The B29 Superfortress

Non-naval discussions about the Second World War. Military leaders, campaigns, weapons, etc.
Byron Angel
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Re: The B29 Superfortress

Post by Byron Angel »

OpanaPointer wrote: Sun Dec 18, 2022 2:03 pm Chuck Yeager flew against the MiG and beat it. Then he flew the MiG and won.

https://theaviationgeekclub.com/in-1953 ... tested-it/
I don't doubt it, OP; Yeager had shown himself to be an exceptional combat pilot in the ETO. But Mig-15s (I'm guessing driven by Russian pilots) nevertheless drove B29s from daylight bombing operations over North Korea; US straight wing jet fighter escorts simply could not keep the Migs away from the bombers and the 23mm + 37mm armament of the Migs proved lethal versus the B29s. B29s reverted to night intruder operations thereafter.

I have an account of the (big) climactic battle somewhere on a bookshelf. I'll try to track it down.

Happy Xmas,
B
Byron Angel
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Re: The B29 Superfortress

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Hi OpanaPointer,
Go here - https://apps.dtic.mil/sti/pdfs/ADA440137.pdf

Good coverage of FEAF/B29 operations in the Korean War. The decision to withdraw B29s from daylight operations come in the back half of the book, but the entier book is IMO worth a read.

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paul.mercer
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Re: The B29 Superfortress

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marcelo_malara wrote: Sun Dec 11, 2022 12:31 am
Byron Angel wrote: Sat Dec 10, 2022 5:16 pm Ran across an article last night that was highly critical of the B29 on several technical grounds -

- that the remote control fire control system was a calamitous unreliable failure, so bad that short circuits in the FC computer would cause one bomber to indiscriminately fire upon neighboring B29s in the formation. By the end of the war PTO B29s had had the remote control system and all armament removed, except for a manually operated twin-50cal tail position.

- that new model P&W R3350 radials were unreliable and subject to overheating at high altitudes and that any engine fire had a good chance of igniting the magnesium crankcase (think giant thermite grenade) that would burn at 5,000+ degrees F and destroy the wing spar in a matter of a few minutes. It is claimed that one of the reasons for altering to low altitude bombing operation over Japan was to reduce the load endured by the engines when flying at 30k+ ft. Another reason for low altitude operations was that daylight bombing accuracy from 30k+ ft was terrible - something like less than 1 in 3 a/c delivering their bombs within 5 miles of the target.

- that the fully pressurized fuselage of the B29 (a technical first) made both plane and crew subject to the dangerous effects of explosive decompression when hit by heavy AA.

- that, of 414 x B29s lost during the bombing campaign against Japan, only 1 in 3 was lost to enemy action; the other 2/3ds being lost to mechanical failures and accident. As well, the early raids over Japan were averaging loss rates of 8-10 pct.

Sounds crazy, I know. But the author seemed to be quite knowledgeable.

B
Hi Byron. I agree wtih some points.

-the engine, Wright, not P&W, was troublesome, this is a very well known fact, it led to many overheating failures. The cause was the massive increase in size from other extant engines, the displacement volume went from 2800 cubic inches in the previously biggest engine to 3350, and the power increased by 50%. But, when all this was ironed out, it turned to be a well liked engine, powering civilian aircraft as the Lockheed Constellation and Douglas DC-7.
I believe the B29 engines were barely up to the job. I remember seeing a documentary saying that if they had one engine failure on take off when fully loaded they went down
Byron Angel
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Re: The B29 Superfortress

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paul.mercer wrote: Wed Dec 21, 2022 10:31 am
marcelo_malara wrote: Sun Dec 11, 2022 12:31 am
Byron Angel wrote: Sat Dec 10, 2022 5:16 pm Ran across an article last night that was highly critical of the B29 on several technical grounds -

- that the remote control fire control system was a calamitous unreliable failure, so bad that short circuits in the FC computer would cause one bomber to indiscriminately fire upon neighboring B29s in the formation. By the end of the war PTO B29s had had the remote control system and all armament removed, except for a manually operated twin-50cal tail position.

- that new model P&W R3350 radials were unreliable and subject to overheating at high altitudes and that any engine fire had a good chance of igniting the magnesium crankcase (think giant thermite grenade) that would burn at 5,000+ degrees F and destroy the wing spar in a matter of a few minutes. It is claimed that one of the reasons for altering to low altitude bombing operation over Japan was to reduce the load endured by the engines when flying at 30k+ ft. Another reason for low altitude operations was that daylight bombing accuracy from 30k+ ft was terrible - something like less than 1 in 3 a/c delivering their bombs within 5 miles of the target.

- that the fully pressurized fuselage of the B29 (a technical first) made both plane and crew subject to the dangerous effects of explosive decompression when hit by heavy AA.

- that, of 414 x B29s lost during the bombing campaign against Japan, only 1 in 3 was lost to enemy action; the other 2/3ds being lost to mechanical failures and accident. As well, the early raids over Japan were averaging loss rates of 8-10 pct.

Sounds crazy, I know. But the author seemed to be quite knowledgeable.

B
Hi Byron. I agree wtih some points.

-the engine, Wright, not P&W, was troublesome, this is a very well known fact, it led to many overheating failures. The cause was the massive increase in size from other extant engines, the displacement volume went from 2800 cubic inches in the previously biggest engine to 3350, and the power increased by 50%. But, when all this was ironed out, it turned to be a well liked engine, powering civilian aircraft as the Lockheed Constellation and Douglas DC-7.
I believe the B29 engines were barely up to the job. I remember seeing a documentary saying that if they had one engine failure on take off when fully loaded they went down

Hi Paul,
Back on the 18th, I posted several web articles which discuss the operational travails of the R3350. IIRC, one of the issues was basing of the planes in locations with high temperature, high humidity tropical conditions. The problem was exacerbated by poor cowling design and shoddy manufacturing processes by the firm building the R3350. These technical problems were apparently worked out by the time of the Korean War, but plagued the B29 in 1945.

Happy Xmas to all,
B
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marcelo_malara
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Re: The B29 Superfortress

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paul.mercer wrote: Wed Dec 21, 2022 10:31 am
I believe the B29 engines were barely up to the job. I remember seeing a documentary saying that if they had one engine failure on take off when fully loaded they went down
Hi Paul. May be true, in some conditions. It all depends in the stall speed and max speed achievable with three engines, in a certain load condition. Obviously if the aircraft is so heavy that three engines can not provide a speed above stall, it would go down.
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marcelo_malara
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Re: The B29 Superfortress

Post by marcelo_malara »

A further complication with an out propeller engine, is that the propeller MUST be feathered in case of engine malfunction, which means that the chord of the individual blades are parallel to the direction of flight, in which condition they offer minimum drag. If this is not done, and sometimes the governor mechanism that sets the propeller pitch fails completely to do so, the propeller will passively windmill in the air stream, what generates huge drag that can not always be compensated by the remaining engines. This happened in some cases with the Boeing 377, powered by another difficult engine, the P&W R-4360.
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marcelo_malara
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Re: The B29 Superfortress

Post by marcelo_malara »

Both the R-3350 and R-4360 got bad press. Undoubtedly they were the most powerful engines of the era, and, may be partly for the US obsession for air cooled radials, were problematic due to high temperatures.
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Re: The B29 Superfortress

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marcelo_malara wrote: Wed Dec 21, 2022 6:59 pm Both the R-3350 and R-4360 got bad press. Undoubtedly they were the most powerful engines of the era, and, may be partly for the US obsession for air cooled radials, were problematic due to high temperatures.

Hi Marcelo,
The NASA document on the R3350 is enlightening (to me at any rate) and worth a read. it asserts that the problems with the early R3350s stemmed from cost-cutting changes made to the original design and location of the manufacturing facility chosen on the basis of cheap labor costs in an area with far too few qualified staff and employees. Not a pretty story. Greedy people are not reliable business partners.

When the manufacturing contract was finally taken away and transferred to a different corporation, the faults in the engine were rapidly resolved.

FWIW.

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marcelo_malara
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Re: The B29 Superfortress

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Hi Byron. The most difficult part in the construction of this engines (I believe) was the machining of the cooling fins, they are essential to dissipate the heat in the air. They are made from a single ingot, machined in one piece, encompassing the exterior of the cylinder and the fins, you can imagine the huge waste of aluminum removed to form the space between fins.

An interesting and unique evolution of the R-3350 was the Turbocompound version, in which there were 3 additional turbos, whose function was not to power the compressor, but to help turn the crankshaft, recovering power that would be wasted into the atmosphere. The turbocompund undoubtedly represents the high water mark in the big piston engine.

Regards
Byron Angel
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Re: The B29 Superfortress

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marcelo_malara wrote: Thu Dec 22, 2022 5:58 pm Hi Byron. The most difficult part in the construction of this engines (I believe) was the machining of the cooling fins, they are essential to dissipate the heat in the air. They are made from a single ingot, machined in one piece, encompassing the exterior of the cylinder and the fins, you can imagine the huge waste of aluminum removed to form the space between fins.

An interesting and unique evolution of the R-3350 was the Turbocompound version, in which there were 3 additional turbos, whose function was not to power the compressor, but to help turn the crankshaft, recovering power that would be wasted into the atmosphere. The turbocompund undoubtedly represents the high water mark in the big piston engine.

Regards

Hi Marcelo,
I recall reading claims that the manufacturing techniques required to produce cylinder heads with complex cooling fin arrays have become something of a "lost art". True? Untrue?

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Steve Crandell
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Re: The B29 Superfortress

Post by Steve Crandell »

From reading this thread I would tend to get the impression that the B-29 was a complete failure, and I don't believe that was the case.
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marcelo_malara
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Re: The B29 Superfortress

Post by marcelo_malara »

Byron Angel wrote: Fri Dec 23, 2022 4:18 am
Hi Marcelo,
I recall reading claims that the manufacturing techniques required to produce cylinder heads with complex cooling fin arrays have become something of a "lost art". True? Untrue?

B
For sure! But now you have numerical control lathes, that do not need operator expertise, just the detailed plans....
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marcelo_malara
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Re: The B29 Superfortress

Post by marcelo_malara »

Strangely enough, the Hughes XF-11, portrayed in the movie The aviator, with its streamlined nacelles, was powered by the the big R-4360. Look at the accident:

"An hour into the flight (after onboard recording cameras had run out of film), a leak caused the right-hand propeller controls to lose their effectiveness and the rear propeller subsequently reversed its pitch, disrupting that engine's thrust, which caused the aircraft to yaw hard to the right."

https://en.wikipedia.org/wiki/Hughes_XF-11
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marcelo_malara
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Re: The B29 Superfortress

Post by marcelo_malara »

Steve Crandell wrote: Fri Dec 23, 2022 4:57 am From reading this thread I would tend to get the impression that the B-29 was a complete failure, and I don't believe that was the case.
Far from that Steve, but it was a novel and advanced machine that had its troubles, may be a consequence of rushing her into service.
OpanaPointer
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Re: The B29 Superfortress

Post by OpanaPointer »

Anyone have an idea of how many aircraft, B-29 or otherwise, never left Iwo under their own power? Barn yard figures acceptable.
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