Wow, what a great thread! I started reading it yesterday and am up to page 19 so far! I flew on the wonderful white bird once, in 1999, a Manchester - round the bay at Mach 2 - Paris flight in G-BOAD. And the wonderful thing was I did the entire flight, push back at Manchester to parking at Paris, in the jump seat! What a fabulous experience - thank you Roger!

Here's a picture I took as the aircraft turne left towards the French coast:

http://i18.photobucket.com/albums/b1...ersonicres.jpg

One memory is climbing through 50,000 feet over South Wales before turning down the Bristol Channel. It was glorious August day and I had a great view forward past the captain and particularly out of the left window. The speed over the ground at Mach 0.95 seemed noticably faster than a subsonic jet, and that view was breathtaking! The Bristol Channel was edged in golden yellow beaches, and I could see right across south west England to the English Channel. In my headset the controller called another aircraft; "Speedbird 123 if you look up now you will see you are about to be overflown by Concorde". I leaned towards my side window and there was Speedbird 123, a tiny scurrying beetle miles below us. From this height the fair-weather cu looked as if they were on the ground - like small white splodges from some celestial artist's paint brush.

We cruised at Mach 2 and 60,000' over the Bay for a while and the pax came forward to view the flightdeck. I was amazed how patient was the supernumery captain who was answering the same questions over and over again was (the flight crew were too busy to chat).

The approach to CDG looked far steeper than other airliner approaches I had witnessed from the flight deck; more like one of my glide approaches in the Chipmunk! But it wasn't, of course, as we were following the 3 degree glideslope. I guess it was an illusion brought about by the steep pitch angle.

I remember the captain resting his hands on the throttles as they shuttled back and forth under autothrottle control, the smooth touchdown, the 'landing' of the nosewheel followed by full forward stick, and thinking "we'll never make that turn off". Then on came the powerful reverse and the brakes, I was thrust foreward in my harness, the speed disappeared, and we made the turnoff easily!

Oh, and that stange bouncy ride in the flight deck on the ground as the long nose forward of the nosewheel flexed over every joint in the taxyway. So bad at times it was difficult to take a photograph!

What an experience!

I have a question which I hope hasn't been answered in the pages (20 to this one) that I've yet to read.

From an earlier post I understand that the anti-skid used a rotational reference from the unbraked nosewheels to compare to the rotation of the mains, and that with gear down in the air a substiute nose-wheel referance is supplied which, because the mains are not yet rotating, allows the anti-skid to keep the brakes off.

But what happens when the mains touch down with the nosewheels still high in the air? What (if anything) inhibits wheel braking until the nosewhels are on the ground (and therefore rotating)?

Also, this thread started with a question about the lack of an APU. When Concorde was parked could the aircon and cabin lighting be powered by external electrical power, or did the cabin aircon without engine power require an external 'aircon unit' to be connected? Or was aircon simply not available without at least one engine running?

And one for Landlady or any other CC. If a table top was set up between the cabins during service, how did the 'front' crew service the first 2 rows of the rear cabin?

Being 'up front' for my entire flight, I missed out on the cabin service. But superb though I'm sure that was, under the circumstances it's not something I regret! ;)

atakacs

Quote:

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Just wondering was that the maximum speed "in" the design ? I understand that "the higher & the colder = the faster" was the key to the performance and that the Mach +/- 2.0 cruise was implied by limiting altitude to FL 600 in order to mitigate cabin depressurization consequences. I guess there where also thermal issues but was, say, Mach 2.2 @ FL700 "warmer" than Mach 2.0 @ FL600 ?

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Really an answer for CliveL, but I'll have a go. The short answer to your question is 'oh yeah, big time'. Total temperature varies with the SQUARE of Mach number and static temperature. Depending on the height of the tropopause itself as well as other local factors, there can be little or no significant variation of static temperature between FL600 and FL700. The 400°K (127°C) Tmo limit was imposed for reasons of thermal fatigue life, and equates to Mach 2.0 at ISA +5. (Most of the time the lower than ISA +5 static air temperatures kept us well away from Tmo). In a nutshell, flying higher in the stratosphere gains you very little as far as temperature goes. (Even taking into account the very small positive lapse above FL 650 in a standard atmosphere). As far as the MAX SPEED bit goes, Concorde was as we know flown to a maximum of Mach 2.23 on A/C 101, but with the production intake and 'final' AICU N1 limiter law, the maximum achievable Mach number in level flight is about Mach 2.13. (Also theoretically, somewhere between Mach 2.2 and 2.3, the front few intake shocks would be 'pushed' back beyond the lower lip, the resulting flow distortion causing multiple severe and surges).
On C of A renewal test flights (what I always called the 'fun flights') we DID used to do a 'flat' acceleration to Mach 2.1 quite regularly, as part of the test regime, and the aircraft used to take things in her stride beautifully. (And the intakes themselves were totally un-phased by the zero G pushover that we did at FL630). This to me was an absolute TESTAMENT to the designers achievement with this totally astounding aeroplane , and always made me feel quite in awe of chaps such as CliveL. :D

Quote:

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Also wondering what was the max altitude ? Was high altitude stall (for the lack of a better word) ever experimented during tests or training ?

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Well the maximum altitude EVER achieved in testing was I believe by aircraft 102 which achieved 68,000'. As far as the second part of your question goes, not to my knowledge (gulp!!) but perhaps CliveL can confirm.

Shaggy Sheep Driver
So glad you are enjoying the thread, and absolutely loved the description of your flight in OAD and your photo is superb. I don't think it is possible to name a single other arcraft in the world that could be happily flown hands off like this, in a turn with 20° of bank at Mach 2. (One for you ChristiaanJ; The more observant will notice that we are in MAX CLIMB/MAX CRUISE with the autothrottle cutting in in MACH HOLD. Oh, we are in HDG HOLD too :)).
Now for your question A very good question. The anti-skid system used a fixed simulated nose wheel rolling speed Vo signal as soon as the undercarriage was down and locked, this was confirmed by the illumination of the 8 'R' lights on the anti-skid panel. The illumination of these lights confirmed that there was full ant-skid release from the relevant wheel, due to there being of course zero output initially from the main gear tachos but this simulated Vo output from the nose gear tacho. The Vo signal therefore ensured that the aircraft could not be landed 'brakes on' (all the main wheels think they are on full skid) and that there was anti-skid control pending lowering of the nose-wheel. As the main wheels spin up on landing, their tacho outputs now start to back off the Vo signal, and braking can commence. As the nose leg compresses, the Vo signal is removed and the Nose-wheel tachos(their were 2 wired in parallel) spin up, their output will now replace the Vo signal, and full precise anti skid operates.
As far as your air conditioning question goes, you needed an external air conditioning truck to supply cabin air on the ground. Not needed in the hangars of course, but come departure time if these trucks were not working, then the cabin could become very warm/hot place indeed (depending on the time of year). Oh for an APU :\
Best regards

Dude :O

As usual Dude you beat me to it! I really must give up having another lifehttp://images.ibsrv.net/ibsrv/res/sr...lies/wink2.gif

As Dude says, the 'cruise' condition was set by the aircraft specification for transatlantic range on an 85% (ISA +5) day and the chosen mach Number was 2.0 (of which more anon). This gives a Total Temperature of 400.1 deg K. [Dude, I know your pipe-smoking thermodynamicist and he was having you on - he is quite capable of memorising the square/square root of 407.6 or whatever!]
To give margins for sudden changes in ambient temperature (we had to cater for a 21 deg change in one mile) the Mmo was set at 2.04 which matches 400 degK at ISA +1. In theory then we could have flown faster than our chose Mmo at anything colder than this, but there are two limits:

1) The object is not to fly as fast as you can but to fly with minimum miles/gallon. If you have a nice cold day and enough thrust to go either faster or higher which do you choose? For best specific range you go higher every time.
2) The thing that everyone forgets is that civil aircraft have to have margins around their authorised envelope. In Concorde's case these were set principally by the intake limits and engine surge.

Dude also says quite correctly that 101 flew to 2.23M but the production aircraft was limited to 2.13M. Now you may not believe this, but 101 could fly faster than the production aircraft because she (101) leaked like a sieve!.

I doubt I will get away with that without some explanationhttp://images.ibsrv.net/ibsrv/res/sr...lies/smile.gif

Once you get past a certain Mach Number the airflow into the intake is fixed. The performance (intake pressure recovery and engine face flow distortion) then depends on how this air is shared between the engine and the throat 'bleed'. This bleed was ducted over the engine as cooling air and then exhausted (in principle) throught the annulus formed between the expanding primary jet and the fixed walls of the con-di nozzle. But if you took, or tried to take, more bleed air the intake pressure recovery went up and the primary jet pipe pressure went up with it. This meant that the primary jet expanded more and squeezed the available annulus area which restricted the amount of bleed air one could take.

Obviously if there are alternative exit paths between intake and final nozzle then you can take more bleed air off and the engine face flow distortions will benefit along with the surge margin. 101 was fairly 'leaky' in this respect, particularly around the thrust reverser buckets on the original nozzle design. This meant that 101's intake distortions were lower than the production aircraft so she could fly faster without surge - at least with the first attempt at intake control 'laws'. We managed to tweak most of the margin back eventually. Engine bay leaks were good for surge margin but VERY bad news for m.p.g.!

Here are a couple of diagrams to show what I mean. the first shows the surge lines for the various aircraft variants and also the N1 limiter Dude was talking about. NB: the X-axis is LOCAL Mach Number not freestream. The difference comes from the compression of the underwing flow by the bit of the wing ahead of the intake. Mmo + 0.2 is shown

http://i1080.photobucket.com/albums/...1/scan0029.jpg">The next shows the surge free boundaries in sideslip and normal acceleration. You can see the zero 'g' capability Dude was enthusing over.http://i1080.photobucket.com/albums/...1/File0753.jpg">

As for 'high speed stall', I don't think we ever contemplated trying it! Our requirements in 'g' capability were defined and that was it. Besides, the aircraft would fly like the proverbial stone-built outbuilding at those sorts of conditions so I don't think one would have been able to get anywhere near a stall in the conventional sense. Stall as commonly defined for subsonics (deterrent buffet) might have been another matter, but I don't remember anything.

Cheers

Just love this thread - thanks CliveL and all involved :ok:

What was the reason for the kink in the leading edge, shown in the photograph in post #1065? It couldn't have made the wing easier to fabricate or maintain.

Basically we had to recamber the wing to optimise cruise drag. By the time that was discovered metal had been cut on early production aircraft and the only bits that could be altered in time were the wing apex, leading edges and the wing tip. There is a production joint just where the 'kink' appears so it did not affect build difficulty all that much. similarly the detachable leading edges were easy to alter.
There really isn't any significant maintenance on the LE apart from de-icing mats ahead of the intake and they are all inboard of the kink

If you look at it from straight ahead it's not really a 'kink'.

http://i18.photobucket.com/albums/b1...aG1resized.jpg

From the angle the 'kinky' photo was taken the outer sweep of the ogee wing is towards the camera before sweeping aft to the drooped and washed-out tips and it looks like a kink in the LE sweep. The actual shape is seen better in the picture above. I've spent hours studying our G-BOAC at Manchester and to me the wing is a complex and lovely blend of curves and slopes, with no sudden changes such as a kink would require. Standing under the wing and observing it closely, no kink is apparent.

The wash-out on the tips shows particularly well in the above photo (washout is a forward twist of the wing at the tips to reduce the angle of attack of the tips compared to the rest of the wing, to prevent tip-stalling).

A question I have, relating to the photo above, is about the LE. The LE definately 'droops' in the area ahead of the intakes (it doesn't do so nearer the roots or tips). Is this to provoke a clean flow-breakaway in this area at high angles of attack to encourage the votices to form at this point as the wing transitions to vortex lift?

M2Dude Thanks for the kind words and careful explanations. I take it from your description of the anti-skid that once the mains start to rotate the brakes can be used, as the anti-skid comes 'off' (mains no longer think they are skidding).

I thought there was protection to prevent brake use until the nose wheels have landed, else brake application with the nose high would cause a rapid nose-down pitch, slamming the nosewheels on! Is there any such protection?

A really wonderful photo.
As you say, as the main gear tachos spin up the brakes no longer they think that they are in full skid and can be applied. The only electronic 'protection' as such is the anti-skid itself via that Vo signal in the anti-skid unit (known as the S.P.A.D. box). This would still help control and limit main wheel braking. However the professionalism of my friends such as EXWOK, NW1 and Bellerophon was the REAL protection here. I will let one of them explain the normal braking procedure on landing.
Best regards

Dude :O

Such an amazing sight when viewing Concorde head-on....beauty indeed.....:ok:

He's right!!

Did ever a more beautiful aircraft fly??

Wow, an engineer like me moved by such beauty - what's the world coming to???

She is simply a supremely elegant design, something almost every engineer worthy of the profession can admire and love.

Keep posting you who know, please!!

Wet start
 

OK, here is a more unusual photo, but it's not as bad as it looks. It's a photo I took of OAD in 1994 during pushback in IAD. Occasionally if there was an excess of fuel lying in the bottom of the combustion chamber you used to get about 3 or 4 seconds of rather scary looking flames coming out of the jet pipe. It was never a problem, but looked quite spectacular (especially at night :D)
http://i1237.photobucket.com/albums/...e/OADIAD94.jpg




Best regards

Dude :O

No, it is just the opposite. It delays the formation of vortices so that one can develop some leading edge suction on forward facing surfaces and keep the drag down in subsonic cruise. It is there inboard and not outboard because inboard there is some wing thickness which allows one to get some decent forward facing area whereas out board the wing is too thin to make it worthwhile.

The prototype had even more 'droop' in front of the intakes, but that produced a vortex at low incidence (near zero 'g') that went down the intakes and provoked surge.

Normally in subsonic aircraft yes, but in this case the reason is that since the tips are well behind the CG the washout makes the tips give an effective nose-up pitch which helps trim the aft movement of lift as you go supersonic.

Cheers

Clive

PS: Everyone seems to be adding their favourite Concorde photograph so I thought I would be different and add my LEAST favouritehttp://images.ibsrv.net/ibsrv/res/sr...lies/wink2.gif

http://i1080.photobucket.com/albums/...1/scan0024.jpg">

Happy New Year!
 

Hello again, chaps and chapesses, and a belated HNY to all.

I was prompted to post again by a fellow forumite..... I haven't really been in the mood to write after I fell over on the ice :O (well, that's my story and I'm sticking to it...) damaging a few bones, and then caught 'flu (woman 'flu, not man 'flu,) so I'm hoping that after a shaky start, 2011 will brighten up a bit now! :ok:

This is the year I will retire :{..... I really don't know how I feel about that....but if anyone knows a kindly book publisher, perhaps it's time I thought about how to subsidise the pension, and keep Mr LL (or the Landlord, as he likes to be known), in gin and golf balls.

In reply to Shaggy's question with regard to the table top which was put into place after take-off at D2R, it didn't divide the cabins .... it was put accross the actual doorway to make an extra work-space during service. (Rather like a side-board in your dining room. Posh or what!) The fwd crew would take everything that could be needed during service from the front to the mid...wine, fizz, ice, lemon, water, etc., which would help the cabin crew (as opposed to the galley crew) to quickly replenish anything they needed without having to return to the galleys and more importantly, disturb the smooth running of the service...trolleys may be in the cabin and no-one wants to ask the crew on the trolleys to get more wine/water/whatever when they were busy. Of course, you could never second-guess what would be needed, and most probably someone would ask for a drink which you wouldn't have at the mid, but the things we needed all the time were there. The table top remained in place until the seat-belt sign came on for landing, and it was really handy. (Probably designed by a woman!) It was also a place for a couple of pax to stand and have a drink and a chat after the meal service was completed, if they fancied stretching their legs or were waiting for the loo.

Dude, your pic of pushback in IAD is fabulous! Just look what we were missing by being on-board!

With warm regards,
LL x

Many thanks CliveL and LL! Most informative!

CliveL
 

Ohh yuk!! :eek: What is that Clive? It looks photoshopped to me, because why would anyone want Concorde to look like that? :ugh:

Roger.

The dreaded Pepsi scheme? Not on for long; it didn't help with skin temps for one thing. Even worse... it was hideous!

Serious question now. At 60,000 feet outside and 6,000 feet inside, what was the PSI pressure the cabin was subjected to? If I was clever I could probably work it out, but I'm not. :confused:

Not photshopped I assure you. That's 201 in the dress she wore for the celebrations of Concorde's first flight in Toulouse. 'orrible isn't it? I don't think she ever flew like that. As Shaggy said it would completely screw up the skin temperatures.

Shaggy - your serious question - the pressure at 60,000 ft is 1.04 psi and at 6000 ft it is 11.78 psi so 10.74 psi differential.

Clive

Shaggy Sheep Driver
I personally agree about that photo, YUCH!!:}

Now about the cabin pressure thing: The pressurisation system would control to a MAXIMUM differential of 10.7 PSIG. Now at 60,000' the static pressure is 1.04 PSIA and at that altitude we would not QUITE be able to hold a cabin altitude of 6000', more like 6,200-6,300'. This is because 6000' altitude corresponds to a static pressure of 11.78 PSIA, giving us a diff' of 10.76 PSIG. Still as near as dammit mind, and for the MAJORITY of Atlantic crossings 6000' was fine. Such a 'civilised' cabin pressure was just one of the 1000 reasons that you never 'felt' as if you'd just flown over 3000 miles in Concorde.
Here is a diagram of the pressurisation panel.
http://i1237.photobucket.com/albums/...11/Pxpanel.jpg


The idea was that you selected a desired cabin altitude and the system would control to maintain that altitude all the way up to max diff. You could control the rate of presurisation too, to minimise popping ears etc. (Personally I always found Concorde particualarly good in that respect). There is one minor goof in the diagram, in that the discharge valve position indicator show both systems in operation. You only ever had one of the two systems in operation (via the SYS1/SYS2 selector switches). The only exception to this was on the ground when both systems were powered (and both sets of valves fully open).
Best regards

Dude :O

Many thanks CliveL and Dude!

A Journey Back In Time !!
 

OK, here is a photo that I took at Fairford in November 1976. I'd just had my very first Concorde flight on a brand new G-BOAD, and took this flight deck photo in the hangar later that afternoon (the doors are open hence the late afternoon Cotswold sky. The point of this rather poor (sorry guys, I was young for goodness sake) photo is to look at just how subtly different the 1976 flight deck WAS.

http://i1237.photobucket.com/albums/.../OADNov761.jpg

The first thing I know EXWOK and BELLEROPHON will (maybe) notice is that originally OAD had a 'normal colour' electroluminescent light plate on the visor indication panel. (If I remember rightly (it was a million years ago chaps) when this one 'stopped lighting' we could not get a replacement and had to rob 202 (G-BBDG) at Filton; this one being the same black development aircraft colour that OAD has to this day.
The OTHER first thing that you may notice is the Triple Temperature Indicator on the captains dash panel. (The first officer had his in in similar position). These got moved around (twice in the end) when TCAS was installed in the mid-90's. It was amazing just how much equipment got moved around over the years, in order to 'shoe-horn in' various bits of extra equimpent.
The cabin altimeter here fitted just above the #1 INS CDU also got moved (to the centre consul) when the FAA 'Branniff' modifications were embodied later in the 70's. It's spot got occupied by a standy altimeter mandated by the FAA but this was removed after Branniff ceased flying Concorde; the cabin altimeter returning to it's former home. The REALLY observant will notice that there is neither an Autoland Ca3/Cat2 identifier on the AFCS panel (glued on by BA at LHR) or the famous and precision built 'Reheat Capabilty Indicator' flip down plate fitted to the centre dash panel a few years later by BA.
Also not shown here, as they were buyer furnished equipment also fitted at on delivery LHR, are the two ADEUs (Automatic Data Entry Units, or INS Card readers). These were located immediatel aft of the CDU's and were used for bulk waypoint loading ('bulk' being 9, the most that the poor old Delco INU memory could handle). These were removed in the mid 90's when the Navigation Database was fitted to Concorde INUs, and bulk loading then was achieved by simply tapping in a 2 digit code. (Hardly the elegence of FMS, but still very elegent in comparison with the ADEU's, and worked superbly). A little note about these ADEU things; You inserted this rather large optically read paper data card into the thing and the motor would suck the unsuspecting card in. As often as not the ADEU would chew the card up and spit the remnants out, without reading any data, or not even bother spitting out the remnants at all. Removing these things FINALLY when the INUs were modified was absolute joy!!
ps. When G-BOAG (then G-BFKW) was delivered in 1980 it had neither any of the Branniff mods or ADEUs fitted. (Also the INS was not wired for DME updating). This meant that obviously she could not fly IAD-DFW with Branniff but also she could not do LHR-BAH either, because of the lack ADEUs. (You could not manually insert waypoints quick enough over the 'Med', or so the guys told me. So for the first few years good old FKW/OAG just used to plod between LHR and JFK. And plod she did, superbly. She never did get the ADEUs (not necessary thank goodness when the INUs got modified) but we wired in DME updating and so she could navigate around with the best of them.
My gosh I do prattle on, sorry guys.
Best regards

Dude :O

PS Welcome back Landlady, hope you've recovered from your fall XXXX

Don't worry Dude, its the 'prattle' we're here for! :) And I echo your greetings to Landlady. :ok:

Thank goodness that dreadful paint job never flew - somebody might have been tempted to have a proper go at shooting her down!! (Not that they could catch her.:rolleyes:)

Roger.

Landroger

If you look here it suggests that it did fly on a limited number of flights.

"Afterwards, "Sierra Delta" started a promotion campaign in Europe and the Middle East. For the Pepsi commercial operation, there were a total of 16 flights (including the ferry flights from ORY) and 10 cities visited. Each flight, except the first and last ones, would have been occasions to go supersonic"

Don't want to be 'picky', but my photograph was of AS's 201 at Toulouse on the occasion of the party to celebrate the 20th anniversary of 001's first flight. If I understand correctly, the 'Pepsi' aircraft was 213 and belonged to AF. I don't think 201 flew with that Tricolour paint scheme. Can anyone throw more light on this?

CliveL

Clive, you're right.
F-WTSB (201) was painted in that horrific scheme by students at Toulouse.
Since that was in 1989, and 'SB made his last flight in 1985, and was not maintained airworthy, he never flew with that colour scheme....
The 'Pepsi' aircraft was indeed F-BTSD (213), and leased from AF for the occasion.

CJ

I'll get back in my box then:ouch:

A quick question for the technical chaps...

I remember that she had 3 channels of signalling for the flight controls - 2 electrical ( 1 main and 1 standby ) with the third being mechanical. How was the mechanical system 'de-coupled' from the electrical channels thus that any movement from the control column was 'ignored' by this channel ? Was it by somehow disabling the hydraulic jack that ultimately connected to the flying control units ? Was this mechanical channel ever used during service ?

Regards,

d

It´s a privilege to read so much knowledge. Thanks for taking the time to post it all.

Am just curious about the Emergency Descent/Rapid Depressurization profile that was used by Concorde.

TUC is so small at 60,000ft...I reckon that masks were not used at all times during cruise, so, what procedure was used?

How fast could the descent be completed to a safe altitude?

I don´t think that any explosive decompression really puts the cabin altitude at 60,000ft instantaneously, but am just curious about this aspect of the Concorde.

Thanks for your time.

SEQU

I went to have a poke around G-BOAD this afternoon at the Intrepid museum.

Am sad to say she's in a bit of a sorry state - paint peeling off in places which is no doubt due to being outside in the full weather of NYC. For example, there's still several inches of snow on the wings/elevons from the storm half a week ago.

Inside is no better - visible mould on some of the seats which are enclosed underneath a plastic display case type affair, printed on which are some alleged facts about Concorde, but at least one of them was completely wrong.

Such a shame. I have only been to see two of the preserved frames, this one and G-BOAA at East Fortune and I have to say the latter is a far better experience. At least someone seems to care about educating people about the aircraft and keeping it in good 'nic, which is not what you can say about the one in New York.

I'm sure Christiaan or Dude will have better explanations, but in brief :


http://i1080.photobucket.com/albums/...1/File0940.jpg

In mechanical back-up control demands were fed to relay jacks which acted as force amplifiers so the pilot was unaware of control run friction. The autopilot also fed into these relay jacks. This meant that the control precision and ability to harmonise control forces given by the electrical control system was not degraded by mechanical system shortcomings.
In electrical signalling there was a dead space at the Powered Flying Control Units (PFCU) to allow for the difference between mechanical and electrical commands produced by autostabiliser activity. Variation of this dead space with flight condition gave the autostabiliser authority limits. Autostab. was not available in mechanical signalling when the PFCU servo valve was locked to the mechanical control system.
So the control column movements were never 'ignored' by either system, but the mechanical system never 'saw' the autostabiliser commands.

Cheers

Clive

SpeedbirdConcorde
Hi again my friend. To further expand on CliveJ's superb explanation: Mechanical control inputs were fed to each of the 8 Powerd Flying Control Units (PFCUs), but in electronic signalling (either Blue or Green) these inputs were de-clutched at the PFCU input lever. When Fly By Wire' signalling is not available, the mechanical inputs (which as CliveL quite rightly points out) are driven by the Relay Jacks, now are locked to the input lever and can now move the input jack of the PFCU (known as the spool valve) and subsequently cause the PFCU to drive the control surface. (The body of the PFCU moved, the main jacks were attached at each end to structure and so obviously did not move). Hopefully this diagram will help visualising the process a little easier:
http://i1237.photobucket.com/albums/...corde/PFCU.jpg
The diagram shows Green & Blue hydraulics supplied but the electro-valves (opened by the respective FBW channel) are both closed. You can see that the mechanical input lever is 'locked' to the PFCU input lever which will drive the SPOOL VALVE directly. When FBW is enabled, either the Blue or Green (never both together) ELECTRO-VALVE are signalled open, the ensuing hydraulic pressure then pushing the input clutch upwards and disengaging the mechanical input. FBW demands are now fed to the respective SERVO VALVE which will hydraulically send the SPOOL VALVE in the desired direction.
The Relay Jacks could be considered to be a little like a PFCU (you had 2 RJs per axix) but instead of the servo valves being driven by the FBW system they were driven by the autopilot and instead of driving a control surface, they drove the control runs. In manual flight the input spool was driven via a mechanical input lever, which would drive the RJ spool a little like Mech' signalling drove the PFCU spool. In A/P mode the mechanical input rod was de-clutched à la PFCU, but (and here's the clever part) this input was locked to the body of the Relay Jack which when it moved, drove the pilot's control in sympathy. (Control column, yoke or rudder pradals). As the respective control(s) was moved by the Relay Jack, the corresponding FBW position sensor (resolver) would change position and generate the FBW demand. (As the surface moved there was a feedback resolver at PFCU level).
As far as the FBW channels themselves went; there were 2 electronic signalling modes, Blue and Green, sub-divided into 3 groups (Inner Elevons, Outer & Mid Elevons and Rudders). Each group was independently monitored, and a fault in say the Rudder channel alone, would result in the rudders ONLY changing lanes. NOW ( ), The normal control channel was BLUE, and if this failed you would drop the respective channel into GREEN and if this failed you would drop into MECH. The selector switches (1 per group) enabled you to select BLUE/GREEN/MECH in that order. If for some reason you were selected to GREEN, a failure of that signalling lane would not drop you 'up' into BLUE, but into MECH. Your switch would only be in this position if you'd had a problem with BLUE, however you would select this on pushback while you were testing the flying controls, otherwise you spent your whole life selected to BLUE. As far as BA went, I can never remember a time personally when all 3 groups dropped from BLUE to MECH, but very rarely you might get a fault that caused a single group to briefly drop to MECH. Just about one of the very few common mode failures to each of the 3 groups would be a failure of the respective FBW static inverter. This thing, which was rightly monitored up to the hilt, produced a 26 Volt 1800 Hz output. (1800 Hz was chosen as this is not a harmonic of aircraft mainline 400 Hz AC supply)
Best regards

Dude :O

Dude - that really brings back pain form the past! I remember knowing (just) enough about the flying controls to pass the ARB, but a diagram similar to that one was presented at one "Technical Refresher" day (remember those?) by one of our more chatty training EOs (could have been you?!) together with a coloured plastic overhead projector schematic complete with slidey moving jacks and PFCUs and things and it worked! I completely understood the system right up until the first pint of Brains that night...

Flying in mechanical signalling was a different experience - losing the autostabs was bad enough (and proved how good that system was). A mate on the fleet once described it as like trying to fly around on a supersonic dustbin lid. I think that description was too kind - the thing was barely controllable in that configuration. One of our skippers described an airtest when he was on the JS where the crew were trying a decel in MS: as the phugoids were diverging he thought he was about to lose his life so leant forward to restore things. Sadly the switches had been left in MS, so he had to move the switches up to "Blue" as well as then pressing the reset tits - a procedure which he described as almost impossible due to the ever more extreme manoeuvres. Recovery, fotunately, was instant. Resetting electrical signalling and autostabilisation always felt like slotting into a groove on the Concorde.

For that reason, I believe, flight in mechanical signalling was removed from transonic flight on airtests and altogether from Base Training. The simulator was the only sensible way of trying to fly like that...

And that flying control pre-flight check! Learning it was a conversion course rite of passage: one of the sadder parts of reading this thread was realising I'd forgotten it. Great times, great aircraft, great people. Nostalgia isn't necessarily a thing of the past... see you in March?

NW1
Ahhh the Tech refresher days.;) Not being an EO it would not have been me, no. But the 'trainers' often used to come seek me out in the hangar and (over coffee, not beer I'm afraid) confer about various system quirks and nasties to use on you guys during the tech' refreshers. (So I guess can be blamed for a few of the 'stinkers', sorry :sad:). And I definately know who you mean by describing him as a 'chatty' EO.... a truly great guy though.
Mech' signalling during decel'??, OUCH!! I would have thought that the 'supersonic dustbin lid' description would have been quite an accurate description of what must have been a very uncomfortable experience indeed. It was quite a vivid and scary description, I can just imagine trying to move the 3 switches up to BLUE from MECH and stabbing the reset buttons while your seat and the selector panel are seemingly going backwards and forwards, up and down in different directions!!:yuk:. On the C of A renewal test flights I seem to remember that MECH was only tried fairly briefly at a very subsonic 300 KTS during the early stages of the flights, but even then it felt like the aeroplane was riding a sea of different sized golf balls and the outer wing sections seemed to flap about quite enegetically in a world of their own; it was pure bliss when we reset into BLUE. It really shows us all just how good the FBW and autostab really was, the fact that the aeroplane handled so beautifully throughout such an enormous envelope. Well done CliveL and ChristiaanJ and all you designer chaps.:D.
Now NW1, I bet you can still really do the flying control check in your sleep (:E), but 'Great times, great aircraft, great people' is certainly a marvelous way to sum up such an amazing time of our lives. I still feel honoured and very lucky to have been a small part of it all for so many years.
And as for March... Yes I will be there; see you on the 4th.
Best regards

Dude :O

Another pie-in-the-sky Q for you guys:

Concorde carried 100 fare-paying pax.

Hence, If you were looking to redesign Concorde today, to be more cost effective, you would I assume look to increase passenger loads?

Would this purely be a case of sticking everything in the photocopier and hitting the 'enlarge 150%' button? or could you have got away with expanding the cabin width or lengthwise without totally ruining the performance envelope? (a total redesign of the structure notwithstanding)

and which way would you expand? cabin width or length? or both?

Also, I assume a lot of the heavy analogue avionics kit would be replaced with lighter, microprocessor-controlled kit, giving more space and weight for fuel?

The Olympus engines replaced with more efficient ones given the march of technology?

So basically, if the British & French governments had another brain-fart and decided in 2011 to build Concorde2, what would you keep? what would you junk? and what realistically would we end up with in terms of pax numbers, performance, range, etc?

(you have an unlimited budget but need to make the thing a better economic prospect than if just presented with a fleet of de-mothballed Concordes).

Cheers,
Mike.

Brit312 wrote:
Really alternate side Ignitors? All RR aero engines I have worked on always sparked up both sides every time, well the Avon, Spey 202, RB199 & the Oly 20202 (Vulcan) and industrial Oly did. Would this have made a difficulty with starting logic??

Was there LH & RH Ignition selector switch maybe?

I hope I haven't missed further comment on this since page 50 but just back off my Hols and raced through to the end.

Also on a tangent a bit; the roll out picture further on was that a Nimrod's tail in the corner of the Hanger??

regards
Howie

Knowing the location and the 'extra' contracts Bristol's had at the time I think it is a 'Whispering Giant'.

Cheers

CiveL

Since it was me who took the photo, I can confirm that.
Filton was 'taking in' RAF Brittanias for major overhaul at the time.

Reminds me of a funny tale, not Concorde-related.

Years before (mid '60s) I'd bought an ex-RAF vacuum-driven artificial horizon in one of those surplus shops in London, dated by a War Ministry label to 1939. I'd already run it once with a vacuum cleaner (oh, the vandalism the young get up to...).
Since the Brit had some vacuum-driven instruments, there was a test bench in the Filton lab for such instruments. So I brought in my ancient horizon, had it tested.... and it still met the basic specs! They made them well in those days.... :ok:

CJ

During the early years there was some doubt from the CAA that the aircraft could be handled in Mech signalling in the transonic region. Lots of meetings were held, and finally on a test flight the gentleman was invited again and one of the original training Captains flew the aircraft perfectly through the transonic area whilst descending in Mech Signalling. With that said it was a delicate area and control inputs had to be gentle and small so I understand



Yes there was an Ignitor selector labelled LH--Both--RH, however the engines would be started using only one ignitor. This caused a few small but annoying delays as if the selected ignitor failed the start would have to be stopped the starter given a cooling period and then a further engine start using the other ignitor would be attempted, however it did give a running check that both ignitors were working.

This was not very popular with the crews and the ground engineers were persuaded to test the ignitors before presenting the aircraft for service. However due to the engine starting Fuel Pump switching, this resulted with a small fire in the hanger, and so the crews were back to starting on Lh or RH ignitors.

If I remember correctly the RR Conways on the VC-10 also had 2 ignitors per engine with a LH--Both-RH selector.

At one time there was a suggestion that BA adopt the Air France technique where the F/E did this check on the ground pumps prior to engine start, which did not go down very well with the F/E. It was fortunate that some one came up with the suggestion that this would wear the ground pumps out , and so this check stayed as apilot check after the engined were running [Thank God]

If you remember, if something went wrong with the Flying control check the F/E was always busy. This gave him a chance to think up a suitable answer or even better the pilots did the check again and it now worked.

No dude we never came to see you boys for the "Pilots Tech Refresher" as we always had to keep those lectures very simple as otherwise the pilots would go to sleep.

Now I have to admit coming across the hanger to consult with you boys when preparing for a new sequence of F/E "Tech Knowledge Checks". Not that we did not understand it, you understand, but mainly to make sure that we were correct before some clever line F/E informed you of your error. Very embarrising that, and I should know:O

Good to have you back here again Howie :ok:

Quote:

---

Really alternate side Ignitors? All RR aero engines I have worked on always sparked up both sides every time, well the Avon, Spey 202, RB199 & the Oly 20202 (Vulcan) and industrial Oly did. Would this have made a difficulty with starting logic?? Was there LH & RH Ignition selector switch maybe?

---

There was no automatic ignition selection logic as such built into the start sequence, but a manually selected L & R ignition selector switch. The reason of course to alternate L & R selection during starting was to detect otherwise dormant ignition failures if 'BOTH' was always selected. (Modern A/C with AUTOSTART do not have this problem, if an ignitor fails during the engine start sequence the other is automatically selected and an ignition status message is set on the lower EICAS screen). The ignition L/R selector switch was bypassed during engine operation by the auto-ignition system, where if the engine control unit detected a flame out (set at 58% N2) both ignitors would automatically fire up. The sequence would release onece the perceived N2 rose above 63%. The ignition system had several reliability issues, the first was the plugs themselves. Penetration into the 'can' was crucial; if it were more than about 130 thou', the tip would very quickly burn off. We soon learned that a penetration check was vital when fitting a plug and shims needed to be used to get the correct penetration. The other reliability issue was the ignition leads themselves; For the first 10 years of service they were a major pain until 'they' (Rolls-Royce) finally got it right. Also until Rolls modified the lead clipping, it could take 3 to 4 HOURS to change a lead. The dual channel HEIU itself was as good as gold, and seldom let us down, It was a very powerful 8 Joule 2KV beast, and you obviously treated it with utmost respect.

Best regards
Dude :O

ChristiaanJ
You young vandal you Christian. I'm just conjuring up the visual, a young ChristiaanJJ, vacuum cleaner hose in one hand and horizon in the other, the gyro whirring round at warp speed. (What voltage and frequency suction air did you use :E? HAHAHA).
I seem to remember the Chipmunk used to use a cute little 'vaccy' gyro horizon. I pulled many of these apart during my RAF training. (Sometimes I even managed to get the odd one or two back together and working again).

Best regards
Dude :O

Brit312
The main problem with testing ignitors in the hangar was residual fuel. The LH ignitor sat right at the bottom of the can, and sometimes had a small puddle of fuel lying over it. This would produce a small 'whoof' of smoke out of the jet-pipe for about a second or two as the ignitors fired, but no more than that. The main danger was forgetting to trip the START PUMP C/Bs before you did the ignition check. If you did you had a guaranteed fire in the can (the pump would run as you know as soon as 'START' was selected and stayed running for 30 seconds after the start switch was returned to NORMAL) which was very messy (and scary as hell too). The only remedy was to grap a start truck, make sure the C/B is finally tripped and dry motor the engine until all the smokey stuff is gone. (It did no damage, but made a hell of a lot of smoke; the fire brigade were never best pleased). But provided the ignition checks were done correctly there was no ptoblem. (In nearly 30 years of doing ignition checks CORRECTLY, I never once saw a problem. Saw a few when people did forget to trip the start pump C/B however.
In any case as far as the 'ground engineers' doing the check of the ignitors, in my opinion if you are doing a pre-flight check, there is no point doing it unless it is pre-FLIGHT. Just about every other system on the aircraft got tested right up to when you boys arrived at the aircraft, but quite rightly you tested them again. (The whole point of 'us' testing systems was to pre-empting failures before they could impact the departure time).
If you even bothered to read what I wrote "But the 'trainers' often used to come seek me out in the hangar and .....confer about various system quirks and nasties....". I never suggested that anyone but the trainers themselves wrote the tech refreshers; but several of the guys (not you, obviously) waited 'til I was back from leave etc to ask away over coffee about some specific system QUOTE quirks and nasties UNQUOTE they figured I would know about and could use in their refresher.
Or perhaps you are suggesting that I am hallucinating or worse?

Dude :O