snap - followed over from SELOC
Actually feel a bit depressed now which is not usual after a few glasses of wine :p

You mean you actually were on one of the Concorde landings at Kai Tak?
You'll have everybody here green with envy....
Even if it was on a "blunty" it was still spectacular.
And I think Kai Tak is already in the Brooklands sim database.... so you can now come and fly it yourself....

I'll let Bellerophon answer.... but there once was a low-weight take-off from Cardiff straight out to sea, without any restrictions, that IIRC still holds the record for the shortest time to Mach 1 and Mach 2 from brake release....

No thanks needed... I hope you'll enjoy it as much as I did !

CJ

I wish Christiaan. No it was always "blunties" for me into Kai Tak. Still exciting though!
Well I never knew that about Concorde and Cardiff airport. Would love to know more as Cardiff is my local field. In fact my first flight was from there in 1967 in a Cambrian Viscount to Genoa. Another great British plane.
Regards
Nick

The route from Bahrain to London was quite good to, as once the throttles were opened for Take-off they were never touched again until the decel in the north of the Adriatic. The departure went if I remember correctly like

Throttles opened for take -0ff
At 500 ft switch off reheats
At 1000ft select Climb Rating with the switches on the overhead panel
At M0.95 select reheats in pairs
At M1.7 switch off reheats
At 50,000ft select Cruise Rating on the switches on the overhead panel

Sit back and have lunch before decel

The aircraft would be heavy and the ground temps high so the climb accel would be slower than out of Cardiff,but it was still impressive.

Which was the same as the profile for BGI-LHR: Throttles pushed to the stops at the start of the take-of roll and not touched again until the decel/descent.

Gentlemen,

I am new to this thread, and indeed to Pprune. PBL pointed me at this fascinating Concorde thread and I think I may be able to throw in a few points from the point of view of one of the original design team.

It may take a while because there are so many interesting aspects, so I propose to start with early postings and work through. My apologies if this results in some duplication!

I suspect I may have worked with some of the major contributors.

Autotrim
 

It wasn't quite as simple as that. The fuel transfer system really fixed long term problems like getting the elevator trim broadly at optimum throughout (and really at optimum in cruise of course). The Mach trim/autotrim really worked on a shorter timescale to maintain stability at constant CG.

Sure the autopilot made it superfluous to some extent, but to certificate the aircraft it had to be conventionally stable when flow manually, and applying a nose down command to get a speed increase is a basic airworthiness requirement for all aircraft.

Welcome Clive !

See you again sometime after Xmas, when you've worked your way through the 45 pages this thread has already generated......

Sure, Concorde was the first aircraft to fly with FBW flight controls, but electric signalling on a major aircraft system was introduced on the Proteus engines that powered the Bristol Britannia. These were of course built by the same company, Bristol Aero Engines, that built the Olympus.

There are some (I am not among them) who would say that the Concorde project was a good way to learn how NOT to run a major international collaboration

Concorde was unique in having take off performance scheduled for a 'point'CG. Before that all aircraft had FM performance based on the most adverse CG in the certificated range - normally the forward limit. I well remember lying on the grass on the airfield at Madrid waiting for Concorde to get back from a 'hot and low performance' test flight and chatting to the CAA surveyor responsible for that aspect of the certification and speculating on whether we could cash in on the ability to control the CG accurately.

After about half an hour we came to the conclusion that provided we put certain checks in place, and still retaining the 'classic' performance in the Flight Manual, we could insert a special TO technique using a single point CG which would give, from memory, about 1.5 tonnes more TO weight - something not to be sneezed at when your payload fraction is as low as Concorde. Needless to say this 'special' soon became the norm. I doubt if we could get agreement on such a topic in that timescale today!

I noted in another post that memory was blurring after seven years from active flying. I am writing about events thirty or even forty years ago, but I still have my notes.

Clive,
Re the autotrim, tell us some more?
I wasn't directly involved with the control laws themselves, more with trying to assure those control laws were respected to well below 1%.

I thought it was the first civil aircraft, and that the Vulcan had already been there and done that...

I know what you're saying.....
Still, I think you'll agree that lessons were learnt, rather than totally ignored.
I would say Airbus can trace its history back to the lessons learned from Concorde.

CJ

I haven't worked out how to reply to postings and quote the relevant remarks yet - cut and paste doesn't seem to work, sorry.

Anyway, after that 1980 engine fire incident we did find a couple of small holes in the centrewall and as a result we fitted some ceramic coated steel plates in the vulnerable areas.

But as stated, the fire precautions built in did a good job. In this connection though it is worth saying that the cooling air passing over the engine comes from the ramp bleed in the intake and that it is controlled by 'secondary air doors' in the corners left between the circular engine and the square nacelle. These are there to stop air flowing back from the engine bay into the intake during takeoff and are opened once the pressure diferential between intake and engine bay is favourable. Part of the fire drill was to close these doors so the engine fire was deprived of oxygen, which helps a lot

CliveL

Way back in August Tim 00 was asking about preset limits on the fuel transfer system.

One of the major challenges was to match the fuel transfer rate and initiation point to the aircraft performance. Once started the fuel pumps change the rate of CG shift in a more or less constant manner, but the aircraft acceleration through the transonic range is very dependent on weight and OAT, so the actual CG at any one mach number will vary from flight to flight. But it must be possible to make an emergency deceleration form any point in the acceleration backdown to subsonic conditions where the aerodynamic centre will be further forward and hence there is a risk that the aircraft might get into unstable conditions.

A lot of work went into this problem and the allowable CG boundaries reflect thsi to some extent.

CliveL

Why the switches for climb and cruise ratings. What was being accomplished that modulation of the throttles couldn't. Which brings the question, why switches for the reheats rather than throttle aka military style?

When this thread is finished I think we should have the info necessary to retire to the back shed and knock one up. Keep it up Gents.

Good question, Brian. Reminds of the A-10 joke when I flew it--remove the throttles and install switches marked, OFF, IDLE and FLY. Idle was more than sufficient to taxi, line up and select FLY because it was so underpowered, full throttle was pretty much the only power used except in cold wx.

GF

Concorde and SR-71
 

I didn't read all 45 pages only the first 30 and the last page so my question about how much thrust was acquired from the front of the engine because of the pressure differential may have been answered. Also the question may not pertain to the Concorde like it was to the SR-71, but a large quantity of the SR-71 thrust was acquired at the front of the varible nose cone because of the huge pressure differential of the engine. This issue was relayed to me by a Lockheed test pilot who tested both the A-12 and SR-71.This test pilot also said the limiting speed factor of the SR-71 was the wing leading edge temperature of 734 degrees which was 3.2 mach although the plane could go faster. Above FL600 there is no wind so the flight times were always the same either way for the SR-71 and I assume that was true for the Concorde although the SR-71 normally flew at FL800+ except when they came down for a quick drink from a tanker.I really appreciate the ex Concorde drivers and engineers sharing their experiences and time. It should be interesting reading by our great-grandchildren in 100 years.

"I haven't worked out how to reply to postings and quote the relevant remarks yet - cut and paste doesn't seem to work, sorry."
Can someone with greater skill than I have please post some instructions for Clive and myself on how to include quotes from others posts in replies?

I, like all here I suspect, look forward to CliveL's posts on this wonderful aircraft.
Great to have another of the inside team contributing to this fantastic thread. It is probably turning into a valuable historic document, if I may indulge in a little hyperbole.

John

Paste what you want to quote between [-quote-] and [-/quote-] but without the hyphens.

Keith

As with any aircraft the 71 was subject to any number of limitations, but airframe temperature was not one of them. The crew had no info on skin temp in any event. However compressor inlet temperature was the major limiting item (427°C).

Thread on the Concorde inlets here http://www.pprune.org/tech-log/42690...ke-thrust.html

To everyone who has contributed to this thread, a BIG thanks. It has been an absolute pleasure to read ( unlike other threads on pprune :ugh: ). The time and effort spent to share stories and knowledge is truly appreciated and no doubt an appropriate reflection on the brilliance that was Concorde. To everyone that was part of the Concorde dream you have my deepest admiration. Have yourselves a safe and fabulous holiday wherever you are. Looking forward to reading many more great posts in the coming year.
Thanks for keeping the memory of our GREAT ICON truly alive. She was a beauty ! :D:ok:

cheers !


https://files.me.com/speedbirdconcorde/zlqzvw

Copy and paste should work - you either have to copy the text before clicking reply, or open the previous post in another window (or tab) and switch between. Once you have pasted the text, use the "quote" button (third from the right on the lower row of buttons) to turn it into a quote.

Alternatively, to just reply with quote to one post, click the "reply" button, and then look at the address bar (where you type website addresses) in the browser. The address will end with: "&noquote=1". Click in the address bar, and replace that last "1" with a "0", press enter and the page will refresh with the post you are replying to already quoted.

[Edited: swapped the last 1 and 0 to the right way round - oops... thanks ChristiaanJ for spotting]

Hope this helps.

Point CG for Take off Performance - Post 890
 

Minor correction (typo) about quoting from a post.As, said, the address will end with "&noquote=1" (meaning 'noquote' is "on").
Either replace that last "1" with a "0" or just delete the "1", then press enter.
CJ

Other forums I frequent using the same V-Bulletin software have a quote button in every post. Why doesn't this one?

Basically because we operated the Concorde at full throttle all the time except for noise abatement until decel / descent. The schedules and ratings fine tuned the full throttle performance according to a tightly tuned regeme - and reheat was selectable on switches rather than throttle lever angle because we spent most airborne time supersonic at full (dry) power without reheat. At the time that was the unique achievement of Concorde: reheat was used for a tiny proportion of the flight and so was relegated to four little switches. It wasn't even used for a go-around. Even on three. But that's another story.

Once you know how the rating selections work, enabling the throttles to be left fully forward throughout normal flight, you can draw a line to the Airbus FBW thrust lever arrangement - the detents equating to different ratings.

Mercifully no-one had thought of that when Concorde was being designed; I still think it's a diabolical system.

BTW I was told in the conversion course that during the design phase the idea was mooted to only have one thrust lever for all four engines. This would probably have worked - even non-normal engine shutdown drills didn't require the engine's throttle to be closed, the first thing you did was pull the shutdown handle.

CliveL
First of all a hearty welcome from myself also to the thread, speaking as a fellow old Filtonian/Fairfordian. (I'm sure I must have bumped into you during my years at BAC Clive).
It is thanks to the tremendous skill and dedication of 'designer chaps', such as yourself and ChristiaanJ, that Concorde became this breathtakingly amazing aeroplane that she was. I can't wait to read some more of your informative posts; you obviously have one hell of a story to tell, and can obviously teach us all (especially me) a thing or three.:ok:
It was thanks to this superb system for sealing off the engine bay (as well as actuating closed the nacelle ground running flap) when the ESDH (fire handle) was pulled, that generally limited the damage caused by the engine bay fire you mentioned on G-BOAF in 1980 to the affected engine only. (Save as you say, those small holes in the centre wall). Also worth mentioning is the fact that extinguisher pressure would also trip a 'fire flap', that would isolate the ram airflow into the air conditioning heat exchangers, that were mounted directly above the engines.. In the case of the aforementioned incident, this was just as well, as both heat exchangers were seriously damaged by the fire, and another potential source of oxygen was fortunately removed. Yet another truly brilliant piece of design.

Best Regards
Dude :O

ChristiaanJ
Not quite right I'm afraid here my friend. The superb Vulcan used self-contained electro-hydraulic PFCUs, similar in concept to the VC10. The pilot signalling from the fighter type joystick to the PFCUs however was still mechanical, no FBW here.

EXWOK
Oh Amen to that. Although quite complex in its concept, at least 'our' system was logical and intuitive, with full pilot control throughout.:ok:

Best Regards
Dude :O

And how do we know they weren't designed by the very same people?

PBL

It's entirely possible;, in fact there's a probability of at least some crossover since one idea, as I suggested, is to some extent an extension of its predecessor.

My views on their relative merits aren't affected by that, however.

PBL
As far as the Autothrottle side of things (you know, the throttles actually MOVING in response to autothrottle action, how novel :p), that was designed by the Elliot part of the Anglo-French AFCS consortium. (This then became Marconi-Elliot, and then GEC-Marconi, and finally part of BAe Systems). I doubt very much if this is in anyway connected with Airbus at all. (I know,...Duh!!).
As far as the Concorde engine power control philosophy, well this was Rolls-Royce, through and through, with some BAe input, so again I think you can rule that out too.
Basically PBL, I would say that in answer to your question, we can say that they were definately not, thank goodness :D... (Naughty boy, Dude :\). Bearing in mind of course that the current Airbus philosophy can be traced back to the early A320s.... not a Roller in sight there.

Best Regards
Dude :O

quote:Re the autotrim, tell us some more?unquote

It is a little complicated, but let me go back half a step.
Concorde was not certificated to FARs or BCAR (the French code was essentially a straight translation of FAR) but to completely new set of requirements known as TSS (Transport Supersonique Standards). The old UK ARB had initiated discussions about these even before cooperation negotiations had started. The result was that young, junior engineers got to debate the basics of airworthiness rules with older, experienced airworthiness specialists. In hindsight it was wonderful training!

But to get to the point, it was this thinking that allowed us to ignore some of the older rules which, although great for the aircraft flying at the time they were written, had little or no relevance to SSTs. We could interpret that as trying to find out what the pilots really wanted the aircraft to do and then to try and provide it.

In the particular case of trim/speed stability it was quite clear that what they wanted was an aircraft that could be flown with minimal trim changes and which once trimmed would not go wandering off all over the place. We also knew that in some cases the 'elevator angle per 'g' ' could get as low as one degree/g in some cases and that the pilot could not tell exactly where his hands were positioned to that precision, although he would always know if he was pushing or pulling. So we could abandon the old rules for stick movement and instead supply classic stick force stability for deviations from the trimmed state.

All this had to be matched to the varying aerodynamics through the transonic region (where everything varies rapidly) and the fuel transfer system characteristics. The resulting Mach trim laws were quite complex and were not, in fact just Mach Number sensitive. We also had two airspeed (Vcas) terms, one of which had a variable gain which was itself Mach dependent and kicked in above Vmo = 5kts and the other was a straight nose up elevator command as a function of Vcas. The Mach trim itself was highly nonlinear. The best way to illustrate this is probably a diagram but now I've run into another gap in my knowledge of this thread - how do I do that?
Anyway, the result was that the fuel transfer held the trim setting variation down to between 2 deg down to 1.5 deg up through the acceleration from 0.95M up to 0.5 deg down at Mach 2.0. Without fuel transfer the trim at Mach 2 would have been closer to 10 deg. The trim between say 0.95 and 1.2 varies in a nonlinear fashion and the Mach trim law shows roughly similar variations.

But the best measure of our success is the comments we are getting here from the guys who actually had to fly it.

Clive


[IMG]file:///C:/Users/Clive/AppData/Local/Temp/moz-screenshot.png[/IMG][IMG]file:///C:/Users/Clive/AppData/Local/Temp/moz-screenshot-1.png[/IMG]

quote:The only real area of concern was the crown area (the roof http://images.ibsrv.net/ibsrv/res/sr...s/embarass.gif). There was a design flaw here in that the structure had not been designed fail-safe (allegedly by designed a Korean designer at Aérospatiale who, it was said, went a bit loopy) unquote

I think he was Vietnamese actually, cerainly there was a guy of that nationality working in the Sud Aviation Stress Office, but he wasn't loopy - just cussed!

Clive

quote:You then needed the zero fuel weight (ZFW) and zero fuel CG (ZFCG);unquote

So you need to know where the payload is going to be. Sud did flirt wit a 'bumsonseatometer' but eventually settled for allocated seating and simple preflight calculations (by the dispatcher I think, but ex-pilots would be able to help out on that)

Clive

CliveL
At BA the ZFW & ZFCG were sent to the aircraft from Load Control via NOCARS :O:p:O. Only joking folks, with no third VHF ACARS never happened, it was VHF verbal. On charters a despatcher would usually either fly with the aircraft or be positioned at the charter destination in order to make the load control calculations. My pilot buddies will confirm this I'm sure :ok:
(I seem to remember that in the early 90s we were looking to fit Concorde with ACARS, but when informally approached, Filton pleaded 'please, not another aerial position:{'.... we had only just got over the TCAS installation issues you see).



... Oh, he was Vietnamese eh? And not LOOPY?????? :E:E
tee hee, We are certainly living and learning here thanks Clive, keep on posting :).

Best Regards
Dude :O

quote:I don't know why this popped into my head but what was her glide ratio if all the engines stopped? Maybe because I remember from my early training being told the a B707 had a better glide ratio than the PA28-140 I was learning in. Now that was an eye opener at the time.unquote

A lot depends on how fast you were flying. You can get pretty good values of Lift/Drag ratio (that defines the potential glide slope with all engines operating, if that is not a contradiction in terms) from the Concorde B pages of the Concorde SST site. The actual glide slope with engines out would have been a lot worse than those numbers because of windmilling and (supersonically) intake spillage drag.

Nowhere near any subsonic values!

Clive

We wish!

L&B was done by the flt crew on charters; if the flight had a PR flt crew member on board it was his job, otherwise it was the NHP's. (Unless the Captain was the NHP when it became the SFO's job.....)

At some BA stations arrangements might be made to get a L&B through company, but generally for charter flights we operated the way charter companies did!

Edit: Actually, I now recall we did sometimes get a dispatcher sent to UK stations occasionally. No big deal, either way - you just got on with it.

Thanks EXWOK, as always I humbly stand corrected. We DID take one with us when we took OAG to BKK, and I do remember a few other occasions when a 'cap' got positioned. But this worn out brain does remember you guys doing L&B stuff when away.

Best Regards (And I hope you're not working over Christmas... I am :{)

Dude :O

quote: One has to remember that the aircraft is effectively statically unstable in pitch at approach speeds, so a pilot up-elevator input would soon be followed by a countering autostab elevon-down to contain the tendency to keep pitching up, and vice-versa.unquote

Sorry EXWOK, but I just don't agree that the aircraft was statically unstable in pitch at approach. When I think of the hours we put in trying to straighten that damned pitch curve!

It WAS designed to operate with low CG margins on approach, and that meant that the elevator (elevon) deflection needed to trim any desired incremental 'g' was quite small. On the other hand the pitch inertia was high and the elevon moment arm low, so if you just applied the elevon needed for the final state the pitch response would have been pathetic. This meant that the elevon needed to be 'overdriven' to get the aircraft moving and then backed off to hold it to the desired final state. Maybe the apparent reversals you are seeing in the video come from this source.

CliveL

quote:Also, regarding the 4000psi pressure adopted - the control surfaces most definitely did need powerful actuators; as you now know they were very active, especially on approach and transonic, and as well as IASs of up to 530kts you have all the lever arm changes brought by shifting centres of pressure over the surfaces caused by shockwave movements.unquote

Yup, I agree with that. I did the original control hinge moment calculations before we joined up with Sud, and the static hinge moments generated are quite impressive!

In fact the most critical zone is the transonic region and some (most) of the CG boundaries in the 'transonic corridor' are defined by hinge moment capability to provide the necessary manoeuvre 'g', especially with one system inoperative. The control rates aren't all that demanding, but the static hinge moment definitely was critical, and as you say, frontal area is everything and the jacks lie outside the wing section profile.

CliveL