B-29 Bomb-Bay & Silverplate

[Zipper730]

From what I remember being told, the initial nuclear-bomb design was to require a bomb-bay of 33-feet. This would have required the B-29's bomb-bay to be re-designed from two individual bays to one single huge bay.

What structural modifications were needed to make this so?

 

[fubar57]

From the Squadron book "B-29 Superfortress in Action"

 

[wuzak]

I think hat describes the modifications for carrying Fat Man and Little Boy. Where only one bomb bay was modified.

I think what he is after is how the B-29 was modified to fit the Thin Man bomb.

Which I guess is the same as how they carried the Grand Slam/Tallboy.

 

[tyrodtom]

The Thin Man bomb was 17 ft long, it was never fully developed, eventually the Little Boy bomb was developed operating on the same basic gun barrel principles, but shorter at 10 feet. The Fat Man bomb was around 10 foot also, but also about 5 foot in diameter.

Most of the modifications on the silver plate aircraft were to take the weight of the weapons, though the extra girth of the Fat Man might have required some modifications, the length of neither bomb would have caused problems.

 

[Robert Porter]

From the Book "B-29 Combat Missions" both Atomic bombs were carried in the forward bomb bay. In the case of Fatman Boxcars crew access tunnel had to have a section flattened to allow the bomb to be raised high enough for the bomb bay doors to close.

 

[fubar57]

I think hat describes the modifications for carrying Fat Man and Little Boy. Where only one bomb bay was modified.I think what he is after is how the B-29 was modified to fit the Thin Man bomb.

Ahh, I just saw B-29 & Silverplate in the title

 

[Zipper730]

Wuzak,

I think what he is after is how the B-29 was modified to fit the Thin Man bomb.

Which I guess is the same as how they carried the Grand Slam/Tallboy.

Exactly, I'm curious what structural modifications were needed?

 

[wuzak]

The Thin Man bomb was 17 ft long, it was never fully developed, eventually the Little Boy bomb was developed operating on the same basic gun barrel principles, but shorter at 10 feet. The Fat Man bomb was around 10 foot also, but also about 5 foot in diameter.

Most of the modifications on the silver plate aircraft were to take the weight of the weapons, though the extra girth of the Fat Man might have required some modifications, the length of neither bomb would have caused problems.

I think one of the main changes was to remove the bomb racks and replace them with a central bomb carrier.

 

[wuzak]

Wiki has a page on Silverplate B-29s.

Silverplate - Wikipedia

 

[c1951]

I researched this for Sonic to Standoff - "The Silverplate modifications were entirely in the B-29 bomb bay and included the installation of a new H frame, C-6 hoist, sway braces, carrier assembly, antenna equipment, junction box, the British Type F release unit and type G shackle assembly, Winkler type bomb bay doors installed and the turret armament deleted. On 20th February 1944 the first Silverplate modified B-29 flew to Muroc Field and testing of the aerodynamic qualities of the bombs started on the 28th. By June 1944, for technical reasons, Thin Man became a uranium bomb and with that a change of name, to "Little Boy". By then the British bomb release gear had been adapted for the bombs. These tests confirmed that Silverplate worked and as a result, on the 23rd August 1944, the Glenn L. Martin Company, Nebraska, received the contract to modify the first three B-29s. Some more changes came about in January 1945 when the Americans produced a release and shackle much better-suited for atomic bombs than the British Type F and Type C gear." The engine cowling modifications and modified electronics suite were a purely post war modification.
During the research I found the Avro Lancaster was actively considered as a weapons carrier for the bomb. If the bomb was to be used in Europe the Lancaster was to drop it

 

[Zipper730]

I researched this for Sonic to Standoff - "The Silverplate modifications were entirely in the B-29 bomb bay and included the installation of a new H frame, C-6 hoist, sway braces, carrier assembly, antenna equipment, junction box, the British Type F release unit and type G shackle assembly, Winkler type bomb bay doors installed and the turret armament deleted. On 20th February 1944 the first Silverplate modified B-29 flew to Muroc Field and testing of the aerodynamic qualities of the bombs started on the 28th. By June 1944, for technical reasons, Thin Man became a uranium bomb and with that a change of name, to "Little Boy". By then the British bomb release gear had been adapted for the bombs.

Why did we use the British bomb-release gear over ours? Also, how did the bomb-release and racks differ in function and appearance?

During the research I found the Avro Lancaster was actively considered as a weapons carrier for the bomb. If the bomb was to be used in Europe the Lancaster was to drop it

That, I didn't know -- I would have thought the B-29 would have just delivered both or the B-32 would have dropped it in Europe.

 

[wuzak]

Why did we use the British bomb-release gear over ours? Also, how did the bomb-release and racks differ in function and appearance?

Because the British had been dropping long and heavy bombs for some time, while the USAAF didn't.

As noted in c1951, the USAAF had to develop a suitable bomb release mechanism for the atomic bombs.

That, I didn't know -- I would have thought the B-29 would have just delivered both or the B-32 would have dropped it in Europe.

The first atomic bomb expected to be used was Thin Man, which was, as the name suggests, long and thin.

The Lancaster could carry such a load without modifications - having already adopted bulged bomb bay doors to carry the 38" diameter 8,000lb and 12,000lb HC bombs, as well as Tallboy.

Thin man was also 38" in diameter.

Because of its diameter and length, it would not fit into a B-29 or B-32 without extensive modification. Which was one of the first jobs of the Silverplate program.

Also, the B-32 was not ready.

 

[c1951]

The bomb release gear was copied from a Polish airman's patent. It was the Swiatecki bomb gear used for grand slam and tallboy. This resulted in Swiatecki suing the British and American governments for patent infringement, at the Royal commission of Awards to Inventors Swiatecki received an ex gratia payment. How he faired with the United States I have not been able to find out.
Swiatecki was at Farnborough when he saw them testing a Lancaster with his bomb slip. He informed the Ministry of Aircraft Production but they ignored him. He never has been given any credit for his work. Some people credit the bomb slip to Barnes Wallis but they are wrong. A simple patent search will reveal the truth of the Polish airman's claim.