Posts about: "Landing Gear" [Posts: 54 Pages: 3]

Well, the deHavilland Dash 7 has one, and I will take exception to anyone denying it airliner status. A small handpump is used to ensure downlock after freefall extension. (The Dash 8 and Fokker 50 have - much larger and draggier - backwards retracting main gear, assisted by handpump and springloading respectively for downlock after emergency freefall extension.)

Thanks to all Concorde experts for this truly wonderful thread. The ingenuity of design and the complexity of design that enabled the technological marvel that is Concorde never cease to amaze this humble airline driver. Having missed the opportunity to fly on Concorde is high on my list of aviatic regrets as well, and I'll have to make do with the memories of watching Air France Concordes taking off from CDG during our turnarounds there.

I could (and actually have) spent hours following this thread.

Is it true that Concorde was always flown by the highest seniority BA captains, copilots and flight engineers? Would Concorde usually be the last rung on the ladder before retirement for Captains/FEs or was it usual to return to slower equipment after a stint on Concorde?

And, sorry if I missed this, would Concorde thrust levers move during autothrottle operation?

Lastly, Concorde was originally to have had a large moving map system. Any insights into why and how that got scrapped along the way?

Thanks!

The Trident did it sideways

More on wheels and brakes
Concorde was without doubt the first ever aircraft to have a fully automatic, active braking system, with NO mechanical linkages to the brakes whatsoever: Firstly there was the 'normal' anti-skid, but the Concorde system was far from normal. Instead of the universally used anti-skid concept that monitors main wheel deceleration, we of course did it differently. Main wheel rotational velocity was compared with (un-braked of course) nose wheel rotational velocity. With zero skid the RELATIVE velocities would of course be the same, any difference would relate to the % skid value. That was the the real advantage of 'our' system; the percentage of main wheel skid could be calculated by the SNECMA (Hispano) SPAD Box, maximum runway 'stopping power' being achieved at around 20% skid. (I always thought that it was strange, the maximum runway adhesion being achieved while the wheel was skidding, but that's what it said on the tin). When the aircraft initially touched down, and the braking/anti-skid system was enabled, a fixed nose wheel speed Vo was used until the nose wheel touched down. (Can't quite remember what equivilant ground speed this related to though).
As well as anti-skid there was also torque modulation also, due to the use of carbon fibre brakes and the enormous amount of rotational torque involved. (A maximum figure of 8.5 MILLION ft./lbs. of torque springs to mind!!!). When a brake demand was input into the BRAKE ADAPTOR BOX (this also manufactured by SNECMA /Hispano) it was compared with a reference torque. As this brake demand input was applied to the 'box', the torque feedback from a torque link connected at one end to the brake would feedback the actual applied torque, where it was compared to reference torque, and the demand was modulated to suit.
The beauty of it all was that the anti-skid, basic brake demand as well as brake torque limits could all be superimposed on one another, giving a wonderfully flexible system that the pilots could have and did had an enormous amount of faith in.

Dude

In response to your query: V1 was typically about 160kts on a transatlantic sector, with a Vr of about 190 and a V2 approx 220.

It wasn't in the flight manual but I seem to recall that the standing signal prior to nosewheel spinup was 100m/s. Presumably this also prevented brake application until the nose was down, being much higher than touchdown speed.

Anyone who travelled in the beast will know that we didn't use the brakes gently - they worked far better if you stood on them firmly and also seemed to wear less; certainly there seemed to be a lot more dust on the wheels if you used them gently.

Taxying out one had to be careful, it was easy to get a brake temp light on (was it 200degs? 220?) which meant waiting ages for it to cool. The watchword was minimum number of brake applications and make them firm, not feathery. And be careful on the lightweight departures as you needed them more.

EXWOK
Mate I know the Concorde V Speeds, my query relates to the comparison with the 744.
Yeah that figure sounds familier, and you are correct on the presumption also. (That's why you got the eight 'R' lights illuminated on the anti-skid panel with the gear down on approach). With the fixed Vo signal and no output from the main wheel tacho's, the system sensed full skid and gave a FULL anti-skid release. The brakes were electronically held off by this, nomatter what, prior to landing.
Regards as ever EXWOK

Dude

My one abiding fear (apart from obesity) about buying a ticket on Concorde was 'what the hell happens' in event of a nose gear collapse, or landing after failure of the nose gear to extend?? The very tall nose gear with the relatively short wheelbase geometry would suggest such an event would be carastrophic.

Can any of the learned design types on this forum tell about the considerations involved - was there a procedure to handle it, or would it just do a pole vault and compress into an accordion? Were special design features incorporated to make such an event unlikely, or was it even survivable?

hmmm.. As far as the design goes the failure of a nose gear to downlock was extremely, EXTREMELY remote. There were three ways o lowering the nose leg (Normal, Stanby,as well as free-fall). As a matter of interest the main gear sort of had four ways, where the free fall could be assisted by bleeding engine P3 air into the equation also.
Being rearward lowering, the airstream of course helps matters a lot with respect to the nose leg lowering
One of the wing'd chappies I'm sure can come up with the flight procedure for such an event. (Never happened in the 35 years of Concorde flight testing and airline operation).

Dude

As M2dude says, there were about three separate ways of extending the nose gear, making the event extremely unlikely, and indeed it never happened in service.
It's a halfway interesting "what if" question...
Bearing in mind the c.g. is already almost over the main wheels... could it have been done by moving the c.g. as far back as possible, keeping the droop nose at 0\xb0, and after touchdown keeping the nose off the ground for as long as possible?
The radome would have shattered, but the droop nose structure would have acted like a skid.
Just as well nobody ever needed to try it.

There is only one well-known case of a landing gear problem.

Visualise a moment the main landing gear. The main leg 'l' is held down in the vertical position by a large hydraulic "stay" '\' .
___
\l

(I know that, to most people, it looks at first like the retraction cylinder, but it isn't. The retraction cylinder is much shorter, and inside the wheel bay.)

Now the story... It happened during what was going to be the last-but-one flight of the British prototype, 002, during a demonstration flight at Weston-super-Mare.
After a slow pass with the gear down, the co-pilot flying the aircraft put it into a steep turn, retracting the gear at the same time.

The next moment, there was a very loud bang, and one of the main gear lights did not go "green".

Somebody from the crew went to the back cabin, where there is a small porthole to look into the wheel well. When asked what he could see, the answer was "nothing..." ; both the main stay and the retraction cylinder had parted company with the aircraft, and the gear leg was dangling free.

The pilot, John Cochrane, took over the controls, and brought the aircraft back to Fairford. With his guardian angel doing overtime, he managed to put down the aircraft and keep it straight during the roll-out, without the gear collapsing.

I didn't see the landing, but I saw 002 in the hangar the next day. By that time a steel bar had been fitted to keep the leg upright, but the damage was still impressive.
Later on, a spare stay was fitted, but 002s flight test career was over. She stayed in storage at Fairford for some time, and was then flown to the Fleet Air Arm Museum in Yeovilton, where she still can be seen to this day.
Wisely, for the few minutes flight, they did not retract the gear....

CJ

Christiaan,


Since you were discussing the scenario of a nosewheel not lowering and that the CG was over the main wheels may I suggest a rather (amusing at least)
possibility ?!!



With a nose gear jammed up but all other gear lowered normally could the Flight Engineer pump fuel rearward adjusting the CG aft sufficiently to allow the Concorde to settle back on her 'Tailwheel'



I realise there would be some damage, especially in light of what has been said about the occasional tailwheel contacts but I imagine it would be less than lowering the unprotected forward fuselage onto the runway.





Of course some pax might have to move to the back of the cabin too !



If the CG was adjusted this far aft would there be controllability issues ?




There could finally be a use for the 'full down position of the visor' landing in this attitude !

Why not?
Let's admit that being faced with that nasty situation in reality would not have been amusing....
But kicking the idea around a moment, why not? It's what I did seeing the question at first.

Obviously depends a bit on the fuel remaining, but yes, I think one could have move the CG sufficiently rearward.

LOL, don't you think they'd all would have moved as far back as possible anyway?

Possibly, but not enough that an experienced pilot couldn't handle it, I would think.

I don't quite follow you there...

One thing that promptly occurred to me for this 'no nose wheel' scenario is braking, since both engine reverse and main gear wheel braking act below the CG, so they'd both act to pull the nose down.
At some point, stick fully back, hence elevons fully up, will no longer be enough to fully counteract that, so you'll have to cancel reverse and braking, and probably commit to an overrun.
Your scenario of doing it as a 'three-pointer' on the tail might wel be the better one !


And while we're at it, what about ditching a Concorde?
It's hinted at in the Safety Cards.
It's been tried lots of times, with models in water tanks.
It wasn't really feasible.......

CJ

Hello Stilton,

Now you really have upset my Sunday as after many years being retired I have had to go up to my attic to get the Concorde books out so as to answer your question

Anyway as M2dude has said there were drills for everything on Concorde and if I remeber correctly the figure came to 194 seperate drills with 13 of them having a memory content. Never mind remembering the memory content it was hard enough sometimes to remember which drill had a memory content


Anyway I have found the drill for

"Landing with Nose gear not locked down "

To give just the essence of the drill you are asked to

Jettison as much fuel as possible

Set the C of G for landing to 53%--- sitting over main gear

After gear lowered select Standby lever to down position----- This ensures the gear jacks remain pressurized down on touch down

After lowering nose/visor on normal system seltct visor stby system to visor down---- this removes hyds from nose and visor system down jacks, so allowing nose/visor to raise if nose leg collapses

Brake lever to standby --- If nose leg collapse there is no ref anti skid signal and normal brakes would not work. Standby has no anti skid system and will work

Then on landing nose up attitude should be maintained and normal engine reverse selected as soon as possible remembering that engine reverse tries to pitch the aircraft nose up

Wheel brakes use gently and cease at 120kts

At 110 kts reduce attitude to touch nose wheel down gently

At 85 kts select engine reverse to idle power

At rest " Passenger Evacuation"

----------------------------------------------
So you can see this drill uses the nose up effect of engine revese to hold the nose gear off the ground for as long as possible.

I fear this explanation will gemerate more questios than it has answered, but
off for a cup of coffee now as grey cell are hurting

See post #328 for the rest of the story.
In "Concorde - The Inside Story" by Brian Trubshaw there is actually a photo of what is almost certainly the same incident.

But there is another story....

After the first-ever landing at Bahrain, a crowd of Very Important Persons was allowed to visit the aircraft.
Of course they had to see it all, including the rear cabin.
Since the aircraft hadn't been refuelled yet, the inevitable happened... the aircraft started slowly but inexorably tilting backwards.
A very undignified stampede towards the front resulted, just in time, so the aircraft did not actually sit on its tail.

But there was a sequel. The incident had been watched by the airport manager, who promptly decreed that from then on a tractor would have to be chained to the nose gear whenever the aircraft was on the ramp.

Urban legend has it, that from then on there was a new item in the pre-taxy checklist for Bahrain.

CHAIN REMOVED FROM NOSEWHEEL - CHECK

CJ

Quite right!
Nevertheless there were three separate sets of landing/taxi lights there.

Quoting from the manual:

Two main landing lamps, one mounted in each wing root leading
edge, have retractable/extensible mountings and when not in
use are retracted in the lamp housing.
Two land/taxi lamps, similar to the main landing lamps, are attached to the
nose landing gear bay doors. The land/taxi lamps extend to
an intermediate position for landing, upon which they
automatically extend to the full position for taxiing, thus
changing the beam angle to compensate for the attitude change.
Two taxi/turn-off lamps, one mounted on each side of the
forward fuselage, provide ground illumination to identify
runway turn-off points.


These are the 'main' lights in the wing leading edge (600W each).





These are the lights in the nosewheel doors ("only" 450W each).





All three of the sets of lights had a cover to blend them in smoothly with the structure, much like the cabin windows.

The heat was less of a problem, actually.
The lights themselves were high-power sealed-beam units, the main units were 6 00W each, and the ones in the nosewheel doors were 450W ... nothing like your car headlights.
As a matter of fact, on the ground you were not suppossed to turn them on any more than 5 minutes in any 10 minutes.... they got a lot hotter when switched on, than they did in supersonic flight.

Good point!
What happened was that the main landing lamps in the wing roots were angled such, that they pointed straight ahead at the right angle to "hit" the runway during the landing itself.
Once the aircraft touched down, the land/taxi lights in the nose gear door extended further and lit a wider expanse of the runway ahead (see the earlier quote from the manual).
And then the third set of lights in the nose helped you to find the turn-off to the taxiway.

One nice little detail.... on F-BTSD, the Concorde at the French Le Bourget museum, those lights still work, and on G-BBDG, the Concorde at the Brooklands museum that was saved from the scrapheap, they brought those lights back to life, too.

CJ

Interesting.
Judging by the picture from the maintenance manual below, once the nosewheel was down, the main landing lights just lit up the ground below the nose, but not ahead.
Did you just rely on the runway lighting plus the ambient light (town lights reflected by the clouds, etc.) or did you usually extend the nosewheel door lights once you were down?





CJ

Self Loading Freight
The aircraft could be very unforgiving regarding rough runways, and was a major design headache in the early days. There was particular concern regarding about runway conditions in JFK, and extensive modifications were carried out to the shock absorbers to help reduce the effects. However simplified solutions WERE sought by the manufacturers, one of these being to try and reduce the damping of the main gear by removing a meausured amount of oil from the cylinders and chage the 'tuning' of the leg, but this proved to be, er... less than successful:
In early 1977, aircraft 210, G-BOAE was doing it's pre-delivery test flying out of Filton (Fairford was now closed as a permanent test base, but day flying was carried out from there, the aircraft returning to Filton at night). and it was decided to try this rechnique on 210. A little French guy from the landing gear manufacturer Messier spent all day, travelling from the other side of France to Filton in the west of England, and arrived at the plant at around 23:30. He spent several hours that night, draining off his carefully calculated amount of fluid from each of the main landing gears, and returned to France a happy little bunny the following morning. BIG MISTAKE !!
When OAE did it's test flying the following day, everything seemed to be going well, but on the final landing of the at Fairford.. THUMP!!! The barrels of the shock absorbers bottomed, sending a sizable shock through the entire airframe. No structural damage was done, but several systems went off line, and I particularly remember one of the incidence vane heaters being knackered by the force of the vane thumping against the stops. Our poor little Messier rep' arrives home LATE that night, only to receive a message telling him to go straight back to Filton. The poor guy was a wreck, but like a true trooper headed straight back to the UK, and inserted his carefully measured amount of oil back into the main landing gears of G-BOAE. (Always thought that this would have made a great comedy sketch)

Dude

OK, I see others have already posted answers.
I've carefully avoided looking at them, but I'll might as well plug in mine now.

My personal problem is that I was involved in the very earliest days, before the aircraft went into service, and then in the last days and afterwards...
So the questions dealing with the in-service period are totally outside my field of experience... all I can do is guess, in case I saw the answers somewhere.

1) How many Concorde airframes were built?
Twenty-two.
Two static-test airframes.
- One at Toulouse, for purely static tests, and tests such as vibration and flutter.
- One at Farnborough, for the long-duration thermal fatigue tests.
(A few bits and pieces of the Farnborough test specimen have survived, and can still be seen at the Brooklands museum).
Two prototypes (001 and 002)
Two pre-production aircraft (01 and 02)
Two production aircraft used for certification, that never entered service (201 - F-WTSB and 202 - G-BBDG)
Fourteen production aircraft, seven that served with British Airways, seven that served with Air France.

2) As far as the British constructed aircraft went, name the destinations that were served?. Regular flight numbers only, excludes charters etc.
Not a clue as to the full list.
- Bahrain, obviously.
- JFK.
- IAD (not sure if that's rated as regular, or only incidental)
- Dallas (with Braniff)
- Barbados (of course, right until the end)
- Sngapore (with Singapore Airlines, and G-BOAD in Singapore Airlines colours on one side)
- Sydney (again no idea if that rated as a regular flight or only a few tries)

3) What was the departure time for the ORIGINAL morning LHR-JFK Concorde services? (Not called the BA001 then either).
Not a clue either. Vague memory of about 10:00 am which gave you a full working day in New York.

4) Further to question 3 above, what WERE the original flight numbers for the BA001 and BA003? (The morning and evening LHR-JFK services?)..
Never flew on them, never had to deal with them.
BA174 comes to mind from the depths of my memory, in that case BA003 would have been BA176?

5) There were no less than FORTY SIX fuel pumps on Concorde. What was the breakdown for these? (Clue; don't forget the scavenge pump )
M2dude, I did AFCS, not the fuel system. I believe you, but without pulling out some diagrams I honestly have NO idea.
I expect each tank had at least two pumps, which gets me up to 26.
Then there were a few emergency pumps for the trim tanks, and I suppose each engine had additional pumps associated with it.
Still nowhere near the 46 I need to find.....

6) What airframe had the only TOTALLY unique shape?
That would have been my old friend, 01 (G-AXDN), first pre-production aircraft, now at Duxford.
It was the first Concorde with the new transparent visor, but it still had the short tail that characterised the prototypes.
It was 02 (F-WTSA), the first French pre-production aircraft, that was close to the final shape of the production aircraft.

7) This one is particularly aimed at ChristiaanJ. What was the total number of gyros on the aircraft?
Good question.... never counted them all. But I'll try a guess.
First a nice one, the SFENA Emergency Standby Artificial Horizon (made by the firm I worked for).
Ran off the Emergency Battery Bus via a small independent inverter.
And if that failed too, it would still run reliably for several minutes on its own inertia.
Next, the rate gyros used by the autostabilisation system ; these measured the angular rate of the aircraft along the three main axes, pitch, roll and yaw.
There were six, three each for the two autostab systems.
Now the rest....
Each IMU (inertial measurement unit, part of the inertial naviagation system) had three gyros.
With three INS on board, that would make nine.
Much as I try, I can't remember other ones, so I'll look forward to the final answer.
I can imagine the weather radar using an additional gyro for stabilisation, but I never went there.

8) How many wheel brakes?
Unless this is a trick question, I would say eight, for each of the main gear wheels.
The nose gear did not have any brakes - unless there were some small ones to stop the wheels rotating after retraction of the gear, but not used during landing.

9) What Mach number was automatic engine variable intake control enabled?
No idea.
Mach 1.0 or thereabouts is my personal guess only.

10) Above each bank of engine instruments were three lights, a blue, a green and an amber. What did they each signify?
I know that they each monitored the status of one of the engines, because it was too complex for the pilots to fully monitor all the parameters of all four engines in the short time between start-of-roll and V1... they had too many other things to do.
But I don't remember what each light meant, would have to look it up in the manual.

11) At what airfied were the first BA crew base training details held?
No idea.
Was it Brize Norton, or Casablanca?

12) What LHR runways did Concorde use for landing and take-off? (Trick question, not as obvious as it might seem).
No idea.
Vague memory of it being systematically the North runway for noise issues.

13) What operator had serious plans to operate Concorde from SNN to JFK in the early 1980's?
No idea.

14) What development aircraft did not exceed Mach 2 until fifteen months after her maiden flight?
I would expect the obvious answer to be 002.
Working up from first flight to Mach 2 was a slow and laborious process, and in the end it was 001 that both flew first, and also went to Mach 2 first.
I don't think any of the other aircraft took that long.

A I said, I tried to answer all questions "off the top of my head", without looking at any other sources.

CJ

Keep the answers coming guys, and yes Mike; their WAS a single nose wheel brake based on an automotive design. This brake was not electronically controlled like the main wheel brakes, but hydraulics for the UP selection was automatically ported to the single brake unit during retraction. (hmmm.. kinda given away the answer for that one ).

Dude

The green 'Go' configuration light depends on the following flowchart:

Ess 28v DC Busbar -> Fwd Thrust Selected -> Arming Switch 'On' -> Landing Gear Relay Operated -> Fuel Flow Attained -> Jet Pipe Pressure (P7) Attained -> Bucket Position Correct -> 'GO'.

How were these engine parameters monitored? (From the AMM)

- Arming Switch 'ON' : it's a manually operated four-pole solenoid-held switch, for the four engine circuits, operative only when a landing gear weight switch is energized.

- Fuel Flow and Jet Pipe Pressure (P7) Attained: Once the circuit to the 'Go' light is armed, the flow and pressure are monitored against the values set on the indicator bugs on the respective instruments. Once they pass those values, their respective change-over relays are energized, completing the circuit.

Here's a simplified schematic for this:



At least I think that's how it works .

Lefteris

OK guys, here are the answers. If you disagree about any of them then fire away, the old memory certainly 'aint perfect.
As many of you have guessed, there were 22: The 14 production airframes, the 2 production series development aircraft (201 & 202), the 2 pre-production airframes (101 & 102) and the 2 prototypes 001 & 002. PLUS, the major fatigue test specimen at the RAE Farnborough and the static test specimen at CEAT in Toulouse. The CEAT tests actually tested the wing to destruction; I seem to remember it was something like a 200% overload before the wing failed at the root. And great but rather sad pictures VOLUME , never seen these before.
OK, from MY memory , we have: London LHR (duhhh!!), Bahrein BAH, Singapore SIN, New York JFK, Washington IAD, Dallas DFW, Miami MIA, Toronto YYZ, Barbados BGI, and Riyadh RUH. As well as charters being ommited, so are some of the special 'surprise' shuttle appearances that Concorde would make, substituting a subsonic to and from destinations such as Manchester and Edinburgh.
11:15
The BA193 and BA 195.
OK, there were 12 engine feed pumps (3 per engine) 8 main transfer tank pumps (2 each for the transfer tanks 5, 6, 7 & 8), 4 'A' tank pumps (2 each for 5A & 7A), 8 trim-transfer tank pumps (2 electric pumps each for tanks 9, 10 & 11 PLUS 2 hydraulically driven pumps for tank 9), 4 electric engine start pumps (there was a single electric start pump per engine that delivered fuel to it's own dedicated start atomiser in the combustion chamber. The pump automatically ran when the engine HP valve was set to OPEN and would continue running for 30 seconds after the DEBOW switch was returned to the 'normal' position), 4 engine first stage pumps (a single mechanically driven pump per engine), 4 second stage pumps (a single pneumatically driven pump, sometimes termed 'the turbopump, per engine. This would cut out at around 20,000'), our scavenge tank pump (triggered automatically when there was 7 US gallons in the tank; pumping it back into tank 2. This pump was identical to an 'A' tank transfer pump), and FINALLY, a single de-air pump for tank 10. The pump would drive the fuel through a mesh, removing air bubbles from the fuel. Tank 11 used the L/H trim pump for de-air (similar principle)and would be switched on during take-off. This is why the tank 5 trim inlet valve being set to over-ride OPEN would result in the tank being highly pressurised in the case of the Gonesse disaster; the pump would obviously pressurise the L/H trim gallery and any tank on that side with an open inlet valve!!!
G-AXDN, aircraft 101. (A production wing, fuselage, droop nose and intakes, but with the short tail section and secondary nozzles of the prototypes.
Ready ChristiaanJ? There were 18....Yes, the single SFENA standby horizon, 9 INS gyros (one per X,Y and Z platform in each of the 3 INUs), 8 autostab' rate gyros (one per axis for each of the 2 autostab' computers PLUS a monitor gyro for the pitch axis). The radar by the way used attitude signals from the INS.
9. One per main wheel plus the single 'in flight braking' nose wheel brake.
Mach 0.7!!! Between this and Mach 1.26 the intake surfaces were positioned as a function of engine N1 if the engine was shut down for any reason. (Otherwise of course the intake surfaces were fully up). You needed a sub idle N1 of 57% and below for all this to happen, and it was to assist relight performance and reduce buffet. Between Mach 1.26 and 1.32 the ramps were driven down slightly to about 5%, full supersonic scheduling itself commencing at Mach 1.32.
Already brilliantly answered by Brit312 (as well as the FSLabs diagram). Yep, Geen GO, T/O monitor armed, fuel flow and P7 at or above datum, A/C on ground, reverse not selected and CON light not on. Amber CON (Reheat selected and not detected, N1 OK or reverse selected and primary nozzle (Aj) not at minimum. Blue REV; steady buckets at reverse, flashing buckets in transit.
Fairford, followed by Brize Norton, and then a host of airfields from Prestwick and Shannon to Chateauroux.
OK, probably no surprises now:
Landing - 27L & R, 9L & R (prior to LHR mag' deviation update were 28L & R & 10L & R) together with 23/05.
Take off - 27L (28L), 9R (10R) and 9L. (10L never happened as take offs on this runway only occurred in 2003).
It was FedEx, they planned to operate two stripped out aircraft, leased from BA, between Shannon and JFK as high value parcel carriers. The idea was that parcels would be flown in from all over Europe by small FedEx feeder aircraft and the parcels transferred to Concorde which would then speed on to JFK in around 2 1/2 hours. It never happened because of a combination of economics appraisal by FedEx and BA deciding that it could would not release the aircraft anyway.
A/C 101, G-AXDN first flew on 17th December 1971 with FIXED INTAKES!! (101 was going to be the launch vehicle for the new digital intake control system, but the 'boxes' were still being designed). This placed an operating limit of Mach 1.5 on the aircraft, limiting her ability with such a restricted flight envelope. She returned to Filton in late 1972 for installation of the system, as well as the new Olympus 593-602 engine. (The engine, very similar to the production Mk 610 version, used a quite revolutionary annular combustion chamber, and eliminated at a stroke the thick smoke exhaust that had up to then been Concorde's unwanted visual signiture). The aircraft flew more or less smokeless on 15 March 1973, achieving Mach 2 soon afterwards. As ChristiaanJ pointed out, the British prototype 002 had a similar gap, actually significantly higher, of 19 months. (The French aircraft 001 had an even longer gap of some 20 months).

I hope you guys had fun with this one, regards to all

Dude

Only the two prototypes had the airstairs. Even preproduction aircraft 01 (G-AXDN) already had the same door arrangement as the production aircraft. Also the airstairs were in the tail section, without any wing structure at that location.
I had to pull out my copies of the "blueprints".....

The picture on 'heritageconcorde' is a good find!

If you look at the perspective drawing bottom right, you're basically looking at the volume of fuel tank n\xb0 6 (which is located under-floor just to the rear of the main landing gear bay) with the floor on top and the sloped area leading into the main landing gear bay in front ; the rear wall of the landing gear bay is in the plane of fuselage frame n\xb0 60 (see the side view at the top of the picture).

The "system routing" would therefore simply refer to the various 'underfloor' services routed to the landing gear.
There was a lot of stuff passing right under your feet in Concorde!

One problem with your photo..... there is no door anywhere looking rearward from frame n\xb0 60, neither on the prototypes, nor on any of the other aircraft.

However.... the forward wall of the landing gear bay is in the plane of fuselage frame n\xb0 54. And the blueprints show the same type of 'sloped area' at that location, this time making an 'indentation' in tank n\xb0 8, which is just forward of the landing gear bay.
And yes, on the prototypes, counting about 6 windows to the front, there is one of the two emergency exits (which were replaced by the mid-cabin passenger and service doors on all the later Concordes).

So the section on your photo was cut roughly at frame n\xb0 54, and the photo looks forward into the cabin.

I hope this helps?

Unfortunately I do not have a flatbed scanner, and all the drawings I have are larger than A4. But I'll see what I can do... a picture always says more than a thousand words.

CJ