Earliest possible introduction of B-29 bomber?

Postwar, the Lockheed Constellation was far more successful than the Boeing Stratocruiser (B-50 with passenger area) for moving people cross country reliably, and that was with the Connies having TurboCompound R-3350s with PRTs that blew regularly

But Kelly Johnson was involved in the Connie.

Yenne, Bill, Lockheed. Greenwich, Connecticut: Bison Books, 1987. ISBN 0-517-60471-X pp 44-47
 
The Boeing Model 334A, with 4 R-2800s, was the B-29 lite, and was built in mock-up form before the spec. added a dozen tons to the weight.
The DC-6 was powered by 4 R-2800s and quite reliable, and long-lived. The DC-7 series was R-3350 TC powered, with higher performance and cost, and lower reliability. The proposed Douglas bomber, the XB-31, had Wrights and a long bomb bay. The Lockheed XB-30, built as a model, retained the low Connie wings, which meant a limited bomb bay.

When it comes to toting bombs to distant places, anything goes. When it comes to carrying THE BOMB, it's difficult to say that anything short of silverplate would do. A bomber with 6 R-2800s would make sense if and only if you knew that Wright was going to pick that moment to let their company fall apart.

I googled "food that makes you smarter". I like salmon and spinach, but not avocados. Perhaps some dark chocolate. Back then, they didn't have google.
 
One issue with the Constellation was that, for aerodynamic efficiency,it had an area ruled fuselage. This was unlike most large aircraft of the time which basically had cylindrical "tube" fuselages for most of their length. This latter sort of design allowed for expansion simply by inserting a plug or putting in a bulge. With an area ruled fuselage you need to redo the entire design to enlarge the fuselage.

Richard Whitcomb hadn't theorized area rule yet, which was in response to transsonic speed issues. The Lockheed 749 became the Lockheed 1049 with an 18 foot plug. They did it on porpoise.
 

CalBear

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I can only go by USAAF assessments. Some of the things suggested about cowlings are not relevant if the R-3350s blow oil and the engines seize up. Fly at 30,000 feet? Only if the crew is wearing heated sheepskins. The plane's self defense system did not work.

B-17s did work. They were being shifted from Europe to supplement the B-29s for Downfall.

The shackling for bombs was different for the Dominator. It could not carry Fat Man. And as noted, it would never survive a drop.
Actually most 8th AF crews being sent to the PTO were being transitioned to the B-29.
 

CalBear

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One question that has not been addressed here is WHY Boeing and the Air Corps insisted on the R-3350 for both the B-29 and B-32. Boeing had actually created a design, the Model 341, with R-2800 engines as an internal company project, this design had to be reworked to meet the requirements of the 1940 VLR "superbomber"(Request for data R-40-B) design requirements. Interestingly, all four of the R-40-B designs submitted the XB-29 (Boeing), XB-30 (Lockheed), XB-31 (Douglas) and XB-32 (Consolidated) used the R-3350 engine.

One issue appears to have been weight. As designed the original R-3350 had a power:weight of 0.9shp:lb. It was, however, later discovered that due to the massive size of the 16.5' prop used on the B-29 the standard shaft mounted vibration dampers common to radial engines were insufficient. The extremely large prop created a secondary vibration that required the addition of a total of eight counter-balancing weights (4 each at the front and rear of the shaft) reducing the eventual ratio to 0.75:1.

I have been unable find anything definitive on the engine issue beyond the fact that Boeing had to change engines to meet the R-40-B requirement and that all competitors for the VLR project used the same engine.
 

Archibald

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Very interesting. We need a TL with the model 341 going past the mockup stage. Perhaps at the expense of P-47s, since those R-2800s must come from somewhere... Is there any pictures of the mockup ?
 
One question that has not been addressed here is WHY Boeing and the Air Corps insisted on the R-3350 for both the B-29 and B-32. Boeing had actually created a design, the Model 341, with R-2800 engines as an internal company project, this design had to be reworked to meet the requirements of the 1940 VLR "superbomber"(Request for data R-40-B) design requirements. Interestingly, all four of the R-40-B designs submitted the XB-29 (Boeing), XB-30 (Lockheed), XB-31 (Douglas) and XB-32 (Consolidated) used the R-3350 engine.

One issue appears to have been weight. As designed the original R-3350 had a power:weight of 0.9shp:lb. It was, however, later discovered that due to the massive size of the 16.5' prop used on the B-29 the standard shaft mounted vibration dampers common to radial engines were insufficient. The extremely large prop created a secondary vibration that required the addition of a total of eight counter-balancing weights (4 each at the front and rear of the shaft) reducing the eventual ratio to 0.75:1.

I have been unable find anything definitive on the engine issue beyond the fact that Boeing had to change engines to meet the R-40-B requirement and that all competitors for the VLR project used the same engine.

Well, as much as I can understand it, the four separate manufacturers who were capable of designing such a bomber rapidly came to the conclusion that the minimum requirement for power was 6000-7000 kWatts. Somewhere in the neighborhood of 8000-8,800 HP. The problem with vibration dampers could have been solved with six blade scimitar props, but that requires 1970s aerodynamics and in 1940 the science isn't there. The only American engine close to specs for a four engine specification as called for R-40-B is the Wright R-3360. The Pratt corncob (R-4360) was not ready and would not be until 1946.
 
Very interesting. We need a TL with the model 341 going past the mockup stage. Perhaps at the expense of P-47s, since those R-2800s must come from somewhere... Is there any pictures of the mockup ?
Then the Dodge Chicago Engine plant would have been making lots of R-2800s, since they wouldn't have to redesign most of the engine like they did with the Curtiss Wright R-3350 so it would be somewhat reliable.
 
F4U (and F6F and P-61) were outfitted with 2-stage supercharged R-2800, contrary to eg. B-26, F7F or F8F with 1-stage S/C. There was no 2-stage supercharged R-3350 in production.
1-stage S/Charged R-3350 were with critical atitude of 16000 ft.



Longer ranged Lancaster would've been an even greater bomber :)
Critical altitude of turboed R-3350s was 25000 ft, same as turboed R-2800 in 1942-44.

Imagine the NIH-Fest from the USAAF flying licence built Lancasters, although with a little extra money and resources a Lincoln/ Shackleton variant might be an option.
(Faster and longer ranged)
 

CalBear

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Very interesting. We need a TL with the model 341 going past the mockup stage. Perhaps at the expense of P-47s, since those R-2800s must come from somewhere... Is there any pictures of the mockup ?
It never went beyond the project design phase since it was overtaken by events. The slightly earlier Boeing Project 334A was advanced to mock-up internally by Boeing but I am unaware of any images being available.

The problem with R-2800 designs appears to be that they can't do the job, hence the universal decision to go to the R-3350 as the VLR engine choice.

There is a reason that the B-29 is accepted as the ultimate piston engine bomber. If one starts to remove the basic elements of the design, starting with less efficient engines, elimination of full pressurization, proper streamlining, and any of the many other innovations that litter the B-29's design the result is a faster debut of the B-29. It is the introduction of an improved B-17. While that is not in itself a bad thing, it is also not the breakthrough that the B-29 represents, it is a better 1930s bomber.

Pressurization was a critical element of the B-29 design. Pressurization allows longer flights at altitude with far less loss of crew effectiveness. It isn't a matter of comfort, it is a matter of the limitations of the human body. People routinely die at over 8,000 meters, just from being there; climbers call 8,000 meters and up the "death zone" (the human body can often adapt to the conditions, given time, but the crews of WW II bombers didn't have that time). Pressurization is what allows 12 hour flights at 30,000 feet.

The B-29 was pretty much a production miracle. The B-32 was never seen as close to the capability of the B-29, yet it was, by most measures the second most advanced bomber of the war. The Air Corps actually cancelled the program in 1943 as the aircraft was seen as obsolescent, before restarting it a month later
 
One question that has not been addressed here is WHY Boeing and the Air Corps insisted on the R-3350 for both the B-29 and B-32. Boeing had actually created a design, the Model 341, with R-2800 engines as an internal company project, this design had to be reworked to meet the requirements of the 1940 VLR "superbomber"(Request for data R-40-B) design requirements. Interestingly, all four of the R-40-B designs submitted the XB-29 (Boeing), XB-30 (Lockheed), XB-31 (Douglas) and XB-32 (Consolidated) used the R-3350 engine.

One issue appears to have been weight. As designed the original R-3350 had a power:weight of 0.9shp:lb. It was, however, later discovered that due to the massive size of the 16.5' prop used on the B-29 the standard shaft mounted vibration dampers common to radial engines were insufficient. The extremely large prop created a secondary vibration that required the addition of a total of eight counter-balancing weights (4 each at the front and rear of the shaft) reducing the eventual ratio to 0.75:1.

I have been unable find anything definitive on the engine issue beyond the fact that Boeing had to change engines to meet the R-40-B requirement and that all competitors for the VLR project used the same engine.

The United States spent vast amounts of money on the B-29. Prior to the war they had been working on the B-36 would it not have been a better idea to work on the B-36 it would not just be used in Europe for dropping a nuke but you have a big Pacific ocean that were flying planes back and forth does anyone know why that Avenue is not followed?
 
The United States spent vast amounts of money on the B-29. Prior to the war they had been working on the B-36 would it not have been a better idea to work on the B-36 it would not just be used in Europe for dropping a nuke but you have a big Pacific ocean that were flying planes back and forth does anyone know why that Avenue is not followed?

Which war? Prior to WWII, Consolidated had to work on the B-24. Baby steps.
 

CalBear

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Very interesting. We need a TL with the model 341 going past the mockup stage. Perhaps at the expense of P-47s, since those R-2800s must come from somewhere... Is there any pictures of the mockup ?
It never went beyond the project design phase since it was overtaken by events. The slightly earlier Boeing Project 334A was advanced to mock-up internally by Boeing but I am unaware of any images being available.

The problem with R-2800 designs appears to be that they can't do the job, hence the universal decision to go to the R-3350 as the VLR engine choice.

There is a reason that the B-29 is accepted as the ultimate piston engine bomber. If one starts to remove the basic elements of the design, starting with less efficient engines, elimination of full pressurization, proper streamlining, and any of the many other innovations that litter the B-29's design the result is a faster debut of the B-29. It is the introduction of an improved B-17. While that is not in itself a bad thing, it is also not the breakthrough that the B-29 represents, it is a better 1930s bomber.

Pressurization was a critical element of the B-29 design. Pressurization allows longer flights at altitude with far less loss of crew effectiveness. It isn't a matter of comfort, it is a matter of the limitations of the human body. People routinely die at over 8,000 meters, just from being there; climbers call 8,000 meters and up the "death zone" (the human body can often adapt to the conditions, given time, but the crews of WW II bombers didn't have that time). Pressurization is what allows 12 hour flights at 30,000 feet.

The B-29 was pretty much a production miracle. The B-32 was never seen as close to the capability of the B-29, yet it was, by most measures the second most advanced bomber of the war. The Air Corps actually cancelled the program in 1943 as the aircraft was seen as obsolescent, before restarting it a month later
The United States spent vast amounts of money on the B-29. Prior to the war they had been working on the B-36 would it not have been a better idea to work on the B-36 it would not just be used in Europe for dropping a nuke but you have a big Pacific ocean that were flying planes back and forth does anyone know why that Avenue is not followed?
B-36 was not ready for prime time. Its teething problems make the issues of the B-29 and B-32 combined look like a bad paint job.

The Air Force never did figure out a way to properly cool the engines, resulting in regular engine fires (this wasn't helped by the remarkable tendency to foul plugs, both with oil and with lead, the lead a result of the, wait for it... 143 octane fuel required by the engine). The engines were such oil hogs that the bomber had a separate 100 GALLON tank for engine oil that was filled to the brim before each flight.

Had the Air Corps waited for the B-36 to be ready enter service rather than driving on with the B-29, the Home Islands would have been invaded (and the supply situation on the Home Islands would have been much better, one of the often overlooked parts of the strangulation of the Home Islands was the massive mining campaign conducted by the B-29 force).
 
It never went beyond the project design phase since it was overtaken by events. The slightly earlier Boeing Project 334A was advanced to mock-up internally by Boeing but I am unaware of any images being available.

The problem with R-2800 designs appears to be that they can't do the job, hence the universal decision to go to the R-3350 as the VLR engine choice.

There is a reason that the B-29 is accepted as the ultimate piston engine bomber. If one starts to remove the basic elements of the design, starting with less efficient engines, elimination of full pressurization, proper streamlining, and any of the many other innovations that litter the B-29's design the result is a faster debut of the B-29. It is the introduction of an improved B-17. While that is not in itself a bad thing, it is also not the breakthrough that the B-29 represents, it is a better 1930s bomber.

Pressurization was a critical element of the B-29 design. Pressurization allows longer flights at altitude with far less loss of crew effectiveness. It isn't a matter of comfort, it is a matter of the limitations of the human body. People routinely die at over 8,000 meters, just from being there; climbers call 8,000 meters and up the "death zone" (the human body can often adapt to the conditions, given time, but the crews of WW II bombers didn't have that time). Pressurization is what allows 12 hour flights at 30,000 feet.

The B-29 was pretty much a production miracle. The B-32 was never seen as close to the capability of the B-29, yet it was, by most measures the second most advanced bomber of the war. The Air Corps actually cancelled the program in 1943 as the aircraft was seen as obsolescent, before restarting it a month later

B-36 was not ready for prime time. Its teething problems make the issues of the B-29 and B-32 combined look like a bad paint job.

The Air Force never did figure out a way to properly cool the engines, resulting in regular engine fires (this wasn't helped by the remarkable tendency to foul plugs, both with oil and with lead, the lead a result of the, wait for it... 143 octane fuel required by the engine). The engines were such oil hogs that the bomber had a separate 100 GALLON tank for engine oil that was filled to the brim before each flight.

Had the Air Corps waited for the B-36 to be ready enter service rather than driving on with the B-29, the Home Islands would have been invaded (and the supply situation on the Home Islands would have been much better, one of the often overlooked parts of the strangulation of the Home Islands was the massive mining campaign conducted by the B-29 force).
I was under the impression that they were working on the B-36 and put it on the back burner when it was obvious that Great Britain was not going to fold. Like a lot of aviation in World War II it was a mechanical Marvel therefore you're bound to have a lot of bugs.
 
I was under the impression that they were working on the B-36 and put it on the back burner when it was obvious that Great Britain was not going to fold. Like a lot of aviation in World War II it was a mechanical Marvel therefore you're bound to have a lot of bugs.

Project was moved from San Diego to Fort Worth after the initial mockup was done in 1942, and then priority lowered
 

CalBear

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I was under the impression that they were working on the B-36 and put it on the back burner when it was obvious that Great Britain was not going to fold. Like a lot of aviation in World War II it was a mechanical Marvel therefore you're bound to have a lot of bugs.
They were constantly shifting priorities.

There are some hard figures however. The first R-4360-5 test engine did not even reach Convair until October of 1943 and didn't actually run until early January of 1944. That was engine # 1. When it reached Convair, it turned out that the engine was heavier than spec'd out. The design team even considered going to an entirely different Lycoming BX liquid cooled design until the company cancelled the BX program. The design team was so unhappy with the R-4360's weight that they were ready to dump it for an entirely different kind of engine, something that would have required a base redesign of the entire aircraft. They couldn't wind tunnel the design until the engine issue was settled (forget about priorities for the test facility, they hadn't even made a final decision on the engine). In the end they adopted the R-4360.

The first XB-36 was a disaster. There were exactly three runways in the CONUS with runways that could handle the aircraft (apparently the landing gear engineering team miss the day that ground pressure was discussed in school). The aircraft couldn't make it to 30K for anything but a dash because the engines overheated so badly. Worst of all, the design was basically a 1941 set up. The original nose lacked defensive guns, requiring the whole nose section to be redesigned, with the addition of gunnery radar that increased weight of the aircraft still further.

I won't even go into the whole SecDef Johnson issue.

Not ready for prime time.
 
There were exactly three runways in the CONUS with runways that could handle the aircraft (apparently the landing gear engineering team miss the day that ground pressure was discussed in school)

wasn't a new problem, the XB-19 had same limitation, and also had huge, single main wheels. And it was only 160,000lbs
 
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