Concorde's Take Off Performance Falsified?
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Concorde's Take Off Performance Falsified?
December’s edition of Scientific American magazine contains the following letter from one Jon Modrey, an MD11 FO with Gemini Air Cargo from Orlando, FLA.
“…masks the inherent reduced safety permitted by the Concorde’s government certifiers. Any other four engined transport aircraft could have sustained the Concorde’s damages and made it back for a safe landing. In order to permit the Concorde to operate on existing runways, it’s certifiers redefined it’s take off safety speed, or V2, to a speed so low that the loss of two engines would not permit the aircraft to climb without first diving a few thousand feet to build up speed. Other four engined transports have not been afforded this convenient definition of V2 and can in fact lose two engines on takeoff and still climb and maneuver to a safe landing.”
Contentious stuff that! If we can ignore the drivel about diving thousands (!) of feet and any other aircraft flying with all that damage I am curious about his main thread, the assertion that Concorde’s V2 figures are unrealistically low. This seems to be a most serious charge, and I am keen to see if there is any factual evidence whatever to back up Mr Modrey’s accusation.
1) Can Concorde genuinely climb with the loss of two critical engines at the published V2?
2) If so, is the climb performance acceptable, or marginal, or only possible under ideal test conditions, as opposed to normal operating parameters?
3) Is there any evidence, anecdotal or otherwise of collusion amongst the certifying authority(s) in the matter of Concorde’s V2?
Concorde pilots, technical or performance experts, or anyone else with a view, can you clear the waters?
“…masks the inherent reduced safety permitted by the Concorde’s government certifiers. Any other four engined transport aircraft could have sustained the Concorde’s damages and made it back for a safe landing. In order to permit the Concorde to operate on existing runways, it’s certifiers redefined it’s take off safety speed, or V2, to a speed so low that the loss of two engines would not permit the aircraft to climb without first diving a few thousand feet to build up speed. Other four engined transports have not been afforded this convenient definition of V2 and can in fact lose two engines on takeoff and still climb and maneuver to a safe landing.”
Contentious stuff that! If we can ignore the drivel about diving thousands (!) of feet and any other aircraft flying with all that damage I am curious about his main thread, the assertion that Concorde’s V2 figures are unrealistically low. This seems to be a most serious charge, and I am keen to see if there is any factual evidence whatever to back up Mr Modrey’s accusation.
1) Can Concorde genuinely climb with the loss of two critical engines at the published V2?
2) If so, is the climb performance acceptable, or marginal, or only possible under ideal test conditions, as opposed to normal operating parameters?
3) Is there any evidence, anecdotal or otherwise of collusion amongst the certifying authority(s) in the matter of Concorde’s V2?
Concorde pilots, technical or performance experts, or anyone else with a view, can you clear the waters?
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I always thought performance was based on only loosing ONE engine.
You might get away with loosing two in some types at light enough weights, but I'm sure that there are no guarantees.
You might get away with loosing two in some types at light enough weights, but I'm sure that there are no guarantees.
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No commercial 4-engined transport can survive the loss of 2 engines on takeoff at normal operational weights. 3 engine ferries (which assume the loss of one of the remaining engines at V1) require special techniques and very low takeoff weights.
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V2 on 4 engine aircraft is based on losing one engine at a critical point in the takeoff, this point is defined as V1 or VEF. I do not know of any commercial airliner that operates on the premise of 2 engines failing at that critical point.
Jim Modey should look closely at the VMCA2 of a 4 engine airliner and then read the accident report of the EL-AL B747 flight from AMS.
I would be extremely surprised if the CAA allowed for a re-definition of V2 to satisfy Concorde!
Mutt
[ 01 January 2002: Message edited by: mutt ]</p>
Jim Modey should look closely at the VMCA2 of a 4 engine airliner and then read the accident report of the EL-AL B747 flight from AMS.
I would be extremely surprised if the CAA allowed for a re-definition of V2 to satisfy Concorde!
Mutt
[ 01 January 2002: Message edited by: mutt ]</p>
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To the uninitiated - which is what this guy looks like - Concorde can look dodgy. However it is a different type of plane so its ability to retain control and its sensitivity to stall allow narrower margins whilst being as safe as an ordinary jet.
All the evidence I've ever seen shows certification to have been as rigorous as for anything else.
Concorde would have survived on two engines I think. The problem was loss of control which was not caused by lack of power but rather lack of physical parts of the wing.
All the evidence I've ever seen shows certification to have been as rigorous as for anything else.
Concorde would have survived on two engines I think. The problem was loss of control which was not caused by lack of power but rather lack of physical parts of the wing.
Point of order, Mr Chairman! In the mighty Vickers VC10 Funbus, we regularly lose one at V1 and another stops producing thrust at V2...at MTOW!! In the simulator, fairly obviously!! It flies perfectly well so long as sound flying skills, well practised drills and good CRM are applied. But try it above RTOW, without having recomputed the speeds, with a FE shutting down an engine still producing thrust before V2 is achieved..........
No-one's told the ac that, when it's full of pax and at MTOW, it is no longer the civil airliner it once was!! I undersand that it had to prove that it had this excess performance in its early days due to the suspicion (unfounded) that a single engine failure would invariably become a double engine failure due to the pairing of the engines?
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It's going to depend how close to Vlof and where you lose the second engine. And what obstacles you have in front of you. If you have no obstacles you will probably be okay as long as you can get to Vlof with two engines.
By the way, the Concorde that crashed was one of the few certified to take off with two engines. It wasn't the lack of thrust that got them, the fire cooked the hydraulics and he lost control. What, you think he steered into that hotel with a nice field right next to it?
By the way, the Concorde that crashed was one of the few certified to take off with two engines. It wasn't the lack of thrust that got them, the fire cooked the hydraulics and he lost control. What, you think he steered into that hotel with a nice field right next to it?
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Here we go again....... <img src="rolleyes.gif" border="0">
BEagle, please give the "RAF obviously have higher standards and are better aviators than everyone else" implication a rest. Its becoming a bit tiresome, old boy.
Please go and fly your "VC10 takeoff on two engines" fantasy sortie in the sim.....Maybe with Blair and Co. commiting many millions of pounds of taxpayers money to making Britain look "big and important" around the world (Afghanistan, Bosnia, Sierra Leone etc) you may well have the chance to get some real hours in...
BEagle, please give the "RAF obviously have higher standards and are better aviators than everyone else" implication a rest. Its becoming a bit tiresome, old boy.
Please go and fly your "VC10 takeoff on two engines" fantasy sortie in the sim.....Maybe with Blair and Co. commiting many millions of pounds of taxpayers money to making Britain look "big and important" around the world (Afghanistan, Bosnia, Sierra Leone etc) you may well have the chance to get some real hours in...
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BEgle you are right in saying that that the VC10 is a commercial airliner, I guess that I should have quantified a 4 engine wing mounted airliner!!!!!! <img src="wink.gif" border="0">
747FOCAL I sincerely wish that you try that profile in the sim, you might be surprised!
MUTT
747FOCAL I sincerely wish that you try that profile in the sim, you might be surprised!
MUTT
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BEagle
The CAA removed the VC10 from my licence because they said that it was no longer in 'commercial' service. One of our (BOAC) VC10s suffered a double failure at RTOW on departure from Calcutta in 1970.
I think that the VC10 is one of the few large four-engine aircraft that could survive a double failure (as well as Concorde????). Certainly the 747-400 wouldn't stand a chance at anywhere near RTOW.
P22
The CAA removed the VC10 from my licence because they said that it was no longer in 'commercial' service. One of our (BOAC) VC10s suffered a double failure at RTOW on departure from Calcutta in 1970.
I think that the VC10 is one of the few large four-engine aircraft that could survive a double failure (as well as Concorde????). Certainly the 747-400 wouldn't stand a chance at anywhere near RTOW.
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Not sure if available thrust would be the critical factor. What about the loss of the vortex lift component from the wing? If memory serves, the aircraft rolled (stalled?) onto the burning wing. Wonder if any training sim would include a sufficiently accurate wing model to show the effects.
basil - please reserve your vitriol for Manuel! I wasn't implying that the RAF's standards are necessarily 'higher', merely that to fly out of the DEFATO scenario safely and competently, you do need regular sim practice, etc - and you do NOT need a FE shutting down an engine which is producing thrust before you know that you can survive without that thrust. In any case, Nigel taught the RAF how to do it properly in the first place...
I certainly agree that a 2-e fail on a wing-mounted 4-jet at high AUW and at V2 would be far less likely to be survivable. The rear-mounted 4-jet design of the VC10 was economically less advantageous in the short term, but the design was probably inherently 'safer' until the advent of highly reliable ETOPS twinjets rendered commercial 4-jets somewhat unnecessary.
[ 01 January 2002: Message edited by: BEagle ]</p>
I certainly agree that a 2-e fail on a wing-mounted 4-jet at high AUW and at V2 would be far less likely to be survivable. The rear-mounted 4-jet design of the VC10 was economically less advantageous in the short term, but the design was probably inherently 'safer' until the advent of highly reliable ETOPS twinjets rendered commercial 4-jets somewhat unnecessary.
[ 01 January 2002: Message edited by: BEagle ]</p>
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I'm sure the fact that they had no hydraulics, the gear stuck down and only half a wing were rather more significant factors than the loss of thrust in two engines. Perhaps Jon Modrey would like to consider the Sioux City DC10 which only lost thrust in one engine but still didn't fly too well without any hydraulics. Of course, if Concorde was made and certified in America this subject wouldn't even have been raised!
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HEY HEY HEY GUYS!
PLEASE!
This is important!
I am trying to ascertain if an unwarranted slur has been cast against one of the finest flying machines ever, and against the inherent integrity of our CAA, and people are bitching about whether an aircraft is one type or another beacuse of the colour of it's paint.
Someone said Concorde is one of the few certificated to fly on two engines. Is this in the take off case? Can you please substantiate that statement?
Secondly, the statement that a B747 cannot survive a double engine failure at limiting TOW, again, can I have a substantiation of this please.
I am not at all happy to see a thoroughly inaccurate seeming report rubbishing our government, our authority and the superlative product of the European aviation industry and all I ask you for is fact to back up a stiff letter to SA to put this matter to rest, and to put this MD FO back in his box if appropriate.
Accurate info requested, please.
(;
PLEASE!
This is important!
I am trying to ascertain if an unwarranted slur has been cast against one of the finest flying machines ever, and against the inherent integrity of our CAA, and people are bitching about whether an aircraft is one type or another beacuse of the colour of it's paint.
Someone said Concorde is one of the few certificated to fly on two engines. Is this in the take off case? Can you please substantiate that statement?
Secondly, the statement that a B747 cannot survive a double engine failure at limiting TOW, again, can I have a substantiation of this please.
I am not at all happy to see a thoroughly inaccurate seeming report rubbishing our government, our authority and the superlative product of the European aviation industry and all I ask you for is fact to back up a stiff letter to SA to put this matter to rest, and to put this MD FO back in his box if appropriate.
Accurate info requested, please.
(;
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Agaricus bisporus, a while back JF posted something that is worth reading (as always) about Concorde.
[quote]So far as Vzrc goes, the perhaps the following data may be of interest. It is for the aircraft at MTOW (185,070 kg) at LHR, on an ISA day with zero wind:
V1: 164 kts
Vzrc-3e-Gear Down: c190 kts (so not routinely calculated)
VR: 193 kts
V2: 215 kts
Vzrc-2e-Gear Up: 260 kts (Calculated for every departure)
Vzrc-2e-Gear Down: 316 kts (Above the sea level Vmo of 300 kts!)
My final comment: Just look at the jump in Vzrc when you go from three engines to two engines. About 70 kts. If the gear is stuck down that becomes an awesome 126 kts.<hr></blockquote>
My mate Nigel says that they fly the climb out at 250 kts, not V2, so not too far away from a two engined climb out capability, so long as the gear is up, but if the gear is down, then no chance!
If that **** Modrey really thinks that a B747-400 will climb away at MTOW after losing TWO engines and with the gear still down, then I hope I never fly on any airline he has anything to do with.
IT WILL NOT.
How he knows exactly what damage the Concorde sustained, and when, is also open to debate, along with his crassly stupid statement that any other four engined type would have survived to a safe landing.
Sounds like a new hire who knows the square root of f$ck all about large jet operations!
[quote]So far as Vzrc goes, the perhaps the following data may be of interest. It is for the aircraft at MTOW (185,070 kg) at LHR, on an ISA day with zero wind:
V1: 164 kts
Vzrc-3e-Gear Down: c190 kts (so not routinely calculated)
VR: 193 kts
V2: 215 kts
Vzrc-2e-Gear Up: 260 kts (Calculated for every departure)
Vzrc-2e-Gear Down: 316 kts (Above the sea level Vmo of 300 kts!)
My final comment: Just look at the jump in Vzrc when you go from three engines to two engines. About 70 kts. If the gear is stuck down that becomes an awesome 126 kts.<hr></blockquote>
My mate Nigel says that they fly the climb out at 250 kts, not V2, so not too far away from a two engined climb out capability, so long as the gear is up, but if the gear is down, then no chance!
If that **** Modrey really thinks that a B747-400 will climb away at MTOW after losing TWO engines and with the gear still down, then I hope I never fly on any airline he has anything to do with.
IT WILL NOT.
How he knows exactly what damage the Concorde sustained, and when, is also open to debate, along with his crassly stupid statement that any other four engined type would have survived to a safe landing.
Sounds like a new hire who knows the square root of f$ck all about large jet operations!
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I seem to recollect a number of years ago a Continental 747 (-100 or -200) suffering a double eng failure whilst departing LGW 26L and only just clearing the hills and the village of Rusper to the west dumping fuel in the process. He had been able to get the gear up I believe so reducing the drag but I am sure the whole thing was more about luck than judgement.
atiuta - the certification of the VC10 was certainly to the exacting standards of the CAA at the time. The fact that it is still flown by non-civil users is nihil ad rem. But it was clearly not certificated to lose 2 engines simultaneously - and hence 50% of its thrust - in the same manner that, say, a 777 losing a single engine would be required to be today.
However, it was required to have sufficient excess thrust to survive the statistically assumed DEFATO likelihood placed upon it by virtue of the close-paired engine design. The difference between military and civil operation is merely that every military captain must practise a heavyweight double engine failure and 2-e approach in the simulator at least every 6 months - we have the luxury of sufficient simulator time available to be able to do so. Training captains also practise 2-engine work in the aircraft, but we only do so with the engines retarded to idle thrust once the landing gear is up, never simultaneously and never at a critical stage of flight; our student captains are required to cope with the simulated failure of an engine above V1 followed by a second failure once the aircraft is safely airborne, the landing gear is up and visual committal height has been achieved. Unlike the near simultaneous smacking closed of 2 HP cocks which Nigels used to have to cope with, so an old 8000+ hour BA VC10 man tells me!
The only 'beyond civil operation' which was once considered was the so-called Military Operating Standard which increased MTOW from 323000 to 340000 lbs if and when operationally essential. It came with various risk assessments; however, I don't think that it was ever used in anger and I don't think that it would ever be considered today.
Lastly may I ask that this pointless 'civil v. miltary' rhetoric is curtailed? It helps no-one, is unwarranted and utterly counter productive.
[ 02 January 2002: Message edited by: BEagle ]</p>
However, it was required to have sufficient excess thrust to survive the statistically assumed DEFATO likelihood placed upon it by virtue of the close-paired engine design. The difference between military and civil operation is merely that every military captain must practise a heavyweight double engine failure and 2-e approach in the simulator at least every 6 months - we have the luxury of sufficient simulator time available to be able to do so. Training captains also practise 2-engine work in the aircraft, but we only do so with the engines retarded to idle thrust once the landing gear is up, never simultaneously and never at a critical stage of flight; our student captains are required to cope with the simulated failure of an engine above V1 followed by a second failure once the aircraft is safely airborne, the landing gear is up and visual committal height has been achieved. Unlike the near simultaneous smacking closed of 2 HP cocks which Nigels used to have to cope with, so an old 8000+ hour BA VC10 man tells me!
The only 'beyond civil operation' which was once considered was the so-called Military Operating Standard which increased MTOW from 323000 to 340000 lbs if and when operationally essential. It came with various risk assessments; however, I don't think that it was ever used in anger and I don't think that it would ever be considered today.
Lastly may I ask that this pointless 'civil v. miltary' rhetoric is curtailed? It helps no-one, is unwarranted and utterly counter productive.
[ 02 January 2002: Message edited by: BEagle ]</p>
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It is curious to know why Scientific American has used information from a First Officer with a minor carrier, are we missing something here? Does this chap have knowledge and experience beyond his rank? Could they not find someone more experienced and knowledgeable?
I fear that the answer goes back to the days when Concorde first flew and the American authorities made every effort to keep it out, because it had not been made by an American company. This article seems to be another crude attempt to discredit Concorde and it is all the more surprising in such a reputable magazine.
I fear that the answer goes back to the days when Concorde first flew and the American authorities made every effort to keep it out, because it had not been made by an American company. This article seems to be another crude attempt to discredit Concorde and it is all the more surprising in such a reputable magazine.