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#1
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Stretching WW2 Designs
I have been wondering why were so few WW2 aircraft designs "stretched" in order
to get more performance or payload? I know of the FW 190D which was stretched in the aft fuselage section in order to compensate for the installation of Jumo V 12 engine. Could other designs have benefitted from the technique of stretching in one way or another? Was it not done because the designs of the era were not suited to it? In recent years even reworked C-47s have been stretched. Was there simply no perceived need to stretch a design? John Dupre' |
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Recall that the inline Allison-powered P-40, developed from a radial-powered
predecessor, benefitted from such an aft-fuselage stretch, improving its fineness ratio, allowing for drag-reduction at the tailfin-rudder interface, and even allowing for fitment of a low-pressure variant of the RR Merlin. Had the stretched P-40 been given the Merlin 20 series engine, it could have become a serious high-altitude competitor. Ballasting was not usually a good solution. In the Spitfire, for example, ballasting was not very efficient when used in conjunction with the wider and heavier Griffons, rendering tricky handling and at least one test-establishment evaluation calling for cessation of production of Griffon variants for that reason. "IBM" wrote in message ... (JDupre5762) wrote in : I have been wondering why were so few WW2 aircraft designs "stretched" in order to get more performance or payload? SNIP |
#4
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On Sun, 22 Aug 2004 09:25:27 -0400, "Lawrence Dillard"
wrote: Recall that the inline Allison-powered P-40, developed from a radial-powered predecessor, benefitted from such an aft-fuselage stretch, improving its fineness ratio, allowing for drag-reduction at the tailfin-rudder interface, and even allowing for fitment of a low-pressure variant of the RR Merlin. Had the stretched P-40 been given the Merlin 20 series engine, it could have become a serious high-altitude competitor. The P-40F and L had the Merlin 20, and the L the stretched fuselage. I suspect you mean the Merlin 60 series, but as the first Packard Merlin 60-series scale production didn't begin until the second half of 1943, I can't see why the better Mustang airframe would have been passed over in favour of what everybody was calling an obselete airframe by 1942. The Merlin 20-engined P40's were out-performed by the Merlin 45-engined Spitfire V as interceptors to start with, so it made no sense to miss out on Spitfire IX/VIII production to use the engines concerned to produce Merlin 60-engined P-40s. Ballasting was not usually a good solution. In the Spitfire, for example, ballasting was not very efficient when used in conjunction with the wider and heavier Griffons, rendering tricky handling and at least one test-establishment evaluation calling for cessation of production of Griffon variants for that reason. That was an early variant of the F.21, where the evaluation establishment went beyond their remit, and where in any case the problem was fixed. Meanwhile, two Griffon-engined versions had previously gone into service, the first (the Mk XII) about eighteen months beforehand, and the second (the Mk XIV) with great success, being called the best single-engined fighter tested by the AFDU to that point. Gavin Bailey -- Apply three phase AC 415V direct to MB. This work real good. How you know, you ask? Simple, chip get real HOT. System not work, but no can tell from this. Exactly same as before. Do it now. - Bart Kwan En |
#5
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In article ,
Presidente Alcazar writes: On Sun, 22 Aug 2004 09:25:27 -0400, "Lawrence Dillard" wrote: Recall that the inline Allison-powered P-40, developed from a radial-powered predecessor, benefitted from such an aft-fuselage stretch, improving its fineness ratio, allowing for drag-reduction at the tailfin-rudder interface, and even allowing for fitment of a low-pressure variant of the RR Merlin. Had the stretched P-40 been given the Merlin 20 series engine, it could have become a serious high-altitude competitor. The P-40F and L had the Merlin 20, and the L the stretched fuselage. I suspect you mean the Merlin 60 series, but as the first Packard Merlin 60-series scale production didn't begin until the second half of 1943, I can't see why the better Mustang airframe would have been passed over in favour of what everybody was calling an obselete airframe by 1942. The Merlin 20-engined P40's were out-performed by the Merlin 45-engined Spitfire V as interceptors to start with, so it made no sense to miss out on Spitfire IX/VIII production to use the engines concerned to produce Merlin 60-engined P-40s. The P-40Fs and P-40Ls were also outperformed by various Allison-powered P-40 models as well. The single stage Merlins, while very, very good engines, weren't the leap in performance over its rivals that the 2-stage (60 series and up) engines were. Ballasting was not usually a good solution. In the Spitfire, for example, ballasting was not very efficient when used in conjunction with the wider and heavier Griffons, rendering tricky handling and at least one test-establishment evaluation calling for cessation of production of Griffon variants for that reason. That was an early variant of the F.21, where the evaluation establishment went beyond their remit, and where in any case the problem was fixed. Meanwhile, two Griffon-engined versions had previously gone into service, the first (the Mk XII) about eighteen months beforehand, and the second (the Mk XIV) with great success, being called the best single-engined fighter tested by the AFDU to that point. A couple of points here - the Griffon's frontal area wasn't that much more than the Spitfires, and it was notably wider only at the top of the cylinder blocks and heads. It wasn't that much longer overall, either, due to clever relocation of the engine accessories. While the Griffon Spits may have lost some of the Spitfire's perfect handling, it didn't lose much. and the Royal Navy was flying them from carrier decks into the 1950s. I couldn't have been that bad. (They chose to dump the Corsair and keep the Seafires, after all.) -- Pete Stickney A strong conviction that something must be done is the parent of many bad measures. -- Daniel Webster |
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#7
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#8
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Peter Stickney wrote:
In article , (JDupre5762) writes: I have been wondering why were so few WW2 aircraft designs "stretched" in order to get more performance or payload? I know of the FW 190D which was stretched in the aft fuselage section in order to compensate for the installation of Jumo V 12 engine. Could other designs have benefitted from the technique of stretching in one way or another? Was it not done because the designs of the era were not suited to it? In recent years even reworked C-47s have been stretched. Was there simply no perceived need to stretch a design? For "stretch" it's rather hard to beat the Spitfire. I began the war perfoeming at same level as its main competitors, and through continual redesign and refinement was still in peak form when the war ended. Of course, installed power had more than doubled, the tail was completely new, the feselage adn wing structure was completely redone, they reshaped teh fuselage for a bubble canopy, and made a fighter-bomber (And Carrier-borne Fighter-Bomber to boot) out of it. Spits stayed in RAF and RN service well after the war. Not too half bad. I think that transports didn't get the same treatment for a number of reasons. Most transport types didn't have options which afforded greatly increased power, and the load carrying performance of airplanes at that time was limited by available power more than anything else - you'd run out of payload weight available before you ran out of payload volume. Getting more payload required a whole new airplane. The C-46 was considerable bigger than the C-47 it supplanted. That being said, I suppose you could make a case that DOuglas did start a program of stretching transports with the DC-4-DC-6-DC-7 line. Speaking of transports, I'm surprised no one's brought up the Herk's recent 50th birthday. -- James... www.jameshart.co.uk |
#9
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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. |
#10
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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. |
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