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#11
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Peter Stickney wrote in message ...
(Wasn't the Mk VIII actually based on the Mk III, which was to be a Merlin XX powered flavor that was abandined in favor of the Mk V when it was decided that the 2-speed Merlins were better off being put into Hurricanes? It's Rivet Counting, I know.) The answer is not quite, the Mk III prototype N3297 was used for trials on the merlin 60 series engines, but it was not a mark VIII prototype. If anything the mark III was in fact considered a mark IX prototype, along with R6700 (ex mark I) and AB196, AB197 both ex mark V, but N3297 was very non standard. The Air Ministry Certificate of design for the Spitfire Mk III, Merlin 61 conversion, N3297, and for R7600 "Spitfire Special" was issued on 1 April 1942. This was the mark IX. It appears AB196 and AB197 were the definitive prototypes. Technically the mark VIII was the mark VII without the pressure cabin, and some early versions even came with the extended wingtips of the mark VII. The mark VII prototype was AB450, originally built as a mark V, there was no official mark VIII prototype. Rivet count 123 and a third and counting. Geoffrey Sinclair Remove the nb for email. |
#12
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In article , Peter Stickney
writes In article , "Graham Salt" writes: SNIP "Peter Stickney" wrote in message Before the 2 stage Merlin appeared, The folks planning Brit War Production were getting ready to close down Merlin production in favor of its intended followons - the Sabre and the Vulture. You missed out 'YIKES!' here... (The Griffon was another Rolls private venture) It's a good thig that didn't happen. Mastery of understatement? Cheers, Dave -- Dave Eadsforth |
#13
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I'm not sure the B-54 would count since it never was built. OTOH, the
Tu-4 was stretched even further than a B-29; the Tu-80 & even bigger Tu-85, & to an extent, even the Tu-95. Tupolev had a number of other stretches proposed, but not built. The B-36 was stretched to the XC-99 & even the YB-60. I suppose the F-82 could be considered a stretch of the P-51. The Heinkel He-177 was developed into the He-274 or something. I think that was a stretch anyway. Sorry for any duplications from previous posts if I made any. "Kyle Boatright" wrote in message ... One aircraft which was stretched considerably was the B-29. It eventually morphed into the B-50, the B-54, the C-97, the KC-97, the TU-4, the Guppy, the Super Guppy, and probably a few more variants I've left off. |
#14
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"Peter Stickney" wrote in message ... In article , "Graham Salt" writes: I had originally thought of the Spitfire as a good example of stretching when this question first came up. However, on reflection, there was very little airframe stretch during the service life of this type which contributed to its ability to maintain parity in air combat. Essentially there were two major airframe changes (Mk.VIII and F.21), and two major engine ones (2-stage supercharging in Merlin 60's, and introduction of the Griffon). The basic Mk.I led to the Mk.II, Mk.V, and ultimately the Mk.IX. The Mk.IX was essentially an interim type allowing use of the series 60 Merlin engine before the definitive Merlin powered Mk.VIII was ready. With the introduction of the Griffon engine, the definitive Spitfire was to be the F.21 (and followed by F.22, and F.24). Again, to facilitate early introduction of the engine upgrade, an interim model was introduced, based on the Mk.VIII, and called the Mk.XIV. I have to disagree, a bit. (While the basic Spitfire Shape was retained, the Griffon engined Spits were much different, structurally. You couldn't make a Mk IX into a Mk XII with a conversion kit. The wing structure also evolved quite a bit, as well. (Wasn't the Mk VIII actually based on the Mk III, which was to be a Merlin XX powered flavor that was abandined in favor of the Mk V when it was decided that the 2-speed Merlins were better off being put into Hurricanes? It's Rivet Counting, I know.) Not sure what structural difference you are referring to, other than the provision of a different engine. I disagree with your comments about the Mk.XII. These were taken off the existing production lines, originally being built as Mk.V / Mk.IX, and later as Mk.VIII airframes. Apart from replacement of the tubular engine mounts with a girder mount to support the new powerplant, there was no other change. The early Mk.XII's had fixed tailwheels, the later ones retractable, indicating the airframes' original provenance.This was of course a factory conversion, not a field one, but nonetheless a simply solution to getting Griffon powered aircraft into the line quickly. The Mk.XII was the only type to employ the single stage blower Griffon. With regard to wing structure evolution, this did not really occur until the F.21 / 22 / 24 series. The Mk.VIII was a consolidation of the improvements that were put into the specialised Mk.VII high altitude fighter, although the pressurised cabin of the latter was not required or retained. But the most significant cause of the Spitfire's extended longevity was the remarkable work of Ernest Hive's team at Derby in forcing more and more power from the Merlin engine, and ultimately the successful installation of the Griffon engine. Without the engineering brilliance of Rolls Royce, the Spitfire, as a contemporary fighter, would have become obsolescent by 1941-42. T'warnt so mach Hives as Stanley Hooker, and his almost mystical ability to squeeze that last bit of efficiency out of a supercharger. Not only did he develop teh improved blowers for teh XX adn 40 series engines, but he came up with the 2-stage blower for the 60 Series and up, which was what transformed the Merlin from a good engine to a classic. Two stage blowers weren't new, by any means - the U.S. was very fond of them in the turbosupercharged R1820s and R1830s used in the B-17 and B-24, and the V1710 installations on the P-38 and the prototype P-39. (It was deleted from teh P-39 because there wasn't room for both the turbosupercharger and the requisite intercoolers, and installed drag on a tiny airframe like an Airacobra went through the roof.) and the mechanically driven second stages of the Wildcat's R1830 and the Hellcat & Corsair's R2800s - but they tended to be complicated and space-intensive, with teh auxiliarry stage blower driven at its own optimum speed by a separate drive. Hooker figured that if he sized things just right, he could have both blowers on the same shaft, turning at the same speed, and have them match throught th eperformace range of the engine. And he made it work, with nothing more than slide rules and graph paper. Before the 2 stage Merlin appeared, The folks planning Brit War Production were getting ready to close down Merlin production in favor of its intended followons - the Sabre and the Vulture. (The Griffon was another Rolls private venture) It's a good thig that didn't happen. -- I know much credit has been given to Hooker for his work on supercharging the Merlin, and this needs to be recognised. However, the point that I wanted to make was that the Rolls Royce team under Hives was something special, and so was his leadership. It wasn't just Hooker, but Cyril Lovesey who also worked on supercharging. Hooker was an academic mathematician, and what he did was remarkable. By his own admission, he was not an engineer (see his biography "Not Much of an Engineer"), but Lovesey and Rubbra (who managed the Merlin within Rolls Royce) were, and all formed an incredible team, without which the Merlin as a power plant for contemporary fighters was age limited. Graham Salt |
#15
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In article ,
"Graham Salt" writes: "Peter Stickney" wrote in message ... In article , "Graham Salt" writes: I had originally thought of the Spitfire as a good example of stretching when this question first came up. However, on reflection, there was very little airframe stretch during the service life of this type which contributed to its ability to maintain parity in air combat. Essentially there were two major airframe changes (Mk.VIII and F.21), and two major engine ones (2-stage supercharging in Merlin 60's, and introduction of the Griffon). The basic Mk.I led to the Mk.II, Mk.V, and ultimately the Mk.IX. The Mk.IX was essentially an interim type allowing use of the series 60 Merlin engine before the definitive Merlin powered Mk.VIII was ready. With the introduction of the Griffon engine, the definitive Spitfire was to be the F.21 (and followed by F.22, and F.24). Again, to facilitate early introduction of the engine upgrade, an interim model was introduced, based on the Mk.VIII, and called the Mk.XIV. I have to disagree, a bit. (While the basic Spitfire Shape was retained, the Griffon engined Spits were much different, structurally. You couldn't make a Mk IX into a Mk XII with a conversion kit. The wing structure also evolved quite a bit, as well. (Wasn't the Mk VIII actually based on the Mk III, which was to be a Merlin XX powered flavor that was abandined in favor of the Mk V when it was decided that the 2-speed Merlins were better off being put into Hurricanes? It's Rivet Counting, I know.) Not sure what structural difference you are referring to, other than the provision of a different engine. I disagree with your comments about the Mk.XII. These were taken off the existing production lines, originally being built as Mk.V / Mk.IX, and later as Mk.VIII airframes. Apart from replacement of the tubular engine mounts with a girder mount to support the new powerplant, there was no other change. The early Mk.XII's had fixed tailwheels, the later ones retractable, indicating the airframes' original provenance.This was of course a factory conversion, not a field one, but nonetheless a simply solution to getting Griffon powered aircraft into the line quickly. The Mk.XII was the only type to employ the single stage blower Griffon. Steel Longerons vs. Duralumin, for teh most part. That may sound trivial, but it wasn't. (Among other things, the longerons had to be hand-hammered into shape. This wasn't a big deal with the Dural parts, but bashing the steel into shape was a wholly different matter. With regard to wing structure evolution, this did not really occur until the F.21 / 22 / 24 series. The Mk.VIII was a consolidation of the improvements that were put into the specialised Mk.VII high altitude fighter, although the pressurised cabin of the latter was not required or retained. But the most significant cause of the Spitfire's extended longevity was the remarkable work of Ernest Hive's team at Derby in forcing more and more power from the Merlin engine, and ultimately the successful installation of the Griffon engine. Without the engineering brilliance of Rolls Royce, the Spitfire, as a contemporary fighter, would have become obsolescent by 1941-42. T'warnt so mach Hives as Stanley Hooker, and his almost mystical ability to squeeze that last bit of efficiency out of a supercharger. Not only did he develop teh improved blowers for teh XX adn 40 series engines, but he came up with the 2-stage blower for the 60 Series and up, which was what transformed the Merlin from a good engine to a classic. Two stage blowers weren't new, by any means - the U.S. was very fond of them in the turbosupercharged R1820s and R1830s used in the B-17 and B-24, and the V1710 installations on the P-38 and the prototype P-39. (It was deleted from teh P-39 because there wasn't room for both the turbosupercharger and the requisite intercoolers, and installed drag on a tiny airframe like an Airacobra went through the roof.) and the mechanically driven second stages of the Wildcat's R1830 and the Hellcat & Corsair's R2800s - but they tended to be complicated and space-intensive, with teh auxiliarry stage blower driven at its own optimum speed by a separate drive. Hooker figured that if he sized things just right, he could have both blowers on the same shaft, turning at the same speed, and have them match throught th eperformace range of the engine. And he made it work, with nothing more than slide rules and graph paper. Before the 2 stage Merlin appeared, The folks planning Brit War Production were getting ready to close down Merlin production in favor of its intended followons - the Sabre and the Vulture. (The Griffon was another Rolls private venture) It's a good thig that didn't happen. -- I know much credit has been given to Hooker for his work on supercharging the Merlin, and this needs to be recognised. However, the point that I wanted to make was that the Rolls Royce team under Hives was something special, and so was his leadership. It wasn't just Hooker, but Cyril Lovesey who also worked on supercharging. Hooker was an academic mathematician, and what he did was remarkable. By his own admission, he was not an engineer (see his biography "Not Much of an Engineer"), but Lovesey and Rubbra (who managed the Merlin within Rolls Royce) were, and all formed an incredible team, without which the Merlin as a power plant for contemporary fighters was age limited. No, it certainly wasn't just Hooker. And it wasn't strictly Rolls, either. Many of the 60 series and later improvements came from Packard, as well. There's plenty of credit to go around. Hives deserves a tremendous amount of credit for his vision, and his willingness to pursue officially unpopular directions. Hives was willing to back the 2-stage Merlin, and adandon the Vulture. (One wonders if he subscribed to the "Every ohter Rolls engine is good" conundrum) and push the Griffon as well. Given the travails of the Napier Sabre, that was wisdom indeed. (If it were a Curtiss-Wright Vulture, they'd have stuck to it through the entire war.) Hives was also the guy who got Rolls into the jet engine business, and Rover out. This was vital to British jet development. The Rover-Power Jets feuds had cost more than half a year in engine development and production. -- Pete Stickney A strong conviction that something must be done is the parent of many bad measures. -- Daniel Webster |
#16
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You must take into account that any such 'stretching' will affect
production, so unless a marked increase in performance is attained the stretch isn't going to happen. Wartime priorities all involve time, and losing production for a minor advantage isn't going to happen. The stretch to the 190D was because of the drastic engine change, involving more length and weight up front countered by a longer aft fuselage. The long wing on the TA152 was for high altitude work; the original BMW-190 couldn;t get up there and the 109G/K could but wasn't good enough by 44. BTW The B50 started out as the B54. Why the change I don't know, unless it was appropriation bills, playing games with which which changed some other designations (whence the F86D, formerly the XF95, ISTR). Walt BJ |
#18
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#19
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#20
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"Presidente Alcazar" wrote in message ... On Tue, 24 Aug 2004 08:47:13 -0400, (Peter Stickney) wrote: Well, some of that comes down to the exigencies of supply politics, e.g. the end of lend-lease and the termination of any substantive dollar-procurement programmes due to lack of dollars. I think the Seafire was an underestimated carrier fighter, but if I'd had the option in late 1945 I would have kept the FAA on (certainly) Hellcats and (possibly) Corsairs. Trouble is the double decked hangar ships (Implacable and Indefatigable) didnt have the hangar clearance to operate Corsairs and there were problems getting enough Hellcats. In fact the performance of the Seafires with the BPF in the fleet defence abd CAP role was quite good with landing accidents being much reduced as they gained experience. Keith ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= 19 East/West-Coast Specialized Servers - Total Privacy via Encryption =--- |
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