Posts about: "Tyres" [Posts: 12 Pages: 1]

Biggles,

The Braniff crews [ I think it was 5 sets of crew] were trained for Concorde with some of crews trained in France whilst the others were trained in the UK. Flying training was done using an Air France Concorde
F-BVFA with flying being at Shannon initially but when they ran out of fuel it was moved to Montpellier. As their operation was to be subsonic they were only trained to operate the aircraft subsonically, but they were given a supersonic trans Atlantic trip as an observer.

ChristiaanJ

If I remember correctly ground effect tended to force the aircraft nose down, so requiring the pilots to pull back on the stick as if they were flaring ,but in fact what they were doing was as you say maintaining the pitch attitude constant. I have to say that in the early days the landing could be a bit of a hit or miss affair with some being perfect and some less so. The crews were originally taught to pull the power off in one stroke at about 15ft, but later they used to bleed it off and in my opinion this improved the landings greatly.

The problem with landing Concorde was when it got into ground effect if you let the nose drop you lost a lot of lift and arrived somewhat heavily. However if you pulled too hard you could raise the nose too much and suffer a big loss of speed causing a subsequent un-attractive landing, and you could also touch the tail wheel. This touch would be noticed by the ground engineer after landing as a scuff mark on the tail gear tyres. Therefore your friendly F/E on his external check prior to departure would always check the tail wheel tyres for scuff marks and if there were any you could inform the engineers at the other end of the trip that they were there prior to you taking the aircraft, and they would have to go and find another crew to blame


At touch down the pilots eye height was similar to that of a 747 pilot at touch down. Below 800ft when the aircraft had slowed down to landing speed the pitch attitude was such that the F/E could not see the runway ahead

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.

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

Thank you Exwok and M2Dude for your continuing information.


The Concorde tyres were obviously under enormous stress. The only other Aircraft that I can think off whose Tyres have such a hard life (on landing only of course!) are those installed on the Space Shuttle.


I would imagine, however these are replaced after each flight. How long would the Concorde Tyres last in normal service ?

Not sure how the landing and takeoff speeds compare, but the SR-71 tires had the additional disadvantage of a prolonged heat soak to far higher temperature than any large Concorde component, I think. Sources say the tires were good for 15 cycles, other say 6, and attribute two early hull losses (64-17950 and 64-17954 in 1967 and 1969) to tire failures progressing to magnesium wheel fires propagating into the rest of the airframe.

I don't know whether the shuttle tyres are actually reused or not, but if a remember right, the side wall printing says good for 12 uses.

Here's a link to michelin's description of loading and lightweighting:
Michelin Air: The very best in aviation tires.

ALPINE FLYER

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?



To answer your question fully the fleets history has to be broken into two halves, that is the first 10 years and then all the time after that

The first ten years

When the fleet was very new 1976 and crews were bidding for it you have to remember that it was a BOAC aircraft and only BOAC crews could bid onto it. Very few people saw a long future for the aircraft and so were reluctant to go through the long training if it was only going to last for a few years

Also because it always had a limited route net work then there was far more money to be made on say the B747 with it's large route network

Anyway this all opened up the fleet to the younger members of the flight crew fraternity, and indeed the youngest Captain on Concorde at that time was only 32 years old with the youngest F/E being 29 years old. Indeed most of the crews on joining the fleet were in their 30's or early 40's and nowhere near being the most senior. With the exception of the F/Os most of these crews stayed with the aircraft until retirement so in the end it became a senior fleet. Indeed 20 years and even up to 24 years was the term that some stayed on the fleet for.

After 1985 when cross bidding was allowed between the old BEA and BOAC
and Concorde started recruiting crews again then people had to be fairly senior to get onto the fleet as people could see a future for the aircraft and realized it looked exciting.

It was never really a fleet for the most senior as you could as a Captain or F/E only bid for the fleet if you had at least 7 years to go to retirement and the F/Os had to be willing to forgo their oppurtunity for cammand for at least 5 years although this was sometimes ignored

F/O had to leave the fleet to get their command, but many came back as soon as their new Captains seniority allowed them to

Some Captains and 2 F/Es did leave the fleet for another aircraft prior to retirement

Therefore you can see with crew numbers hovering around 20 sets and this was reduced near the end it was no wonder that Concorde was known as the Boys club and Barbara was one of the boys too

On Circuit training tyres were always our problem, especially when we could not have the spare hubs /tyres made up locally by a man from the tyre workshop. Instead we had to bring ready made up wheels with us and the rest delivered by truck. This was no real problem when we did our circuit training in the UK ,but when we moved it to France then the logistics became more difficult.
If I remember correctly you would be lucky to get more than 20 landings out of a tyre, with the rear mains taking the biggest hammering and often being changed quite a bit before 20 landings. With up to 6 details a day and each detail consisting of up to 10 landings you can see that tyre usage on training was heavy

Fingers tired now

Given the frequency of Shuttle sorties 12 landings would mean a lifetime longer than most airline tires, at least if expressed in years.

It was a loooong course!

In essence -

6 weeks groundschool, then type technical exam
Long sim course (lots to learn!)
Base flying
The usual SEP days
20 sectors of line training

In total - a shade under 6 months beginning to end.

You had to do a couple of months online before being released to charter flying and lightweight take-offs.

The sim was great, but couldn't quite replicate the unusual handling in the flare so, yes, we did circuits.

More fun it is almost impossible to have in a commercial jet!

It was, of course, eye-wateringly expensive in fuel, tyres and engineering time which was why one had to commit to a large number of years on type if one got a course.

And it was worth every second.

All due respect but this is the CONCORDE thread and it would be really nice if it could stay as such. If you wish to debate wing technology of other aeroplanes then please I would suggest a new thread be started on that subject. I daresay it would also make for an interesting discussion.
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LandLady said in a post many moons ago that there was a pool of some 240 "Concorde Ambassadors" (sorry but CC and FAs don't sound right for this aeroplane) for Her. What was the numbers of Captains, First Officers and the all important Flight Engineers (sucking up to M2 with that one )

Does anyone know how long did it take to fly from NZ (AKL if I remember correctly) to SYD (very early 90s I think). It is about the same distance at John O Groats to Lands End so I am guessing the 20 to 25 minute mark and how did the 2mt piece of rudder parting company with the fuselage at Mach 2.04 over the Tasman Sea affect or effect the handling characteristics? I remember the papers saying it was hardly a noticable event but I suspect the BA publicity department had a hand with that information.

I looked at the photos posted by a thoughtful member in an earlier post and wonder how former crew felt looking at them. The photos give the impression that you could kick the tyres and light the fires and they would be once again gracing the skies. Obviously they are unairworthy BUT the photos project a different image.

Final one for this post. If She was still flying, do you still think that BA (sorry but going to ignore AF on this one) would have sufficient patronage to keep Her as a going and profitable concern?

I would say that the SR-71, and the Tu-144, are in a way honorary members of the Concorde family, so I don't mind if they fly into the discussion every now and then.

The full list of names (up to 2002) for both BA and AF can be found in "The Concorde Story" by Chris Orlebar. For BA, a quick count shows about 170 names. That book also mentions, that the maximum number of crews qualified at any one time was 28, in 1980, and that the average was about 20 crews.

Photos can lie.... or rather, they are rarely close-up enough to show clearly where corrosion has set in.

As an example, F-BVFC at Toulouse, which was the last one to remain at least taxyable, now has some patches of corrosion starting to show, when you know where to look. Not to mention the nasty smell of damp and mould in the cockpit which bodes no good for what's going on underneath the floor.

And even F-BTSD, kept "live" to some extent at Le Bourget, leaks some hydraulic fluid (like all Concordes did on the ground), so it's easy to imagine the dried-out hydraulic and fuel seals on the other museum aircraft.




And yes, that's kitty litter...
The composite material of the floor and the hydraulic fluid don't agree too well.

I'll leave M2dude to answer that one.

CJ