B-29 Modifications

[Zipper730]

I remember seeing different figures in the post-war periods for range & payload for the B-29. It would also appear that the altitude seemed to have gone up. I'm curious what changes were made on the B-29 during and after the war?

Particularly variables that affected speed.

Airframes , M MIflyer , MiTasol

 

[FLYBOYJ]

Well aside from the Silverplate modifications, this is where the B-29 ultimately went

Boeing B-50 Superfortress - Wikipedia

 

[Zipper730]

Well aside from the Silverplate modifications, this is where the B-29 ultimately went

No, I know the B-50 was the ultimate result of the B-29. What I was talking about was the various modifications made to the B-29's during operational use (which include Silverplate), and into the post war (not including B-50's).

I remember seeing a video which involved the RAF discussing interceptor attacks which involved jet-fighters flying at bombers from the sides and from behind, then curving into and then coming head-on against them. For this test, a series of B-29's were used for the test. The B-29's were given speed figures that seemed higher than the ones cited in WWII.

I'm curious if changes were made to the cowlings, the engines, the turbochargers, and stuff?

 

[FLYBOYJ]

No, I know the B-50 was the ultimate result of the B-29. What I was talking about was the various modifications made to the B-29's during operational use (which include Silverplate), and into the post war (not including B-50's).

I remember seeing a video which involved the RAF discussing interceptor attacks which involved jet-fighters flying at bombers from the sides and from behind, then curving into and then coming head-on against them. For this test, a series of B-29's were used for the test. The B-29's were given speed figures that seemed higher than the ones cited in WWII.

I'm curious if changes were made to the cowlings, the engines, the turbochargers, and stuff?

There were some mods done to the B-29 in the post war (I believe they were relatively minor) but ultimately the "goal" was the "B-29D" which eventually became the B-50. The re-designation was done to get money appropriated to new aircraft programs.

 

[GrauGeist]

The post-war B-29D, which led to the B-50, had the Pratt & Whitney R-4360 engines (rated at 3,500hp each), as opposed to the Wright R-3350 engines (rated at 2,200hp each).
Perhaps this is the B-29 you're thinking of?

 

[FLYBOYJ]

There were operational mods done to late production B-29 that were more role related too.

 

[Graeme]

RAF discussing interceptor attacks which involved jet-fighters flying at bombers from the sides and from behind, then curving into and then coming head-on against them. For this test, a series of B-29's were used for the test.

That sounds like the Meteor interception trials with 616 Squadron - but they were against B-24s...

 

[Zipper730]

There were some mods done to the B-29 in the post war (I believe they were relatively minor)

Such as?

There were operational mods done to late production B-29 that were more role related too.

Like the 300 that were built without the gun-computer for fire-bombing missions?

 

[MIflyer]

Some of the B-29's had most of their guns removed for the nighttime fire raids. By Korea the guns were back, but maybe they used some of the ones with only tail guns for those tests.

 

[Skyediamonds]

I heard about "Silverplate" but never knew what exactly was involved. Can anyone briefly describe?
Gary

 

[GrauGeist]

"Silverplate" was the delivery program for the Atom bombs destined for Japan.

The size and weight of the bombs (there were four - one was tested state-side and two if the three remaining were deployed on Japan) dictated airframe modifications as well as additional instrumentation installed on all the bombers in the B-29 composite group.

 

[manta22]

I heard about "Silverplate" but never knew what exactly was involved. Can anyone briefly describe?
Gary

In the '70s a forward section of a B29 fuselage arrived in a local Tucson salvage yard. Nose art identified it as "The Dutchess" and the salvage yard owner maintained that it had been one of the planes involved in the A-bomb program. If this were true it should have been placed in the Pima Air Museum or some other place to preserve it. I undertook to try to trace The Dutchess' history and talked to Paul Tibbets on the phone for 45 minutes about it. Tibbets was friendly and quite helpful and gave me some things to check to see if it had been one of the 509th Composite Group's planes. The most significant feature was the single bomb-bay rather than two shorter bomb bays on a standard production B29. He also related that many other changes were also made to the Wichita production run of these special versions. He gave me Chuck Sweeney's phone number and I talked to him as well. He did not know of a B29 named The Dutchess but said that it might have been one of the Los Alamos research planes.

I never did find out the history of The Dutchess B29 and it disappeared from the salvage yard thereafter.

 

[FLYBOYJ]

From wiki:

Silverplate - Wikipedia

 

[Juanita]

"The most significant feature was the single bomb-bay rather than two shorter bomb bays on a standard production B29."

Very interesting to hear this remark about the bomb-bay doors. Did he go into detail?
I have drawn several Silverplate examples and I didn't notice a change to the doors. Admittedly many of the photos are post-WW2 but they all seem to have the radar fitted (radar sits between the two bomb bays).
Would be very interested to hear more...I'll modify my artworks if they have an error.

There is a link to one of the artworks (yes, I know, the nose art is incorrect - if flew the mission with no nose art, and the full Bockscar artwork was applied soon after the mission)


Juanita

 

[Juanita]

Just for fun. Here is a size comparision between the largest Allied bomber of WW1 (Handley Page V/1500) and a B-29.
The V/1500 was designed to bomb Berlin but the war ended before the type had flown any combat missions.

 

[GreenKnight121]

The B-29B was a lighter version, with improved performance. 311 were built. Boeing B-29B Superfortress

Six B-29s were fitted with R-3350-CA-2 fuel injection engines and the revised "Andy Gump" nacelles that were intended for late production B-29As in a program to service test these new engine installations. These aircraft were redesignated YB-29J. Some of these YB-29Js were used for photo-reconnaissance work as RB-29J. Boeing YB-29J Superfortress

Info from Boeing B-29 Superfortress by Joe Baugher


The single bomb bay was only on the initial test Silverplate B-29 - all of the operational ones had the standard bomb bay configuration. Silverplate

B-29-5-BW 42-6259 (referred to as the "Pullman airplane" from an internal code name assigned it by the Engineering Division of Army Air Forces Materiel Command) was delivered to the 468th Bombardment Group at Smoky Hill AAB, Kansas, on 30 November 1943, and flown to Wright Field on 2 December.

Modifications to the bomb bays of 42-6259 were extensive and time-consuming. Its four 12-foot (3.7 m) bomb bay doors and the fuselage section between the bays were removed and a single 33-foot (10 m) bomb bay configured. The length of the initial gun-type bomb shape was approximately 17 feet (5.2 m), necessitating that it be carried in the aft bomb bay, with some of its length protruding into the forward bay. The implosion-type bomb was mounted in the forward bay.[8] New bomb suspensions and bracing were attached for both shape types, and separate twin-release mechanisms were mounted in each bay, using modified glider tow-cable attach-and-release mechanisms.

.....

Thin Man as a plutonium-based design was therefore abandoned and the weapon was re-designed to use uranium-235. The muzzle velocity required was much lower, reducing the barrel length of the resulting bomb, now code-named Little Boy, to less than 10 feet (3.0 m). This allowed the device to fit into a standard B-29 bomb bay, so the Pullman was modified to its original configuration with the rear bomb bay of a standard B-29 design. All subsequent Silverplates were also configured in this manner.

Second increment Silverplate B-29s were modified as follows:

They were fitted with British single-point bomb releases mounted on a re-designed H-frame suspension rack fitted in the forward bomb bay, so that additional fuel tanks could be carried in the aft bay. A new crew position, called the "weaponeer station", was created in the cockpit with a panel to monitor the release and detonation of the bomb during the actual combat drops.

.....

By February 1945 the seventeen aircraft of the second increment were themselves in need of upgrades, particularly those of the 216th Army Air Force Base Unit. Four of the planes assigned to the 393d Bombardment Squadron (now part of the 509th Composite Group) were transferred to the 216th to meet an increase in its testing tempo. Rather than attempt to modify the existing aircraft a few at a time, a decision was made to start a new production series. The first five of this third increment, known as Project 98228-S, also went to the test unit. The order totaled an additional 28 aircraft, with delivery of 15 designated combat models for the 393d beginning in April.

.....

The final wartime Silverplates incorporated all technical improvements to B-29 aircraft, as well as the final series of Silverplate modifications that included Curtiss Electric reversible-pitch propellers, and pneumatic actuators for rapid opening and closing of bomb bay doors. The British F-type bomb release and G-type attachment were installed, along with dual electrical and mechanical bomb release mechanisms. Early model B-29s were plagued by a host of engine problems, and the early Silverplate bombers were no exception. One was written off after being badly damaged as a result of an engine fire in February 1945. The fuel-injected Wright R-3350-41 engines in the later model bombers delivered in July and August 1945 were greatly improved and far more reliable.

.....

The Fat Man and Pumpkin bombs (non-nuclear bombs that resembled and handled like Fat Man) weighed over 10,000 pounds (4,500 kg), so weight was a concern, even with the more powerful engines. Weight reduction was accomplished by removal of all gun turrets and armor plating. This work was done by the 509th Composite Group for the early Silverplate aircraft, but later models were delivered without them. These B-29s represented a significant increase in performance over the standard variants.

Silverplate B-29 with Little Boy:

 

[nuuumannn]

There was a B-29 (42-24441) that was fitted with existing manned gun turrets instead of the production remotely operated ones, and another, YB-29 was modified with the nose turret and side blister turrets (fitted in the forward fuselage aft of the cockpit and one on the fuse side where the remote operator's blister was) for the PB4Y Privateer and B-32 Dominator.

 

[nuuumannn]

Very interesting to hear this remark about the bomb-bay doors. Did he go into detail? I have drawn several Silverplate examples and I didn't notice a change to the doors. Admittedly many of the photos are post-WW2 but they all seem to have the radar fitted (radar sits between the two bomb bays). Would be very interested to hear more...

The single bomb bay Silverplate aircraft was modified to fit the Thin Man bomb, which had a length of 17 feet, so it couldn't fit within the confines of the B-29's two bays without removing the central section where the radome sits in your illustrations, Juanita. The Thin Man was the first atom bomb designed for carriage by an aircraft and was based on the gun portion's length (that fired the 'bullet' at the fissile material to create a chain reaction). Once it was realised that the uranium isotope U235 could be used instead of plutonium, the gun size and therefore the bomb was reduced in length, thus Little Boy was born and the B-29 could carry a bomb within the confines of one of its existing bays - with two inches to spare. Until then, the USA didn't have an existing aircraft to carry the Thin Man internally without modification and it was suggested that the only aircraft in 1943 that could was an Avro Lancaster.

 

[GrauGeist]

Until then, the USA didn't have an existing aircraft to carry the Thin Man internally without modification and it was suggested that the only aircraft in 1943 that could was an Avro Lancaste

But the USAAF command, being what it was, would have used the B-19 before using anything British.

 

[nuuumannn]

But the USAAF command, being what it was, would have used the B-19 before using anything British.

Now, we've been over this subject before....