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#381
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It's happening! Um... sort of.
On Thu, 05 Jun 2014 06:38:42 +0100, Phil W Lee
wrote: John B. considered Wed, 04 Jun 2014 08:49:14 +0700 the perfect time to write: On Tue, 03 Jun 2014 04:25:16 +0100, Phil W Lee wrote: John B. considered Wed, 28 May 2014 07:57:25 +0700 the perfect time to write: On Tue, 27 May 2014 01:39:34 +0100, Phil W Lee wrote: Frank Krygowski considered Sun, 25 May 2014 22:51:30 -0400 the perfect time to write: The problem is that the exact fuel burn curve is different for every airframe and engine combination, and the Vulcan had not had any in-flight refueling capability since it's earliest days - and when it DID have it, it was intended to be used in combination with a single, high yield bomb or missile, of relatively light weight, where even brim-full tanks would give something like 8 or 9 tons lower gross weight, and with the earlier, slightly less powerful (and more economical) engines, not the Olympus 301s as fitted to all of the But the fuel use to gross weight equation is common to all aircraft and the Vulcan people must have know about it. After all a jet burns a vast amount of fuel just to get off the ground and to cruising altitude - which admittedly combines gross weight and operation in denser air, but still... You've just demonstrated how little you know about aerodynamics. The equation may be the same, but the variables that you have to plug into it are different (as already noted, for each airframe and engine fitment) - and they didn't have them. Stop being ridiculous. I said that the equation is common to all aircraft not the details. But if you say that the RAF flew the aircraft from 1956 when they apparently entered service until 1984 when they flew to the Falklands without ever considering the fuel use/weight characteristics of the aircraft, I can only say that the RAF must have gone down hill at a remarkable rate since the Big War ended. All the had were the (fairly coarse) graphs in the operations manual, which didn't go high enough. And the pocket calculator wasn't up to the job of extrapolating from them without the formulae from which they were derived. So not only was there no current data on what the fuel consumption at that loading would be, there never had been any. Perhaps not but certainly the effects of full fuel loads combined with large bomb loads must have been known. No, they weren't. No Vulcan had ever been flown at that total weight before, ever. And since so much fuel is normally burned in takeoff and climb, and the Vulcan had never had a properly functioning in-flight refueling system, the cruise consumption had never been established at anything even close to that weight, only at max takeoff weight minus takeoff and climb fuel burn, which is considerably lower. Slow down there. The RAF must have known what fuel consumption was for a max gross take off and climb to altitude as that is probably the most critical portion of an aircraft flight plan as it takes a considerable portion of the fuel load just to get off the ground and get to altitude. And I can't believe that there weren't air density or pressure tables to correlate that information. Twenty years before the Falkland flight those figures were in common use even for ground grunts. I can remember calculating temperature, vapor pressure and pressure altitude to calculate the horsepower output for a recip engine. The charts were even printed in the maintenance manual. The British bombers in WW II made some pretty long flights and I can't believe that fuel management was a mystery to them. Remainder snipped -- Cheers, John B. (invalid to gmail) |
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#382
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It's happening! Um... sort of.
On Thu, 05 Jun 2014 06:38:42 +0100, Phil W Lee
wrote: John B. considered Wed, 04 Jun 2014 08:49:14 +0700 the perfect time to write: On Tue, 03 Jun 2014 04:25:16 +0100, Phil W Lee wrote: John B. considered Wed, 28 May 2014 07:57:25 +0700 the perfect time to write: On Tue, 27 May 2014 01:39:34 +0100, Phil W Lee wrote: Snipped No, they weren't. No Vulcan had ever been flown at that total weight before, ever. And since so much fuel is normally burned in takeoff and climb, and the Vulcan had never had a properly functioning in-flight refueling system, the cruise consumption had never been established at anything even close to that weight, only at max takeoff weight minus takeoff and climb fuel burn, which is considerably lower. No Vulcan had EVER flown with a 21,000lb bomb load and full fuel tanks (and a Dash-10 Radar jamming pod - another addition made purely for the Black Back missions) until 31st April 1982, the date of the first Black Buck raid (well, it was about 4 am on the 1st of May when they hit their target). While I don't doubt your statement it does seem strange that fuel consumption versus gross weight tests were not flown during the initial testing of the aircraft so that at least an educated guess could have been made about what the effects of a 10 ton bomb load and a heavy fuel load would be. The initial testing was done with the original and less powerful engines, and the aircraft was always intended to be a nuclear deterrent, not a conventional bomber (so a lower payload). And the first attempt at in-flight refueling was abandoned because in all the early testing it proved to be unreasonably difficult to keep a Vulcan close enough to it's tanker without loss of stability in the wake turbulence - which is why it was removed. I'm not sure what changed to make it possible, other than a pressing need which changed the risk/benefit ratio. Maybe the Victors were modified to be able to use longer hoses in later developments, giving more separation between aircraft. It was converted in the course of the few weeks immediately before the raid to carry conventional 1,000lb bombs, accept the Dash-10 jamming pod, and to have it's in-flight refueling reactivated (most of the internal pipework and probe had been removed and the hole in the fuselage plugged with epoxy - which had to be carefully drilled out). And there was never any comparable aircraft type to derive data from - the "tin triangle" was and is unique in it's configuration - and so the discovery that it's fuel consumption rose quite so steeply with that last few thousand pounds of gross weight could not have been easily predicted except by test flying in that configuration, which was not something that there was time to do under the circumstances. They'd only refueled a Vulcan from a Victor successfully within the previous two weeks (after a desperate race to reinstate the in-flight refueling system), so the crews were only just qualified for the task in time. Conducting test flights to establish precise fuel burn rates was simply never considered - they just projected from what data they had, which seemed perfectly reasonable at the time. I can't comment on British practice but I was in the U.S.A.F. F-111b test program and fuel consumption use versus various gross loadings as well as various external configurations was flown so at least an educated guess of what will be the effect of adding some new device could be made. And I bet that the actual effect was not the same as the educated guess every time, was it? I don't know whether it was or not. But the aircraft was tested with clean wings, bare pylons, internal load, external load, combination load and they even tested every weapon in the inventory that might be carried in the aircraft. And when they dropped the dummy weapons even the "shapes" were instrumented so that the weapon drop path could be accurately calculated. Even the Bombay mounted 20 mm gatling gun was test fired (it blew the bomb doors off the first time :-) Particularly when you make several changes at once. They didn't make several changes at one time. Every test was instrumented and usually the instrumentation was changed for every test. Other than being in the middle of the desert it was a pretty easy life. Recover the aircraft and than sit around waiting for Instrumentation to do their job :-) That is, after all, why you do testing. In the case of Black Buck, they simply didn't have the time, and relied (wrongly, as it turned out) on the educated guess. Later missions modified the fuel plan, so that the Vulcan was flying most of the way with a lighter fuel load, only filling right up for the last run-in to target. The testing time was so short that they rigged a jump-seat for an in-flight refueling instructor to ride along on the raid, as the pilots had so little experience of it, and the risk of them being unable to tank in unknown weather was deemed to be too high a risk to take. In the words of Bob Tuxford AFC (the captain of the (reserve) long-shot final tanker: "We were flying in towering cumulous clouds, at night, your visual references for formating on the aircraft in front are reduced, therefore with the turbulence, the distracting lightning, St Elmo's Fire all around the cockpit windows, the whole process of achieving a stable contact and maintaining it for long enough to get the fuel on becomes much more difficult." But this wasn't a new discovery, for God's sake. The U.S. had been flying in air refueling, since 1948 - 49, 30 years before Black Buck and the British had known about it since Cobham plc. was formed in 1934 as " Flight Refueling Limited". In-flight refueling is about the most demanding task required of any pilot, and NONE of the pilots qualified for Vulcan bombers had any experience of it at all (as it wasn't relevant for the type) until less than 2 weeks before the mission was flown. In the same time frame, they had to learn bombing with conventional weapons (remember, the Vulcan was only ever intended to be a delivery vehicle for a nuclear deterrent, where anything within half a mile is a hit). Not one Vulcan crew had ever dropped an actual iron bomb before, although they were all proficient in the "idiot's loop" manoeuvre for delivering an H bomb. But that's a whole different game. In fact Bob Tuxford had to exchange roles with the other Victor on the final outbound leg of BB1, as they'd broken their refueling probe taking fuel from his Victor, which meant he could only take fuel from the other Victor, not give it to them, and.the fourth completed mission (BB6 - 3 & 4 were scrubbed) had to divert to Brazil for internment, owing to breaking it's refueling probe during it's recovery tanking. Breaking a probe is not something unique to the British use of the system. The U.S. has broken a number also :-) Well, of course - the probe is designed to be the weak link, and fail before anything else does or either aircraft is destabilised. But at that time the only tanker in the world capable of acting as both receiver and donor was the Victor. Without the ability to swap roles seamlessly with other tankers in the fleet, that broken probe would have aborted the mission (and the mission would not have been possible at all anyway). That flexibility meant that only damage to the probe on the Vulcan could not be accommodated by role-swaps within the fleet. I understand that lessons from that have been adopted by the US since then, in making their own tankers dual role capable. It should be noted that the Black Buck raids are still the longest bombing missions ever conducted from a single fixed base - longer missions conducted since have all had the benefit of forward positioned tankers, and some have not even returned to their base of origin. So it's not all that surprising that it was something of a learning experience for all concerned. The important thing is that they knew it was a learning experience, so noted the fuel remaining in the returning Tanker fleet was below expected reserves (well, what are reserves for?), did the sums, and knew to launch additional recovery tankers. So it worked, but it took 18 sorties by 12 tankers to get 1 Vulcan over the target, where they were expecting 16 sorties. by the same 12 tankers. There is a lot of information on-line about the raids, as well as in the book "Vulcan 607" by Rowland White, but you can't beat speaking directly to those involved. Not to demean the action as it set a record for long range bombing flights but I very much doubt that the level of ignorance in the RAF was as high as seems to be claimed. My guess was that the mission planners had a very good idea of how much weight could be carried at what gross load and planned the mission accordingly as well the approximate drag of any added devices. After all the first attempt was successful. You are calling the crews involved liars. The fact that Bob Tuxford (the tanker pilot) was awarded the Air Force Cross for his action in giving up his own fuel to the Vulcan, and risking his own aircraft's safe return, shows that it was well outside the expected mission parameters.. Do you think that all those who recommended him, considered the recommendation, and approved it were idiots? Given that I have recommended two blokes for medals and had the recommendation turned down on what I thought was a rather far out technicality I suspect that at least some of the people in the approval chain may be a bit off They would have all had access to the actual data from the mission. No decorations were awarded to the crews of any but Black Buck 1, because they didn't have to take the same risks to get the job done. The wiki report mentions 7 BB missions and while several had aircraft problems only the first seemed to have had fuel problems. Well, that's called learning from experience. Call BB1 the test flight if you like - in many ways, it was. As they say, no plan survives first contact with the enemy. And the much mentioned account of adding a chemical toilet... I worked on the B-29 and B-50's and their chemical toilet" weighed all of, say 10 lbs. :-) Hardly worth mentioning when one is hauling around 10 tons of bombs. You clearly don't know how cramped the crew compartment of a Vulcan is. Adding an extra crew member and a chemical toilet was a considerable achievement. I suppose they could have saved a bit of space by putting the extra crew member on the chemical toilet! Not that it makes any measurable difference to the fuel burn, of course. I must admit that in-light refueling is a scary enough concept for me as a private pilot in the first place (Deliberatly arranging a mid-air collision seems crazy enough to me, even before pumping fuel through the point of contact), without trying to do it in a thunderstorm with St. Elmo's Fire all over the plane, knowing that when you break connection there WILL be a brief leakage of jet fuel as the valves shut off (bad enough on the Victor/Vulcan combination that it obscured visibility through the windshield, and even on one occasion flamed out an engine). I believe that the Vulcan used the old probe and drogue system which is much more laid back then the modern system of flying up close... real close, to another airplane and being stabbed in the nose :-) But listening to the crews, many attempts at refueling are not successful and apparently it is not unusual for the receiver have to make several tries before he gets a full load. Again from listening to the crews it appears that the biggest problem is the rapid weight transfer to the receiver. There you are sitting there all trimmed up and motionless compared to the Tanker; and someone dumps several thousand pounds of fuel into you :-( -- Cheers, John B. (invalid to gmail) |
#383
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It's happening! Um... sort of.
On Mon, 09 Jun 2014 05:15:32 +0100, Phil W Lee
wrote: John B. considered Fri, 06 Jun 2014 07:24:04 +0700 the perfect time to write: On Thu, 05 Jun 2014 06:38:42 +0100, Phil W Lee wrote: John B. considered Wed, 04 Jun 2014 08:49:14 +0700 the perfect time to write: On Tue, 03 Jun 2014 04:25:16 +0100, Phil W Lee wrote: John B. considered Wed, 28 May 2014 07:57:25 +0700 the perfect time to write: On Tue, 27 May 2014 01:39:34 +0100, Phil W Lee wrote: Snipped No, they weren't. No Vulcan had ever been flown at that total weight before, ever. And since so much fuel is normally burned in takeoff and climb, and the Vulcan had never had a properly functioning in-flight refueling system, the cruise consumption had never been established at anything even close to that weight, only at max takeoff weight minus takeoff and climb fuel burn, which is considerably lower. No Vulcan had EVER flown with a 21,000lb bomb load and full fuel tanks (and a Dash-10 Radar jamming pod - another addition made purely for the Black Back missions) until 31st April 1982, the date of the first Black Buck raid (well, it was about 4 am on the 1st of May when they hit their target). While I don't doubt your statement it does seem strange that fuel consumption versus gross weight tests were not flown during the initial testing of the aircraft so that at least an educated guess could have been made about what the effects of a 10 ton bomb load and a heavy fuel load would be. The initial testing was done with the original and less powerful engines, and the aircraft was always intended to be a nuclear deterrent, not a conventional bomber (so a lower payload). And the first attempt at in-flight refueling was abandoned because in all the early testing it proved to be unreasonably difficult to keep a Vulcan close enough to it's tanker without loss of stability in the wake turbulence - which is why it was removed. I'm not sure what changed to make it possible, other than a pressing need which changed the risk/benefit ratio. Maybe the Victors were modified to be able to use longer hoses in later developments, giving more separation between aircraft. It was converted in the course of the few weeks immediately before the raid to carry conventional 1,000lb bombs, accept the Dash-10 jamming pod, and to have it's in-flight refueling reactivated (most of the internal pipework and probe had been removed and the hole in the fuselage plugged with epoxy - which had to be carefully drilled out). And there was never any comparable aircraft type to derive data from - the "tin triangle" was and is unique in it's configuration - and so the discovery that it's fuel consumption rose quite so steeply with that last few thousand pounds of gross weight could not have been easily predicted except by test flying in that configuration, which was not something that there was time to do under the circumstances. They'd only refueled a Vulcan from a Victor successfully within the previous two weeks (after a desperate race to reinstate the in-flight refueling system), so the crews were only just qualified for the task in time. Conducting test flights to establish precise fuel burn rates was simply never considered - they just projected from what data they had, which seemed perfectly reasonable at the time. I can't comment on British practice but I was in the U.S.A.F. F-111b test program and fuel consumption use versus various gross loadings as well as various external configurations was flown so at least an educated guess of what will be the effect of adding some new device could be made. And I bet that the actual effect was not the same as the educated guess every time, was it? I don't know whether it was or not. But the aircraft was tested with clean wings, bare pylons, internal load, external load, combination load and they even tested every weapon in the inventory that might be carried in the aircraft. And when they dropped the dummy weapons even the "shapes" were instrumented so that the weapon drop path could be accurately calculated. Even the Bombay mounted 20 mm gatling gun was test fired (it blew the bomb doors off the first time :-) So you should be capable of understanding that although the fuel burn for takeoff and climbout (starting at MTOW) was well established, the fuel burn in the cruise at MTOW was a complete unknown, particularly with pylons added to the aircraft for the jamming pod (the hardpoint in the wings had been included in anticipation of a standoff missile that never actually materialised) so the aircraft had never flown with even a pylon, never mind any external stores at all). That wasn't my point. I was arguing against the (apparently) supposed concept - which I might add that the Wiki account of the initial Black Buck operation certainly encourages, that the RAF was too stupid to understand the effects of flying an aircraft with a maximum gross weight at altitude. I contend that they weren't and did understand the effects. The Vulcan was never really intended to be a multi-role aircraft, but a single purpose delivery vehicle for an H bomb (with an option for the stand-off missile which as already mentioned, was never developed), so there was no reason to test a wide variety of configurations, and as in-flight refueling had never previously worked properly (even though it had been attempted many years previously), no reason to test for fuel burn in the cruise at any weight greater than MTOW-(takeoff+climbout). So it was well off the top of the graph which was the only reference available. A direct quote from "Vulcan 607": "The Victor planners knew the capabilities of their aircraft inside out. They needed watertight information from someone with comparable knowledge of the Vulcan. So they asked Monty: "What do you expect the Vulcan fuel consumption to be?" Monty and Bill Perrins got to work. Using the new photocopier, they copied and enlarged the fuel graphs from the Vulcan Operating Data Manual. The big delta's normal maximum take-off weight was 204,000lb. With full tanks, the bombs and the Dash 10 pod, the weight was going to be a lot higher than that. Off the graph. The ODM simply didn't include the figure they needed - a Vulcan wasn't supposed to try to take off at that weight. The curve on the fuel consumption graph they had was exponential, rather than linear. Monty and his co-pilot tried to extrapolate a figure from where the curve on the graph ended, and estimated 13,500lb per hour. They passed this figure on to the Victor planning team to weave into their refueling plan and wondered why it had fallen to them to figure it out. What, thought Monty, about the other resources available at HQ 1 Group?" They (the supposed experts with all the aircraft data) had actually been asked, and given the normal figure of 10,000lb per hour - which is normally correct for MTOW-(take-off+climbout), in the cruise, averaged over a flight of maximum range with (peacetime) legal reserves - but they didn't even know what that figure referred to. The ACTUAL figure comes from another quote from "Vulcan 607": "Wing Commander Colin Seymour's return to Wideawake provided Jerry Price and Red Rag Control with a nasty shock - hard evidence of how much fuel the Vulcan was burning. Half an hour after the four first-wave Victors had shown how little margin for error there was, the 55 Squadron boss's figures underlined it. In the thirty-four minutes between the first and second fuel transfers, 607 had burned 9,200lb of fuel. During that time, the overloaded bombers weight had never even dropped to its theoretical maximum, let alone below it. They were flying outside the aircraft's notional limits and the fuel burn reflected it: 16,250lb an hour. The BLACK BUCK fuel plan was going to the dogs. But while he could see big trouble ahead, there was little Price could actually do other than try to be ready for it when it happened. Particularly when you make several changes at once. They didn't make several changes at one time. Every test was instrumented and usually the instrumentation was changed for every test. Other than being in the middle of the desert it was a pretty easy life. Recover the aircraft and than sit around waiting for Instrumentation to do their job :-) All very relaxed if you have the time for it. In the Falklands War, there was under one month from the decision to re-purpose the Vulcan and Victor as long range conventional bombers and long range reconnaissance aircraft, re-train all the crews (none of the Vulcan crew had any in-flight refueling experience at all and there wasn't a single air-to-air-refueling instructor qualified on the Vulcan, nor had any of the crews ever dropped an iron bomb) adapt and convert the aircraft with added pylons (fabricated in the base workshops out of scrap angle iron, and faired in with fibreglass), reactivate the in-flight refueling, install conventional bomb racks (some even rescued from scrapyards) release/fusing panels and wiring, solve the problems of long-range /accurate/ navigation over a completely featureless south atlantic and train the navigators appropriately (which meant adding INS systems cannibalised from some obsolete VC10s the RAF had sitting around), move the whole fleet of Victor tankers/ reconnaissance aircraft and the Vulcans to Ascension Island, create a complete RAF base there under canvas, with planning, engineering, ordnance, refueling, stores, briefing, intelligence, communications, medical and accommodation facilities, and plan the mission. Just to add to the fun, Wideawake Airfied on Ascension Island only has a single runway and insufficient parking for the vast fleet of aircraft which needed to use it. OK, OK, I accept the fact that the RAF was comprised of many ignorant people who were quite happy to fly what must have seemed a suicide mission in support of an inconsequential war, and, again from what I read, was very inapt at doing it as in seven missions they managed to get one bomb on the target. -- Cheers, Jphn B. |
#384
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It's happening! Um... sort of.
On Thu, 12 Jun 2014 01:48:37 +0100, Phil W Lee
wrote: John B. considered Tue, 10 Jun 2014 07:09:26 +0700 the perfect time to write: On Mon, 09 Jun 2014 05:15:32 +0100, Phil W Lee wrote: John B. considered Fri, 06 Jun 2014 07:24:04 +0700 the perfect time to write: On Thu, 05 Jun 2014 06:38:42 +0100, Phil W Lee wrote: John B. considered Wed, 04 Jun 2014 08:49:14 +0700 the perfect time to write: On Tue, 03 Jun 2014 04:25:16 +0100, Phil W Lee wrote: John B. considered Wed, 28 May 2014 07:57:25 +0700 the perfect time to write: On Tue, 27 May 2014 01:39:34 +0100, Phil W Lee wrote: Snipped No, they weren't. No Vulcan had ever been flown at that total weight before, ever. And since so much fuel is normally burned in takeoff and climb, and the Vulcan had never had a properly functioning in-flight refueling system, the cruise consumption had never been established at anything even close to that weight, only at max takeoff weight minus takeoff and climb fuel burn, which is considerably lower. No Vulcan had EVER flown with a 21,000lb bomb load and full fuel tanks (and a Dash-10 Radar jamming pod - another addition made purely for the Black Back missions) until 31st April 1982, the date of the first Black Buck raid (well, it was about 4 am on the 1st of May when they hit their target). While I don't doubt your statement it does seem strange that fuel consumption versus gross weight tests were not flown during the initial testing of the aircraft so that at least an educated guess could have been made about what the effects of a 10 ton bomb load and a heavy fuel load would be. The initial testing was done with the original and less powerful engines, and the aircraft was always intended to be a nuclear deterrent, not a conventional bomber (so a lower payload). And the first attempt at in-flight refueling was abandoned because in all the early testing it proved to be unreasonably difficult to keep a Vulcan close enough to it's tanker without loss of stability in the wake turbulence - which is why it was removed. I'm not sure what changed to make it possible, other than a pressing need which changed the risk/benefit ratio. Maybe the Victors were modified to be able to use longer hoses in later developments, giving more separation between aircraft. It was converted in the course of the few weeks immediately before the raid to carry conventional 1,000lb bombs, accept the Dash-10 jamming pod, and to have it's in-flight refueling reactivated (most of the internal pipework and probe had been removed and the hole in the fuselage plugged with epoxy - which had to be carefully drilled out). And there was never any comparable aircraft type to derive data from - the "tin triangle" was and is unique in it's configuration - and so the discovery that it's fuel consumption rose quite so steeply with that last few thousand pounds of gross weight could not have been easily predicted except by test flying in that configuration, which was not something that there was time to do under the circumstances. They'd only refueled a Vulcan from a Victor successfully within the previous two weeks (after a desperate race to reinstate the in-flight refueling system), so the crews were only just qualified for the task in time. Conducting test flights to establish precise fuel burn rates was simply never considered - they just projected from what data they had, which seemed perfectly reasonable at the time. I can't comment on British practice but I was in the U.S.A.F. F-111b test program and fuel consumption use versus various gross loadings as well as various external configurations was flown so at least an educated guess of what will be the effect of adding some new device could be made. And I bet that the actual effect was not the same as the educated guess every time, was it? I don't know whether it was or not. But the aircraft was tested with clean wings, bare pylons, internal load, external load, combination load and they even tested every weapon in the inventory that might be carried in the aircraft. And when they dropped the dummy weapons even the "shapes" were instrumented so that the weapon drop path could be accurately calculated. Even the Bombay mounted 20 mm gatling gun was test fired (it blew the bomb doors off the first time :-) So you should be capable of understanding that although the fuel burn for takeoff and climbout (starting at MTOW) was well established, the fuel burn in the cruise at MTOW was a complete unknown, particularly with pylons added to the aircraft for the jamming pod (the hardpoint in the wings had been included in anticipation of a standoff missile that never actually materialised) so the aircraft had never flown with even a pylon, never mind any external stores at all). That wasn't my point. I was arguing against the (apparently) supposed concept - which I might add that the Wiki account of the initial Black Buck operation certainly encourages, that the RAF was too stupid to understand the effects of flying an aircraft with a maximum gross weight at altitude. I contend that they weren't and did understand the effects. Oh, they certainly understood the concepts, but had never had to apply them to that aircraft. And the Vulcan, as it turns out, increases it's fuel burn very steeply just above the point where the graph in the operating manual reaches. It's a matter of having to supply the extra lift by increasing the angle of attack, and the huge area of that vast delta wing being overexposed to the airflow with a steeper than designed nose-up attitude. The same effect is used on landing, to allow the Vulcan to operate off the same length runways as the Victor without using a braking parachute - they just keep the nose high for much longer in the roll-out, and use it as a massive air-brake. The Victor doesn't have anything like the wing area, so proportionately less aerodynamic braking available, despite the clamshell airbrake in the tail, hence it needing a 'chute where the Vulcan doesn't. The other problem was that they'd never operated Victor and Vulcan together as a formation over any distance - and the best economy cruise speeds are somewhat incompatible. The formation speed was therefore a compromise which raised fuel consumption on both. This was not as significant as the problem of operating continually at loads which were over (peacetime) maximum gross weight on the Vulcan though. Later missions dealt with both problems by not flying as a single formation and not overloading the Vulcan, reducing overall fuel burn considerably. And the wiki article is not a particularly good source on those missions (as you say, where the chemikhasi is barely mentioned in "Vulcan 607" it seems to have been an object of much fascination for the Wiki author, despite there being many other additions of far greater significance). The Vulcan was never really intended to be a multi-role aircraft, but a single purpose delivery vehicle for an H bomb (with an option for the stand-off missile which as already mentioned, was never developed), so there was no reason to test a wide variety of configurations, and as in-flight refueling had never previously worked properly (even though it had been attempted many years previously), no reason to test for fuel burn in the cruise at any weight greater than MTOW-(takeoff+climbout). So it was well off the top of the graph which was the only reference available. A direct quote from "Vulcan 607": "The Victor planners knew the capabilities of their aircraft inside out. They needed watertight information from someone with comparable knowledge of the Vulcan. So they asked Monty: "What do you expect the Vulcan fuel consumption to be?" Monty and Bill Perrins got to work. Using the new photocopier, they copied and enlarged the fuel graphs from the Vulcan Operating Data Manual. The big delta's normal maximum take-off weight was 204,000lb. With full tanks, the bombs and the Dash 10 pod, the weight was going to be a lot higher than that. Off the graph. The ODM simply didn't include the figure they needed - a Vulcan wasn't supposed to try to take off at that weight. The curve on the fuel consumption graph they had was exponential, rather than linear. Monty and his co-pilot tried to extrapolate a figure from where the curve on the graph ended, and estimated 13,500lb per hour. They passed this figure on to the Victor planning team to weave into their refueling plan and wondered why it had fallen to them to figure it out. What, thought Monty, about the other resources available at HQ 1 Group?" They (the supposed experts with all the aircraft data) had actually been asked, and given the normal figure of 10,000lb per hour - which is normally correct for MTOW-(take-off+climbout), in the cruise, averaged over a flight of maximum range with (peacetime) legal reserves - but they didn't even know what that figure referred to. The ACTUAL figure comes from another quote from "Vulcan 607": "Wing Commander Colin Seymour's return to Wideawake provided Jerry Price and Red Rag Control with a nasty shock - hard evidence of how much fuel the Vulcan was burning. Half an hour after the four first-wave Victors had shown how little margin for error there was, the 55 Squadron boss's figures underlined it. In the thirty-four minutes between the first and second fuel transfers, 607 had burned 9,200lb of fuel. During that time, the overloaded bombers weight had never even dropped to its theoretical maximum, let alone below it. They were flying outside the aircraft's notional limits and the fuel burn reflected it: 16,250lb an hour. The BLACK BUCK fuel plan was going to the dogs. But while he could see big trouble ahead, there was little Price could actually do other than try to be ready for it when it happened. Particularly when you make several changes at once. They didn't make several changes at one time. Every test was instrumented and usually the instrumentation was changed for every test. Other than being in the middle of the desert it was a pretty easy life. Recover the aircraft and than sit around waiting for Instrumentation to do their job :-) All very relaxed if you have the time for it. In the Falklands War, there was under one month from the decision to re-purpose the Vulcan and Victor as long range conventional bombers and long range reconnaissance aircraft, re-train all the crews (none of the Vulcan crew had any in-flight refueling experience at all and there wasn't a single air-to-air-refueling instructor qualified on the Vulcan, nor had any of the crews ever dropped an iron bomb) adapt and convert the aircraft with added pylons (fabricated in the base workshops out of scrap angle iron, and faired in with fibreglass), reactivate the in-flight refueling, install conventional bomb racks (some even rescued from scrapyards) release/fusing panels and wiring, solve the problems of long-range /accurate/ navigation over a completely featureless south atlantic and train the navigators appropriately (which meant adding INS systems cannibalised from some obsolete VC10s the RAF had sitting around), move the whole fleet of Victor tankers/ reconnaissance aircraft and the Vulcans to Ascension Island, create a complete RAF base there under canvas, with planning, engineering, ordnance, refueling, stores, briefing, intelligence, communications, medical and accommodation facilities, and plan the mission. Just to add to the fun, Wideawake Airfied on Ascension Island only has a single runway and insufficient parking for the vast fleet of aircraft which needed to use it. OK, OK, I accept the fact that the RAF was comprised of many ignorant people who were quite happy to fly what must have seemed a suicide mission in support of an inconsequential war, and, again from what I read, was very inapt at doing it as in seven missions they managed to get one bomb on the target. It only needed one on the runway, and anyone would have been ignorant of the performance and fuel burn when using an ancient aircraft for a purpose it was never intended to fulfil. Of course, considerable other damage was caused around the airfield by the bombs which hit elsewhere than on the runway, and the plan was never to do more than cut it - which they did on the first mission. All the subsequent missions had different objectives. But it was a mixture of ingenuity, bravery, hard work, and very careful planning that they succeeded. As for inconsequential, it was the cause of the eventual downfall of the military dictatorship in Argentina, so I doubt the relatives of all the disappeared would agree with you. I recommend you read the book which I've already referred to, and which I have not found any major inaccuracies in. It's available in Epub, Kindle, .pdf dead tree, and possibly other formats. I've pretty much given up reading war stories. In a couple of cases I was there, or knew someone that was there, and strangely the events I remember, or the other guy remembered, aren't the same thing written in the book. But as they say, history is written by the winners. -- Cheers, Jphn B. |
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