Author Topic: Carriage of Very Large Bombs (Grand Slam, Tall Boy, etc.)  (Read 1075 times)

Offline Jeffry Fontaine

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Carriage of Very Large Bombs (Grand Slam, Tall Boy, etc.)
« on: May 13, 2021, 11:51:49 PM »
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? 

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Offline Geoff

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Re: Carriage of Very Large Bombs (Grand Slam, Tall Boy, etc.)
« Reply #1 on: May 14, 2021, 12:34:41 AM »
Hope this is some help

Offline kitnut617

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Re: Carriage of Very Large Bombs (Grand Slam, Tall Boy, etc.)
« Reply #2 on: May 14, 2021, 01:35:06 AM »
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.

Offline GTX_Admin

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« Last Edit: May 14, 2021, 02:22:35 AM by GTX_Admin »
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Offline kitnut617

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Re: Carriage of Very Large Bombs (Grand Slam, Tall Boy, etc.)
« Reply #4 on: May 14, 2021, 04:51:04 AM »
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.

Offline Jeffry Fontaine

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Re: Carriage of Very Large Bombs (Grand Slam, Tall Boy, etc.)
« Reply #5 on: May 14, 2021, 06:14:29 AM »
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.
Makes perfect sense to have that feature when you consider the size of that chain.  It would be in poor form to leave that flapping in the breeze creating additional drag on the Lancaster. 

It appears that Tamiya ignored [or missed] the sway brace details associated with the Cookie, Grand Slam, and Tall Boy bombs.   

The heavy chain feature in the Tamiya kit surrounds the Grand Slam which is contrary to what the drawing depicts in the image shared by Geoff and the same image in the link provided by GTX. 

So the chain in combination with the sway braces are what held the bomb in place while carried.  That really hits home as to how sturdy that chain and sway brace combination must have been in order to accommodate the weight and the stresses incurred during a mission. 


*** addendum***

I took another look at the Lancaster images and realized that in the one drawing it indicates a suspension lug is actually used on one or both of the bombs (Grand Slam and Tall Boy).  This is interesting since no image of the actual weapons that I have seen so far shows such a suspension lug installed on the bomb body. 
« Last Edit: May 14, 2021, 08:32:15 AM by Jeffry Fontaine »
"Every day we hear about new studies 'revealing' what should have been obvious to sentient beings for generations; 'Research shows wolverines don't like to be teased" -- Jonah Goldberg

Offline kitnut617

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Re: Carriage of Very Large Bombs (Grand Slam, Tall Boy, etc.)
« Reply #6 on: May 14, 2021, 10:14:52 PM »
Nice to see Geoff's top photo of inside the B-29 bomb bay, I've saved that one  :smiley: :smiley: :smiley:

Offline GTX_Admin

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Re: Carriage of Very Large Bombs (Grand Slam, Tall Boy, etc.)
« Reply #7 on: May 15, 2021, 02:25:21 AM »
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.

You can see the reference to cables in this drawing:

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Re: Carriage of Very Large Bombs (Grand Slam, Tall Boy, etc.)
« Reply #8 on: May 15, 2021, 02:30:11 AM »
I took another look at the Lancaster images and realized that in the one drawing it indicates a suspension lug is actually used on one or both of the bombs (Grand Slam and Tall Boy).  This is interesting since no image of the actual weapons that I have seen so far shows such a suspension lug installed on the bomb body.

No lugs as far as I'm aware.  you might be looking at a standoff to keep the bomb in place and not moving but not something suspending it per se.

Cool video here too:

https://youtu.be/R-Mm-zFW_nA
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Offline GTX_Admin

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Re: Carriage of Very Large Bombs (Grand Slam, Tall Boy, etc.)
« Reply #9 on: May 15, 2021, 02:57:59 AM »
Some Useful B-29 pics here too:




Click to see bigger.
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Offline Jeffry Fontaine

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Re: Carriage of Very Large Bombs (Grand Slam, Tall Boy, etc.)
« Reply #10 on: May 15, 2021, 03:48:06 AM »
I took another look at the Lancaster images and realized that in the one drawing it indicates a suspension lug is actually used on one or both of the bombs (Grand Slam and Tall Boy).  This is interesting since no image of the actual weapons that I have seen so far shows such a suspension lug installed on the bomb body.
No lugs as far as I'm aware.  you might be looking at a standoff to keep the bomb in place and not moving but not something suspending it per se.

Cool video here too:

https://youtu.be/R-Mm-zFW_nA

Thanks Greg, I was thinking the same thing too after looking at the image by zooming in on it.  At first glance, it was looking like a suspension lug but there was no further reinforcements around it to strengthen it for the weight of the bomb. 
"Every day we hear about new studies 'revealing' what should have been obvious to sentient beings for generations; 'Research shows wolverines don't like to be teased" -- Jonah Goldberg

Offline kitnut617

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Re: Carriage of Very Large Bombs (Grand Slam, Tall Boy, etc.)
« Reply #11 on: May 15, 2021, 05:59:55 AM »
My Dad was an Instrument Fitter on 'C' Flight, he told me his shack where he did the repairs was situated just off the end of a runway which the Lancasters landed on when they brought a bomb back (if they couldn't see the targets they had to bring the bombs back). If he was in the shack, he was always evacuated to the slit trenches until the aircraft had landed safely. A job my Dad had was to remove anything that was not absolutely necessary from inside the fuselage, this apparently included the navigator and all his equipment. The Grand Slam Lancs always flew daylight ops and in a gaggle of Tallboy carrying Lancs who did the navigating.
« Last Edit: May 15, 2021, 06:01:31 AM by kitnut617 »

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Re: Carriage of Very Large Bombs (Grand Slam, Tall Boy, etc.)
« Reply #12 on: May 16, 2021, 02:29:34 AM »
I'm curious to know if anyone has more details and/or images of the pylons etc used in this configuration:

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Offline Jeffry Fontaine

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Re: Carriage of Very Large Bombs (Grand Slam, Tall Boy, etc.)
« Reply #13 on: May 16, 2021, 02:33:04 AM »
I'm curious to know if anyone has more details and/or images of the pylons etc used in this configuration:
Same here. 

The external bomb rack used on some B-17 Flying Fortress for carrying stores too large for the bomb bay is a good example of what to expect for an external bomb rack but it is still a crap shoot on what lies just out of our view in that image. 
"Every day we hear about new studies 'revealing' what should have been obvious to sentient beings for generations; 'Research shows wolverines don't like to be teased" -- Jonah Goldberg

Offline kitnut617

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Re: Carriage of Very Large Bombs (Grand Slam, Tall Boy, etc.)
« Reply #14 on: May 16, 2021, 05:20:25 AM »
The photo I got from Boeing is a high resolution photo, it wasn't a "pylon" as such, just two I-Beams probably joined together by a sway brace arrangement for each bomb like in the other photos posted above I suspect. Just to illustrate the resolution, there's a guy's face in the bubble window with a great big grin on it. Mind you that is looking at it with a magnifying glass.

Offline kitnut617

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Re: Carriage of Very Large Bombs (Grand Slam, Tall Boy, etc.)
« Reply #15 on: May 16, 2021, 05:37:14 AM »
This might be a bit clearer. Notice the notch in the flap trailing edge.

« Last Edit: May 16, 2021, 05:38:50 AM by kitnut617 »

Offline GTX_Admin

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Re: Carriage of Very Large Bombs (Grand Slam, Tall Boy, etc.)
« Reply #16 on: May 17, 2021, 01:41:15 AM »
Some more info in the captions here:

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Offline elmayerle

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Re: Carriage of Very Large Bombs (Grand Slam, Tall Boy, etc.)
« Reply #17 on: May 18, 2021, 05:17:01 AM »
If Operation Olympic had gone ahead, I can see those being used.