slf]

If the quote in message #1504 is correct, why would there be a vibration problem on take off in engine #4 only?
Ref: p80 Haynes 'Owners Workshop Manual'

I make no claim to technical knowledge but this seems unlikely. Is there a source for this?

[911slf]

ref #1496
I have still got my key ring from my 1980 flight. Thank you Birmingham Evening Mail competitions department.

Still cost me an arm and a leg. I arrived in Paris by Concorde and tried to live up to the image. Trip to the Lido, dinner on the Champs Elysee. Never did admit to the wife what I spent. :)

[ChristiaanJ]

Sorry to have caused some confusion....

BN2A is right : some of the pipes, pumps, generators, ancillariy gearboxes, connectors and suchlike on the outside of the 'round peg' are installed either on the left or the right side of the engine, so that they fit inside the 'square hole' while remaining accessible for inspection/maintenance.

911slf, all engines rotate in the same direction. However, the vortices rolling off the leading edges of the wings into the air intakes rotate in opposite directions.
Now if you look at a photo or a model, you'll see that the intakes of the outboard engines (#1 and #4) are quite close to the leading edges.
No problem for engine #1, because the rotation of the air entering the intake is the same as that of the engine itself, but for engine #4 there is a conflict between the senses of rotoation, leading to vibration at low speed.
Engine #3 is further back from the wing leading edge, so the airflow into the intake has already been 'straightened out' more, hence the problem doesn't occur there.
Maybe M2dude has some more details?

CJ

[CliveL]

I've said it before to Dude, but it will bear repeating I think: it was the vortex coming off the intake sidewall that caused the problem, not anything coming off the wing. The highly swept, sharp leading edge was perfect for generating vortices at high engine demand and low aircraft forward speed.

CliveL

[ChristiaanJ]

CliveL,
Many thanks for chipping in.... I gave the explanation to the best of my knowledge, but as you know I'm not an aerodynamicist, nor an engine expert, so I was actually hoping either M2dude or you would add the corrections.

What caused the actual vibration? Incipient stall of the first compressor stages, or some separate phenomenon?

CJ

[CliveL]

Christiaan,

To be honest, it was all a long time ago http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/smile.gif

#4 intake was marginally worse than #1 in several ways. Obviously this particular problem was linked to the engine face distortion pattern and may have been associated with the combination of the 'handedness' of the incoming vortex with the non-radial inlet guide vanes which together could have given some subtle variations in distortions between sides. But it was all pretty fine drawn stuff, and the problem disappeared by 60 kts or thereabouts.

CliveL

[Mike-Bracknell]

Anyone got £1.25m under the sofa?

Concorde Rolls-Royce Olympus 593-610 Turbojet Engine with Reheat | eBay (http://www.ebay.co.uk/itm/Concorde-Rolls-Royce-Olympus-593-610-Turbojet-Engine-Reheat-/110783047958)

[howiehowie93]

Hi

I had a look on the eBay link and I question the engine model - the Forward Bearing supports are 5 struts but not the same configuration as the Series 200. I thought the 593 was derived from the 300 Series.

see below a picture of a 593 from Wiki:
http://www.pprune.org/%3Ca%20href=http://s665.photobucket.com/albums/vv20/howiehowie93/?action=view&current=Olympus593.jpg%20target=_blank%3E[IMG]http://i665.photobucket.com/albums/vv20/howiehowie93/th_Olympus593.jpg
File:Olympus593.JPG - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/File:Olympus593.JPG)

regards
Howie

[911slf]

Thanks ChristiaanJ#1508 and CliveL#1509. That's what I thought. It was the quote in #1504 that implied left and right handed engines with all the stock problems that would cause.

At risk of thread drift I think that anything with propellers would be likely to suffer much more from asymmetry, but I think folk just put up with it - except in the few cases where there are contrarotating propellers.

Am I right in thinking that once the necessary minimum rpm was achieved, reheat was selected on all four engines, but that some (automatic?) control restricted the power to engine#4 until 60kt was achieved?

[Heliport]

M2dude John Hutchinson - The Wind Beneath My Wings
A superbly interesting read, written about arguably the most eloquent of all Concorde pilot speakers. One of life's true gentlemen and a superb pilot, it is a long overdue biography, well done Hutch.

Not surprisingly, the first edition of this excellent book sold out very quickly.

It's now available again.


Reviews here (http://www.pprune.org/aviation-history-nostalgia/455846-wind-beneath-my-wings-john-hutchinson-concorde-pilot.html)

H.

[Jofm5]

I must say a very interesting and worthwhile read, it is so excellent that the general oiks like I have the opportunity to pose some questions - for the participation of those in the know I applaud you :D. My first memory of her is when I was 8 from the top of the Queens building (IIRC) watching her taxy and take off, I have visited her many times at RNAS Yeovilton but alas did not have the funds in 2003 to make one of the final flights.

I have some questions if I may, they are very general and aimed at getting some more fascinating discussion going - I am only a student ppl so cant go into the nitty gritty so hope to prompt some memories.

1) I adore the lady in many ways but I would imagine she was far from perfect with the challenges that had to be overcome. I would imagine the positives way out weighed any negatives. So what were the downsides for the Capt/FO/FE that were most discussed - was anything done to alleviate these is design/Pre-Production and what if any gripes made it through to production.

2) For each of you (I would imagine they would be different based upon your skill set) what were the biggest challenges you personally had to overcome when switching to/designing our iconic aircraft.

Finally some more anecdote's from LandLady and Concorde Trivia from M2 would be good.

Many thx

[nicolai]

Christaan

That video company is ITVV - Intelligent Television and Video. DVD copies are still around on Ebay. 300 minutes of pure delight.

DVD copies are also available direct from ITVV (http://www.itvv.com/manufacturers.php?manufacturerid=3) where I got mine from. Well worth the money, it's fascinating!

[ChristiaanJ]

1) I adore the lady in many ways but I would imagine she was far from perfect with the challenges that had to be overcome. She was pretty well 'state-of-the-art', really.
And through the long proto-preprod-prod developent cycle, I would say she was as near 'perfect' as we could make her at the time she went into service.

Maybe I should mention that in 'my field' (automatic flight control systems) the 'state-of-the-art' was changing significantly almost from year to year.

I would imagine the positives way out weighed any negatives. So what were the downsides for the Capt/FO/FE that were most discussed - was anything done to alleviate these is design/Pre-Production and what if any gripes made it through to production.I'd be interested too.

2) For each of you (I would imagine they would be different based upon your skill set) what were the biggest challenges you personally had to overcome when switching to/designing our iconic aircraft.LOL.....
Being Dutch, I had to convert my school French to engineering French on the one hand, and 'argot' on the other hand, while at the same time getting familiar with the way 'my' firm was implementing the latest developments in electronics.

Finally some more anecdotes from LandLady and Concorde Trivia from M2 would be good.Has anybody here read "The Soul of a New Machine", by Tracy Kidder?
It's a pity no book quite like that has ever been written about Concorde... and I can't imagine it could be written today. Too many of the 'actors' have retired, or are not there anymore....

Maybe somebody ambitious could use this thread as a base, and do some interviews, and write "Concorde, From Then to Now" ?

CJ

[Shaggy Sheep Driver]

I'd vote for M2 for writing that book.

[db737]

Hi folks. Christian,M2 etal.

On numerous cockpit photos I have seen,; sometimes the cockpit panels seem to have a bluish tint to them. Other times they look like the standard gray, I see in the 737NG I fly.

Can you shed a little light on the actual color of the cockpit panels.

I realize that different panels installed maybe slightly different colored, but overall, what was the general color of the panels.

Thank You, for ALL your Wonderful insight and Stories of the Beautiful Aircraft; I missed out on.

Best,
David

[db737]

Hi folks. Christian,M2 etal.

On numerous cockpit photos I have seen,; sometimes the cockpit panels seem to have a bluish tint to them. Other times they look like the standard gray, I see in the 737NG I fly.

Can you shed a little light on the actual color of the cockpit panels.

I realize that different panels installed maybe slightly different colored, but overall, what was the general color of the panels.

Thank You, for ALL your Wonderful insight and Stories of the Beautiful Aircraft; I missed out on.

Best,
David

[ChristiaanJ]

On numerous cockpit photos I have seen,; sometimes the cockpit panels seem to have a bluish tint to them. Other times they look like the standard gray, I see in the 737NG I fly.
Can you shed a little light on the actual color of the cockpit panels.
I realize that different panels installed maybe slightly different colored, but overall, what was the general color of the panels.I just looked at the one cockpit item I possess, and indeed I would call it dark gray, without a bluish tint. Unfortunately I don't have the color/paint reference....
I suspect the bluish tint is the result of lighting and camera settings.
If you're really interested, I can ask my wife to dig out her "Munseill Book of Color" (standard color chips) and try to match it up.

CJ

[db737]

Hi, Christaan. Thank You for the info. No, we don't have to go to that extreme.

Best,
David

[ChristiaanJ]

Hi, Christaan. Thank You for the info. No, we don't have to go to that extreme.LOL.... OK.
Anyway, for modelers (not your case, I take it) a Munsell chip ref wouldn't be much use..... they'd need a Humbrol paint number !

"Matching colors" is a Concorde problem to this day....
A small group of enthusiasts is trying to re-paint F-WTSA (the French preprod Concorde, now at a small museum south of the Paris Orly airport) in the same paint scheme as in the olden days... ancient BA livery on one side, ancient AF livery on the other side.
Getting hold of all the paint color references is not obvious!

CJ

[Mr Hoppy]

Could I ask a performance question of you folks?

I was watching the ITVV Concorde program the other day and a couple of things really stood out. The noise abatement take off from JFK looked pretty alarming from a climb rate point of view, looked like the aircraft tottered over the coastline with a pretty low rate of climb compared to the subsonic stuff. That being said she was supersonic 12 minutes after the thrust levers were advanced so she could certainly pick up her heels.

So the question is, if you were operating the aircraft out of somewhere with no climb or noise abatement restrictions (BGI?) on an average day with make take off weight what would be the typical time to M1? Course the 7 year old in me also want to know what the fastest time was that you saw on a revenue trip.

[Shaggy Sheep Driver]

I've spent hundreds of hours in AC's flight deck. The panels are grey!

[Concorde Rules]

I heard a while back that the quickest to M1 was 6 minutes, no passengers tho.

[ChristiaanJ]

I heard a while back that the quickest to M1 was 6 minutes, no passengers tho.
IIRC (somebody else can confirm?) that's right.
It was a JFK-LHR BA Concorde which landed at Cardiff (in Wales) with some kind of tech problem. The paxs were ferried to LHR and the repairs were done at Cardiff.
Then the a/c was flown back to LHR. Since the take-off was over the sea (so no noise abatement needed), and the plane was empty, with only little fuel, she went "like a scalded cat" and hit Mach 1 in about 6 minutes.

Mr Hoppy,
I am aware it doesn't quite answer your question... I hope one of the pilots can answer that. But I doubt they would normally have kept specific records.

CJ

[Shaggy Sheep Driver]

And I think they were level at 60,000' and M2 in under 9 minutes from brakes off!

[Nick Thomas]

Great thread and I am still enjoying reading it over a year later. I was again watching ITVV Concorde DVD the other night and noticed the Heading/Track button on the A/P. I wondered how you could chose to fly in Track instead of Heading i.e. did you say have to push the button quickly twice to get the track mode?

[ChristiaanJ]

Great thread and I am still enjoying reading it over a year later. I was again watching ITVV Concorde DVD the other night and noticed the Heading/Track button on the A/P. I wondered how you could chose to fly in Track instead of Heading i.e. did you say have to push the button quickly twice to get the track mode?Nope.
IIRC you had to push/pull the HDG/TRK SET button in or out to set either heading or track which would then show on the HSI.
This from memory only... I may well be wrong.

CJ

[ChristiaanJ]

And I think they were level at 60,000' and M2 in under 9 minutes from brakes off!I doubt the "scalded cat" went all the way to 60,000 ft on that particular trip....

CJ

[Shaggy Sheep Driver]

S'what I heard. I wasn't there mind, but it was on good authority.... ;)

[Bellerophon]

Nick Thomas

... I wondered how you could chose to fly in Track instead of Heading i.e. did you say have to push the button quickly twice to get the track mode?...

We should establish which button you mean, because there are two buttons, both associated with TRK/HDG, either of which might be the one you are referring to.

On the auto flight control panel there is a white push-button switch engraved with the letters TRK and HDG.


http://www.concordesst.com/inside/cockpittour/flightcontrols/pictures/ap10.jpg

Photo courtesy of, and copyright to, Gordon Roxburgh, from his ConcordeSST.Com website.


When pressed, this will initiate the acquisition and subsequent hold of the preselected track or heading selected on the three digit counter beneath it (and repeated on the track/heading pointer on the HSI). This switch will illuminate White when this mode is engaged.


http://www.concordesst.com/inside/cockpittour/flightcontrols/pictures/ap9.jpg

Photo courtesy of, and copyright to, Gordon Roxburgh, from his ConcordeSST.Com website.


So what determines whether this mode, if selected, would follow TRK or HDG? Beneath the three digit counter is a combined push-pull and rotary control, beside which is marked HDG PULL and TRK PUSH.

The rotary function of this control altered the reading in the counter and the Push/Pull function determined whether the entered number was a TRK demand or a HDG demand. With TRK/HDG illuminated on the push-button control, and with the rotary control pulled out (and thus in HDG mode), this little rotary control was effectively the steering wheel for the aircraft.

Why HDG and not TRK? Mainly because nearly all ATC vectors are HDG vectors. In practice TRK was rarely used, with the aircraft either in HDG or INS.

Best Regards

Bellerophon

[Nick Thomas]

I was referring to the button in the top picture. On the DVD you can see the co-pilot moving the lower button but the camera view is from the side and below so it's not possible to see the button label. Thank your Bellerphon for your clear explanation and for going to the trouble of finding the photos.

[green bean]

Time for a foodie slot.. :)

way way back in the T3 days, catering ex JFK.. does the term "Hero Roll" ring bells with anyone here?

GB.

[gordonroxburgh]

Re : 9min to mach 2.

Not sure you can get CG back that quickly.

In the (restored) Sim with a lightweight fuel load that will not get you anywhere and not bothering about the CG, the absolute minimum time to Mach 2 at 50,000ft on a pretty constant VMO chase is just over 15mins, so really unlikely that this was possible in real life....but will stand corrected if someone says other wise.

The A/C had diverted to cardiff as they had suffered a engine surge due to a double intake lane failure and had to slow to subsonic early. That coupled with additional time with engines running at JFK meant they were just not comfortable about coming to London and possibly declaring a fuel emergency.

[Da-20 monkey]

Hello,

Because this is such an interesting plane, I have a few questions. Maybe someone can answer, would be interesting:

When a concord(e) is in supersonic cruise, is there one main compression/ expansion wave? If so, where is it located, on the longitudinal axis?

Also:

It is quite obvious that the plane doesn't have a horizontal tail. Now I know that a plane without a tail can be statically stable (I think), but is concorde dynamically stable?

If so, how is this achieved?

[CliveL]

Two shock waves - the main one located on the nose, then an expansion field over the wing and a final shock at the tail where the flow was recompressed. [That is ignoring all the intake shocks!] The two compression shocks are what gives rise to the characteristic Boom-boom on the ground.

The aircraft was dynamically stable (just) because it had natural pitch damping, but in practice to give good handling qualities some artificial damping was required via the autostabiliser.

[Da-20 monkey]

OK.. It is a FBW aircraft, right? Did the flight control software include this artificial damping?

I would not expect that it has a ,,direct law'' type FBW where a control deflection gives a control surface deflection, right?

Thanks CliveL

[CliveL]

One for Christiaan I think :)

Sure it had electrically signalled controls, but this is 1960s technology - it was (sshhh) an analogue system. No "control laws", just a direct relationship between stick and surface - the autostabiliser signals (also analogue) were just added to the stick commands.

The only bit of digital control on the airplane was in the hybrid intake control system.

[ChristiaanJ]

One for Christiaan I think

Sorry all, this is now forty years back, literally....
So no, I don't have all the block diagrams and circuit diagrams in my head any more... I'll have to look through what I still have in the way of documentation.
i'll try to give some quick answers.

Da-20 monkey,
Yes, Concorde had "artifcial damping", or "autostabilsation" as we called it, on all three axes (pitch, roll and yaw), even if it could be flown without it.
On the prototypes there were three separate computers (one per axis).
On the preprod and production aircraft the A/S function was 'compressed' into a single unit (I still have one).

CliveL has given the basic answer.
Don't confuse the Concorde FBW (which we referred to as "electrical signalling") with the current "Airbus" digital FBW.

One, rather than in previous-generation aircraft, the pilot no longer pushed and pulled on cables and rods to move the control surfaces. Instead, when he moved the controls, those movements were translated into electrical signals that were sent to the electro-hydraulic control surface actuators (even if in the Concorde days there still was a mechanical back-up).

Two, the entire system was "analogue". A concept difficult to explain in these days, where nearly everything is digital.....
Very briefly, you can convert 'physical' data, like control positions, or altitude, or pitch or roll rate, or Mach number, into 'analogue' electrical signals. You can then perform all kinds of 'computations' on those signals, like filtering them, or add or subtract them, or even multiply them, using electronic circuits based on 'operational amplifiers'.

In digital systems you go one step further.... you convert all those data into digital values, and use a digital computer to perform all your calculations, in accordance with the 'system software', then convert all the results back into physical data, such as control surface commands.

In analogue systems there is no "software". The entire system is defined by 'control laws ' (not the same thing at all as in the Airbus FBW aircraft) that are fixed in terms of 'transfer functions' of the various control loops.
Those in turn are determined by the values of the components in the various electronic circuits (resistors and capacitors mostly). So in those golden days.... we didn't re-write and re-program software.... we changed resistor and capacitors, and re-wired logic circuits.

I admit, you almost have to have been there to understand it....

I'm not sure whether it's worth starting an entire new thread on 'analogue computing' (maybe there's something on wikipedia, I haven't looked)....

CJ

[MathFox]

There is Analog computer - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Analog_computer)

I've done a few study exercises on a hybrid system; programming digital computers now. However when designing machines there still are tasks we delegate to analog electronics or mechanical non-linear transmissions.

[ChristiaanJ]

There is Analog computer - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Analog_computer)

I've done a few study exercises on a hybrid system; programming digital computers now. However when designing machines there still are tasks we delegate to analog electronics or mechanical non-linear transmissions.Thanks MathFox, for looking up the link to the Wiki article.
I just read it, and I wasn't impressed... it's more historical than a clear explanation of what analogue computing really is and does. I wouldn't advise it to somebody who's trying to get his head around the basic concept.

CJ

[mm43]

A collection of links to videos, articles and much more on the rise and fall of analogue computing (http://www.analogmuseum.org/english/introduction/) should prove interesting.

For those cutting their teeth in the computing field in the last twenty years, the analogue concept was already well and truly buried. As we all know, the Concorde project epitomized analogue computing which peaked in the decade between 1960 and 1970. One can only but wonder how much weight could have been saved and performance improved if current FBW digital computing was available at the time. That the aircraft type soldiered on well past its "use by date" is a credit to the designers and engineers who implemented the "state of the art" systems of the time.

[dixi188]

Analogue computers are still very active on the Airbus A300-B4 100/200 srs.
A lot of the Concorde technology was transferred to the Mark 1 Airbus, and it still works very well. We are Cat IIIa certified and I have never had a failure when it was needed.
Yes we get a lot of drop out of things, but usually they work after a reset.

[Da-20 monkey]

Thanks Cristiaan,

From the way you explain this autostabilisation it looks similar to the way a yaw damper works. With a rate gyro, ac current that is phase advanced, filtered and then amplified, but on all 3 axes?

Not being a real bright light on engineering I can see that such a system works to give ,,apparent'' dynamic stability..

Another question perhaps: Does concorde have real trim tabs? Or is it just an artificial feel unit that ,,changes the neutral point in the stick?

I've seen the (awesome, by the way) ITVV documentary but don't remember this being mentioned...


mm43 That's a nice link:ok:

[Bellerophon]

Da-20 monkey


... Does concorde have real trim tabs?...

No, there were no trim tabs on Concorde.


...is it just an artificial feel unit that changes the neutral point in the stick?...

Yes, just so.

Concorde had conventional trim controls (electric trim in pitch, manual in roll and yaw), but operating a trim control merely changed the artificial feel datum position and thus the neutral position of the flying controls.

The electric pitch trim not only operated automatically whenever an autopilot was engaged, but could and would also operate automatically in manual flight, independently of any pilot input, to provide pitch stability corrections in various situations.

Best Regards

Bellerophon

[Da-20 monkey]

Thanks all :ok:

[fizz57]

Perhaps more an operational than a technical question, but it's nice to see one of the sky-gods back on this thread!

I confess to occasionally firing up Microsoft Flight Simulator and SSTSIM, and am particularly impressed by the Barbados route - especially as half-way between the Azores and Barbados, you are literally a thousand miles from anywhere with limited diversion options and marginal fuel in case of engine failure and subsonic cruise. While I'm sure you had all the angles covered, was it really a nail-biting moment and what sort of contingency plans were in place?

[Bellerophon]

fizz57

... Barbados route...half-way between the Azores and Barbados...a thousand miles from anywhere with limited diversion options and marginal fuel in case of engine failure and subsonic cruise...what sort of contingency plans were in place?...


As well as carrying sufficient fuel to arrive at BGI with standard fuel reserves remaining, there was also a requirement that sufficient fuel be carried to ensure that, following an engine shut-down at any stage in the flight, Concorde could divert, on three engines, to a suitable diversion airfield, and still arrive there with standard fuel reserves remaining.

It was this requirement - the three-engined diversion requirement - that often required more fuel to be loaded - above the basic LHR-BGI flight plan fuel figure - often bringing the total fuel required up to or over the full tanks figure and so became the limiting factor on this route.

Perhaps the main difference between Concorde and most subsonic aircraft, following an engine shutdown in cruise, was that Concorde would suffer a much greater loss in range. From four-engined supersonic flight to optimum three-engined subsonic cruise the loss in range would have been in the order of 30-35%.

This was mainly because Concorde, following an engine shut-down in cruise, would have to decelerate and descend, and thus leave a very efficient flight regime, at M2.0 and 55,000-60,000ft, with relatively low drag, low winds and very cold outside air temperatures, for a much less efficient regime, at M0.95, at around 30,000ft, in a higher drag subsonic cruise with warmer outside air temperatures and much stronger, probably adverse, winds.

The forecast weather at the principal en-route diversion airfields of Santa Maria, Lajes, Bermuda and Antigua, along with the calculated wind components at subsonic cruise levels to these airfields, were all taken into account at the flight planning stage, with the forecast subsonic cruise wind component to Antigua generally being the most critical factor.

If the weather conditions at and en-route to these diversion airfields were favourable, flight planning was straightforward. If the weather conditions were unfavourable, flight planning got more difficult, but the necessary fuel was always carried, passenger numbers limited or a re-fuelling stop planned.


...While I'm sure you had all the angles covered, was it really a nail-biting moment...

No, not really.

LHR-BGI was certainly the most demanding route on Concorde, and required careful planning, good tactical awareness and diligent in-flight monitoring, however the flight planning procedures and tactical decision making processes were standard and would have been very familiar to any ETOPS rated pilot.

With one exception.

Concorde would still have got you to a diversion airfield following a second engine failure! :D

Best Regards

Bellerophon

[fizz57]

Thanks for your insightful reply Bellerophon. Business as usual then, at Mach 2 1000 miles from anywhere and only an hour to destination. If it wasn't nail-biting, it must at least have brought a smile to your face.

[Shaggy Sheep Driver]

Two shock waves - the main one located on the nose, then an expansion field over the wing and a final shock at the tail where the flow was recompressed. [That is ignoring all the intake shocks!] The two compression shocks are what gives rise to the characteristic Boom-boom on the ground.


Thanks for this, CliveL. Could you please explain 'expansion field over the wing '?
Thanks.

Also, how was the flow re-compressed at the tail? What is the aerodynamic explanation of this?

As the intakes produced shocks, what about other protruberances such a aerials and drain masts etc? Did these also produce (small) shocks?

[Shanewhite]

Down here in Devon, the only contact we had with Concorde was the spine-tingling "whomp-bomp" every evening as flights out of CDG lit up down the channel. Replaying that sound in my memory, I would say that the time between the two thumps was between 1/3 and 1/2 sec, and yet a bit of maths tells me that at 1300 MPH, Concorde travelled her own length in less than 1/10 sec. This always puzzled me at the time, and I still can't explain it. Any ideas, anyone?

[Shaggy Sheep Driver]

Although the nose and tail shocks are 204 feet apart at the point they leave the aeroplane, I'd guess that they diverge away from each other with distance, so the further away you are from Concorde when they reach your ears, the longer the gap between the shocks.

[CliveL]

SSD: [quote]Thanks for this, CliveL. Could you please explain 'expansion field over the wing '?
Thanks.

Also, how was the flow re-compressed at the tail? What is the aerodynamic explanation of this?

As the intakes produced shocks, what about other protruberances such a aerials and drain masts etc? Did these also produce (small) shocks?[unquote]

I was generalising a bit and referring to the shocks as heard on the ground which take the form of a classic 'N' wave. This is a sudden rise in static pressure followed by a drop in static pressure to below atmospheric and then another sharp pressure rise. In supersonic flow any increase in static pressure is associated usually described as some sort of compression and conversely a drop in static pressure as an expansion. Since this happens over the region where the wing sits I described it as an expansion field over the wing.

The N wave is OK for the 'far field' shock characteristics, but as you hint, the flow near the aircraft is more complex than that - all the separate shocks gradually. merge into the bow and tail shocks. In the near field all the aerials, drain masts etc have their own little shock waves of course.

I have never seen a completely satisfactory explanation for the drop in static pressure, but if you will accept a much simplified description .....

I think there are two parts to the explanation.

The pressure over the upper wing surface will be below atmospheric static in the usual sense when lift is being generated - this will depend on the amount of lift (and hence weight)

Besides that there is a term related to the volume of the aircraft. One graphic description I have seen is that flying along at 2.0M the aircraft 'tears a hole' in the atmosphere that the surrounding air, being limited to 1.0M cannot fill. Consequently there is a drop in static pressure around the airframe. When the aircraft is past the 'void' is filled up and the resulting rapid increase in static pressure goes with the rearmost shock. This tail shock is sometimes described as the rarefaction shock.

This may not be scientifically accurate, but it satisfies me http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/smile.gif

CliveL

[CliveL]

I think the explanation is that the sound you heard was (and could only be) travelling through the air to reach your ear at the speed of sound. The distance between the shocks would be 204 ft, but the speed would have been 1100 ft/sec - i.e.about 0,2 seconds between them

[ChristiaanJ]

I really like this question..... and I admit to still being baffled....

A Mirage 2000, a Rafale or a Mirage F1 is only about 15m (50ft) long.
Yet the booms we get locally (see above re returns from exercises over the Med), are still the same double boom - "whah-boom" (N-wave).

Of course, when it comes to judging the exact duration of a sonic boom, things get very subjective.... I wouldn't trust my own judgment, since it's as much based on the rattling of the window/door as the actual sound.

CliveL, are there any documented records of the trials in "Boom Alley" we could use to settle some of the issue?

CJ

[CliveL]

Quote:
CliveL, are there any documented records of the trials in "Boom Alley" we could use to settle some of the issue? Unquote:

Christiaan, there isn't anything particular to "Boom Alley", but there is enough data around to quantify the issue.

SSD, you were quite right when you said that the shock waves diverge as they get farther from the aircraft; that could be as much as 25% of the aircraft length at the ground. Near the aircraft the rise time would be proportional to length/speed of sound.

To cut a long story short, plotting all the available data leads to a pretty good expression for the rise time:

T = 0.011*LOA + 0.0001*FL

To give you a feel for the numbers, the measured value for an F18 at FL600 is 0.18 secs, for Concorde at FL520 about 0.25 secs or for an F104 at FL190 0.08 secs.

After that it would depend on your own perceptions I think, but I could easily envisage either a single or double bang for a fighter size aircraft depending on altitude.

[Shanewhite]

.25 seconds for Concorde sound about right.

[Shaggy Sheep Driver]

Here's something I've wondered about; I understand that the proposed 'B' model of Concorde was to have leading edge slats. How does that fit with vortex lift?

Vortex lift relies on controlled flow breakaway at the LE, while slats delay such breakaway.

[CliveL]

Although the Concorde site describes them as slats, the LE changes were a simple LE droop as shown in the Concorde 'B' site sketch.

The intention was to give some forward facing area (at low speed) so that the LE suction had something to work on and give "LE thrust". The AoA for vortex generation would have been delayed, but the net effect was to reduce TO drag and hence power required in noise abatement climb. For cruise the LE went back to its normal position of course.

The original prototype had a similar LE droop to the Concorde 'B' (but a bit less extreme). It was changed when it was found that the droop generated an underwing vortex at low AoA (towards zero 'g') at supersonic speeds and that this vortex went down the intake with unpleasant effects on engine face distortion. This could be avoided with the moveable LE.

[Shaggy Sheep Driver]

Many thanks CliveL!

[johnjosh43]

Concorde grows as she gets warmer. How does the mechanical cable connection of the controls cope with the growth ?
I assume the electrical cabling has nice loops to allow growth but a mechanical cable connection needs to be pretty taut all the time.
One theory today was that the cables expand as they warm up at the same rate as the structure but surely they aren't as warm ?

[ChristiaanJ]

johnjosh43,
You're quite right about the cable 'problem'.
It's not even typical to Concorde.... airframes are aluminium, while the control cables are steel, so the expansion factor is not the same, and the same problems exist even in subsonic aircraft.

The problem is solved with 'cable tensioners'.

Unfortunately I have no drawing instantly to hand. Maybe some other reader here does, and can post it.... if not I'll try and do a sketch from memory and post it.

As said, the problem is/was much older than Concorde, and we just 'borrowed' from existing technology.

And of course, the expansion differential, and the length and flexibility of the airframe, were some of the reasons why Concorde went for 'fly-by-wire', or - as we called it at the time - 'electrical signalling'.

CJ

PS And yes, there was deliberate 'slack' in the electrical wiring, and also various arrangments of expansion joints in the fuel and hydraulic systems.

[YearoftheTiger]

This is one of the most incredible and informative threads on Concorde that I have found!

An introduction: I'm an artist currently living in NYC, and I've been in love with aviation since I was very little. Concorde has a very special place in my heart ever since I saw a very bad VHS copy of Airport '79 when I was 3.

The reason why I bumped into this thread was soon after her retirement, I wanted to understand how she worked, and why she was shaped and built the way she is.

I had a lot of questions, for example how was she built to allow for thermal expansion? what are those small canards behind the nose for? How do the landing gears shorten, etc. Although I am an artist, I have an above average understanding of mechanics, physics, and aviation -- at least compared to the general public.

Since I also build 3D models for animation, I decided that the best way to learn about the aircraft was to actually build one in 3D. This is a very very ambitious project, but it's the same way famous painters learnt to paint by copying the masters before them.

So, my question is, where did some of you get all those detailed diagrams of internal structures from? They're unlike any of the other line drawings I see on the internet. I'm looking for them because I want to accurately model the internal structure as a way to learn on how the plane dealt with thermal expansion / contraction and the stresses that resulted from it.

At some point I plan to release the 3D model for the public to use in CFD simulations, and to "peel back the skin" and look inside. An interactive model is better than a flat 2D drawing!

Sorry for the long post, but I wanted to let you guys know where I'm coming from.

Thank you!

[Mike-Bracknell]

So, my question is, where did some of you get all those detailed diagrams of internal structures from? They're unlike any of the other line drawings I see on the internet. I'm looking for them because I want to accurately model the internal structure as a way to learn on how the plane dealt with thermal expansion / contraction and the stresses that resulted from it.

I think you might find you're conversing on this thread with some of the people who actually had a hand in creating the diagrams in the first place, etc.

[Shanewhite]

Someone's done the same sort of thing, albeit on a smaller scale, for the Bugatti Type 35. Is this the sort of thing you're contemplating?

1924 Bugatti Type 35 (http://www.3dengineers.co.uk/projects-bugatti-type-35.html)

[YearoftheTiger]

Someone's done the same sort of thing, albeit on a smaller scale, for the Bugatti Type 35. Is this the sort of thing you're contemplating?

1924 Bugatti Type 35 (http://www.3dengineers.co.uk/projects-bugatti-type-35.html)Yes! That's exactly what I am contemplating.

I think you might find you're conversing on this thread with some of the people who actually had a hand in creating the diagrams in the first place, etc. One of the best things about this thread and what makes it very informative.

I think I'll try modeling the nose cone w/cutouts and the visor operations when I get some time next week. It's very simple, and a good place to begin animating the mechanics of lowering/raising the nose cone/visor.

[ChristiaanJ]

I think I'll try modeling the nose cone w/cutouts and the visor operations when I get some time next week. It's very simple, and a good place to begin animating the mechanics of lowering/raising the nose cone/visor.I'm not sure to what extent you intend to model the mechanism... but I wouldn't call it simple.

It's not Rube Goldberg, but it's still a pretty complex mechanism, with rails, hydraulic cylinders, uplocks (both hydraulic and manual), intermediate stops for the 5° and 12.5° positions, etc.
And you'll discover that (even on the production aircraft) the nose can still be lowered to 17.5° by removing a set of mechanical stops (IIRC the reason for that is already mentioned earlier in the thread).

Wishing you luck and courage with your venture, and I will be curious to see the final result!

CJ

[Shanewhite]

If you succeed, it will be the most fantastic resource, but I don't envy you the task. The Bugatti took 4000 hours to complete and has around 3000 components. Anyone care to hazard a guess at how many components Concorde contained?

[ChristiaanJ]

If you succeed, it will be the most fantastic resource, but I don't envy you the task. The Bugatti took 4000 hours to complete and has around 3000 components. Anyone care to hazard a guess at how many components Concorde contained?Shanewhite, define "components"....
If you count every rivet, every bolt, every resistor in the electronics... you'l easily get to a few million....
I don't think YearoftheTiger is going to quite that level of detail.

CJ

[Shanewhite]

One would hope not! I suppose you just have to make a decision about what sort of level of detail to co to. Brilliant idea though, if it's feasible.

[CliveL]

Year of the Tiger

I don't envy you your self imposed task, you will I'm afraid find it quite difficult to get any detailed drawings as they were long ago buried in the archives of two now non-existent companies - Sud Aviation and British Aircraft Corporation.

The best source of overall structure drawings I have seen is that on the HeritageConcorde.com site. which also gives some explanations of the structural concepts. The Haynes Concorde Owners Workshop Manual also has some interesting data. One problem is that the loading conditions on the various bits of the wing varied so much and the whole thing was so finely optimised for weight saving that there are many different structural concepts used.

You (and others here) may find a 1999 lecture given by Dudley Collard (a much respected Concorde design engineer) of interest. You can find it at www.svfw.ch/Archiv/ConcordeDev.pdf (http://www.svfw.ch/Archiv/ConcordeDev.pdf)

Felicitations!

[YearoftheTiger]

Year of the Tiger

I don't envy you your self imposed task, you will I'm afraid find it quite difficult to get any detailed drawings as they were long ago buried in the archives of two now non-existent companies - Sud Aviation and British Aircraft Corporation.

The best source of overall structure drawings I have seen is that on the HeritageConcorde.com site. which also gives some explanations of the structural concepts. The Haynes Concorde Owners Workshop Manual also has some interesting data. One problem is that the loading conditions on the various bits of the wing varied so much and the whole thing was so finely optimised for weight saving that there are many different structural concepts used.

You (and others here) may find a 1999 lecture given by Dudley Collard (a much respected Concorde design engineer) of interest. You can find it at www.svfw.ch/Archiv/ConcordeDev.pdf (http://www.svfw.ch/Archiv/ConcordeDev.pdf)

Felicitations!

I agree with all of you. It's a very very difficult challenge, but I figured I might merge two things I enjoy very much: studying airplanes and being creative.

The modeling in it self isn't difficult, I've been doing it for many years. To me, proportions and correct dimensions are more important than detail, so the real challenge is finding drawings that show major structural components accurately.

As for the detail, ideally I'd love to capture it all, but that is impossible. In my experience helping friends who were studying Industrial Design in college, once you have the correct proportions down for the main components, you can continue adding smaller and smaller parts / details later on with relative ease as information on them become available. Whereas building the smallest detail and working up is a very bad way to start.

Thank you all for your support. I'll keep reporting back as I make progress. Hopefully I haven't come across too crazy (but a little bit is OK and probably a given).

[Shanewhite]

Not crazy at all. If it's in any way feasible, it's a brilliant project. Best of luck, and keep us posted!

[ChristiaanJ]

YearoftheTiger,
Good sources of detailed drawings are the 'IPC' (illustrated Parts Catalogue) and the 'SRM' (Structural Repair Manual).
Originals (paper) are rarer than the proverbial rocking horse poo.... but they also exist on CDs. Those occasionally pop up on the well-known auction site, but maybe some of the readers here have them and would be willing to make you a copy.

Also see my PM.
CJ

[lasernigel]

Someone I know said he flew Miami to Washington and then on to London on Concorde. He said the turn around time at Washington was only 30 mins. The leg from Miami to Washington was partially supersonic. This seems to be hard to believe, as I know it takes the best part of an hour to refuel a 747. Surely topping off the tanks on Concorde would take more than 30 mins????

[kwateow]

This says 20 minutes. I can't verify it.

Concorde Refueling Operations « Heritage Concorde (http://heritageconcorde.com/?page_id=6728)

[Shanewhite]

There's a lot of info on Heritage Concorde that would be useful to Year Of The Tiger as well, come to that.

Heritage Concorde (http://heritageconcorde.com/)

[ChristiaanJ]

Surely topping off the tanks on Concorde would take more than 30 mins????
MIA-IAD is less than a 1000 nm hop, so the question is really "was the fuel cheaper in Miami, so they tanked up there and only topped up in Washington?" (unlikely, flying fuel around is a waste of money in most cases).

Otherwise, the max fuel on Concorde is listed as 26,400 gallons (Imp), so if you feel like it, you can do the sums with the figures quoted on the Heritage Concorde site.

[kwateow]

I don't remember it being stated that Concorde was designed to have a 'rapid pit stop' capability, but those refuelling speeds seem to bear it out.

Do you know of anything to support this?

[johnjosh43]

I had a guy on a tour at MAN last week who asked a question - what were the differences between the BA Concordes and the French ones ?

Broadening it out a bit this was touched on earlier in the thread with the APU for Iran discussion and a bit about AF & AG being slightly different.

Is there a definitive list anywhere of what each of the airlines wanted ?

[EXWOK]

Just thought I'd drop by and see what was happening on this thread........

My best personal experience of a quick t/round was a tech stop at SMA which we turned around in 45mins. Fuelling was taking place for about 30 of that. AF used to tech stop SMA on the way to GIG, I believe, so the station had some Conc experience.

As for the differences between AF and BA a/c I think most have been dealt with before. AG stood out in BA as a partly 'French' hull; the stuff noticed by pilots was generally:

NiCd main batts, with slight differences to the DC system (no SSB I recall).
No ability for flt crew to 'steal' pax O2.
Perspex flip up visual level on the glareshield instead of open metal construction. Sounds trivial, but I hated it!
No annunciation of DTG to next INS WPT on HSI unless in NAV mode (or was it TRUE?)
Undercarriage monitor not fitted.
Different audio select panels - get this: 6 a/c in the fleet you pushed for TX and pulled for intercom.....AG.......the other way round. Genius.
Probably a lot of other stuff under the skin that I've forgotten.

Allegedly this was representative of the AF fit (certainly as far as the batts/DC) but I can't say for sure. Obviously the cabin fits were very different and over the years the two airlines will have carried out different non-mandatory mods (e.g. the infamous 'cowcatcher' mod).

OAF was a standard BA machine, except that being younger it (like OAG) didn't have the 'crown area' mods done.

All from memory, usual health warnings apply......

[nomorecatering]

Just watched the documentary on the life and demise of the Concorde. The pride of everyone who was involved is clearly evident.

It's brought me to tears.

[doxeee]

The rear tank on Concorde needed to be full at take off for trim purposes.
As speed increased fuel was transfered forward to the main tanks as fuel was burnt. If you are interested in the complete fuel management for trim I will be happy to oblige.

[Bellerophon]

doxeee

...The rear tank on Concorde needed to be full at take off for trim purposes....

No, it didn't, and it wasn't.


...As speed increased fuel was transfered forward to the main tanks...

No, it wasn't. As speed increased fuel was in fact moved rearwards into tank 11.


...if you are interested in the complete fuel management for trim...

I am, but, with respect, either your source of information is incorrect or you have misunderstood it.

[CliveL]

Last time I logged in someone was asking why the Vmo/Mmo was the way it was, but it seems to have disappeared along with Bellerophon's suggestion that someone else might be able to throw some light on it. This might help.

SORRY - senior moment - this should have been posted on another thread! http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/embarass.gif
http://i1080.photobucket.com/albums/j326/clivel1/ProductionVmo.jpg

To be honest I can't remember exactly why 530 kts was chosen for the supersonic Vmo, but it was probably the best climb speed.
Mmo/Tmo was limited by a combination of intake and structural temperature.
The 'cut-off' in the sloping/530 kts boundary was, if I remember correctly, to avoid a minor aeroelastic problem at the Vd/Md condition one arrived at from that corner.
The variation of Vmo with weight was a device which, when associated with the CG corridor, allowed the aircraft to meet the manoeuvre requirements when flying on half hydraulics.
400 kts CAS gave 0.93M at around 28000 ft if I recall correctly, which was just below drag rise and gave optimum subsonic cruise performance

[Stuck_in_an_ATR]

Not sure on which thread to post this :), but great thanks to both Bellerophon and CliveL on sharing their knowlegoe of the Concorde :ok:

[TomTTom]

Hi Guys,
first, thank you for this wonderful thread!!!

AFAIK, the FDR of Concorde hasn't been discussed here yet.
What are it's capabilities, i.e. parameters logged, speed, capacity, etc. ?
Where is it located?
Did it survive the Paris crash? If so, did the investigators get useful data from it?

Thanks much in advance.

[markredgwell]

The FDR is Located in Racks at the Rear of Concorde"s Rear cabin near the emergancy doors.

Which also contain other Boxes such as the Radio Tran-ceivers, ADF receivers and Intake Computers among them which are all coverd over and out of site!

They did survive the Paris Crash from memmory.

[TomTTom]

Is there a list of parameters captured by the FDR?

[TomTTom]

In the ITVV documentary, the SFE Roger Bricknell mentioned the selection of debow of #3 engine upon startup on the JFK to LHR leg, due to the downtime of the engine. This essentially delays the heat-up of the turbine shaft in favor of a more evenly temperature distribution.

Why wasn't the debow selected for all the other engine? (Roger explicitly mentioned to not needing to select the other engines for debow)

Forgive me, I'm probably missing something that was mentioned earlier in this great thread.

[TomTTom]

Since I am a fan of checklist, can anybody make a copy of the checklists available?

SFO Les calls out "Flight Control Inverters On" in his C/L. What are these?

Thanks much in advance.

[gordonroxburgh]

OAF was a standard BA machine, except that being younger it (like OAG) didn't have the 'crown area' mods done


OAF was indeed a true BA aircraft, it title was bought for £1000 and 10,000FF, but significant sums ( million+) were then spent to deliver it to the BA spec. BA did fund and purchase it as their 6th Concorde, albeit at a greatly reduced price.

OAG sort of fell into BA's use. They had "bought" it for under £100,000k, with a must sell back clause , before OAF was delivered to give their services resilience while OAC whet back to Filton for repair. During its use it suffered contamination of its hyd systems, so was grounded, before this was repaired the Concrde programme all but shut down and BA held onto the aircraft fully registering it as OAG, initially it had been G-BFKW.

OAG flew for a short while but was eventually grounded, as I understand it mainly for spares recovery, but as it was a million miles aware spec with from the other BA ( cabin was even different) it was a easy choice to make.

When BA acquired all the spares and full access to G-BBDG a decision was made to bring OAG as close to BA spec as possible and be the first to have a new interior on the fleet. OAG was then then launch Concorde in the land our livery and a lot OAF was a standard BA machine, except that being younger it (like OAG) didn't have the 'crown area' mods done the air to air shots from this time are of it in 1985.


Crown area mods...were these not mandated and embodied fleet wide at the 12,000 major?

[gordonroxburgh]

The flight control inverters were the 26v AC power supplies for the flying controls working (from memory) at 1500hz rather than the normal 400hz.

There are people on here far more qualified, but i believe using the much higher frequency all but ruled out interference from any other aircraft system for the control signalling to the flight control surfaces

[ChristiaanJ]

The flight control inverters were the 26V AC power supplies for the flying controls working (from memory) at 1500Hz rather than the normal 400Hz.
There are people on here far more qualified, but i believe using the much higher frequency all but ruled out interference from any other aircraft system for the control signalling to the flight control surfaces
Gordon is right: the flight control inverters converted the 28V DC aircraft supply to the 26V AC 1800Hz that supplied the flying controls.
And the 1800Hz was chosen because it's halfway between the 4th and 5th harmonic of 400Hz, so yes, it minimised interference of the 400Hz main AC supply in the flying control system.

[TomTTom]

Thanks Gordon and CJ,

Is this 26V @ 1.8kHz system used anywhere else in the industry?
How many Inverters and with what redundancy where on Concorde?

[markredgwell]

This has info on the FDR and Accident!

It is Gordons website!

CONCORDE SST : Accident Report (http://www.concordesst.com/accident/englishreport/11.html)

[Shanewhite]

Several times I've seen mention of the cockpit crown mods. What were these, and what was the reason for them? Were they applied to all the airframes?

[m.Berger]

Many thanks for this thread. Thank heavens Concorde didn't have an APU otherwise I wouldnt have had the pleasure of reading it.
I was at school in Basingstoke when Concorde first attended the Farnborough air show. Maths lessons were constantly interrupted by the third floor windows filling up with a very noisy aeroplane flying over at high alpha and wheels down. After the third circuit, the teacher (an Australian,) shouted at us that we'd seen your BXXXdy aeroplane now get back to work. Phillistine!
I never saw one flying without looking up in reverent awe and I cannot recall a time when anybody else wasn't doing so.
Came the day that I woke up to hear the sad news on the morning radio of the retirement. I emailed my comment and it was read out on the Today programme. Looking on the 'net at work at the other comments there was a small window telling me that BA were offering celebration flights. 1,000 tickets at £2,000 a go.
I'd just bought a house and my meagre savings were needed for a bathroom, hot water and some further essentials. I held out until tea break and dialled There were three tickets left. Make that two, please. I booked the first flight I could get in case something went wrong and the project was canned early.
Paying was another matter. All my money was in France and the BA desk at Southampton wouldn't take my cheque so I transferred money to my British account and tried it again. "There must be some mistake" said the nice lady at the desk. "This booking ref is coming up very expensive. I'm going to see if I can get it cheaper."
"Please don't." I replied.
"But you don't understand, This flight is VERY expensive. "I know." The people behind me were becoming disgruntled.
"I just don't get it. What class are you travelling?"
"Concorde."
The people behind me suddenly backed off.
I had a good trip out, my first trip on a 747. Ask for a Whiskey and get a nice little bottle of Johnny Walker.
I had a better trip back. Ask for a Whiskey and get enough eighteen year old Glenfiddich to drown a small child.
The experience changed my life. The only thrill that could get anywhere near it would be to pilot an aircraft myself. I now have about eight hours solo. It doesn't compare. Being SLF on Alpha Golf was the thrill of a lifetime and I have never regretted a penny of it.
To those contributors who worked on the programme in any capacity, Thank you for the enormous priviledge of being able to experience such a fine and beautiful thing.
Having rambled on for far too long already, I'll just recall a line from Radio 4's Week Ending: "Following a question in the House, the minister admitted that Concorde made more noise than the Bay City Rollers but pointed out that it was of far better quality."

[Shaggy Sheep Driver]

There's a question (OK, 2) I wonder if those on here can answer.

1) I undertsnd that skin temperature is calculated from OAT and Mach number. Why wasn't it simply measured directly by sensors on the nose skin?

2) The Air Data Computer calculates Mach (so skin temp is a calculation on a calculation!). Presumably one parameter it uses is IAS. What else is used in the calculation of Mach?

[EXWOK]

1) Effectively it was (not the skin, but the TAT probe. The highest temp rise would be at the stagnation point so one can be confident that TAT is a realistic answer for max skin temp).

2) AFAIK pretty standard:

Q from pitots
S from statics
T from temp probe

Modified by ADC for position error. It's possible that ADC used beta inputs and I'm sure it used alpha inputs to achieve this.

[asc12]

The exhibit at the Seattle Museum of Flight (Alpha Golf, I think) has the story of the flight engineer who placed his cap in what's called "the expansion joint."

But I can't figure out how the "expansion joint" got itself closed when the airplane was cold, and open when the airplane was hot. Seems backwards to me.

In my mind, the cool airplane has smaller parts, and therefore larger gaps in the joints.

What am I missing?

(I shudder to ask this question, since I have the tingle on the back of my neck that usually tells me I'm missing something simple.)

[TopBunk]

In my mind, the cool airplane has smaller parts, and therefore larger gaps in the joints.


Sort of .... the aircraft expanded when at Mach 2, so it grew in length etc. This growth translated itself into the gap that the hat was put in. When it cooled on decel/descent, the gap closed wedging in the hat.

Simples...

[EXWOK]

Yep that's it.

Imagine it this way - the outside of the hull is hot and expands. The floor and other interior components, however, are about 100 degs cooler and so not subject to the same expansion. In a very simplified description, if you imagine the floor on rollers but attached at one end then you'll see a gap at the other end when the exterior hull stretches. That's the effect you see when the expansion gap appears aft of the FE's panel in supersonic flight. (The floor is, by the way, not just sitting on rollers.....)

Electrical looms had a little sag between fixed points if they were attached to 'expanding' parts of the airframe.

And so on.

It's amazing there was ever any hydraulic fluid left on board if you consider the stresses and aggro involved in routing the pipes and hoses.

[Shaggy Sheep Driver]

1) Effectively it was (not the skin, but the TAT probe. The highest temp rise would be at the stagnation point so one can be confident that TAT is a realistic answer for max skin temp).

2) AFAIK pretty standard:

Q from pitots
S from statics
T from temp probe

Modified by ADC for position error. It's possible that ADC used beta inputs and I'm sure it used alpha inputs to achieve this.

Thanks Ex Wok but now I'm even more confused!

1) So there is a direct temp reading, from the TAT probe. But where is TAT probe? Is it in the needle nose probe that also measures pitot/static for the intake computers? And how many TAT sensors are there (failure of a single one if that's all there is would not be good)?

2) Mach comes from dynamic pressure (pitots), from static ports, and from temp. But what temp? OAT perhaps?

[Shanewhite]

Several times I've seen mention of the cockpit crown mods. What were these, and what was the reason for them? Were they applied to all the airframes?

This seems to have got lost at the bottom of the last page. Any answers?

[CliveL]

http://i1080.photobucket.com/albums/j326/clivel1/Picture16.jpg

SSD:- this answers your question on where the TAT probes were located. Strictly, you don't need temperature to calculate Mach as it is independent of temperature when expressed in EAS (or CAS) terms.

Shane:
The "crown modifications" were external straps to be applied to the upper part of the fuselage to extend its life in those areas which had been designed to safe life concepts - basically the Aerospatiale bits since BAe designed their bits according to damage tolerance rules. It wasn't a small job, but I'm afraid I can't tell you how many aircraft were modified.

[Shaggy Sheep Driver]

Thanks Clive but I'm still going around in circles. Those sensors measure OAT do they not? They are spaced out from the (hot) skin to do that, presumably.

Can you confirm just how that tells the crew the skin temp? Are there no direct-reading temp sensors on or under the nose skin or in the probe?

[CliveL]

So far as I know, they were standard TAT measurement instruments, so they gave Total Air Temperature directly.

There was, so far as I recall, no measure of skin temperature - the aircraft limit (Tmo) was simply based on a measured TAT of 400 degK. The implied limits on skin temperature at various points were built into the design cases.

[EXWOK]

No part of the skin will be warmer than the TAT probe, if that helps......

[Shaggy Sheep Driver]

Here's the cockpit temp gauge I photgraphed today:

http://i18.photobucket.com/albums/b132/GZK6NK/TAT1.jpg

So the TAT probe provides TAT (obviously) which effectively is skin temp (as evidenced by the TMO legend of 127C just below the TAT window?).

(TAT being static air temp plus the temp due adiabatic heating).

[stilton]

For some reason I seem to remember a picture of a Concorde Cockpit with four INS sets side by side, was this ever the case or just my imagination ?


Also, were the INS installed specially developed for Concorde or were they the same as fitted in the B747 for example.


Finally was GPS updating to the INS position ever developed and installed ?

[CliveL]

http://i1080.photobucket.com/albums/j326/clivel1/SkinTemps.jpg

Not exactly skin temperature, just the maximum temperature on the nose. The rest of the aircraft was cooler.

[Shaggy Sheep Driver]

http://i1080.photobucket.com/albums/.../SkinTemps.jpg

Not exactly skin temperature, just the maximum temperature on the nose. The rest of the aircraft was cooler.

Indeed, but as a pilot you look after the nose temp... and the rest of the aeroplane will be just fine.

So TAT is skin temp at the probes, which are rearward of the hottest skin according to that diagram. Was there a 'compensation' built into the TAT readout to account for the relatively rearward position of the TAT probes?

And.. How was static temp readout derived?

Sorry to keep asking, but I really want to understand this!

Thanks.

[CliveL]

So TAT is skin temp at the probes, which are rearward of the hottest skin according to that diagram. Was there a 'compensation' built into the TAT readout to account for the relatively rearward position of the TAT probes?

And.. How was static temp readout derived?


Er - no, the TAT probes measure just what they say Total Air Temperature.

They are mounted off the skin and in freestream, so they measure the same temperature as would a probe on the nose.

Somewhere near the nose (not exactly on it, as the aircraft flies with a small AoA) there will be a 'stagnation' streamline where the oncoming air is brought to rest. At this point the skin temperature will be equal to the stagnation temperature (TAT). Behind that it gets more complicated! The skin temperature would depend on SAT, local Mach No, local skin friction coefficient (Mach and Re dependent, so varies with distance from nose), amount of heat radiated into space (paint colour!) and the amount of structure available to conduct heat away from the skin into the fuel (so roughly varying with thickness/chord and fuel distribution perhaps?

Static temperature and total temperature are related by a simple expression:

TAT = SAT *(1+0.2m^2) all in deg K

So in the troposphere at ISA +5 and Mach 2, SAT = 222 and TAT = 400.

[gordonroxburgh]

For some reason I seem to remember a picture of a Concorde Cockpit with four INS sets side by side, was this ever the case or just my imagination ?

G-AXDN and G-BBDG in the UK have the 3 INS controllers across the front of the pedestal under the primary engineer gauges. I can only suggest that this was dow to the Pilots being the navigators and the engineer being the engineer. Once in Airline service ensuring each crew member has an INS control panel greatly speeded up the checks. Of note 001/002 actually had a navigator in the cockpit behind the Captain, rather than the jump seat.

Also, were the INS installed specially developed for Concorde or were they the same as fitted in the B747 for example.

Standard spec INS systems for that time. Someone may have more information, but they were upgraded over time to having very little memory requiring load from a data card, to having memory for the core routes the aircraft flew in the system permanently, but still only 10 Waypoints could be loaded live at any one time.


Finally was GPS updating to the INS position ever developed and installed ?

GPS would been a complete replacement for an INS. The clever thing the INS system could do was use DME updating to refine their position when in range of a ground station....a bit like how your smart phone can work out your location by cell mast triangulation if it does not have a GPS receiver in it.

Very relevant for the current time: it was a similar INS system that was hashed into the Vulcan to allow it to find the falklands for the blackbuck raids.

[ExSp33db1rd]

Just watched the documentary on the life and demise of the Concorde. The pride of everyone who was involved is clearly evident.

It's brought me to tears.

Me too, knew most of the Brit. characters, too.

(Only recently shown downundda )

[77]

GPS would been a complete replacement for an INS. The clever thing the INS system could do was use DME updating to refine their position when in range of a ground station.

747-400 used GPS to update INS as well as DME when within range. Not a replacement.
At least the ones I was familiar with.

[gordonroxburgh]

..a bit like the space shuttle evolved to using GPS in addition to the tried and tested systems. Very interesting.

[Shaggy Sheep Driver]

Er - no, the TAT probes measure just what they say Total Air Temperature.

They are mounted off the skin and in freestream, so they measure the same temperature as would a probe on the nose.

Somewhere near the nose (not exactly on it, as the aircraft flies with a small AoA) there will be a 'stagnation' streamline where the oncoming air is brought to rest. At this point the skin temperature will be equal to the stagnation temperature (TAT). Behind that it gets more complicated! The skin temperature would depend on SAT, local Mach No, local skin friction coefficient (Mach and Re dependent, so varies with distance from nose), amount of heat radiated into space (paint colour!) and the amount of structure available to conduct heat away from the skin into the fuel (so roughly varying with thickness/chord and fuel distribution perhaps?


OK, so the skin temperature at the stagnation point will be equal to TAT. This can be taken as the hottest part of the aircraft (behind it, the skin temperature will be less than the TAT).

The temperature shown in the top window of the flight deck gauge is TAT, with the legend 'TMO 128C' beneath it. So the aircraft was flown with reference to TAT, and provided TAT was no greater than 128C then the skin rearward of the stagnation point would be <128C?

[stilton]

All modern jet transports still use INS, it's output is used for more than just navigation, e.g. Attitude indicator, vertical speed input and others.


GPS (and other sources) merely update and refine the INS position.


I am sure Concorde would have done the same.

[EXWOK]

Shaggy Sheep Driver:


Yes!

:ok:

[Shaggy Sheep Driver]

Thanks EXWOK! :ok:

[EXWOK]

Minor correction, though: TMO was 127, not 128.

[Shaggy Sheep Driver]

Indeed. Typed in a hurry. Didn't even check my own photo of the temp gauge which clearly shows 'TMO 127C'.

[jcjeant]

Hi,

Concorde creator passed ...
Le Figaro - International : Le Concorde orphelin de son crateur (http://www.lefigaro.fr/international/2012/05/07/01003-20120507ARTFIG00753-le-concorde-orphelin-de-son-createur.php)
Google Traduction (http://translate.google.be/translate?sl=fr&tl=en&js=n&prev=_t&hl=fr&ie=UTF-8&layout=2&eotf=1&u=http%3A%2F%2Fwww.lefigaro.fr%2Finternational%2F2012%2F05%2 F07%2F01003-20120507ARTFIG00753-le-concorde-orphelin-de-son-createur.php&act=url)

[CliveL]

Oh dear that is sad news.
Henri was one of my favourite Frenchmen. Not only was he a very fine engineer but also a very nice guy.
Maybe stretching it a bit to describe him as the creator of Concorde, but he was certainly one of the principal midwives on the French side.

[MTomm]

Hi,


I have an operational question regarding flight crews and aircraft. For routes between Europe and NYC, did crews fly roundtrip flights each day? Or would they layover before returning?

[EXWOK]

Layover: BA001 landed as BA002 was taxying out, so a there and back was impossible with those timings.

In the days of BA001,2,3&4 operations it was possible to operate BA002 JFK-LHR then BA003 LHR-JFK and this occasionally happened if there was a sudden crew shortage or other disruption.

I did it once and it was a heavy day's work.......

[M2dude]

OK, so the skin temperature at the stagnation point will be equal to TAT. This can be taken as the hottest part of the aircraft (behind it, the skin temperature will be less than the TAT).

The temperature shown in the top window of the flight deck gauge is TAT, with the legend 'TMO 128C' beneath it. So the aircraft was flown with reference to TAT, and provided TAT was no greater than 128C then the skin rearward of the stagnation point would be <128C? TAT varies with the square of Mach Number and SAT, and although all temperatures for calculation purposes are obviously ABSOLUTE temperature, they are 'converted back' to °C here. So shown below are a range of TATs shown at four different Mach numbers and three specific SATs (or OAT if you prefer). Altitudes can be assumed as being in the lower stratosphere (ie. above tropopause) and ISA relates to International Standard Atmosphere. ISA is of course -56.25°C, ISA -5 is -61.25°C and ISA +5 is -51.25°C.

MACH 0.5.ISA -5: TAT = -50.6°C. ISA: TAT = -45.3°C. ISA +5 TAT = -40°C
MACH 1.0. ISA -5: TAT = -18.5°C. ISA: TAT = -12.5°C. ISA +5 TAT = -6.5°C
MACH 1.5. ISA -5: TAT = 34.8°C. ISA: TAT = 42°C. ISA +5 TAT = 49.3°C
MACH 2.0. ISA -5: TAT = 109.5°C. ISA: TAT =118.6°C. ISA +5 TAT = 127.6°C

Hopefully it all makes a little more sense with some 'real' numbers. You can see that as Mach Number increases the gap between SAT and TAT increases hugely. The Mach 2, ISA +5 case was particularly significant for Concorde, as it breached the 127°C/400°K airframe temperature limit (TMO) and Mach Number would therefore be automatically reduced by the autopilot. (An overspeed warning would be generated at TMO +7 (134.°C). Fortunately sustained ISA +5 or above conditions were relatively rare over the North Atlantic but not unheard of either.

[M2dude]

stilton
All modern jet transports still use INS, it's output is used for more than just navigation, e.g. Attitude indicator, vertical speed input and others.


GPS (and other sources) merely update and refine the INS position.


I am sure Concorde would have done the same.


Actually not technically correct mate. The generation(s) of aircraft after Concorde does not use INS as such at all. They either use an Inertial REFERENCE System (IRS) or an Air Data and Inertial Reference System (ADIRS). In both cases inertial data, such as attitude, present position, heading (both true and SYNTHESISED magnetic) acceleration data etc. are output to various user systems. (eg. FMS, EFIS, Autopilot etc.). Wind data, being a function of True Air Speed (TAS) and Ground Speed (G/S)requires in the IRS case TAS data to be input into the IRS from an Air Data Compter, whereas in the ADIRS case we can have muliple ADCs/IRUs effectively crammed into one box, and so wind is kept 'in house'. In either case the autopilot steering signals (LNAV/VNAV) come from the FMS and NOT the IRS. (If you like you could say that an INS knows where it is and where it wants to go, where an IRS just knows where it is and hasn't a CLUEwhere it's going to. In all cases GPS data is fed into the FMS itself, as 'just another input'.
Although Concorde HAD no GPS, (The most difficult part was always finding a part of the upper fuselage where chunks could be cut out for locating antennae) it was coming! EGPWS was being mandated, which required a simplex GPS antenna mount, and GPS updating for the INS was being seriously looked at. In the first case, the EGPWS requires accurate present position to check agaings it's terrain database for known obstacles and the latter case was because the Concorde INS navigational accuracy fell outside of future (now actually) long range navigational accuracy requirements.
Sorry for such a long winded blurb, but I've been away for a while and am gradually looking back over our wonderful thread to see if there is anything I can contribute to/prattle on about.

[stilton]

Agreed and well said, my point was and is that an Inertial source, whatever form that may take is still an invaluable input even these days.


The previous poster had insinuated that a GPS installation in the Concorde would have completely replaced the existing INS fit.


Not that simple.

[M2dude]

Humble apologies stilton. (A definate case of RTFQ then). You are quite correct in your comment, inertial position is still the 'prime' source of navigation, in modern aircraft with GPS etc being used to refine this position. GPS can never on it's own replace an INS/IRS, in fact at the moment it's difficult to imagine what ever could. (And after all an aeroplane is not an aeroplane without ATTITUDE :p).

Best Regards
Dude :O

[stilton]

No apology necessary whatsoever, you brought a more accurate and refined aspect to the conversation.


Despite the advent of GPS , in my humble opinion having three independent inertial sources on board that function perfectly well without any updating from any source is invaluable.

[notfred]

Saw the obituary for Sir James Hamilton with heavy emphasis on the design of Concorde's wing, thought others here might be interested:
Sir James Hamilton - Telegraph (http://www.telegraph.co.uk/news/obituaries/technology-obituaries/9295956/Sir-James-Hamilton.html)

[Shaggy Sheep Driver]

Did Roy Chadwick really contribute to delta wing design? I though Kutchmann and his team did most of the ground work developing the basic delta (as fitted to Chadwick's Vulcan) into the thin narrow delta with vortex lift.

[CliveL]

Well AFAIK, the basic delta concept was devised by Lippisch in Germany, and developed there during WWII.
It would be true to say that Chadwick was one of the first outside Germany to use it, but that was essentially with a rounded leading edge, which is a very different animal from the slender delta with a sharp leading edges to deliberately produce strong vortices which give non-linear lift at high AoA.
That concept was definitely the brainchild of Kuchemann and his team (mostly fellow Germans :D) at RAE Farnborough.

[Gnato]

Welcome everyone. I am new to this forum and thread but must confess that I have read all the pages of this amazing topic. I am an aviation enthusiast flying on different planes in FS9. One of them is SSTSIM Concorde. My question concerns engine rating modes in general with Concorde in mind.

AFAIK (and this is a perfect time and place to fix my knowledge) engine rating modes on ordinary turbofan engine are:

- TO- dictated by safety - full power in order to get obstacle clearence/ GA
- CLB - cut down in power for engine prolonged life, but still high to get to fuel efficient altitude ASAP
- CRS - for economic and long, stable flight

Concorde is not an airplane, so things look quite different, huh?;)
We have a pair of switches, one is take off - flight, second climb- cruise, so we have:

1. Take off with TO and CLB
2. Climb with FLT and CLB
3. Cruise with FLT and CRS
4. Descent with FLT and CLB
5. Approach with TO and CLB

Can somebody explain, what really engine rating modes change in the work of the engine, why we have CLB again for descent (when they work close to idle) and why there are two systems overlapping?
I don't need strict numbers, just general idea confronted with ordinary planes. Thank you in advance.

Dan

[Shanewhite]

I just watched a video of Concorde turning onto a runway prior to takeoff. The turn was sufficiently sharp for the aircraft to be virtually rotating around the main gear. This is the equivalent of a vehicle the size of a small truck being dragged around in a circle whilst at the same time carrying a load of around 90 tonnes. Howcome it didn't screw the main gear straight out of the wing?

[fyrefli]

As others have done before, I'd like to add my thanks to the many contributors who continue to make this such an engrossing thread :)

As I look to my left, on the wall is a framed, fading, roughly A2 photo of three of these fabulous aircraft, outside the hanger at Filton in the mid-seventies - presented to my grandfather, who worked there on Concorde production. When I was about ten years old, I was lucky enough to be taken by him on a tour of the works, and can remember being allowed to have a good look around the inside of the aeroplane.

The photo that hangs next to it was taken a few years ago by my bestest flying buddy, Alex, as we thermalled out together over the Brecon Beacons, sitting in bucket seats, suspended, by looms of kevlar, from large, sailcloth kites...

Not too difficult to see where my own inspiration for flying came from :)

[NHerby]

Wow!!! What a wonderfully interesting, gripping, riveting thread. It took me about one week to read it entirely and that was quite fantastic; so thanks a lot to all the main contributors (I'm sure everybody knows who I'm talking about):Dhttp://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/thumbs.gif:D.
Unfortunately, I never had the opportunity to take a ride on the beauty but I really felt in awe of her as soon I as I sarted to look at her more closely. This plane is a lot more than just a plane; to my eyes, it is simply one of (if not THE) the biggest achievment of mankind so far and something that inspires wonderment and sadness at the same time, a huge step forward in aviation history that sadly ended up in a huge step backward. I had a look at the video of the final concorde going out of Filton in 1979 posted earlier in this thread (BBC - Bristol - The story of the final Concorde (http://news.bbc.co.uk/local/bristol/hi/people_and_places/history/newsid_7989000/7989702.stm)) and keep in mind the faces of the 2 guys looking at the production line starting to be demolished... Heartbreaking!

Of course, I have many questions to ask to the experts here so let's just start with a serie of questions regarding the birth of the beast:
The 1962 treaty talks about an equal share of work and expenditure between Fr and UK... That sounds very political and not very realistic! A more pragmatic way would have been to take the best each country had to offer. But, in the end, was the share really fair for everybody? Did this treaty lead to some redundancies in terms of R&D or manpower and to an increase of the total cost of the project?
Also, was there really a technical need to build 6 a/c before the entry in service?
I ould really appreciate if one the living concorde bible in this thread give me an answer and, BTW, keep this thread alive.

[CliveL]

NHerby
The 1962 treaty talks about an equal share of work and expenditure between Fr and UK... That sounds very political and not very realistic! A more pragmatic way would have been to take the best each country had to offer. But, in the end, was the share really fair for everybody?

WOW! Talk about asking the 64000$ question up front!

It would take a book to answer your questions properly. Luckily someone has already written it - try to get hold of Ken Owen's "Concorde New Shape in the Sky" ISBN 0 7106 0268 5. It is an excellent account of the genesis and development of the machine that drove my life for 25 years.

You are right - it was a political agreement, but politics after all the art of agreeing what is possible, and we are talking of the UK and France of the 1950s. No way that either of those two proud countries was going to let the other have the lion's share of the kudos and fun of developing and flying the world's first supersonic airliner. Fun? yes, exciting, challenging, exhausting but definitely fun.:) and no way it was going to be other than an equal split.

But one can easily argue that it was arranged so that each country contributed the best it had to offer. The actual split was 50/50 on total costs, but arranged so that the UK had 60% of powerplant and 40% airframe. At the time, France had nothing to compare with the Olympus as an engine suitable for supersonic cruise, so that was logical. Out of our 40% on airframe we had responsibility for the intake and for powerplant/airframe integration. But when it came down to brass tacks Onera had a more flexible intake design than anything we Brits had to offer, and later in the project the "TRA" nozzle also came from France. We can take a lot of credit for melding these into a very successful powerplant, but I think it fair to say that each country did, in fact, contribute the best it had to offer.

As for fair shares for all, well all I can say is that there was more than enough work to go around ;)

[john_tullamarine]

No point asking Clive .. he's an aerodynamicist and, hence, only talks in slugs/cubic foot.

[CliveL]

No point asking Clive .. he's an aerodynamicist and, hence, only talks in slugs/cubic foot.

:ouch:

That's because of my age not my profession - real aerodynamicists get around all that by using non-dimensional quantities like CL and Cd.:D

IIRC, the drawings were dimensioned in both units, but all threads etc were metric. Dude would know that better than I though. There was never any real difficulty with it.

[NHerby]

Thanks a lot for this answer.
try to get hold of Ken Owen's "Concorde New Shape in the Sky" ISBN 0 7106 0268 5. It is an excellent account of the genesis and development of the machine that drove my life for 25 years.Added to my list, just below the "The Wind Beneath my Wings" by John Hutchinson.
we are talking of the UK and France of the 1950s. No way that either of those two proud countries was going to let the other have the lion's share of the kudos and fun of developing and flying the world's first supersonic airliner.That makes me bounce back to the last question of my previous post. Just regarding the 2 prototypes, since they were built simultanuously, I assume that, from a technical point of view, they were identical. And I assume also that the reason to build 2 identical prototypes was mainly to respect this principle of fair and equal share between the 2 countries; am I right?

[CliveL]

And I assume also that the reason to build 2 identical prototypes was mainly to respect this principle of fair and equal share between the 2 countries; am I right?

To use a well known French technical response: "Oui, mais..."

Partly out of equal shares, but there was also more flight test development work than could be handled by just one aircraft in a reasonable timescale, and each partner had their own sphere of responsibility to cover so if you have to have two airframes it made some sense to have one each.

[ozaggie]

Ummm....... Dunno! Just wanted to keep the thread on the front page, I guess?

[Ranger One]

Four engine flameout is a very unlikely event, unless one runs into a volcanic cloud.

GF

Hah.

I'm pretty sure my memory isn't betraying me too far when I say I seem to remember a case, in the dim and distant past, of a management pilot (no less) taking a Concorde sector and... mismanaging things... badly. In fact they came so close to a four engine flameout (with no volcanic cloud in sight) that the thing was unable to be disembarked after landing for... CoG reasons... if you take my meaning!

Someone confirm?

R1

[gordonroxburgh]

The 2 prototypes weren't prototypes in today's meaning of the word, they were essentially experimental supersonic passenger aircraft, in mid 1960s when their design was frozen a lot of work needed to be done before you had a mature SST.

The next 2 per-production were nearer today what we would call prototypes for a design, much much closer to the final spec of systems and design.

The 2 first production aircraft, after re work and re certification could have been sold on to operators should the market have been there.

The pre production set could have been dropped in many peoples view, but due to the way the design was maturing the EIS would have been delayed a few years, and there was simply a requirement to allow the next stage of testing to move on.

Very much like the NASA moon programme, they could have taken a delay and flown more apollo missions and completely dropped Gemni, but at that point in time they needed to be flying to get the data.

[gordonroxburgh]

Ranger one, the fuel incident has been discussed on here

[Shanewhite]

I have a query about the thrust of Concorde's engines. The quoted static thrust of the Olympus 593 is 32,000lb, but it has been frequently stated that in supercruise, the majority of the thrust was provided by the intakes. That being so, how much thrust was actually produced overall at Mach 2, and how was this measured (if indeed it ever was)?

[TURIN]

Already discussed on this thread Shane.

Try a search.....;)

[garylovesbeer]

Just received my copy of "Concorde New Shape in the Sky".

Ex library copy.

Big stamp on Contents page saying "Smithsonian Libraries"! :ok: Score!

Looking forward to a nice, long read!

Thanks for stoking the addiction everyone here.

-Gary

[NHerby]

Partly out of equal shares, but there was also more flight test development work than could be handled by just one aircraft in a reasonable timescale, and each partner had their own sphere of responsibility to cover so if you have to have two airframes it made some sense to have one each.Thanks again CliveL

A few pages earlier on this thread some of you have posted some of their favourite photos of Concorde. Here are very sad, chocking and rare photos:
http://maripa.free.fr/photos/ccd/ccd-3.jpghttp://maripa.free.fr/photos/ccd/ccd-2.jpg
This is 211 (F-BVFD) after "Air France's special treatment" (shame on them). The photos were taken in 1994. More photos of this can be seen here: Maripa : Documentation photographique. (http://maripa.free.fr/photos/ccd/ccd.htm)

To compensate, here's one of my favourite:

http://le.pointu.free.fr/historique/large/historique_1_41.jpg
Most of those photos were taken at Toulouse (we saw a lot from Filton in this thread but very few from France). The caption of the top left picture says it is 102 (F-WTSA) and 201 (F-WTSB) in the background. The image comes from a french website (Concorde dans la presse de 1965 à 2003 (http://le.pointu.free.fr/index.php)) gathering hundreds of articles about Concorde. Very interesting but in French only.
I particulary like this last serie of photos because it shows the process of a dream turning into reality, the beginning of such a beautiful adventure and the symbol of a time where national pride and technical achievment had more importance and value than the basic investment/profitability ratio that rules the world today! And now, more than 40 years later, not only we are not able to build a SST but we are also not able to make a SST flying again.
And this leads to a new question (maybe another 64000$ one):
As we can see in those photos and as I have seen in photos from Filton, several pre-production and production airframes were built at the same time. Did the fabrication of pre-production or production a/c had to be stopped at some point to wait for in flight test results? Similar question: did the early flights revealed unforseen problems that needed to be sorted out before the program can move on?

[CliveL]

Did the fabrication of pre-production or production a/c had to be stopped at some point to wait for in flight test results? Similar question: did the early flights revealed unforseen problems that needed to be sorted out before the program can move on?

Can't say I remember the production line being stopped to wait for flight results, but then the production rate wasn't that spectacular anyway and most of the changes (not all of them) came from wind tunnel and design developments.

All flight tests reveal unforeseen problems! This could result in a pause in the prototype/pre-production flight test programme whilst the test aircraft was being modified, but this didn't delay build of later vesrions.

[Gnato]

This is a repost, but I'm not sure if the question was missed by people with knowledge, or ignored, so I put it up again.

Welcome everyone. I am new to this forum and thread but must confess that I have read all the pages of this amazing topic. I am an aviation enthusiast flying on different planes in FS9. One of them is SSTSIM Concorde. My question concerns engine rating modes in general with Concorde in mind.

AFAIK (and this is a perfect time and place to fix my knowledge) engine rating modes on ordinary turbofan engine are:

- TO- dictated by safety - full power in order to get obstacle clearence/ GA
- CLB - cut down in power for engine prolonged life, but still high to get to fuel efficient altitude ASAP
- CRS - for economic and long, stable flight

Concorde is not an airplane, so things look quite different, huh?
We have a pair of switches, one is take off - flight, second climb- cruise, so we have:

1. Take off with TO and CLB
2. Climb with FLT and CLB
3. Cruise with FLT and CRS
4. Descent with FLT and CLB
5. Approach with TO and CLB

Can somebody explain, what really engine rating modes change in the work of the engine, why we have CLB again for descent (when they work close to idle) and why there are two systems overlapping?
I don't need strict numbers, just general idea confronted with ordinary planes. Thank you in advance.

Dan

[phil@LFPG]

the best thread ever on the net and so polite.

all those technicals and in deep infos.

i never flown myself the Concorde but my dad made one CDG DKR RIO and one CDG JFK and as others mention he was smiling back from those flights even the flights were for work.

i had the chance to see the Concorde at night in the AF maintenance at CDG it was called Airbus-Concorde division and despite i was more on the other side : the 747 division i loved to stay around and just watching that wonderful Bird waiting to fly the next morning.

alas when moving to Canada we lost all the pictures and souvenirs of those days but they re back with you.

thank you Lady and Gentlemen.

and Bravo, merci.

[booforty]

Wow, what an amazing thread which I have only recently found.

Congratulations to all for a fascinating read :D

Although I never got the opportunity to fly on Concorde, I will never forget seeing her fly some charters from Filton in the late 1990's. On one occasion I was stood at the wire fence at the end of runway 27 and watched Concorde taxi directly towards me, do a 360 degree turn and line up for takeoff. Concorde was only around 100ft-150ft away from me when the throttles were opened. Luckily I was holding tightly onto the fence and got a face full of dust as the reheats kicked in! :eek: The noise, power and heat I felt from those Olympus engines was phenomenal. She looked stunning as she rotated amongst the heat haze and the slender delta climbed steeply away towards the Bristol Channel. What an aircraft!

My grandfather worked on the Olympus 593 engines at Rolls Royce in Filton, so I will always hold Concorde close to my heart. I have been onboard Foxy at Filton when she was open to the public and I have visited 002 at Yeovilton and 101 at Duxford. I live quite close to Delta Golf at Brooklands and have been onboard her about 4 times now (including a sit in the cockpit) and recently flew the fantastic Concorde simulator with Captain John Eames and First Officer Ian Smith which is a day I will treasure. Opening up the throttles for take-off on 31L at JFK and tackling the checkerboard landing at Kai Tak were experiences I will never forget.

Keep up the great postings everyone! :ok:

[LTCTerry]

I am on page 49 of this amazing thread about an incredible aircraft. I have spent many "unproductive" hours at my desk – when I should be defending the free world – reading here.

I must say, this is an incredibly brilliant (in the US sense of "intellect" rather than the British "cool/great") people. The history; the technology; and, most importantly, the people here make this a thread beyond compare – more alive than any book on the topic could hope to be.

Sometime, roughly ~1987?, I was driving from Norfolk, Virginia, to Washington, DC. As I drove by the Wilmington, Delaware, airport I saw an unusual looking tail rising above a building. I thought, "That looks like Concorde, but she wouldn't be here. Several seconds later the building no longer blocked my view, and it was indeed Concorde!

I had previously seen the a/c on display at the Musee de l'air in Paris and have since seen the one in Sinsheim, Germany. Wilmington, though, was the only time I actually saw one in service.

Long into, now to my question:

A few pages back I read about "left rudder" on takeoff because "engine number four was at 88% thrust." I understand the need for rudder based on asymmetric thrust, but why was the thrust asymmetric in the first place?

I need to push on through the next 40 pages to get the answer to my question! :)

[Bellerophon]

LTCTerry

...but why was the thrust asymmetric in the first place?...

Allow me to direct you to my colleague M2dude's answer here (http://www.pprune.org/tech-log/423988-concorde-question-4.html#post5887403).

[CliveL]

Just a slight correction to Dude's explanation - the vortices came off the intake sidewall not the wing LE. Otherwise spot on.

[CliveL]

Brian,

I don't think there is any published explanation, but maybe this will help.

Basically the problem with #4 intake was that it was on the RHS of the airplane. We are talking about low speed right? and especially zero forward speed when the engine is trying to suck as much air as it can get from wherever it can get it. That means that the induced angle of attack on all the intake leading edges is going to be high.

The best drawing I can find that shows the flow into the right hand pair is this
http://i1080.photobucket.com/albums/j326/clivel1/Concorde-modified-intakewkg.jpg

The intake leading edges were all sharp, so the flow would separate if subjected to a high AoA. The upper lip was protected a little by the wing leading edge, and we were obliged to modify the prototype LE ahead of the intakes to prevent underwing vortices developing at low AoA in cruise which also helped a bit.

The lower lip had a substantial separated flow 'bubble' at low forward speed as shown in red, but this cleared up quite quickly as the aircraft gathered speed. It was'cured' by the blow-in doors.

The inner sidewalls were shielded by the landing gear doors, so the AoAs on the sidewall on that side were quite modest.

The splitter was of course subject to equal flow demands on either side so the flow over that was pretty well symmetric.

That leaves the two outer sidewalls which, look for all the world like highly swept delta wings with sharp LEs mounted vertically.

Like all such wings when operated at high AoA they develop powerful vortices on the 'leeward' side. Looking back towards the engine the vortex on #4 engine was anticlockwise and that on #1 was clockwise. [Hope I got that one the right way round ;)]

The OL593 rotates clockwise looking aft so the induced incremental AoA on the compressor blades was different on #1 and #4. The difference was enough to trigger some mild blade vibration - hence the rpm restriction until the intake capture was good enough to reduce the vortex strength.

[stilton]

Just finished the Haynes 'Concorde workshop manual'


This is a collaboration between a retired Concorde Captain and Flight Engineer.


The one excerpt that really caught my eye was the reference to the method of construction and differences between the British and French built Aircraft.


'The French fuselage was designed to safe life principles while the British was designed to fail safe. From window line to window line across the top of the fuselage Bristol used three skin panels overlapping at 10 o'clock and 2 o'clock while Toulouse used two, overlapping at 12 o'clock'



This revelation was a big surprise to me, for a production run of 14 airframes two different construction methods were employed apparently, amazing.


I had always thought the airframes were virtually identical.


Anyone have any further insight on this ?

[The late XV105]

Earlier this week I had the great pleasure of a late afternoon followed by a full day at the Sinsheim technical museum near Heidelberg. Highly recommended and much more than just a museum; just ask my children what they thought of the helter-skelter from elevated Ilyushin IL-18 back down to the ground, or the twisting and turning stainless steel tubular slide from museum roof mounted DC3, through a hole in the roof, and back to the ground level entrance! The staff I encountered were all friendly and informed and I now look forwards to a day at the sister museum in Speyer - replete with 747-200 on the roof on which visitors can walk the wing.

Anyway, of relevance to this thread I thought I'd shared some of my photos of Concorde F-BVFB and Tupolev TU-144 77112. It was tremendous to be able to walk backwards and forwards between the two, directly comparing design features and relative elegance of execution. Both are achievements for mankind but I have to say that to me not being an aeronautical engineer, Concorde won every time - dreary Air France cabin notwithstanding - with the larger Tupolev coming over as somewhat clumsy; let alone knowing engine technologies to be a world apart, just compare the wheel bogies as one example, and then the cleanliness of wing design as another. Yes, the Tupolev canards were a novel feature, but I understand they were only necessary in the first place because of lower speed control issues as a result of more basic aerodynamics.

Like any aircraft on static display exposed to the elements both airframes could do with some TLC, but here are the photos:

http://i1062.photobucket.com/albums/t493/PPRUNE64/Sinsheim/IMG_120827151313.jpg

http://i1062.photobucket.com/albums/t493/PPRUNE64/Sinsheim/IMG_120827154149.jpg

http://i1062.photobucket.com/albums/t493/PPRUNE64/Sinsheim/IMG_120827155237.jpg

http://i1062.photobucket.com/albums/t493/PPRUNE64/Sinsheim/IMG_120827155141.jpg

http://i1062.photobucket.com/albums/t493/PPRUNE64/Sinsheim/IMG_120828085327.jpg

Concorde aft cabin door
http://i1062.photobucket.com/albums/t493/PPRUNE64/Sinsheim/IMG_120828081934.jpg

TU-144 aft cabin door
http://i1062.photobucket.com/albums/t493/PPRUNE64/Sinsheim/IMG_120828084402.jpg

http://i1062.photobucket.com/albums/t493/PPRUNE64/Sinsheim/IMG_120827154334.jpg

http://i1062.photobucket.com/albums/t493/PPRUNE64/Sinsheim/IMG_120828084341.jpg

http://i1062.photobucket.com/albums/t493/PPRUNE64/Sinsheim/IMG_120827155028.jpg

http://i1062.photobucket.com/albums/t493/PPRUNE64/Sinsheim/IMG_120827155819.jpg

TU-144 No 4 engine location viewed from exhaust towards inlet (and directly in to the sun!)
http://i1062.photobucket.com/albums/t493/PPRUNE64/Sinsheim/IMG_120828084257.jpg

http://i1062.photobucket.com/albums/t493/PPRUNE64/Sinsheim/IMG_120828085833.jpg

http://i1062.photobucket.com/albums/t493/PPRUNE64/Sinsheim/IMG_120828085718.jpg

To be continued in separate post as I have hit the photo count ceiling in this one.

[The late XV105]

...and the second post to conclude the photos and ask a question:

Concorde cockpit (through hazy perspex screen)
http://i1062.photobucket.com/albums/t493/PPRUNE64/Sinsheim/IMG_120827154610.jpg

TU-144 cockpit (also through hazy perspex screen)
http://i1062.photobucket.com/albums/t493/PPRUNE64/Sinsheim/IMG_120827155448.jpg

A sign that made me chuckle
http://i1062.photobucket.com/albums/t493/PPRUNE64/Sinsheim/IMG_120828084546.jpg

http://i1062.photobucket.com/albums/t493/PPRUNE64/Sinsheim/IMG_120828094144.jpg

http://i1062.photobucket.com/albums/t493/PPRUNE64/Sinsheim/IMG_120828094336.jpg

http://i1062.photobucket.com/albums/t493/PPRUNE64/Sinsheim/IMG_120828094423.jpg


I hope that these pictures were of interest and can spark some further discussion in this amazing thread. If I can have the temerity to start the ball rolling with a TU-144 question, I was intrigued to notice the following tiny vane situated on the fuselage base between engines 2 and 3. Closer inspection revealed an adjacent hole, perhaps indicating pressure measurement? Anyway, ideas or proven fact welcome!

As observed
http://i1062.photobucket.com/albums/t493/PPRUNE64/Sinsheim/IMG_120828085601.jpg

Cropped
http://i1062.photobucket.com/albums/t493/PPRUNE64/Sinsheim/IMG_120828085604.jpg

[Pugilistic Animus]

Look at that wx radar..funny all this new computing technology nowadays just to go slower and slower...happy this thread has been revived...:ok:

[TURIN]

I think the TU144 needs an entirely new thread. Oooh questions questions....:D

[BN2A]

Best book ever:-

Amazon.com: Soviet SST: The Techno-Politics Of The Tupolev-144 (9780517566015): Howard Moon: Books

:ok:

PS - Other web based retailers are available....

[CliveL]

@ Stilton
I had always thought the airframes were virtually identical.


They were. Just that all the UK manufactured subassemblies had three skin panels and the French bits two. Made no difference when they were mated up - the stringers matched and the skins were simply riveted to the frames.

@ The Late XV105

Pure speculation - a drain hole with some sort of guide to deflect the fluid away from some other part?

[John Farley]

The late XV105

Yes, the Tupolev canards were a novel feature, but I understand they were only necessary in the first place because of lower speed control issues as a result of more basic aerodynamics.

Dunno about the source of your info on this but it may have got a bit garbled in the telling.

With a plain slender delta on the approach the trailing edge control surfaces will be slightly up and as speed is reduced this angle will increase slightly. If you want to raise the nose in the flare then even more stick back will be needed. This gives - if you like - a wing with a negative flap angle and so rather less lift needing a higher speed than you miught wish.

If you add some canards to give a big nose up force then to trim the aircraft the trailing edge surfaces will all be down a bit - giving a flapped delta with considerable benefit in terms of reduced approach speed.

The Tu144 with canards was able to land on the display runway at Le Bourget and take the second turn off right to the aircraft park - a quite remarkable demonstration of its modest speed on finals.

[CliveL]

I entirely agree with John Farley's comments. We were planning to fit canards on the second generation SST for exactly those reasons - they also gave a slightly better L/D in take-off climb which was useful for noise abatement, but they only just earned their keep in terms of economics!

[The late XV105]

Thank you, Mr Farley! Nicely explained, and although at odds with an article I read a very long time ago, your words make perfect and easily-understood sense. :ok:

[stilton]

Clive,


While not disputing what you are saying about the construction why was the French method described as 'safe life' and the British 'fail safe ? '


It sounds significantly different.

[CliveL]

@stilton

I can't give you much detail I'm afraid - as JT said a few posts ago:

No point asking Clive .. he's an aerodynamicist and, hence, only talks in slugs/cubic foot.

Basically the differences lie in the fine details of the structure. To quote from a Googled article:
Safe-life refers to the philosophy that the component or system is designed to not fail within a certain, defined period. It is assumed that testing and analysis can provide an adequate estimate for the expected lifetime of the component or system. At the end of this expected life, the part is removed from service.

whereas:
Fail-safe designs are designs that incorporate various techniques to mitigate losses due to system or component failures. The design assumption is that failure will eventually occur but when it does the device, system or process will fail in a safe manner.


On the UK parts there were detailed features such as crack-stoppers and multiple load paths whereas the French design relied on analysis and testing to establish where and when any failures might be expected to occur. The consequence was that the ultimate life of the airframe was dictated by the number of thermal fatigue cycles accumulated in the Farnborough major fatigue facility divided by the factor of safety demanded by the airworthiness authorities which was conservative because one was really into unknown territory.

[john_tullamarine]

as JT said a few posts ago

.. I really shouldn't be as cheeky as I tend to be at times ...

[stilton]

I realize it's all academic now Clive but the two philosophies do sound significantly different.


Just for the sake of argument if the two fleets were still operating surely BA's would be approved for a longer life with the fail safe method of construction ?

[Landroger]

I am not in any position to offer an answer to your question XV105, but may I offer a 'speculation'? I would hazard that the projection you highlight might be a Radio Altimeter aperture? It looks like a casting or even a forging and far too fancy for a drain. It seems to me the surface in which the aperture is 'machined', would be pretty much horizontal in the landing configuration and thus offer accurate height of the centre of gravity perhaps? Given that the cockpit would be many feet above that, it makes sense.

Errr..... I'll get me coat. :O

[CliveL]

.. I really shouldn't be as cheeky as I tend to be at times ... John, you should know that engineers live their lives in an atmosphere of mutual jovial insult :D

[CliveL]

Just for the sake of argument if the two fleets were still operating surely BA's would be approved for a longer life with the fail safe method of construction ?

No, the aircraft in each fleet were structurally identical. Every aircraft was built with front and rear fuselages made in the UK and central fuselages and wings made in France. Only the final assemblies were specific to each country.

[CliveL]

Don't know much about radio altimeters. First thoughts were that it was some sort of vortex generator, but seems a funny place to have one. Second thoughts were that the 'vane' standing off the surface was there to generate some sort of suction (the 'hole' seems to be on the leeward side) to make sure that the inside did drain in all conditions.

[Landroger]

I know exactly what you mean Clive and ordinarily I would agree with someone with vastly greater knowledge and experience, but it just looks too.........'classy' for a drain. The aperture is a rounded rectangle, very wave guide in nature and that vane is beautifully made, whatever it was made of. The only thing is, I'm a bit concerned the aperture is not covered in some way.

Somebody, somewhere must know what it is and now I'm fascinated. :)

[john_tullamarine]

engineers live their lives in an atmosphere of mutual jovial insult

Indeed, good sir. Having been exposed throughout a lifetime to various disciplines, including aerodynamics (djpil and I shared adjoining desks under AW's watchful glare in an earlier life at the Bend), I invariably upset various parties from time to time when I line select and execute the wrong set of social mores for the company in question.

Oh well, it's been anything but a boring life.

[johnjosh43]

One of the guys on the Save the TU144 Facebook page says that the thing in that picture on the TU144 is connected to the Air Conditioning.

There is also a TU144 website now. Format donated by Gordons ConcordeSST

TU-144 SST - Flying Forever on the Internet (http://www.tu144sst.com/index.html)

[blind pew]

hi guys, thanks for a very informative thread.
In the mid 70s I lived in a thatch cottage 31nm west of LHR at the bottom of a hill in the Thames valley.
One particularly grotty dark autumn evening our cottage started shaking, I rushed out into the dark expecting to see a car crash but realised it was a low flying aircraft. (I wasn't a stranger to low aircraft noise as we were in the Greenham Common circuit and the F111 had been based here when Upper Heyford was resurfaced).
I later read that droop snoop had an engine go into reverse in cruise.
The subsequent report in the horror comic was of it's following take off when it happened again on rotate.
What I remembered was some sort of award to engines or probably the whole crew and that she didn't get above three thou until crossing the Bristol coast.
questions...
Was it a simple electrical failure?
Was there any protection to stop it happening again?
Was there a significant speed loss when it happened?
Was there a problem with the adjacent engine?
Flying questions.
What was the engine out climb procedure?
Was there another double engine failure procedure as on the iron duck with immediate fuel dumping?
Was it just a coincidence that the flight was routed outside of CAS but along the Thames valley avoiding the high ground to the north and Membury mast?
Thanks
sorry if it has already been covered but have only got through to page 50...

[The late XV105]

One of the guys on the Save the TU144 Facebook page says that the thing in that picture on the TU144 is connected to the Air Conditioning.

There is also a TU144 website now. Format donated by Gordons ConcordeSST

Thanks for following up my question, johnjosh43, and also for posting the TU144 link; I shall take a gander tonight. :)

[blind pew]

Green bean
Remember the Heros well, one of the pleasures of JFK especially having grown up on spam.....

Sonic booms
Experienced the trials in the sixties over East Anglia, one rogue one over Berkshire in the 70s, three or four from the French concorde whilst sailing across the channel and latterly annual ones from the French airforce.
The Concorde ones seemed much louder and frightening - first time I thought we had hit a mine (wouldn't be the first time although fortunately it didn't explode).
And contrary to a previous opinion they did do damage - odd window and a vase.

[peter kent]

First I would like to agree with others on the priceless content of this Concorde forum. The published books are gems in their own right but always leave more questions than could ever be answered without all your input.

Whilst looking for some engineering background on the intake flow I came across this paper which goes into some detail

https://docs.google.com/viewer?a=v&q=cache:S7xqHOIH7MAJ:ftp.rta.nato.int/public//PubFullText/RTO/EN/RTO-EN-AVT-185///EN-AVT-185-05.pdf+ramjet+intakes+t+cain&hl=en&gl=ca&pid=bl&srcid=ADGEESjLh09LMnYAHUUFF3Ulme1sLqOisHGz6HNtrf9D7kqqlAjS-Nz-RF5eI3YsXrGYmQaFrzeCcLffUsUARhAIHQC67RdBp2AnpxaXpNlTiMQmRVfI 78f0m9sXJsZVOVTHS0ptzpOV&sig=AHIEtbToC68nlhVrqXb070XxfUcy8PWNyw

The author says for example "..pressure recovery at Mach2 was 95%, with 1% of the loss attributed to subsonic diffusion,0.5% to the 1st shock,, 0.02% to the 2nd and 3.7% to the 3rd and final oblique shock."

I was looking for mention of a normal shock as I always understood that was a prerequisite for finally getting to subsonic.

A normal shock is only mentioned in connection with an alternative design with a lengthened forward ramp.

So, was there one or not? Or is it just not that simple?

Thanks.

[CliveL]

How about this:

http://i1080.photobucket.com/albums/j326/clivel1/Image19.jpg

In normal operation (centre picture), the flow in the upper half of the intake was supersonic with a normal shock as required to decelerate to subsonic conditions. In the lower half the flow was decelerated to just sonic by the cowl shock. If the engine demand increased the region of supersonic flow got bigger until it nearly filled the intake (right hand picture).

The small reversed "D" zone just below the bleed slot is the supersonic region. The bleed flow entered the bleed aft of the normal shock.

[peter kent]

Thanks for the pictures which I will try to absorb.
In the centre picture it looks like the cowl shock is the 3rd oblique shock mentioned in the paper.
As you have said, the region below the reversed "D" is subsonic and there appears to be no plane shock as I understand it, so I'm still a bit mystified.
Maybe I should give up on this very complex subject.

[CliveL]

@ peter kent

As you say, a complex subject!

Maybe the missing link is that a plane shock is not the only way to decelerate through Mach 1.0. If the nose of a body is blunt, or if the angle you are trying to turn the flow through is too big then the shock wave becomes detached from the leading edge of the body. The bit of the shock on the 'cusp' is then actually a very strong plane (normal) shock and the flow immediately behind that part is subsonic. In the case of a sharp surface with a large tuning angle this subsonic flow allows air to escape from the high pressure side of the surface to the low pressure side. This would be the case for example if the flow onto the leading edge of an intake hit it at too big an angle.

Supersonic intakes come in two basic guises - external compression and internal compression. The ramjet intakes you have been reading about are the latter type in which all the deceleration/compression takes place inside the intake. In these designs the final compression is through a normal shock situated at the minimum area 'throat' of the intake where the flow is close to Mach 1.0. This flow is delicately balanced and if some engine disturbance causes the shock to move into the converging supersonic bit of the intake the whole shock system can be expelled giving all sorts of problems (inlet unstart). Generally they are used for high Mach numbers where their higher theoretical efficiency and low external/spillage drag count for more than the additional control system complexity and performance requirements.

In external compression intakes (a simple pitot intake would be an extreme example), all the compression is done by a system of shock waves that sit outside the intake. These intakes are less efficient than internal compression intakes and they also spill a lot of air which produces external drag. Usually restricted to low supersonic Mach numbers.

Concorde's intake was a "mixed compression" design which had some features of each type. At low engine mass flow demands the flow coming on to the cowl lip could be at too great an angle to maintain attached shock waves so it behaved a bit like that described earlier. You can see this most clearly in the left hand picture where the lower efficiency and higher spillage can be seen in the graph of efficiency against intake capture (epsilon). In this state the intake behaved more like an external compression type and there was no appreciable final normal shock.

At high engine demand the angle of flow hitting the cowl was such that the shock waves remained attached and the intake functioned more like an internal compression design. Again you can see this in the right hand picture which shows most of the intake throat covered by a normal shock and in the graph where total intake flow (engine plus bleed) is constant.

On condition there was a bit of each, but since it was designed to minimise spillage you cannot see the detachment of the cowl lip shock at the scale of the diagram.

Hope this is helpful rather than additionally confusing!

PS: Looking at the centre picture again, it occurs to me that the curved shock running from the lip back and up to the reversed "D" would actually be normal to the approaching local flow which was being turned by the ramps and the isentropic compression. This would be the shock you are looking for to decelerate the flow to subsonic conditions. In other words the intake was functioning as an external compression design over this part.

[peter kent]

ref question from Joliste

why were the Olympus 593 s so smoky to start with, did they use excess fuel to help with cooling as some petrol engines do or was there some design feature which caused the smoke. It seeems to have been cured in later engines
rod

As I was working my way from 1 to 85 I read the above which reminded of a paper I filed 35 years ago:
"Development of Pollution Controls for Rolls-Royce RB211 and Olympus 593 Engines" by A B Wassall. I have picked out stuff relevant to the question:


The engines of the day generated smoke in the primary zone and partially consumed it in the rest of the combustor.
It was easier to reduce the production than increase the consumption but leaning the primary zone had an adverse effect on relight capability which then needed its own corrective action as was done on the 211. Metal temperatures went up with the leaning (as intimated by Joliste)
The 593 did not have the leaning option as it had to maintain an over-rich primary zone at TO to ensure an adequate weak extinction margin when throttled back at completion of supersonic cruise when the combustor had to operate at A/F ratios over 180.
In addition to the smoke problem the combustor weight and pressure loss had to be reduced.
These other two requirements led to the annular combustor and vaporizers which also reduced the smoke substantially. These three benefits were expected based on Pegasus experience.

[taichi40]

Hi all, amazing thread! I hope I can add a couple of autopilot questions:

1. Did anyone ever use the IAS Hold button in the vertical mode, i.e. control speed with pitch instead of autothrottle? I always thought it might be used during climbout to maintain 250 knots under 10000 feet at full throttle.

2. How did the autopilot work in 'Go Around' mode and was it ever used, or were go arounds always done manually?

Thanks in advance,

Jim

[gordonroxburgh]

The IAS hold in the pitch mode as used every flight as it was SOP for a decent.

Alt Hold engaged
Throttle back the engines to an intermediary point.
When speed came back to 350knts engage IAN hold to start the decent all the way at 350knts until a primed new altitude was reached, where the aircaft would level and the Autothrottles would come back into play

For sustained decent at M0.95, Mach hold would be used.

[db737]

I was doing some research for a little project, ran into a dead end.

I have seen the take off data card used by flight crews.

But, I can't seem to locate any images of the landing data card utilized.

So, wanted to ask. Did you have an official landing data card, similiar to the take off data card.

If so, do you perhaps have an image/scan of one? I've looked all over the internet, I can't locate anything.

If it was just written on a notepad then that explains everything.

I have an image of the Landing card used by Air France, just need to try and locate the one used by British Airways if there is/was a card/form. Any insight or help appreciated.

Best,
David

[db737]

Any Concorde crews follow this thread anymore?

Been awhile since any replies. If you have any ideas on above question, would really appreciate the help.

Best,
David

[EXWOK]

From an occasional visitor:

I don't recall using landing data cards.... There may have been a version buried deep somewhere, but we generally just set the limits and did any necessary perf calculations.

Hope that helps.

[db737]

EXWOK, Thank You for taking the time to answer my question.

This will save me some hunt time now.

Best,
David

[Faltahan]

Ladies and Gentlemen,

I would just like to thank the contributors to this thread - it is by far and away the best piece I've ever visited on the internet. Bar none. It has taken me months (and many arguments with a jealous girlfriend!) to get this far - I didn't want to ask any questions which had already been answered.

My experience; never flew on her but when I heard she was being decommissioned, I decided to make every effort to watch a Concorde take off and hang about for the final three consecutive landings at LHR. I have never seen so many grown men cry. I would have counted more but I think I got something in my eye..

As a Chartered Engineer working on a multi-disciplinary rail project, I am amazed that a project as complex as this was managed across the Channel in the 1960's; how was the Systems Engineering managed - who drove the requirements for the Jet, potential carriers, engineers or politicians?

CliveL - your input to this has been amazing - a quick question if I may; you say wind modelling played a big part in the development of the aerodynamics, how big did the models go? Did you have the luxury of testing a full-scale model? or maybe full-scale parts or sub assemblies?

Dude - its my understanding that you worked on the Maintenance Engineering of the jet, many thanks for your thoughtful remarks. Please keep those grey cells going! Was any maintenance every brought forward when it became clear a member of the Royal Family was to fly? How much input did the carriers have in generating the maintenance periodicities for the works? Did these change mid-life? If so, what and why?

ChristiaanJ - I am blown away by just how much cutting-edge (for the time!) kit was provided to get her up. In the railway, we try and steer clear from 'New and Novel' because of the increased assurance risk required. Did the onboard systems required extended testing to assure the authorities? Please forgive my memory, but I seem to recall seeing the test craft have many 'computers' in the passenger areas while testing - what did these record? How did the data support development?

Bellerophon - your post on 18th Dec 2010, 15:20 #875 had me in tears for about 20 minutes - wife to be thought I'd found out someone had died. hhmmmm..

As someone who's hoping to secure their PPL in March / April I found your piece extraordinary - can you confirm rough altitude above aerodrome (AKA QFE for us GA boys?) before instigating the 25° left bank to commence the turn out over Jamaica bay?

A thoroughly enjoyable and often moving read. Thank you all. Like a good book / film I think I'll come to read it from page one before long - who'd have thought missing out the APU would cause such a stir?!

[DRDR]

Thanks from me too for this great thread!

Does anyone remember a Concorde passing a manned balloon? I have seen footage of it and it did not look planned. You can find more details in an old thread:

some years ago: Concorde passes balloon crossing atlantic ocean [Archive] - PPRuNe Forums (http://www.pprune.org/archive/index.php/t-109030.html)

[CliveL]

As a Chartered Engineer working on a multi-disciplinary rail project, I am amazed that a project as complex as this was managed across the Channel in the 1960's; how was the Systems Engineering managed - who drove the requirements for the Jet, potential carriers, engineers or politicians?


For sure not the politicians, who could not distinguish between their rectum and middle arm joint so far as aircraft systems were concerned :D
Once it was decided to go, I would say that the system requirements were largely driven by the difficulty of the task - more a question of finding out how to make it work than of optimising. The overall aircraft requirements were driven by the engineers, but criticised by the potential customer airlines in regular meetings.

Safety requirements were specified in a completely new airworthiness code - a sort of comprehensive set of special conditions, which were generally more severe than the subsonic codes of the time. Concorde, for example, was, AFAIK, the first civil aircraft to be certificated against the requirements that now exist as 25.1309.
But nobody really knew what to write for supersonic flight and, in particular, the transition from subsonic, so to some extent one made it up as one went along, using prudent common sense and engineering judgement. Fuel system transfer rates for example had to match a requirement that it should be possible to abandon the acceleration at any point and return safely to subsonic conditions - and the deceleration was much quicker than the acceleration!

wind modelling played a big part in the development of the aerodynamics, how big did the models go? Did you have the luxury of testing a full-scale model? or maybe full-scale parts or sub assemblies?

Well some people might say we had four full scale models - two prototypes and two pre-production models :) Supersonic testing mainly at 1/30 scale; low speed 1/18. The biggest model was a 1/6 scale half model used mainly for icing tests. Isolated intake tests, IIRC, about 1/10 scale, but we did have a full scale intake operating in front of an Olympus 593 at Mach 2.0 in Cell 4 at NGTE Pyestock.

[toffeez]

I take no credit for this interesting read. Hope it's not copyright.

http://www.svfw.ch/Archiv/ConcordeDev.pdf

My only connection with the bird was as an apprentice to "assist" the gents assembling the cockpit structure. Later on I sat in an office overlooking the fin assembly area, trying to get to grips with its (very particular) performance manual.

[atakacs]

Toffeez: very interesting read ! As concluded by the author a real shame that airframe 19 was never constructed...

[stilton]

Just for theories sake, if there were no noise, speed or boom considerations what would be the optimum profile for Concorde to fly after departure ?



In normal service I understand it had to comply with normal noise abatement departures, speed limits and remain subsonic until far enough from land to prevent the boom being a consideration.


But what if it could accelerate immediately, with no restrictions of any kind ?


I imagine you would stay in afterburner, accelerate to VMO and on to M2 in the climb ? or would airframe heating at lower altitudes prevent this ?



Lastly, was this ever done in testing, or for example leaving Barbados ?

[Slatye]

I suspect that, given the Concorde's rather unusual fuel consumption figures, the most efficient climb profile was also the fastest one, since pretty much anything other than the M2.0 cruise-climb was fairly inefficient. From way back in the thread (here (http://www.pprune.org/tech-log/423988-concorde-question-77.html#post6904411)) the minimum time to hit M1.0 was about six minutes, and M2.0 came at 9 minutes (although a few posts later someone mentions that these figures may be wrong as the fuel transfer rate wouldn't allow such a fast climb).

Some questions from me, after reading through the thread:

- Someone mentioned that, as a result of Concorde's sustained supercruising across the Atlantic, the twenty-odd Concordes have more supersonic flight hours than all other aircraft combined. Does anyone know what the figures are?

- What was the minimum range for supersonic travel to be worthwhile? Obviously if you were only going a few hundred kilometres it'd make more sense to cruise at 29000ft an M0.95 rather than climbing all the way up to 40000ft+ and M2.0.

- What other aircraft are/were more efficient supersonic than subsonic? The modern supercruising fighter jets (eg. the F-22) are still more efficient at subsonic speeds. The original Tu-144 would certainly have been much more efficient subsonic (since it couldn't supercruise); I'm not sure about the later models. The SR-71 was more efficient at high supersonic speeds than at low supersonic speeds, but I can't find anything about subsonic fuel consumption. And that leaves the XB-70, which is just a big unknown.

[fizz57]

@ stilton

see posts 883 and 884 ... december 2010!

[EXWOK]

FALTAHAN -

I can answer just one of your earlier questions - the one about the turn initiation off 31L.

As Bellerophon noted in a distant earlier post, we 'bugged' 20ft on the rad alt for this departure. As one climbed through 20' the DH light would go out and, subject to the gear being selected up, and V2 being achieved (that normally happened at about the point of lift-off), and a definite positive rate being achieved, the turn was initiated then. In deference to the low level we rolled gently, 6secs to achieve 25 degrees, but it's still a great testament to the handling qualities of this machine that we would initiate this turn - in any weather - at a height I'd be most uncomfortable if doing the same thing in a single-engined tourer.

So - in short - forget QFE; the answer is a height of 20ft.

Hope the PPL is coming along well, keep us posted.

[E_S_P]

Like a good book / film I think I'll come to read it from page one before long - who'd have thought missing out the APU would cause such a stir?!

I wonder if they are thinking "if only" on the 787 :}

[E_S_P]

I just had my jaw flop open with EXWOK's post about them begining the turn off 31L at 20ft :eek: and wondered what the typical pitch attitude would have been at that point and troughout the turn?

Many thanks (again) for such a wonderful thread :ok:

[stilton]

It has been a fantastic and extremely enjoyable thread.

[Rolling-Thunderbird]

I'll second that Stilton !

Was lucky enough to catch the Concorde as she came into Schenectady Airport ( now Stratton ANG) on a solid overcast day. We heard her coming long before she popped out of the clouds at about 500 feet, perfectly lined up and ready to land on Runway 4. But she had other ideas, as she went gear up and flew by us at about 100 feet, and then climbed back up into the overcast sky. After circling around the field, the Concorde once again popped out of the clouds at the same exact spot and made a flawless landing.
After a short taxi and shut-down, we were allowed to take a walk-through before the charter flight(s) began. What a day to leave the camera at home...sigh

Recently, while surfing around on You Tube, I came across some footage of the Concorde flying the checkerboard approach into Kai Tak. What a thrill that must have been for the pilots, crew, and passengers.


Does anyone have any more details to share about that particular flight?

[hissinsid]

10 years this year. What a horrible and tragic thought.

[NHerby]

Recently, while surfing around on You Tube, I came across some footage of the Concorde flying the checkerboard approach into Kai Tak. What a thrill that must have been for the pilots, crew, and passengers.

Does anyone have any more details to share about that particular flight?Do you have more infos about this video like the date or the aircraft tail number? Can you give a link to this video? After watching it, I'll probably be able to tell you more.

[NHerby]

For the french speaking (or reading) people here, I just found a mine of very interesting informations about Concorde on this website:
Accueil (http://www.lesvolsdeconcorde.com)
This site has a database of thousand of concorde flights with the following datas: Date and time of the flight, airframe used, technical and commercial crews, guests, departure/arrival airports and flight type (regular, charter world tour...).
On top of that, many infos and stories around Concorde can also be found there.
I can't resist to translate one of those stories (I'm far from being a native english speaker or a professional translator; so forgive me for the misspellings and other translation mistakes). It is a report about one of the biggest incident that happened to the prototype 001 during the flight tests:

Shock of shockwaves
We were flying with Concorde at Mach 2 since 3 month already on both side of the Channel. The prototype 001 did outstrip 002 which was supposed to be the first to reach Mach 2.
Unfortunately, a technical issue delayed 002 and Brian Trubshaw fairly let André Turcat be the first to reach Mach 2 with the 001 which was ready to go.
The flight tests were progressing fast and we were discovering a part of the atmosphere that military aircrafts hardly reached before. With Concorde, we were able to stay there for hours although limited by the huge fuel consumption of the prototypes.
The Olympus engines did not reached their nominal performance yet and, most of the time, we had to turn on the reheat in supersonic cruise to maintain Mach 2.
The reheat is what we call afterburner on military aircrafts. Fuel is injected between the last compressor stage of the low pressure turbine and the first exhaust nozzle. This increases the thrust for the whole engine and its nozzle.
The 4 reheats, one for each engine, are controlled by the piano switches behind the thrust leavers on the center pedestal between the two pilots. Air was fed into the engines through 4 air intakes, one for each engine, attached 2 by 2 to the 2 engine nacelle, one under each wing. The advantage in terms of drag reduction was obvious.
However, tests in wind tunnel showed that, at supersonic speed, if a problem happens on one engine, there was a great chance for the adjacent engine to be affected as well by the shockwave interference from one air intake to the other despite the presence the dividing wall between the two intakes. So we knew that an engine failure at mach 2 would result in the loss of 2 engines on the same side, resulting in a lateral movement leading to a strong sideslip that would likely impact the 2 remaining engines and transform the aircraft into the fastest glider in the world.
This is why an automatic anti sideslip device was developed and installed on the aircrafts.
The air intakes are very sophisticated. At mach 2, it creates a system of shockwaves that slows down the air from 600 m/sec in front of the aircraft to 200 m/sec in front of the engine while maintaining a very good thermodynamic performance. In supersonic cruise, the engines, operating at full capacity all the time, were sensitive to any perturbation and reacted violently with engine surge: the engine refusing the incoming air.
Stopping suddenly a flow of almost 200kg of air per second traveling at 600m/sec causes a few problems. As a result, a spill door was installed under the air intake and automatically opened in such event.
To control the system of shockwaves and obtain an efficiency of 0,96 in compression in the air intake, 2 articulated ramps, controlled by hydraulic jacks, are installed on the top of the air intakes in front of the engines. Each ramp is roughly the size of a big dining room table, and the 2 ramps, mechanically synchronized, move up or down following the instruction of an highly sophisticated computer that adapts the ramp position according to the mach number, the engine rating and other parameters such as skidding.
At that time, it was the less known part of the aircraft, almost only designed through calculation since no simulator, no wind tunnel, did allow a full scale test of the system.
The control of the system was analog and very complex but it was not easy to tune and we were moving ahead with a lot of caution in our test at mach 2.
On the 26th of January 1971, we were doing a nearly routine flight to measure the effect of a new engine setting supposed to enhance the engine efficiency at mach 2. It was a small increase of the rotation speed of the low pressure turbine increasing the air flow and, as a result, the thrust.
The flight test crews now regularly alternate their participation and their position in the cockpit for the pilots.
Today, Gilbert Defer is on the left side, myself on the right side, Michel Rétif is the flight engineer, Claude Durand is the main flight engineer and Jean Conche is the engine flight engineer. With them is an official representative of the flight test centre, Hubert Guyonnet, seated in the cockpit's jump seat, he is in charge of radio testing.
We took off from Toulouse, accelerated to supersonic speed over the Atlantic near Arcachon continuing up to the north west of Ireland.
Two reheats, the 1 and the 3, are left on because the air temperature does not allow to maintain mach 2 without them.
Everything goes fine. During the previous flight, the crew experienced some strong turbulence, quite rare in the stratosphere and warned us about this. No problem was found on the aircraft.
We are on our way back to Toulouse off the coast of Ireland. Our program includes subsonic tests and we have to decelerate.
Gilbert is piloting the aircraft. Michel and the engineers notify us that everything is normal and ready for the deceleration and the descent.
We are at FL500 at mach 2 with an IAS of 530 kt, the maximum dynamic pressure in normal use.
On Concorde, the right hand seat is the place offering the less possibility to operate the systems. But here, we get busy by helping the others to follow the program and the checklists and by manipulating the secondary commands such as the landing gear, the droop nose, the radio navigation, comms, and some essential engine settings apart from the thrust leavers such as the reheat switches.
The normal procedure consists in stopping the reheat before lowering the throttle.
Gilbert asks me to do it. After, he will slowly reduce the throttle to avoid temporary heckler. Note that he did advise us during the training on the air intake to avoid to move the thrust leaver in case of engine surge.
As a safety measure, I shut down the reheat one by one, checking that everything goes fine for each one. Thus I switch off the reheat 1 with the light shock marking the thrust reduction. Then the 3…
Instantly, we are thrown in a crazy situation.
Deafening noise like a canon firing 300 times a minute next to us. Terrible shake. The cockpit, that looked like a submarine with the metallic and totally opaque visor obviously in the upper position, is shaken at a frequency of 5 oscillation a second and a crazy amplitude of about 4 to 5 G. To the point that we cannot see anymore, our eyes not being able to follow the movements.
Gilbert has a test pilot reaction, we have to get out of the maximum kinetic energy zone as fast as possible and to reduce speed immediately. He then moves the throttle to idle without any useless care.
During that time, I try, we all try to answer the question: what is going on? What is the cause of this and what can we do to stop it?
Suspecting an issue with the engines, I try to read the indicators on the centre control panel through the mist of my disturbed vision and in the middle of a rain of electric indicators falling from the roof. We cannot speak to each other through the intercom.
I vaguely see that the engines 3 and 4 seem to run slower than the 2 others, especially the 4. We have to do something. Gilbert is piloting the plane and is already busy. I have a stupid reaction dictated by the idea that I have to do something to stop that, while I can only reach a few commands that may be linked to the problem.
I first try to increase the thrust on number 4 engine. No effect so I reduce frankly and definitively. I desperately look for something to do from my right hand seat with a terrible feeling of being helpless and useless.
Then everything stops as suddenly as it started. How long did it last, 30 seconds, one minute?
By looking at the flight data records afterward, we saw that it only last… 12 seconds!
However, I have the feeling that I had time to think about tons of things, to do a lot of reasoning, assumption and to have searched and searched and searched…! It looked like my brain suddenly switched to a fastest mod of thinking. But, above all, it's the feeling of failure, the fact that I was not able to do anything and that I did not understand anything that remains stuck in my mind forever.
To comfort me, I have to say that nobody among the crew did understand anything either and was able to do anything, apart from Gilbert.
The aircraft slows down and the engine 3 that seemed to have shut down restart thanks to the auto ignition system. But the 4 is off indeed.
Michel makes a check of his instruments. He also notes that the engine 4 has shut down but the 4 air intakes work normally, which makes us feel better. After discussing together, we start to think that we probably faced some stratospheric turbulence of very high intensity, our experience in this altitude range being quite limited at that time. But nobody really believes in this explanation. Finally, at subsonic speed, mach 0.9, with all instruments looking normal, we try to restart engine 4 since we still have a long way to go to fly back to Toulouse.
Michel launches the process to restart the engine. It restarts, remains at a medium rotation speed and shuts down after 20 seconds, leaving us puzzled and a bit worried despite the fact that the instrument indicators are normal.
Gilbert then decide to give up and won't try to restart this engine anymore and Claude leaves his engineer station to have a look in a device installed on the prototype to inspect the landing gear and the engines when needed: an hypo-scope, a kind of periscope going out through the floor and not through the roof.
After a few seconds, we can hear him on the intercom:
"****! (stuttering) we have lost the intake number 4."
He then describes a wide opening in the air intake, the ramp seems to be missing and he can see some structural damages on the nacelle.
Gilbert reacts rapidly by further reducing the speed to limit even more the dynamic pressure.
But we don't know exactly the extent of the damage. Are the wing and the control surfaces damaged? What about engine 3?
We decide to fly back at a speed of 250 kts at a lower altitude and to divert toward Fairford where our british colleagues and the 002 are based. I inform everybody about the problem on the radio and tell them our intentions. However, I add that if no other problems occur, we will try to reach Toulouse since we still have enough fuel.
Flying off Fairford, since nothing unusual happened, we decide to go on toward Toulouse. All the possible diversion airport on the way have been informed by the flight test centre who follows us on their radar.
At low speed, knowing what happened to us and having nothing else to do but to wait for us, time passes slowly, very slowly and we don't talk much, each one of us thinking and trying to understand what happened. However, we keep watching closely after engine 3.
Personally, I remember the funny story of the poor guy who sees his house collapse when he flushes his toilets. I feel in the same situation.
Gilbert makes a precautionary landing since we don't rely much on engine 3 anymore. But everything goes fine.
At the parking, there is a lot of people waiting for us and, as soon as the engines stop, we can see a big rush toward the nacelles of the right hand side engines.
Gilbert and myself are the first to get off the plane and we are welcomed down the stairs by André Turcat and Jean Franchi who came out from the crowd watching at the right hand side nacelle.
They both behave the same way, with a slow pace attitude, the same look, a mix of disbelief and frustration.
André is the first to speak: "I can't believe we were not on this flight, really unlucky…". Yes, this flight was supposed to be just a routine flight…!
The condition of the nacelle is impressive. We come closer and everybody move aside for us with a look of disbelief and respect as if we were hell survivors.
The ramps of the intake 4, those 2 "dining tables", have completely disappeared leaving a hole where we can see the hydraulic jacks and the stub rod where the ramps were attached.
Indeed, only the ramps were missing, apparently ejected forward which was unbelievable knowing how fast we were flying. The ramp slipped under the nacelle causing some damages on it and on the hood of one of the elevon's servo control. Fortunately, the control did not suffer any damage.
What is left of the rear ramp seems to be blocked down inside the intake in front of the engine and we can see behind it the first blades of the compressor, or what is left of it, not much.
The engine swallowed a huge amount of metal but no vital parts of the aircraft has been damaged, no hydraulic leaks, no fuel leaks. I remembered at that time the stories of some B58 Hustler accident where the loss of an engine at mach 2 almost certainly ended with the complete loss of the aircraft. Our Concorde has only been shaken. This incident strengthened the trust I had in this plane. And I was not unhappy to have experienced this ordeal, especially when I saw the frustration on the face of André Turcat and Jean Franchi.
But we had to understand what happened and how; and also why the ramp's fixing broke.
It didn't take much time to get the answers.
I unintentionally triggered the problem when shutting down the reheat of engine 3. The sudden stop of the fuel flow did of course stop the combustion and the back pressure behind the low pressure turbine. But, probably because of the modification made on the engine before the flight, the stop of the reheat has not been followed by the normal closing movement of the primary nozzle to compensate the pressure drop. So the low pressure turbine ran out of control, dragging down the low pressure compressor which reacts by surging.
Despite the opening of the spill door, the engine surge led to a sudden movement of the shockwaves in the air intake creating a surge in the intake itself. A similar surge happened in the adjacent intake 4 followed by a surge of the corresponding engine. This caused an excessive pressure above the ramps and the fixings of the intake 4 did not hold.
Since it was the first time we experienced a surge in the air intake, we had little knowledge of the stress it would create on the ramps. This led to miscalculation of the strength of the ramps's frames and they did brake.
Another mistake: instead of installing the motion detectors on the ramp itself, to make the production easier, they have been placed on the arms of the hydraulic jacks. This is why Michel Rétif thought that the position of the ramps were correct. The hydraulic jacks did not suffer any damage and were still working normally even if the ramps were missing.
All the data recorded during this event helped us in redesigning the air intakes and the flight test program resumed three month later.
After this, we deliberately created dozen and dozen of air intake surge to fine tune the way to regulate them with digital calculator this time.
From now on, even if it was still very impressive, it was safe and their intensity was not comparable with what we experienced with the missing ramps.
However, a french president may kept a lasting memory of this, much later, during a flight back from Saudi Arabia. This time, I was on the left side, Gilbert on the right and Michel was still in the third seat… But that's another story.
For me, the lasting impression of failing and being helpless during this incident made me wonder what a commercial pilot would have done in this situation. This plane was designed to be handled by standard commercial pilots and not only by the flight test pilots.
At that time, I was interested in taking in charge the management of a training center for the pilots of the future Airbus's clients. This event pushed me that way and I made it clear that I wanted to add the flight training on Concorde in this project. This has been agreed and I did it.
And the Concorde training program now covers the air intake surges and how to deal with them.
Jean PINET
Former test pilot
Member and former president of the Air and Space Academy

[peter kent]

I've always seen it mentioned as SNECMA reheat until the other day..

The ORIGINAL design for the reheat was done by SNECMA, but due to them getting into all sorts of trouble with the fuel injection system and flame stabilisation, Rolls-Royce baled them out, and it became a Rolls-Royce/ SNECMA design.
ref heritageconcorde.com

Does anyone have any details on the 'joint' development alluded to above?

Thanks.

[CV880]

Rolling Thunder,
There were quite a lot of Concorde flights to Kai Tak over the years. The first was Air France which was a checker board approach (got out of bed on a damp Sunday morn to watch it arrive). At one time BA had a deal with Cunard where you could fly Concorde to HKG and return on the QE2 or vv so there were regular arrivals in the summer for 2 or 3 years. Normally Concorde was required to take off on 13 presumably for noise reasons. The BA/Cunard flights usually departed around noon. On one occasion I saw a BA Concorde taxiing to the end of 31, so phoned home to tell my wife to go up on the roof as we lived close to the flight path but she was out so missed out on a great sight and a great noise! There may have been other 31 take offs but that was the only one I witnessed.

[PJ2]

CV880;

I was doing Kennedy turns out of Toronto on the DC9 when fortunate enough to not only walk across the ramp (remember those days?), and be welcomed on board Concorde for a short tour of the aircraft but when our turn to taxi/takeoff came, we were next behind Concorde, on 31. The noise was unearthly; we could not speak to be heard. We sat in our DC9, awestruck at the magnificence that was unfolding before us, two very lucky airmen fortunate to watch this wonderful airplane, the sound of the afterburners "filling the windshield", take off and do the left climbing departure. The silence in the cockpit which followed was momentarily deafening!, the meaning of witnessing this airplane slowly coming into awareness. It was the late 70's and I was a young aviator wet behind the ears just starting with my airline; there was nothing merely 'technical' about what we had heard and felt in the belly - one encounters and sees many things in such a career, but the effect of that moment has never been topped.

[Brian Abraham]

You say it better than I PJ2. Was fortunate to be at the Oshkosh show when the aircraft was in attendance and giving flights to those who could afford the price. The big memory was standing at the barrier on the runways edge (insanely close it seemed to the runway) and happened to be standing at the point of rotation. A memory not to be forgotten, nor the noise and visceral vibrations within the body.

[flyboyike]

PJ2 does, in fact, speak well. I presume he meant to say 31L, not just 31. I also like the "left climbing departure". Very professionally spoken.

[DozyWannabe]

@flyboyike - if you haven't read it already, I can heartily recommend post #875 on this thread.

http://www.pprune.org/tech-log/423988-concorde-question-44.html#post6129540

To my eternal regret, I never had a chance to get close to the old girl in her "lifetime", but I'll never forget the day she overflew my Mum's house at what can't have been more than a couple of thousand feet on her way back from Farnborough.

[PJ2]

flyboyike - "31L", yes, thank you for the clarification!

Another 'feature' of the experience, (and those who have seen this phenomenal sight will recall), was the color of the exhaust - a slight 'greenish' tinge to the usual brown-black tint of turbojet exhaust; - it just added to that sense of the 'exotic' of what one was seeing and watching.

There wasn't a single part of our little airplane that wasn't 'in sympathy' with Concorde when the afterburners lit... the only thing I can imagine that takes one's breath as rapidly and involuntarily as that did, is the launch of a Saturn V, or the launch of the Shuttle, even from a distance.

[CliveL]

The ORIGINAL design for the reheat was done by SNECMA, but due to them getting into all sorts of trouble with the fuel injection system and flame stabilisation, Rolls-Royce baled them out, and it became a Rolls-Royce/ SNECMA design.
ref heritageconcorde.com

Does anyone have any details on the 'joint' development alluded to above?

Attended a Powerplant Design Group reunion earlier, so I thought I would try to get an answer from somebody who really knows ....:D

The problem apparently was that flame stabilisation operating in "contingency" rating was sensitive to the point that every engine had to be checked, so there was a lot of engine plus reheat testing, most of which was done at Patchway. The solution was addition of some form of 'spike' at various points on the spray bar (my informant wasn't very specific). It sounded like a sort of vortex generator cum chine that gave the flame somewhere to latch onto. The development process was, as you suggested, a joint activity.

[Chris Scott]

PJ2 reminds us of the way the airframes of other a/c queuing for take-off would resonate as Concorde departed. Whether it was the responsibility of SNECMA or Rolls Royce (or even Bristol Siddeley? ;)), the reheat was certain to set off a random sprinkling of car alarms on the airfield, which used to make my day when lucky enough to be returning to the car park around midday at LHR.

Even without reheat, however, the engine had a distinctly military sound - quite unlike other civil turbojets I can remember. The sound of it in the descent at about 4000ft over my house at 5 pm daily was unmistakeable. On the approach, if you weren't expecting it, it could be quite unnerving. One night in the late 1970s, during a long car journey, I stopped for a call of nature at a well-known public house near Hatton Cross (about a mile from touchdown on LHR 27L). It was pitch dark, and I decided that the hedge at the side of the car park would be a suitable venue. Never having heard Concorde on the approach before, I became increasingly nervous as the sound, initially unidentified, got progressively louder. And then the landing lights were switched on...

[peter kent]

Just out ..

CONCORDE - A Designer's Life by Ted Talbot

I've just found an earlier pprune post educating me on the author

QUOTE]If I may, I would now like to mention the 'some oil lamps and diesel oil' story. This is a true story told to me by Dr Ted Talbot, the father of the Concorde Intake, brilliant aerodynamicist and all round amazing gentleman.[/QUOTE]

Can't wait for it to arrive in my mail box.

[CliveL]

Peter

I've just started reading it, and it's pure Ted (and Ann) :)

Do buy it - it is probably the most amusing (and human) book on Concorde you will ever read. Best seven quids worth I have spent for a long time.

Update: I have now finished it - I couldn't put it down. Definitely autobiographical, but worth buying for the Concorde bits alone. Maybe I'm biased as I share many of his memories. Perhaps UK readers will appreciate the non-Concorde bits more.

[Dont Hang Up]

To my eternal regret, I never had a chance to get close to the old girl in her "lifetime", but I'll never forget the day she overflew my Mum's house at what can't have been more than a couple of thousand feet on her way back from Farnborough.

You can still get up close and personal with G-BOAA at the National Museum of Flight in East Fortune. I know it is a bit out of the way, but if you are ever in that region I can thoroughly recommend a visit. The old girl has her own exhibition hall and looks magnificent.

(The rest of the museum isn't bad either - a good day out).

[NineEighteen]

I wondered if any Concorde flight crew had a favourite airframe and why? I understand Alpha Foxtrot was somewhat lighter than her sisters. Maybe that made for a sportier option?

[Daxon]

BA 2 JFK-LHR 23.08.1992


Could I please ask if someone can tell me which aircraft flew this flight?

The Captain was Stack Butterley. Any other information concerning the other flight deck crew would be gratefully received.

Many thanks in advance.

[tdracer]

Many years ago, I'd flown into Heathrow (after a horrible flight - a 6+ hour delay after pushback at JFK due to weather). I was in line to pick up my rental car when suddenly there was this horrendous noise - a "can't hear yourself think" noise. The strange part was no one else even seemed to notice :confused:. I turned and looked outside, and there was a Concord on it's takeoff run in full afterburner :sad:. It was the only time I was able to see a Concord moving under it's own power :*.

No idea what tail number it is, but there is a Concord at the Seattle Museum of Flight. First time I walked inside I was stunned at how small it was. The windows are tiny, and the seats would not appear out-of-place in economy on todays international flights. The cockpit is blocked off with clear Plexiglas, but looked decidedly primitive by todays (or even 1980's) standards. No doubt the cabin service was top notch, and there is definitely a luxury in making a six hour flight in two hours. But it's also not hard to understand why it wasn't a commercial success :rolleyes:.

But I sure wish I'd had the opportunity to fly on one :E

[ksjc]

G-BOAG lives in Seattle now. And so you know it's Concorde with an " e". Very important.

I flew on G-BOAG, BA 2 JFK- LHR, 6 months before the program was shut down in 2003. The experience is hard to describe and only a Concorde fan would appreciate it anyway.

[tdracer]

And so you know it's Concorde with an " e". Very important.
Sorry, I blame spell check :O

[EXWOK]

The windows are tiny

If you see a prototype, you will note that the cabin windows are bigger; the windows shrank due to a certification requirement. In the course we were informed that, with all four a/c groups working, cabin pressure could be maintained with two windows missing at 60 000'.

cockpit is blocked off with clear Plexiglas, but looked decidedly primitive by todays (or even 1980's) standards

Possibly so, on first glance. In reality it was considerably more sophisticated than its contemporaries (e.g. 747-200), and the systems behind those switches immeasurably more so.

There's not a lot of space for the necessary controls in the front of a pointy aeroplane, and this was done in era when the appearance of the flt deck was inconsequential compared to its efficiency, utility and safety. It's only from the beige cockpit Boeings and onwards that the trend has emerged to for all these swoopy trim panels to be fitted for cosmetic reasons.

As for commercial failure - that may be true for the constructors but I can assure you that there's no way BA would have been flying them if they didn't contribute to the bottom line, let alone invest in the return to service programme.

It always pays to remember the context of operation of this machine when making comparisons with conventional aircraft,as that's what drove much of the design.

[DozyWannabe]

No idea what tail number it is, but there is a Concord at the Seattle Museum of Flight. First time I walked inside I was stunned at how small it was. The windows are tiny, and the seats would not appear out-of-place in economy on todays international flights. The cockpit is blocked off with clear Plexiglas, but looked decidedly primitive by todays (or even 1980's) standards. No doubt the cabin service was top notch, and there is definitely a luxury in making a six hour flight in two hours. But it's also not hard to understand why it wasn't a commercial success...

Following on from what EXWOK was saying, you've got to remember that the spec was hammered out in the late '60s - so it's not surprising that the flight deck could *appear* antiquated by 1980's standards. But in this case, as alluded to, appearances are deceptive. While the gauges and switches are very definitely of that vintage, the systems behind them were very much bleeding-edge technology (by aviation standards) in a contemporary sense. Even when Concorde entered production, the most complex digital displays available to aviation were of the 7-segment LED type (as used in the Apollo Guidance Computer), and they were both wildly expensive and of limited use. The flight and engine controls were in fact a pioneering kind of analogue FBW - way in advance of any other type, even those making their debut at the start of the '80s (though FADEC was becoming more widespread by then - with the advent of the B757 and 767).

Ergonomically speaking, both engineers and pilots of the era write of Concorde's flight deck being the best possible balance of form and function available at the time - sure it looks cluttered to the modern eye, but everything was placed in a logical manner and the sheer number of systems used in the aircraft made the accessibility of all that information a basic requirement. It's worth bearing in mind that even those not particularly well-disposed to Airbus will grudgingly admit that the flight deck ergonomics on those types are extremely good - and a lot of the lessons learned were from cramming all that information into Concorde's limited space.

As for the cabin, again appearances are deceptive - I have sat in one of those seats and they are extremely comfortable for the size. Also one must bear in mind that unlike the subsonic Atlantic crossings, these were happening in about 3 hours - so no need to be particularly wide or convert into a bed like we see in Business and First today - not to mention less chance of a queue for the WC!

I have to thank EXWOK for explaining the windows - but I'll add the more prosaic reason that you don't need a particularly large window to see the curvature of the Earth in all its splendour - which is for the most part all you'd be seeing during the flight!

[EDIT : I should also confirm that EXWOK is also correct in stating that BA had Concorde turning a profit from the early-'80s onward, and it took a combination of a financial downturn and the fallout from the terrorist attacks of September 2001 to end the service.

While Concorde herself never recouped the development money granted by the governments of the UK and France, the infrastructure and R&D her development put in place paved the way for the Airbus project which, as we know, ended up becoming a leading player in airliner design and manufacture in the West. ]

[CliveL]

Dozy

Even when Concorde entered production, the most complex digital displays available to aviation were of the 7-segment LED type (as used in the Apollo Guidance Computer), and they were both wildly expensive and of limited use. Yeah, well when we put a digital computer to generate the AICS laws that was NEW man!



Ergonomically speaking, both engineers and pilots of the era write of Concorde's flight deck being the best possible balance of form and function available at the time - sure it looks cluttered to the modern eye,Again, no digital multifunction displays on offer in those days

It's worth bearing in mind that even those not particularly well-disposed to Airbus will grudgingly admit that the flight deck ergonomics on those types are extremely good - and a lot of the lessons learned were from cramming all that information into Concorde's limited space.Errrr no, I don't think so. Concorde's flight deck was done at Filton and we had no involvement in the Airbus designs in that area.


I have to thank EXWOK for explaining the windows - but I'll add the more prosaic reason that you don't need a particularly large window to see the curvature of the Earth in all its splendour - which is for the most part all you'd be seeing during the flight!Exwok's remark is not quite right IIRC. Certainly the window size was dictated by pressurisation failure, but one couldn't maintain cabin pressure with two windows failed - the design case was to get to a breathable altitude before you killed too many passengers! Also, there is very little to see when you have a delta wing under you.

While Concorde herself never recouped the development money granted by the governments of the UK and France, the infrastructure and R&D her development put in place paved the way for the Airbus project Ummm - most participants reckoned that the Concorde infrastructure showed the way not to do it, and besides the early Airbuses were developed in parallel with the later stages of Concorde development. You have a point where R&D is concerned though - several technologies developed for Concorde found their way onto the subsonic fleet, not the least being the probability approach to system certification.

[DozyWannabe]

Hey Clive - nice to see you!

Errrr no, I don't think so. Concorde's flight deck was done at Filton and we had no involvement in the Airbus designs in that area.

I was thinking more "indirectly" - in general UK/Euro flight deck layouts were more in line with improving ergonomics than those on the other side of the pond for a long time. Later work may not have been done at Filton as Concorde's was, but the Airbus folk would have been foolish in the extreme not to use the fundamental principles as a basis for that work!

Ummm - most participants reckoned that the Concorde infrastructure showed the way not to do it.

Hence the catch-all term "paved the way" - whereby lessons in how not to do it are as useful as those which were a positive example!

[tdracer]

BA was able to make money on Concorde as in positive cash flow. But they were basically given the airplanes. The commercial failure aspect comes from the simple fact that no one wanted them to build any more (what I've heard is that at least one production Concorde was built but never put into service - basically becoming a donor for spares - not sure if that's true). I also suspect it was too much of a point design - it didn't have the range to be useful in the Pacific.

If BA (and Air France) honestly thought Concorde was a profit center (rather than brand prestige), they would have wanted more :ouch:.

BTW, my comments about the flight deck were not intended as criticism - no doubt it was state of the art when it was designed. I was just commenting on how much things have changed since then.

I don't mean to dispute that the Concorde was an incredible airplane and engineering achievement. Just saying that it never really had a chance to be successful. The same thing would have applied to the Boeing SST if it hadn't been cancelled (I knew a guy that worked on the Boeing SST inlet control system - talk about complex :mad:). Cancelling the SST is probably the best thing that ever happened to Boeing - it likely would have bankrupted the company. :ugh:

[DozyWannabe]

BA was able to make money on Concorde as in positive cash flow. But they were basically given the airplanes. The commercial failure aspect comes from the simple fact that no one wanted them to build any more (what I've heard is that at least one production Concorde was built but never put into service - basically becoming a donor for spares - not sure if that's true).

Not as far as I know - the first UK "production" Concorde intended for testing rather than line flying (G-BBDG) did end up as a donor for spares, but it wasn't a case of an aircraft without a home - it was just the way things turned out - they never intended to sell it to an airline. In fact that very airframe is the one now living at Brooklands. Several things kiboshed Concorde as a going concern in the '70s - not least of which was the protest movement in the US making US airlines shy away. Above all it was not an issue with the project itself, but the early '70s oil crisis which had the most drastic effect. In fact, while the UK government effectively wrote off the cost in the '70s, the profits BA ended up making could have made a sizeable dent in the development costs.

I also suspect it was too much of a point design - it didn't have the range to be useful in the Pacific.

There was a B model on the drawing board which could very well have been capable in that arena.

CONCORDE SST : CONCORDE B (http://www.concordesst.com/concordeb.html)

If BA (and Air France) honestly thought Concorde was a profit center (rather than brand prestige), they would have wanted more :ouch:.

In fact, BA significantly underestimated what customers would be willing to pay for Concorde service at first - it was this realisation that enabled them to turn a profit!

The same thing would have applied to the Boeing SST if it hadn't been cancelled (I knew a guy that worked on the Boeing SST inlet control system - talk about complex :mad:). Cancelling the SST is probably the best thing that ever happened to Boeing - it likely would have bankrupted the company. :ugh:

Well, that was kind of the crux of the issue. Boeing had already effectively bet the company on the 747 project, and the 2707 still had technical issues on paper that the Concorde project had already solved. As far as my reading suggests, the runaway success of the 747 in fact owed a lot to the issues that ended up swamping the DC-10 and L-1011 - essentially gifting Boeing a market leading position and rescuing the company from the abyss - the 2707 was cancelled long before that became a reality though. In effect, before the success of the 747 was a done deal, Boeing couldn't stretch to doing both.

[tdracer]

The Concorde and Boeing SST business cases were built on a couple flawed assumptions.

First, jet fuel would remain dirt cheap and the higher fuel burn of supersonic travel not contribute significantly to cost of operation - which was blown out of the water by the first Arab oil embargo.

Second, that the majority of demand for air travel would remain for the 'premium' product - basically that the majority of people would happily pay a premium to get there faster. This assumption applied to most people who flew on jets in the 1960's - either business travelers or well to do people that weren't that worried about what it cost.
Reality was it went the opposite direction - a shift that started with the 747 and other widebodies. The economies of the wide body aircraft lowered the cost of air travel to the 'everybody' level. Suddenly there was a whole new class of air traveler - people for whom an extra $100 airfare meant they just wouldn't go, never mind that they'd get there in half the time. In short, they didn't foresee air travel becoming just another commodity - the low cost trend that continues today.

The reality was, both the Concorde and the SST needed to sell hundreds of copies to even begin to justify the development costs. The evolution of air travel into a low cost commodity, combined with the rising costs of jet fuel, insured that would never happen.

[DozyWannabe]

The Concorde and Boeing SST business cases were built on a couple flawed assumptions.

First, jet fuel would remain dirt cheap and the higher fuel burn of supersonic travel not contribute significantly to cost of operation - which was blown out of the water by the first Arab oil embargo.

Well, the 2707 project never advanced to the point where such practicalities were considered - but it's certainly the case that part of the Concorde "B" spec was intended to do away with reheat (afterburner) entirely, and be much more fuel-efficient as a result.

Second, that the majority of demand for air travel would remain for the 'premium' product - basically that the majority of people would happily pay a premium to get there faster. This assumption applied to most people who flew on jets in the 1960's - either business travelers or well to do people that weren't that worried about what it cost.

Not necessarily - supersonic travel as a "premium" product was always intended to co-exist with subsonic offerings, much as it ended up doing. There's a revisionist narrative that has the USA betting on mass transit with the 747 versus Europe betting on supersonic transit with Concorde - but all the contemporary material I've read indicates no such thing. Even setting aside the protests within the US against the Concorde, the simple fact is that SST was never going to be a viable domestic solution, so that limited the market for the 2707. Whereas a transatlantic SST was very much a viable proposition due to the transoceanic nature of the journey. It could be argued that even with the oil crisis and the subsequent drop in orders, the UK and French governments gave up on the Concorde project too soon.

Reality was it went the opposite direction - a shift that started with the 747 and other widebodies. The economies of the wide body aircraft lowered the cost of air travel to the 'everybody' level. Suddenly there was a whole new class of air traveler - people for whom an extra $100 airfare meant they just wouldn't go, never mind that they'd get there in half the time. In short, they didn't foresee air travel becoming just another commodity - the low cost trend that continues today.

If that were genuinely the case, then there would have been no Airbus project or consortium. As Clive correctly points out, the A300 project started taking shape while Concorde was undergoing her proving flights. While there's no doubt that the Concorde project was completed for political reasons most of all, the idea that she was a forlorn hope before she went into service is grossly unfair.

The reality was, both the Concorde and the SST needed to sell hundreds of copies to even begin to justify the development costs. The evolution of air travel into a low cost commodity, combined with the rising costs of jet fuel, insured that would never happen.

Yet, as alluded to before, the R&D gains and technological knowledge coming from the project helped to lay the foundations of a pan-European aircraft maker which would eventually go toe-to-toe with the best the USA had to offer. The sidestick technology which led to an unprecedented level of commonality between short-haul and long-haul types was first tested on a Concorde airframe (Google "concorde minimanche"). Added to which is the fact that in Concorde, for all the project's problems, an airliner was produced which - on a technological level at least - left every competitor in the world in the dust. That is something that can never be taken away.

[Chu Chu]

It seems to me that if Concorde "failed," it's only because it did not usher in an era of supersonic flight. The significance of airplanes like the DC-3 and the 707 isn't so much that they were great airplanes (though they may have been), but that they were copied and improved upon. That didn't happen with Concorde, and I think the only reason can be that the time just hadn't come for supersonic passenger flight. I guess we'll see if it ever does.

[ruddman]

I've never seen it fly or even static. Hopefully one day. Would be a huge thrill. Thank goodness for youtube. And I'd pay more to halve the time to travel by aircraft if I could!



Maybe, just maybe, the Concorde was so far ahead of its time nobody has caught up to it yet?


One awesome aircfraft. :D

[PJ2]

Chu Chu;
It seems to me that if Concorde "failed," it's only because it did not usher in an era of supersonic flight.
I would like to ponder the words, "usher in". . .

"Success" arrives, and sustains itself in many, many forms as does the more practical notion, "copied and improved upon" have many, many expressions.

Our age is one in which the yardsticks that popularly measure and make account of human endeavour are today exclusively material, and less broadly-speaking, financial.

That something must be a "commercial" success for it not to be a "failure" is a "local", temporal measure of our times.

By such "local" measures the U.S. Space Shuttle was a failure as was the Apollo program.

Yet we have Burt Ratan, Elon Musk.

Concorde was different than the "notion" of the "DC3", the "B707", etc. It seems to me that the success of Concorde is measured in knowledge and spirit, a demonstration of technical success and always a singular mark in our history of aviation. I know that the skill, imagination and "slugging in the trenches" over millions of difficult decisions on Concorde has materially contributed to aviation and specifically certain airplanes. The notion of "variations on a theme" is not the only measure of success!

[Trackdiamond]

Concorde might have taken off too early...not withstanding it paved the way for improved airliner design speeds, advanced flight controls and instrumentation,class of comfort and premium service itenerary of all airliners flying today.Where would Fly By Wire technology of today's airliners and bizjets as well as combat planes be..without the pioneering Concorde?It had its design flaws...and the design of adjacent engines must have been seen as a potential hazard during engine failures and fires or tyre blow ups.Comet and VC10 as well as their russian counterparts had similar flaws in their designs.Had the Boeing Supersonic Airliner taken off with its different engine design who knows if supersonic airliner transport might have taken a different track?

[DozyWannabe]

...and the design of adjacent engines must have been seen as a potential hazard during engine failures and fires or tyre blow ups.Comet and VC10 as well as their russian counterparts had similar flaws in their designs.Had the Boeing Supersonic Airliner taken off with its different engine design who knows if supersonic airliner transport might have taken a different track?

Not really. For one thing, the 2707 design was only at the mock-up stage when cancelled, so the practicalities of its engine arrangement hadn't been touched on. If you go back and read the Ted Talbot 'oil and lamp black' story, you can see for yourself that Concorde had solved problems that even US military designs were struggling with half a decade later.

As for the Concorde nacelle/engine arrangement - it didn't really have that large an impact on the F-BTSC accident - because even if the nacelles weren't grouped, the hot gases from the burning fuel would still have had a negative impact on the airflow to the adjacent engine. If I recall correctly, the investigators calculated the way the damage spread through the structure and control connections and proved that even if all four engines were still producing the correct thrust, the fire would still have caused sufficient structural damage to prevent the aircraft making Le Bourget. The nacelle structure itself was proven to be strong enough to withstand an uncontained failure of the engine when it actually happened on the line.

Apropos of nothing, the separate "podded" design was proven to be no protection against damage to adjacent engines when the inboard starboard engine of El Al 1862 took out the outboard as it fell away.

[Contact Approach]

How was the aircraft operated for base training? I imagine it was a 'rocket-ship' with no payload and little fuel.
Sorry if this has been covered. I didn't want to start a new thread, nor do I have time to read all 88 pages.

[Trackdiamond]

DW thanks for the expanded insights on Concorde's engine design integrity.

I believe there is a study looking into deriving Concorde design features for the development of supersonic biz jets now...hopefully with more cost efficient engines!

[DozyWannabe]

Again, as I referred to earlier, the Concorde "B" on the drawing board when the project was cancelled was intended to do away with reheat/afterburner entirely!

The problems a modern project will run into include the fact that a lot of the research will be in the wind - and sadly a lot of the people involved are no longer with us.

[Trackdiamond]

I know Concorde engines were FADEC. Were the Thrust levers gated like on Airbus? I noticesd cocncorde pilots shovved the levers forward for take off thrust..not the gentle easing forward like most other turbojets..why was there this need?Did they take too much time to spool up?

[AlphaZuluRomeo]

No, IIRC the "slaming" was needed to ensure the correct activation of the T/O specific mode, or something like that. Perhaps something to do with the reheat, too.

[Tim00]

Thanks for this wonderful thread. Apologies from a non-aviator, but was reheat used in the event of a go around? Did its use depend on conditions, or was it a straightforward yes/no answer?

[CliveL]

I know Concorde engines were FADEC. Were the Thrust levers gated like on Airbus? I noticesd cocncorde pilots shovved the levers forward for take off thrust..not the gentle easing forward like most other turbojets..why was there this need?Did they take too much time to spool up?

The engine was electrically signalled, but it wasn't FADEC; the control system(s) were analogue.
I suspect the zero bypass Ol 593 would take less time to spool up than todays high bypass engines.