September 04, 2010, 09:49:00 GMT
permalink Post: 5913033
BRIT312
This story is totally hilarious, can't quite get this visual out of my head. ('100 KTS, POWER SET' sounds so boring in comparison).
I never had the good fortune to meet any of the Braniff guys; sounds like there was certainly a character or two there. It really is a pity that their operation never really got a chance to expand into the proposed Pacific Rim service, who knows, it might really have done something.
It's generally known that the BA aircraft were temporarily re-registered to facilitate Braniff's operation out of IAD to DFW; G-BOAA, B, D & E were re-registered from G-BOAA and so on, to G-N94AA etc. Being an older registration, G-BOAC was re-registered as G-N81AC. At IAD, the 'G' part of the registration was covered over, leaving a now perfect 'American' tail number. Only five aircraft were involved in the operation (at the time BA operated just six aircraft, G-BOAF was still at the manufacturers at Filton, and G-BFKW (later to become G-BOAG) was on loan from British Aerospace. In order for the necessary FAA certification, required for operation by a US airline, a modification package were required by the FAA. Some of these modifications seemed a little 'picky' and irrelevant at the time (they still do). However some modifications were certainly not in this category, and quite honestly should have been 'picked up' by the CAA & DGAC during original certification of the aircraft. As an example, if the flying controls had been operating on GREEN or BLUE hydraulics only (due to an indicated spool valve jam) and that particular hydraulic system was subsequently lost, there was originally no automatic switching to select the standby YELLOW system into the flying controls; the controls would have been completely unpowered until a manual selection was made by the pilot. . One of the 'FAA Mods' was to facilitate just that, so if this (extremely unlikely I grant you) scenario had occurred, then YELLOW would automatically been selected into the controls, and at no time would the controls have been in an unpowered state.
The Braniff operation ended in May 1980, due to heavy losses on the subsonic only route, and it's a rather sad irony that aircraft G-BOAF had been modified and reregistered at Filton, from it's original registration of G-BFKX to G-N94AF. Unfortunately the aircraft was delivered to BA in June 1980, one month too late to participate, and prior to delivery it's registration was converted to it's 'normal' British registration; all other aircraft also reverted to original registrations also.
ChristiaanJ
Not really, being the sad b****d that I am, I still remember the Concorde flare law of: h+5h. = 0, so it was fairly easy to work out the programmed descent rates. (I did have to check the final 1.7'/second figure though). The rest I'm afraid is straight out of this sad old memory of mine.
Bellerophon
A brilliant description of the mechanics of final approach. It's so easy for us mere mortals to forget just what an involved and skilled process it was, to fly, and in particular land our totally amazing aircraft.
Dude
Now the F/E had a couple of calls to make prior to V1 relating to how good the engines were performing the most important being at 100 kts, however before we got that far the Braniff F/E stood up in his harness and let out the cry " Gee Whiz look at the son of a bitch go".
I never had the good fortune to meet any of the Braniff guys; sounds like there was certainly a character or two there. It really is a pity that their operation never really got a chance to expand into the proposed Pacific Rim service, who knows, it might really have done something.
It's generally known that the BA aircraft were temporarily re-registered to facilitate Braniff's operation out of IAD to DFW; G-BOAA, B, D & E were re-registered from G-BOAA and so on, to G-N94AA etc. Being an older registration, G-BOAC was re-registered as G-N81AC. At IAD, the 'G' part of the registration was covered over, leaving a now perfect 'American' tail number. Only five aircraft were involved in the operation (at the time BA operated just six aircraft, G-BOAF was still at the manufacturers at Filton, and G-BFKW (later to become G-BOAG) was on loan from British Aerospace. In order for the necessary FAA certification, required for operation by a US airline, a modification package were required by the FAA. Some of these modifications seemed a little 'picky' and irrelevant at the time (they still do). However some modifications were certainly not in this category, and quite honestly should have been 'picked up' by the CAA & DGAC during original certification of the aircraft. As an example, if the flying controls had been operating on GREEN or BLUE hydraulics only (due to an indicated spool valve jam) and that particular hydraulic system was subsequently lost, there was originally no automatic switching to select the standby YELLOW system into the flying controls; the controls would have been completely unpowered until a manual selection was made by the pilot. . One of the 'FAA Mods' was to facilitate just that, so if this (extremely unlikely I grant you) scenario had occurred, then YELLOW would automatically been selected into the controls, and at no time would the controls have been in an unpowered state.
The Braniff operation ended in May 1980, due to heavy losses on the subsonic only route, and it's a rather sad irony that aircraft G-BOAF had been modified and reregistered at Filton, from it's original registration of G-BFKX to G-N94AF. Unfortunately the aircraft was delivered to BA in June 1980, one month too late to participate, and prior to delivery it's registration was converted to it's 'normal' British registration; all other aircraft also reverted to original registrations also.
ChristiaanJ
Reading your description of the autoland, you must be quoting from documentation, no?
Bellerophon
A brilliant description of the mechanics of final approach. It's so easy for us mere mortals to forget just what an involved and skilled process it was, to fly, and in particular land our totally amazing aircraft.
Dude
Last edited by M2dude; 4th September 2010 at 12:12 .
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Auto-land Braniff British Airways Filton G-BFKW G-BOAA G-BOAC G-BOAF G-BOAG G-N81AC Hydraulic Hydraulic System - BLUE Hydraulic System - GREEN Hydraulic System - YELLOW V1
September 05, 2010, 10:56:00 GMT
permalink Post: 5915045
In-Flight Reverse (A case of Bucket and See)
Capt Chambo
Concorde was, as EXWOK says, could use reverse in flight, on the inboard engines only, and only as far as reverse idle, the mechanism of which was quite complex and did on occasion not do work as advertised. Bear in mind here that the Rolls Royce Olympus 593 was a pure turbojet with no bypass, and so a hot stream reverser only had to be used; the reverser buckets acting directly on the efflux as it did any reverser in the 'old' days. Also the same buckets that were used for reverse were also progressively opened up between Mach 0.55 and wide open at Mach 1.1, this giving a vital control enhancement to the divergencing efflux. The overall effect of this was to give a true overall convergent/divergent nozzle assembly, the ideal for any supersonic aircraft.
As far as inflight reverse goes, the amount of HP compressor delivery air (P3) required to actuate the bucket airmotor in flight at an idle thrust settings, was quite minimal to say the least, and some help was definitely needed here. The moment that inflight reverse was selected (on the inboard engines only remember) the OUTBOARD engines would have their idle N2 automatically increased, and some of THEIR P3 air supply was also automatically ported over (via an isolation valve) to the inboard buckets. This whole process was required in order to give a little added muscle to the bucket airmotors, and give the system a fighting chance. Even this however was still not quite enough, the inboard travelling buckets required minimal air loading on their surface, and so the primary nozzles for the affected engines (the primary nozzle lived just aft of the LP turbine, aft of the reheat assembly) was automatically signalled wide open in order to assist matters here, by reducing gas velocity. One the buckets had reached full reverse the primary nozzle was then signalled full close (this applied for normal ground reverse also) and the automatic increased idle on the outboard engines was cancelled. To enable the described process to occur, provided all four engines were at idle, a solenoid latched button on the F/E's station could be selected. This signalled a circuit that enabled the selection of idle reverse on the inboard engines only, the opening of the P3 isolation valve, the raising of the outboard engine's idle and maximum primary nozzle angle for the outboards as soon as reverse was then selected..
The whole system was just a little fragile here; failure of either the extra air supply, or the raised idle on the 'other' engine was usually enough to stop the process working correctly.
EXWOK
While flying 'up front' I only ever experienced the use of inflight reverse once. (The captain was a bit of an Animal, if you flying guys see what I mean
). I would not say that it felt as if we'd hit a brick wall, as I'd expected the sensation to feel, more like we were flying into the dumped contents of a very large manure truck
. The whole operation was so slick, we'd dumped the required amount of IAS more or less within a second or two, and normal thrust was immediately selected. As so often happened with you guys, you made it look too easy.
As far as the speed of the airmotor goes, I seem to remember that it was something in the order of 80,000 RPM at max chat; as you say faster (around twice as fast) as the standby horizon motor.
The basic core airmotor (not the whole assembly) was the same Garrett unit used on the P&W JT9 as well as the RB-211.
Dude
Concorde was, as EXWOK says, could use reverse in flight, on the inboard engines only, and only as far as reverse idle, the mechanism of which was quite complex and did on occasion not do work as advertised. Bear in mind here that the Rolls Royce Olympus 593 was a pure turbojet with no bypass, and so a hot stream reverser only had to be used; the reverser buckets acting directly on the efflux as it did any reverser in the 'old' days. Also the same buckets that were used for reverse were also progressively opened up between Mach 0.55 and wide open at Mach 1.1, this giving a vital control enhancement to the divergencing efflux. The overall effect of this was to give a true overall convergent/divergent nozzle assembly, the ideal for any supersonic aircraft.
As far as inflight reverse goes, the amount of HP compressor delivery air (P3) required to actuate the bucket airmotor in flight at an idle thrust settings, was quite minimal to say the least, and some help was definitely needed here. The moment that inflight reverse was selected (on the inboard engines only remember) the OUTBOARD engines would have their idle N2 automatically increased, and some of THEIR P3 air supply was also automatically ported over (via an isolation valve) to the inboard buckets. This whole process was required in order to give a little added muscle to the bucket airmotors, and give the system a fighting chance. Even this however was still not quite enough, the inboard travelling buckets required minimal air loading on their surface, and so the primary nozzles for the affected engines (the primary nozzle lived just aft of the LP turbine, aft of the reheat assembly) was automatically signalled wide open in order to assist matters here, by reducing gas velocity. One the buckets had reached full reverse the primary nozzle was then signalled full close (this applied for normal ground reverse also) and the automatic increased idle on the outboard engines was cancelled. To enable the described process to occur, provided all four engines were at idle, a solenoid latched button on the F/E's station could be selected. This signalled a circuit that enabled the selection of idle reverse on the inboard engines only, the opening of the P3 isolation valve, the raising of the outboard engine's idle and maximum primary nozzle angle for the outboards as soon as reverse was then selected..
The whole system was just a little fragile here; failure of either the extra air supply, or the raised idle on the 'other' engine was usually enough to stop the process working correctly.
EXWOK
While flying 'up front' I only ever experienced the use of inflight reverse once. (The captain was a bit of an Animal, if you flying guys see what I mean
). I would not say that it felt as if we'd hit a brick wall, as I'd expected the sensation to feel, more like we were flying into the dumped contents of a very large manure truck
. The whole operation was so slick, we'd dumped the required amount of IAS more or less within a second or two, and normal thrust was immediately selected. As so often happened with you guys, you made it look too easy.
As far as the speed of the airmotor goes, I seem to remember that it was something in the order of 80,000 RPM at max chat; as you say faster (around twice as fast) as the standby horizon motor.
The basic core airmotor (not the whole assembly) was the same Garrett unit used on the P&W JT9 as well as the RB-211.
Dude
Last edited by M2dude; 5th September 2010 at 12:25 .
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Afterburner/Re-heat Captains HP Compressor IAS (Indicated Air Speed) LP Turbine Nozzles Olympus 593 Thrust Reversers
September 05, 2010, 11:12:00 GMT
permalink Post: 5915084
telster
One for the pilots really, but there was generally far less co-operation than you'd have thought. I never saw any cases of a BA pilot flying Air France or visa-versa. I know a couple of our guys had ridden jump seat on an AF aircraft, but that's all that I pesonally recall.
On the technical side of things there were meetings between the two airlines, both together and jointly with the airframe and engine manufacturers, but on a day to day basis there was precious little exchange of information, and you'd have thought that we (BA) were the only operator of Concorde, as I'm sure the AF guys felt the same also. In all of my 30+ years on Concorde, I personally went to CDG only once for an exchange of technical views and to help them out with an air intake defect.
I'm so glad that you are enjoying this post, it's great to have you here telster. (It's certainly forcing me to look deep into the dark corners my poor old grey matter).
Dude
How much cooperation was there between the two airlines in terms of training etc? Did any BA crews fly Air France aircraft for any reason for example? Were cockpit proceedures pretty standardised across the two airlines?
On the technical side of things there were meetings between the two airlines, both together and jointly with the airframe and engine manufacturers, but on a day to day basis there was precious little exchange of information, and you'd have thought that we (BA) were the only operator of Concorde, as I'm sure the AF guys felt the same also. In all of my 30+ years on Concorde, I personally went to CDG only once for an exchange of technical views and to help them out with an air intake defect.
I'm so glad that you are enjoying this post, it's great to have you here telster. (It's certainly forcing me to look deep into the dark corners my poor old grey matter).
Dude
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Air France British Airways CDG
September 06, 2010, 08:17:00 GMT
permalink Post: 5916644
Coffin Corner
Nick Thomas
Just like Christiaanj I'm trying to dig up an accurate flight envelope diagram. (A lot of my Concorde 'technical library' is out on long term loan), but I would suggest that anywhere within Concorde's published flight envelope you never hit any equivilant to Coffin Corner, a la' U2. The whole issue is really one of air DENSITY, rather that pressure, where as you climb at a given Mach Number, your Indicated airspeed (IAS) falls away with altitude. (Velocity of sound being primarily tied to static air temperature). Now if you are climbing in the stratosphere, where temperature is more or less constant up to around 65,000', you can say that your TRUE Airspeed (TAS) is also constant with climb at a given Mach number. But lift and drag are functions of IAS (the equivalent airspeed that the aircraft would 'feel' at sea level) and not TAS. Because the U2 had a very low Maximum allowable Mach number (Mmo) as IAS fell away with altitude, it would get to the point where it's lowest permitted airspeed (we called this VLA) got to within a few knots of Mmo and severe aerodynamic buffering. i.e. you were screwed with nowhere to go but down
.
In the case of Concorde, Mach 2 at FL500 was 530KTS, falling to 430KTS at FL600. Although we have less lift due to 100KTS lower IAS, the aircraft is now much lighter (this is the whole principal of cruise/climb) which keeps the universe in balance, but drag is now significantly lower too, getting us better MPG
.
On the ASI, the only limitation displayed was Vmo; however the Machmeter did display fwd and aft CG limits at a given Mach number. The ONLY time that Concorde would experience relatively low speeds at altitude was at Top of Descent. I'm a little fuzzy here how it all worked exactly (it's an age thing you know), I'm sure one of the pilots can correct me, but I seem to remember that the autothrottle was disconnected, ALTITUDE HOLD was selected on the AFCS, and the throttles slowly retarded. (If you pulled back too far you'd often get a gentle 'pop surge' from the engines, and you had also to be wary of equipment cooling airflow too). The aircraft was then allowed to gently decelerate, still at TOD altitude, until Mach 1.6, when power was tweaked to give 350KTS IAS and IAS HOLD was selected. The aircraft was now free to carry out her loooong descent to 'normal' altitudes. VLA on Concorde was not directly displayed as you never flew anywhere near it, and also every pilot knew his VLA
. (Stray into this and you'd get a 'stick' shaker warning.
I hope this blurb helps Nick
Dude
Just like Christiaanj I'm trying to dig up an accurate flight envelope diagram. (A lot of my Concorde 'technical library' is out on long term loan), but I would suggest that anywhere within Concorde's published flight envelope you never hit any equivilant to Coffin Corner, a la' U2. The whole issue is really one of air DENSITY, rather that pressure, where as you climb at a given Mach Number, your Indicated airspeed (IAS) falls away with altitude. (Velocity of sound being primarily tied to static air temperature). Now if you are climbing in the stratosphere, where temperature is more or less constant up to around 65,000', you can say that your TRUE Airspeed (TAS) is also constant with climb at a given Mach number. But lift and drag are functions of IAS (the equivalent airspeed that the aircraft would 'feel' at sea level) and not TAS. Because the U2 had a very low Maximum allowable Mach number (Mmo) as IAS fell away with altitude, it would get to the point where it's lowest permitted airspeed (we called this VLA) got to within a few knots of Mmo and severe aerodynamic buffering. i.e. you were screwed with nowhere to go but down
.
In the case of Concorde, Mach 2 at FL500 was 530KTS, falling to 430KTS at FL600. Although we have less lift due to 100KTS lower IAS, the aircraft is now much lighter (this is the whole principal of cruise/climb) which keeps the universe in balance, but drag is now significantly lower too, getting us better MPG
.
On the ASI, the only limitation displayed was Vmo; however the Machmeter did display fwd and aft CG limits at a given Mach number. The ONLY time that Concorde would experience relatively low speeds at altitude was at Top of Descent. I'm a little fuzzy here how it all worked exactly (it's an age thing you know), I'm sure one of the pilots can correct me, but I seem to remember that the autothrottle was disconnected, ALTITUDE HOLD was selected on the AFCS, and the throttles slowly retarded. (If you pulled back too far you'd often get a gentle 'pop surge' from the engines, and you had also to be wary of equipment cooling airflow too). The aircraft was then allowed to gently decelerate, still at TOD altitude, until Mach 1.6, when power was tweaked to give 350KTS IAS and IAS HOLD was selected. The aircraft was now free to carry out her loooong descent to 'normal' altitudes. VLA on Concorde was not directly displayed as you never flew anywhere near it, and also every pilot knew his VLA
. (Stray into this and you'd get a 'stick' shaker warning.
I hope this blurb helps Nick
Dude
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): AFCS (Automtic Flight Control System) Auto-throttle C of G Engine surge Flight Envelope IAS (Indicated Air Speed) Mmo Stick Shaker TAS (True Air Speed) Vmo
September 07, 2010, 06:12:00 GMT
permalink Post: 5918834
Hi 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
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
Last edited by M2dude; 7th October 2010 at 17:12 .
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): C of G Flight Envelope IAS (Indicated Air Speed)
September 07, 2010, 06:29:00 GMT
permalink Post: 5918854
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
.......
in a way, that illustrates that for
flying
the aircraft things like TAS and GS are not really that important... that's why there are no big instruments indicating TAS or GS..
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.
dumb question from a techie... the 373 miles is presumably just the distance to the next INS waypoint?
). Yes, the distance window on the HSI related to the next INS waypoint.
Dude
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): British Airways INS (Inertial Navigation System) TAS (True Air Speed)
September 07, 2010, 06:45:00 GMT
permalink Post: 5918876
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
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
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Air France British Airways INS (Inertial Navigation System)
September 07, 2010, 06:52:00 GMT
permalink Post: 5918886
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
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.
Dude
Last edited by M2dude; 7th September 2010 at 07:42 .
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Landing Gear
September 07, 2010, 07:39:00 GMT
permalink Post: 5918963
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.
Yes ChristaanJ, I FINALLY managed to upload stuff here.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Afterburner/Re-heat Nozzles Olympus 593 Thrust Reversers
September 07, 2010, 10:41:00 GMT
permalink Post: 5919303
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
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
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
And as both yourself and EXWOK pointed out, Air France had a ni-cad based DC power system, the same as G-BOAG.
Dude
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): G-BOAG Landing Gear
September 07, 2010, 12:07:00 GMT
permalink Post: 5919495
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
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
.
.
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?[/
Dude
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Airbus Landing Gear
September 08, 2010, 08:20:00 GMT
permalink Post: 5921203
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
prior to the accident did BA and AF use different tyres ?
For some reason I thought that BA used Dunlop and AF Michelin.
For some reason I thought that BA used Dunlop and AF Michelin.
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
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.
Dude
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Air France Air France 4590 British Airways Landing Gear Tyres
September 08, 2010, 10:04:00 GMT
permalink Post: 5921405
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
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
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Airbus Braking Intakes Visor
September 08, 2010, 10:44:00 GMT
permalink Post: 5921513
Agreed, let's not spoil this thread
Dude
Dude
Subjects: None
September 08, 2010, 18:05:00 GMT
permalink Post: 5922493
Another IPhone answer, so apologies for rubbish post. On rotation the process was about as subtle as a coffee grinder. As the elevons were raised the downforce against them caused the aircraft to rotate about the mainwheels, raising the nose, increasing angle of attack and finally allowing the wing to generate some lift. Apologies again to all
Dude
Dude
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Elevons
September 09, 2010, 06:51:00 GMT
permalink Post: 5923538
Alpine Flyer
And a darned good airplane too
One for my 'winged' friends really, but with BA it was an issue of seniority, with a long waiting list for selection. As far as I recall there were only ever a couple of cases when a captain left the fleet for another aircraft, most would very happily fly Concorde until retirement at 55. The senior first officers generally had to (reluctantly) change fleets when they got their commands, however there was as far as I remember two exceptions here, where an SFO was able to 'jump seats' to captain. SEOs would stay on Concorde until retirement. (In all the years that I can remember there was only one case of an
SEO
switching fleets from Concorde). A pilot friend once put it to me that if your passion in life was as a flyer of aeroplanes, then there was really nowhere to go after Concorde.
Oh yes, Concorde had a 'real' full flight flight regime autothrottle. The autothrottle actuator would drive all four levers together via individual isolation clutches and the computer used the sum of all four lever angles. In the unlikely event of an engine being shut down in flight, the A/T could still be used. There was an isolation switch on the roof panel that would enable the affected engine's thrust lever to be isolated and closed to idle, the computer using the sigmals from the other three engines, demanding a now higher lever angle to compensate for the failed engine.
The prototypes I recall had a DECCA moving map, but with the availability of INS (and the decline and finally shutting down of the DECCA chains) made the system a waste of time (not to mention space).
Dude
Well, the deHavilland Dash 7 has one, and I will take exception to anyone denying it airliner status.
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?
Dude
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Auto-throttle British Airways Captains INS (Inertial Navigation System)
September 09, 2010, 07:03:00 GMT
permalink Post: 5923554
stilton
and
archae86
I seem to remember that the average tyre life prior to the NZG tyre was roughly between 12 and 20 landings. One of the main concerns of prolonged high altitude flight was the deterioration of the tyre rubber by atmospheric ozone (above 50,000'). For this reason a small amount of cabin air was bled into the undercarriage bays and expelled through vents in the doors. And archae86, my friend you will find nothing but respect for the SR71A and her crews from the Concorde 'family'.
Dude
I seem to remember that the average tyre life prior to the NZG tyre was roughly between 12 and 20 landings. One of the main concerns of prolonged high altitude flight was the deterioration of the tyre rubber by atmospheric ozone (above 50,000'). For this reason a small amount of cabin air was bled into the undercarriage bays and expelled through vents in the doors. And archae86, my friend you will find nothing but respect for the SR71A and her crews from the Concorde 'family'.
Dude
Subjects: None
September 09, 2010, 11:44:00 GMT
permalink Post: 5924106
"Wheel Meet Again" - More on the rotating stuff
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
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
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Anti-skid Braking Landing Gear
September 09, 2010, 12:07:00 GMT
permalink Post: 5924167
And more.....
Just to round up the braking issuue....
A fully laden Concorde had a V1 significantly higher than a fully laden 747. (A figure of about 50 MPH springs to mind; perhaps one of the 'flyers' will confirm this). Although the Jumbo is twice the take-off weight, the amount of kinetic energy present in Concorde was significantly higher, due to energy = Mass x the SQUARE of the velocity. Added to this, Concorde had only eight braked wheels compared to the Jumbo's SIXTEEN. This really is further testament to the Concorde braking system, that had to have an enormous amount of stopping power, particularly in the case of a near V1 RTO. And all of this achieved with just eight compact, extremely reliable and relatively light brake units.
Dude
A fully laden Concorde had a V1 significantly higher than a fully laden 747. (A figure of about 50 MPH springs to mind; perhaps one of the 'flyers' will confirm this). Although the Jumbo is twice the take-off weight, the amount of kinetic energy present in Concorde was significantly higher, due to energy = Mass x the SQUARE of the velocity. Added to this, Concorde had only eight braked wheels compared to the Jumbo's SIXTEEN. This really is further testament to the Concorde braking system, that had to have an enormous amount of stopping power, particularly in the case of a near V1 RTO. And all of this achieved with just eight compact, extremely reliable and relatively light brake units.
Dude
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Braking V1
September 09, 2010, 15:44:00 GMT
permalink Post: 5924634
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
Mate I know the Concorde V Speeds, my query relates to the comparison with the 744.
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.
Regards as ever EXWOK
Dude
Last edited by M2dude; 9th September 2010 at 21:47 .
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Anti-skid Braking Landing Gear