Mykul10
Small correction

M (dry air within reasonable temperature limits) = Sq.Rt (Gamma x R* x Tabs)

R* is a combined gas molecular value
Gamma is 1.4 (truly adiabiatic compression wave)

I have two recollections which I treasure. The first is of a sales demo ride for a VIP party I had to organise from Abu Dhabi on 29th August 1974; one by one we went to the flight deck to look around, which is when I first saw the gap by the F/E panel as the skin stretched. The flight took us overhead Dubai and then halfway to Bombay with a level turn at M2 and back along the outward track. The contrail was close by the RH side and gave a tremendous impression of what the speed really meant.

Some 13 or 14 years later I had the privilege of a jump seat ride from Exeter for the whole of one of the round-the-bay flights. We flew North to join the westbound route to the acceleration point at minimum separation behind the schedule Concorde to New York (or perhaps Washington?). The display as the other aircraft's nose lifted and the aircraft accelerated was awesome.

Then on landing, handflown by the FO (currency requirement?), we seemed to be heading for a touchdown halfway down the runway. It was truly terrifying to a simple PPL, and just as I was about to let out a strangled sob the mainwheels touched down precisely on the markers, well below and behind. Apart from the terror, what impressed me was that as far as I could see the FO was flying the aircraft exactly as you would a Tiger Moth; stick, throttle and rudder. I know that there was far more to it than that, but that's how it appeared.

What a gorgeous aircraft. My model, in its original Gulf Air colours as presented in 1974, flies in the ceiling of my office.

Once again thanks to everyone who has patiently answered my questions. I have certainly learnt a lot about Concorde over the last couple of weeks.
I also agree with many other people who have said that the valuable information provided on this thread should be recorded for posterity. Not an easy task as she is such a wonderful and complex machine. Mind you I think that such a project would be worthy of a Heritage Lottery grant, I say that as in my "real life" I have had experience of how Lottery grants are awarded.
Regards
Nick

http://i991.photobucket.com/albums/a...e/CGlimits.jpgHi guys, here is a schedule showing CG against Mach number (It's very old just like the author here). I hope that it now completes our collection of flight envelope diagrams. (Bellerophon, by the way, your diagram is precisely the one that I was scouring around for). Great explanations by everybody on the Mach/TAS/IAS etc issue, mostly all clear and concise ( a couple of minor goofs that were subsequently corrected, otherwise very good) .
If I were in the LEAST bit pedantic (and any here that know me would say that the b****d certainly IS :mad: pedantic), I would merely add that Concorde (like virtually all complex aircraft) relied on CALIBRATED airspeed (Vc) and not IAS, taking into acount plate and probe errors. Just as well I'm not pedantic ;).

Dude :O

Main Landing Gear Shortening.
 

I believe that the main landing gear was shortened to fit into the wheel wells during the retraction sequence.
As I see it, as the gear started to retract, the oleo`s were compressed to something like when the weight was on the wheels. Then a latch would have been applied before the gear reached the full up position to hold the gear strut compressed.
I would like to find out more how this was accomplished.

ChristiaanJ
It was one of the strange little differences between the BA and Air France aircraft that the French had a small digital TAS indicator (on the lower F/O's instrument panel) and BA had none.
As you rightly say, as an indicator TAS is not that much use to you, BUT TAS is vital for calculating wind speed/direction within an INS/IRS system, hence that is why any air data computer gives a TAS output to the INS or IRS.
Nothing dumb about the question (I wonder if you are even capable of such a thing ChristiaanJ ;)). Yes, the distance window on the HSI related to the next INS waypoint.

Dude :O

M2Dude,


You mention a minor instrumentation difference between the AF and BA Concordes.


Were there any other technical differences between the two Airlines respective Concorde Fleets that come to mind ?

Stilton
Hi again my friend. There were a few; BA used a Delco Carousel 4AC INS, where AF used a Litton system. BA updated the radar to a Bendix sytem, where I believe that AF retained the original RCA fit. (The RCA radar was awfully unreliable (rubbish actually, and very expensive to fix) , although most of the guys would agree that it gave a superbly detailed picture, better for mapping than the Bendix.
BA used quite a sophisticated Plessey integrated flight data system, where the AF recording system was a little simpler.
There were various other minor differences, but I think that's just about it.

Dude :O

Runaround Valve
This was quite a neat system, as the gear was retracted, a SHORTENING LOCK valve was signalled, allowing a relatively tiny jack to pull the entire shock absorber body into the body of the oleo progressively as the gear retracted. So the shock absorber itself never compressed on retraction, more like the whole shooting match was pulled inside the body of the oleo. On the ground the shortening lock was disabled, and also isolated by a geometric lock, the weight of the aircraft on the leg holding the shortening mechanism over centre.centre. Hope this helps.

Dude :O

I hope this one is interesting; it's a Rolls Royce diagram illustrating what the wildly varying differences were in terms of the engine between take off and supersonic cruise. The primary nozzle can be seen at the rear of the engine, together with the reheat assembly and the secondary nozzle (reverser buckets).
Yes ChristaanJ, I FINALLY managed to upload stuff here.:Dhttp://i991.photobucket.com/albums/a...1/1Olympus.jpg

About 15 years ago I visited a friend living in a rented farmhouse in southern England. It had a huge fireplace (large enough to stand in) that had been retrofitted for a small log-burning stove. Looking up, I noticed the chimney had been blanked off by what appeared to be aluminum sheeting bearing Concorde diagrams: white anodized aluminium with deep blue ink. I wonder if they are still there, and how they got there.

Stilton, M2dude -

Did the French aircraft not have a slightly different DC system a la OAG?

If so, it primarily related to NiCd batteries and chargers to suit same, and the lack of main DC bus tie split IIRC.

Oh, and I believe the French flt crews' seat cushions were grey, not blue!

Makes me wonder... In the event of a complete loss of thrust at Mach 2 (say fuel contamination) would the deceleration be significant ? If so I guess the fuel redistribution / pumping to maintain acceptable CG would become interesting...

Concorde did actually have a four engine failure drill, which covered it's complete speed rsnge including Mach 2.0. There was one assumption made in this drill and that the engines would continue to windmill which would allow them to give you full hydraulic pressure

As you could imagine, If all 4 engines cut at Mach 2.0 the F/E would be quite busy and so the the non flying pilot would use his fuel transfer switch to start the fuel moving forward. This was a pretty basic selection where fuel would be pumped out of Tank 11 using all 4 pumps [2 electrical and 2 hydraulic driven] and into the very forward tank which was no 9.

As a rule of thumb transferring 1000kgs from tank 11 to tank 9 moved the Cof G forward by 1%. Now with all 4 pumps in tank 11 running the tansfer forward was so quick that the pilot had to keep switching the transfer off and then on to stop the Cof G moving forward too quickly. It was usually to everybody's relief when the F/E could find the time to take over the fuel transfer as he had the selections to allow him to be more selective as to where the fuel went and so slow the rate down
---------------------------------------

This was quite a neat system, as the gear was retracted, a SHORTENING LOCK valve was signalled, allowing a relatively tiny jack to pull the entire shock absorber body into the body of the oleo progressively as the gear retracted. So the shock

Forther to M2dude's explanation Concorde's main landing gear consisted of 3 seperate metal castings . there was the normal two for the oleo and these two were fitted inside the outer casting, which was the one you could see.
As the gear retracted a mechanical linkage , which was driven by the gear's retraction movement, would lift the oleo assembly up into the outer casing, so shortening the length of the leg . If I remember the shortening jack was just to assist in breking the geometric lock of the linkage
------------------------------------------

The other difference between AF and BA aircraft was the DC electrical system

AF had Nickel cadmium batteries with an automatic charging system

BA had the good old lead acid battery sysytem, well except for AG where the DC system was one of the systems they never changed when AG was incorporated into the BA fleet

for atakacs:
 

The deceleration would be like very hard braking after landing, so - yes.

The drag incurred flying supersonic was once described to me as like flying through wood, not air. The only times I ever closed all 4 throttles at M2 was dealing with surges (see earlier posts on the subject). While not quite like flying into teak, the decel was very impressive - it more than once resulted in a member of cabin crew appearing in the flt deck in a semi-seated position, grimly trying to stop a fully loaded galley cart.......

As for four-engine flameouts - perish the thought. The checklists, like many, depended on flight phase;

Above M1.2 it was expected that windmilling would provide adequate eletric and hydraulic power so the c/list aimed to start a fuel txfr forward, use the spare hydraulic system to drive half the PFCUs, ensure a fuel supply to the engs and ensure cooling to equipment.

Below M1.2 the RAT would be deployed, it was less likely that the standard means of fuel txfr would work so valves were overridden and the hydraulic fuel pumps brought into use, and the Mach fell further the PFCUs were put on half-body use only, using the stby hydraulic system.

You weren't far from the ground, in time, at this stage so it was a good time to get an engine relit!

Given the Olympus' auto-relight capability a four engine loss was going to be caused by something fairly drastic.

Brit312
Right on the button as usual Brit312, the shortening jack DID just assit breaking of the geometric lock, it was the process of retraction alone that did the actual shortening. Humble aplologies to all for this age induced goof. :\
And as both yourself and EXWOK pointed out, Air France had a ni-cad based DC power system, the same as G-BOAG.

Dude :O

Is this another item that Airbus used for the A330/340? I can't remember the exact arrangement for Concorde, but the 330 uses a clever lever arrangement at the top of the leg. Requires regular lubrication too or:{.

As we're on landing gear.
Why was the sidestay a telescopic affair? Most aircraft use a hinged geometric lock arrangement. More weight saving or down to available space in the landing gear bay?

TURIN
I was not even aware of this A33/340 similarity, sounds yet another case of Airbus using Concorde technology. (Immitation still is the greatest form of flattery I guess). As far as I am aware Concorde had none of the lubrication issues that you describe.
I think it's a space saving issue TURIN, I'm not even sure if 'our' telescopic strut arrangement was any lighter. (The Concorde solution was also somewhat more elegant don't you think)?

Dude :O

Re the CG limits, here is the diagram from the 01 (preprod a/c) flying manual.

http://img.photobucket.com/albums/v3...CGcorridor.gif

The production a/c diagram is slightly different, but it shows the same kind of "corridor".

Edit : here is the production a/c diagram.
Sorry for the distortion during the scan....

http://img.photobucket.com/albums/v3...Envelope2w.gif

For the full A4 page, use this link :

Prod CG enevlope A4 format

CJ

Trident
 

A bit of thread drift - but the Trident had a main undercarriage with four wheels aligned laterally with the a/c - two on one axle and two on the other. This obviously would not retract into the fuselage so had to be swivelled through 90 degrees in the retraction process.

I think this was achieved by the oleo assy being driven down an outer barell with a helix in it. I think it had an A-frame mechanism on top of the gear which was fixed to the wing structure (rib 5?). As the gear went up the wheels rotated into the bay. PFM :O

M2dude----- you might be correct in saying that the side strut was for space saving considerations. However in the design office old habits die hard and you will find that the support stay on the Bristol Britannia was very similar to Concordes main gear side strut, with locking fingers etc.and even looked similar

In fact quite a bit was transferred from previous aircraft designs to Concorde , such as the 4 fwd cabin door are very similar to that of the VC-10 as is the oxygen system.

Brit312 ---- that reminds me....

On the two prototypes, the AFCS controller was located on the centre pedestal, and had two big rotary multiposition switches to select the autopilot/flight director modes, plus the autopilot, flight director and autothrottle engage switches.

On the preproduction and production aircraft, the design was totally changed and became the big box with rows of pushbuttons and little handwheels, to set things like altitude and speed, that one now sees at the top centre of the instrument panel, just under the windscreen and above the engine instruments.

It was not until years and years later that I had an occasion to visit a VC-10 cockpit .... to discover how similar the VC-10 AFCS controller was to the prototype Concorde one.
No wonder... both were made by Elliott.

CJ

Brit312

...In fact quite a bit was transferred from previous aircraft designs to Concorde...

Indeed; I've heard it said that the Concorde nose & visor selector lever:
came out of the spare parts box, it certainly looks similar to the Bristol Britannia flap selector lever (rear right hand corner of centre console):

Best Regards

Bellerophon

Bellerophon

The Britannia and now you are talking about the love of my life and yes I do remember the story of the nose and visor selector, but we have forgotten the most abvious. Where do you think they got the idea for the conrol column from

Concorde
Photos: Aerospatiale-BAC Concorde 102 Aircraft Pictures | Airliners.net

Some other great aircraft

Photos: Bristol 175 Britannia 253F Aircraft Pictures | Airliners.net


Now must stop deviating from the topic ;)

Harryman,

I stand corrected! Many thanks for the pressure vs temperature correction. I will digest your formula another day, but for now I will turn towards Hertfordshire and bow :p

(I'm from Watford originally anyway)

No, no, no, no, no! It is this info that makes this thread so special. We can Google to find out many of the tech specs but it is the personal recollections, anecdotes like this that are not known and must never be forgotten.

If it relates to Condorde then it IS on topic. Keep the titbits coming......please. :ok:

As we've observed in the past, often the most attractive aspects of PPRuNe threads are the digressions.

Similarly to the thoughts of many others, I have been following this thread with great interest.

Please do keep up the good work.

Thanks again M2Dude, since we're into details, prior to the accident did BA and AF use different tyres ?


For some reason I thought that BA used Dunlop and AF Michelin.


I think they both changed to the new design Michelin after the accident, can you offer any more info on this tyre ?


I believe it's design was part of the changes for recertification ?


Any other info on the changes incorporated afther the accident would be welcome.

As per a previous post of mine, I've uploaded a takeoff and landing from JFK - LHR, including the very minor blip on roll from JFK and the 1990mph on the Marilake.


YouTube - uvs040403 002 3

Stilton -

Pre-accident I think we did use different tyres than AF. I also recall that BA elected to not use retreaded tyres while AF did, but am not 100% on that.

A pivotal part of the return to service was the Michelin 'NZG' tyre. (Near-Zero-Growth).

The tyres on Conc were incredibly hard-worked, partly because of the speed and partly because they took the full weight of the a/c throughout take-off (a conventional wing is producing a fair bit of lift prior to rotate - concorde produces none of note).

A LOT of energy is stored in a heavy tyre rotating this fast, so a burst can shed debris at great velocity.

The make-up of the NZG meant that it contained the expansion caused by rotation better (so less stored energy in the carcass), and had a far more robust and damage-tolerant structure. The videos of the destructive testing compared with the original tyres is frankly amazing.

The tyre was being developed by Michelin for the A380, I believe, and the principle was adopted for new Concorde tyres. In my opinion, this was the contribution which ensured we got back in the air.

Stilton
Prior to the Gonez disaster BA used DUNLOP tyres for both the main and nose landing gear. As EXWOK quite rightly states BA did not use retreads (although I recall these were tried in the very first few years of service). After the disaster Dunlop were approached regarding the development of an improved tyre for Concorde, but declined, and so BA went along with the superb Michelin NZG design. BA subsequently also changed the nose gear tyre to Michelin. A final modification was the curious decision to remove the steel cord that the British alone had fitted to their main gear water deflectors. This cord was fitted as a modification in the the early 1990's, it's purpose being that if a tyre burst occured, the water deflecor was held together in one piece, and would not fragment, with the resulting structuaral damage. After this modification was embodied there were no further cases of ANY BA aircraft having skin puncture as the result of a tyre failure. (Having said all this, it would not have been of any benefit at all in Paris).
EXWOKS explanation of the mechanics of why the Concorde tyre had such an incredibly stressful and vulnerable life, as well as the design makeup of the NZG tyre is as usual 100% correct; a high speed, very high pressure tyre bearing virtually the entire weight of the aircraft right up to the point of rotation.
EXWOK
It was as you say being developed for the A380. As well as all the well known benifits, this tyre lasted roughly twice as long as the original article, a further testament to this incredible design.
Oh yes, you are 100% on the ball here EXWOK. I remember hearing that the CAA was even considering 'de-mandating' the tank liner modification, as the new tyre alone was enough to prevent any chance at all of any potential fuel tank rupture. I don't want to spoil the nature of this wonderful thread by discussing the why's and wherefores of the Paris disaster (most of us 'here' have our own opinions about what really happened and why). What we do know that if there had been any case of a high speed falure of an NZG tyre, the airframe would have been safe from damage.

Dude :O

Ohhh.. and bits of Concorde on other aircraft etc:
The emergency generator (and generator control unit) were license built replicas of the units fitted to the F4K and F4M.
The air intake void (Pv) pressure sensor, built by Garrett Aireseach, was used in another 'case' as an inlet pressure sensor on the F14.
Carbon wheel brakes, pioneered on Concorde are now used by just about every modern commercial AND military aircraft. (Although originally trialled on a VC10 in a single brake installation).
(Already bleated on about Airbus pinching our audio warning tones etc). ;)
The Triplex 10-20 glass, developed for and used on the visor panels were used in the automotive industry for many years to come.
I'm sure that there is stacks more.....

Dude :O

Paris Disaster
 

"most of us 'here' have our own opinions about what really happened and why"

I for one would like to hear these opinions, especially if they differ from the official report and/or the documentaries that have followed.

M2Dude

Elegant indeed.
We used to convince the weekend visitors to TBB that it was actually the retraction jack.
I feel so ashamed. :)

bizdev,
So far this thread has been about facts, and stories and anecdotes about Concorde.
While the accident is certainly a subject worth discussing, I've seen enough forum threads on the subject to know they invariably end up with many opinions, but very few facts.
So may I respectfully suggest that, rather than diluting this thread, you open a new one ?

CJ

Agreed, let's not spoil this thread

Dude :O

Yep, agreed.

I agree with that. This thread is so good because everyone involved either designed,operated or flew her; together with onlookers such as myself who are grateful that you are all willing to share your unique experiences. If we get on to the crash we will have all the people with other agendas posting here.
Regards
Nick

This thread has had me re-watching every Concorde video of note on Youtube over the past few weeks.
What an exceptional, emotion inducing aircraft. Designed by exceptional people with drive, passion and vision, maintained by exceptional engineers and crewed by the very best of the best.

My question, if I may? I noticed a tail skid in many videos. Did Concorde ever have a need for it?

Bellerophon, Brit312, ChristiaanJ, EXWOK, , M2dude, et al, you are all legends in my mind.
Thank you all for your very real contribution to the history of Mankind.

Of course! That's what this thread is about !
Two answers.

Only the first three Concordes (001, 002 and 01) had a real tail skid (coated with hardwood, IIRC, to prvent sparks).
From aircraft 02 onwards, the skid was replaced by two small wheels, that look as if they've come off a Spitfire....

To understand why it's there, look at a drawing of a side view of Concorde.
If a Concorde overrotates at take-off, or lands with the nose too high, the first things that would have touched the ground are the exhaust nozzles / thrust reverser buckets. The tail skid/wheels are there to prevent that.

As to the need for it...
"Tailstrikes" were rare, but they did happen.
Now I don't remember offhand whether it was already mentioned here or somewhere else, but more often than not those tail wheels were not much good, and got shoved back into the tail, with the reverser buckets still hitting the ground : there are photos of repairs to the buckets to prove it !

CJ

..........which was one reason it was so important to touch down with the wings level - even a very small angle of bank could result in bucket contact as they translated to the reverse position. It was a surprise coming to Concorde to find it was even more restrictive than the 747 in this respect.