Modelling > Engineering Dept.

Carriage of Very Large Bombs (Grand Slam, Tall Boy, etc.)

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Jeffry Fontaine:
I pose this question to the forum in order to get a better idea of what was done to suspend these very large/heavy weapons from the aircraft that carried them.  I know that in the case of the 4000-pound Cookie there was a single lug used to attach the bomb to the bomb shackle and in the case of the Grand Slam there was a very large chain that secured the bomb to the aircraft but what else was involved?  My reason for exploring this bit of the mundane is to try and get an idea for what would be expected to be in view on an empty bomb rack/bomb shackle for such large weapons. 

Most bomb release mechanism/bomb shackles have two hooks or a single hook used to tightly secure the weapon during flight but these larger weapons never seem to show anything but that chain component in the case of the Grand Slam.  How was the bomb secured to the aircraft?  What does the suspension lug look like? 

The Tamiya Grand Slam bomb does not provide much in the way of details save for the two-piece chain that wraps around the bomb body and is secured in place by a dab of cement on the chain end halves and the small indentation in the body of the Grand Slam which in turn is attached to a square slot in the bottom of the Lancaster.  The one image I recall seeing on-line of a Lancaster right after release of the Grand Slam showed this chain hanging down in to the air stream and it appeared to be the entire length of the chain which would suggest that the end of the chain was secured to the release mechanism and upon release, allow the Grand Slam to fall away.  What else was there to this mechanism? 

There is also an image of a USAAF/USAF B-29 carrying two Grand Slam bombs under the wings between the inboard engines and fuselage.  The image is from below and at a distance so details are minimal save for the fact that the B-29 was carrying both weapons secured to something under the wings. 

So good people, have you any insight into the details of what this mechanism looks like? 

Hope this is some help

Jeff, I have both those photos you refer to, I got them from the Boeing Archives (plus license). Looking at the B-29 with the two Grand Slams under a magnifying glass, the bombs are also held in place by two chains. There appears to be two large I-Beams attached to the underside of the wing, one either side of each bomb, the chains appear to be attached to these I-Beams. These I-Beams run in the same direction as the line of flight.
The photo of a B-29 with a single bomb hanging below the fuselage is actually a T-12 (44,000lb), not a Grand Slam (22,000lb). It is held in place by two chains too. Notice that there's an additional fairing attached to the wing & fuselage which covers some local strengthening of the spars.
Bottom pic here is a good comparison of a T-12, Grand Slam and Tallboy. I made the T-12 from dimensions I found on a website called 'Very Heavy Conventional Ordnance' which has since gone AWOL (at least I can't find it anymore after my saved link closed)
Originally, the T-12 was a direct copy of the Grand Slam, increased in size by "lofting", but it was too long to fit in the B-29's bomb bays. So the tail cone was shortened so it would fit so giving it a slightly different profile.

See here:

My Dad, who served in 617 Sqn 1944-46, told me there was a wire cable along with the chain links. This was used to pull the chain back up after the bomb was released and stopped the chain from flapping around in the slipstream.


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