Heinkel He 177A-7 high-altitude bomber

Snautzer01 said:

That is what i am looking in to. I think (!) the doors became too big to closes the usual way. Hence the hydraulics i think. So was is a Winker Winkler type bomb bay?

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I believe the Winkler bomb bay door was a modified unit designed for the expanded bomb bay

FLYBOYJ said:

I believe the Winkler bomb bay door was a modified unit designed for the expanded bomb bay

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Yes i am sure of that. Question was why hydraulic. As stated before by me i think because of the lenghth and thus weight it had to be..

I thought all B-29's came with quick open bombay doors. A lesson learned from the B-17.

Snautzer01 said:

Yes i am sure of that. Question was why hydraulic. As stated before by me i think because of the lenghth and thus weight it had to be..

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Hydraulic systems are way more powerful for moving large objects (like bomb bay doors, landing gear etc.) especially if you want them to move quickly. I think the B-29's hydraulic system operated at 1000 psi.

B-29 bomb bay doors were operated by pneumatic actuators on their forward bulkheads. On the Enola Gay website at NASM there is a picture of the forward bomb bay from underneath. The long cylinders attached to the bomb bay doors are the actuators. B-29 hydraulics was used for braking on the main landing gear.

EAIAnalog said:

B-29 bomb bay doors were operated by pneumatic actuators on their forward bulkheads. On the Enola Gay website at NASM there is a picture of the forward bomb bay from underneath. The long cylinders attached to the bomb bay doors are the actuators. B-29 hydraulics was used for braking on the main landing gear.

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100% and I'll stand corrected - here's some good info on this.

Nice article, thanks. See page 49 for some comentary on the bomb bays and a shot of the actuators. The system air compressors were rated at 1500 psi, but there was a regulator that fed the actuators and I think it was rated at 250 psi.

FLYBOYJ said:

Additional fuel tanks were installed in the rear bomb bay. The bomb bay doors were operated by quick-acting pneumatic systems. The bomb release mechanism in the forward bomb bay was replaced by a single-point release as was used in special British Lancaster bombers.

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The British single-point release units were installed because during ballistics trials with Fat Man "Pumpkin bomb" shapes and Thin Man dummies in March 1944 at Muroc a bomb shape came unstuck while the bomb doors were closed in-flight, which resulted in damage to the aircraft. Only one B-29 was converted for carrying the 17-foot long Thin Man, AAF Serial No 42-6259 had the bridge below the wing spars deleted to enable the length of the bomb to be accommodated.

c1951 said:

"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.

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This wee potted history describes changes undertaken to the B-29 modified to carry Thin Man, although the text gives the impression the British release cradles were installed as modified; as mentioned above they were incorporated after a failure of one of the original US cradles in-flight following the commencement of ballistics trials.

It's interesting reading through what's on the net about the Silverplate B-29s as most mention the Thin Man bomb but fail to recognise that Little Boy came after Thin Man and was not one of the bombs that the programme initially intended on building. The two US A-bombs under development in 1943 were Thin Man and Fat Man. Little Boy came abut owing to impurities in plutonium being refined at the Hanford site and the decision was made to switch to using uranium instead as a result, which had the added benefit of being able to create a smaller weapon that didn't require as much modification to the B-29. Little Boy was still a gun-type bomb like Thin Man, the project led by Deak Parsons at Los Alamos. The Little Boy could fit in the B-29's bay with 2 inches to spare.

Does anyone have photos of the wing attachment points for the on-board engine changing hoist/crane of the He-177?

P-51-44-72028 said:

Does anyone have photos of the wing attachment points for the on-board engine changing hoist/crane of the He-177?

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Only crane is to load the bombs.

This is the crane I was referencing. It was carried onboard the a/c for engine changes. I'm curious about the permanent attachment points in the top of the wing for this crane?

P-51-44-72028 said:

This is the crane I was referencing. It was carried onboard the a/c for engine changes. I'm curious about the permanent attachment points in the top of the wing for this crane?

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Or....this was the crane used for bombs AND engine changes????