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p1ngu666
09-18-2004, 11:01 PM
anyone know why the didnt fit more powerful engines, like the one from the jug for example?

i know they where turbo'ed and produced around 1200 each but thats roughly half a jug engine.

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p1ngu666
09-18-2004, 11:01 PM
anyone know why the didnt fit more powerful engines, like the one from the jug for example?

i know they where turbo'ed and produced around 1200 each but thats roughly half a jug engine.

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tenmmike
09-18-2004, 11:38 PM
best thing i can come up with is fuel consumtion

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Multimetal
09-18-2004, 11:49 PM
Just a guess, but as far as the B17, being a Boeing product, maybe by the time they could have put the Jug engine in there they were already planning the B-29 with its much more powerful engines? It was probably easier to look forward to the mass-production of a new type than to completely retrofit a plane that was already being produce like mad.

horseback
09-19-2004, 12:17 AM
Ignoring for the moment the major problems of redesign of the nacelles and turbosupercharger installation, consider that the R-2800 engine was already used in the P-47, B-26 Marauder, F4U Corsair, F6F Hellcat, and P-61 Black Widow.

There was some examination of conversion to Allison V-1710s, but the Fortress and Liberator had reached the end of their design lives, and their replacements were already in the pipeline, with much greater payloads and range.

cheers

horseback

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Blottogg
09-19-2004, 01:12 AM
Horseback, they built one prototype of the XB-38, but an engine fire resulted in the loss of the aircraft. USAF Museum link here:

http://www.wpafb.af.mil/museum/research/bombers/b3-87.htm

The site states that no further attempts were made because the Allisons were needed for "higher priority projects", but I suspect the points raised by you and Multimetal had at least as much to do with the decision. An interesting airplane though, kind of like the Lancaster Mk II in reverse.

Blotto

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p1ngu666
09-19-2004, 08:15 AM
hm true, ofcourse i dont know how much work replacing the engines would be
b29 was certainly a big step.

mind the jug engine had been around before the war. it would suck more fuel, but u could carry more fuel cos of extra power

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Aaron_GT
09-19-2004, 09:57 AM
They did massively uprate the B17 engines from the pre war versions to those in the G. Initially there were a lot of problems with engines up to and including 1942, sometimes with up to one third of planes turning back. These seem to have been largely fixed by mid 1943.

From E to G versions the changes were structually minor, so they could be accomodated in mass production. Changing engines would have upset production lines when replacements were urgently required. The next generations were already planned (e.g. B29) anyway.

chris455
09-19-2004, 10:29 AM
The question really becomes "why should they have?"
The poweplants in both Forts and Libs were more than up to the task they were asked to perform.........

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IL2-chuter
09-19-2004, 11:48 AM
How about prop size v. horsepower. The bigger engines would have required larger props than on the fighters to be as efficient as the existing engines. You want to move much more air more slowly on a bomber because of weight. Like how motorcycles can have 1/2 torque/horsepower ratio and cars are 1/1.

bottom line tho, is they would have burned to much gas . . . http://ubbxforums.ubi.com/images/smiley/16x16_smiley-sad.gif

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jenikovtaw
09-19-2004, 12:01 PM
I ask myself this question every time i see those planes with their teeny engines being escorted by jugs...its a mystery to me.

I guess fuel consumption/redesign difficulties were a key, and B29 was coming along nicely.

Also, when you have 1000 bombers available most nights for those huge day long raids, you dont need power, you have numbers.

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Aaron_GT
09-19-2004, 03:22 PM
The largest 8th AF raid was 1900 bombers, plus escorts on top of that. However by late 1944 1000 8th AF bombers in a raid was the norm and 1500 not unusual. Germany was also being hit by 1000 USAAF bombers from the Med and around 1000 RAF bombers at night.

By late 1944 despite some occasional large formations of LW fighters being put up few bombers were being lost, and often only to flak. 50mph greater TAS wouldn't have helped avoid flak and sheer numbers of planes of the existing versions without significant change were getting the job done. In the Pacific the B29 was needed due to the need to deliver greater tonnage over a longer distance than the B17 or B24. It needed bigger engines.

Interestingly a plane that DID need more powerful engines was the Boeing B-15 (which never wenn into production). Essentially the lessons learned from the B15 and 17 went irto the 29.

Much like the B17 initially the B29 had lots of engineers problems to begin with.

Post WW2 surplus B29s got the post war air passenger industry going and gave Boeing market dominance it has only lost in the past couple of years which is a very impressive run!

WOLFMondo
09-19-2004, 03:52 PM
Wasn't the engines on bombers somewhat different than there fighter counterparts? The merlins on Halifax's and Lancasters were different than those put on Spits, Hurricanes and Mustangs. (don't know what was different though).

Hell, they should have put a pair of Merlisn or Griffon 65's on the P38.

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