Pumpkin Bomb

This is a new one on me the Pumpkin Bomb was the practice bomb for Fat Man. It was even dropped in anger I wonder if it was also partly a counter intelligence job to cover these strange bomb casings being built

Pumpkin bomb - Wikipedia, the free encyclopedia.

Now that is interesting.

Too bad they did not have a few left for Korea and 'Nam.

A little info.
Specifications Weight 5.26 long tons (5.89 short tons; 5.34 t) Length 12 feet 5 inches (3.78 m) Diameter 60 inches (152 cm) Filling Composition B Filling weigh 6,300 pounds (2,900

I knew that the bomb group had practiced extensively to assure they were as accurate as possible. Maybe a little ironic considering the final weapon. However it would be necessary to learn all the parameters and quirks of the unusual shaped bomb, Certainly Parson's concern about the radar fuze was valid.

It was however the "Little Boy" bomb based on a 5" canon that was the first to drop. Was there also a pre mission stand in for this one?

Almost 60 Punpkin Bombs killed 400 Japanese people.
People wondered why the enemy did not use the incendiary bombs.
Everything was experiment, wasn't it ?

The "Pumpkins" (actual bombs) were loaded with Composition B, a 60/40 mix of RDX and TNT common in WWII. It was a sensitive explosive and did not age well. Because of its shape the AN/M65A1, also loaded with Composition B, was nicknamed Fat BOY, in effect a miniature version of the Fat MAN
Sixteen of these "Fat Boy" bombs were delivered to the USS Forrestal on 28 July 1967. They had been stored in open air Quonset huts on either Okinawa or Guam exposed to heat, humidity, and rain since the Korean war. Their thin skins were filthy, rusty, leaking paraffin, and still in their original packing crates that were moldy and rotting away. When the Naval Ordinance Depot at Subic Bay received the order to ship the bombs the Commanding officer refused to sign the transfer because of the bombs terrible condition. Eventually he was ordered to do so by CINCPAC.

When delivered to the Forrestal the ordinance crew had never even seen one and did not realize that they were filled with Composition B (mix of RDX and TNT). Composition B was much more sensitive to shock and heat and became even more sensitive as it aged.
The ordinance crews were terrified of the old, leaking bombs. Many felt that they would simply detonate from the shock of a carrier launch and wanted to dump them overboard. Their concerns were reported up the chain of command to the carrier's Captain Beling. Beling however was trapped by circumstance. A bombing run on Vietnam was scheduled for the next day and he did not have replacements for the decaying bombs. Fortunately he decided not to store the 16 bombs in the ships magazine but left them on the open deck, alone in the "bomb farm".

The next morning preparing for their bombing run into Vietnam 27 aircraft had been fueled and armed and lined up on the aft flight deck. A failed safety check had missed the fact that one of the Zuni rockets loaded onto an F-4 had not been installed. When the F-4 was switched from external power to internal power an electrical surge launched the Zuni. The Zuni flew across the flight deck and struck an external wing tank on one or possibly two A-4 Skyhawks. One of the struck A-4s was piloted by John McCain who managed to escape. The other A-4 was piloted by Fed White who was killed. The ruptured tank spilled 400 gallons or more of JP-5 onto the flight deck. While the Zuni did not explode it did break up and the burning rocket engine ignited the spilled JP-5. A fragment of the Zuni also punctured the center-line tank of another A-4 spilling more fuel. Then one of the "Fat Boy" bombs fell into the burning fuel between McCain's and White's A-4s. Fire control teams rushed in to contain the fire. Their previous training had taught them that they had 10 minutes before the thick skinned Mark 83 would explode. Unfortunately the thin skinned "Fat Man" broke open almost immediately igniting the Composition B. One minute and 36 seconds after the fire began the first "Fat Boy" detonated killing 35 men (essentially both fire-control teams). Ten seconds later two more "Fat Man" bombs exploded and 44 seconds later another detonated.

The bomb explosions penetrated the armored deck allowing 40,000 gallons of burning fuel from ruptured tanks to pour into the hanger and berthing compartments below where the night crew was asleep. Fifty night crew were killed in their beds and 41 died in the hanger decks.

On deck ordinary deck crew stepped in to fight the fire, again unfortunately, using sea-water hoses. The sea-water acted to wash away the fire-fighting foam and flushed more fuel into the below-deck spaces. Within less than five minutes, seven or eight 1000-pound bombs, one 500-pound bomb, one 750-pound bomb, and several missile and rocket warheads heated by the fire had exploded.

With the help of two Destroyers the deck fires were controlled in about an hour but the below deck fires continued to burn for another 14 hours. At 4AM the next day all fires were out. The fire left 134 men dead and 161 more injured. It was the worst loss of a life on a U.S. Navy ship since World War II. Of the 73 aircraft aboard the carrier, 21 were destroyed and 40 were damaged.

mikewint said:

Eventually he was ordered to do so by CINCPAC.

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Did the idiot that made that call ever get called out for killing those sailors?

The bomb or bombs that exploded and caused the Forrestal fires and explosions was AN-M65A1 , 1000 lbs bombs nicknamed "fat boys" not pumpkin bombs, and in no way related to the 10 or 11,000 lbs " pumpkin" bomb, except they were both filled with composition B.
The Pumpkin bomb was way, way above the lift capacity, or deck clearance of a A4., F4 or any other aircraft operating from the Forrestal .

It's a line of dominoes ready to fall that may or may not do so. The "Fat Boy" bombs were stored incorrectly to begin with and the age instability of Composition B well known IN 1953. Once stored and time passed the bombs were forgotten UNTIL Vietnam and massive bombing campaigns depleted the store of Mark 83. Then some pencil-pusher notices all this neat left-over WWII and Korean ordinance just sitting around...might as well use it...right.
The Zunis had well known problems, thus a double safety system, i.e. a pigtail wire to connect the missiles electrical system to the launch pod AND a TER safety pin. Written Naval procedure required the pigtail to be attached when the aircraft was on the catapult and then the final safety pin was pulled. The pigtail was a PIA to attach and launches were often delayed while launch crews fiddled with the wire. In addition the safety pin were loose fitting and known to, at times, be blown out by high winds on the flight deck.
Four weeks before the fire the Forrestal's Weapons Planning Board and Weapon Coordination Board had met and agreed to allow the pigtail to be installed before taxi. Captain Beling was never notified though again by regulations he was required to be notified and approve the departure from standard procedure.
So, were the "Fat Boy" bombs a danger to the ship?...Beyond a doubt. Would they have detonated with the shock of a catapult launch?...Open question...who knows. Possibly but it would have involved one aircraft being thrown off the ship.
Without the Zuni launch a fuel tank would have never been ruptured and the initial fire never ignited.
The Naval Investigation Board found that Beling knew of the Zuni problems and therefore should have made more effort to insure that proper safety rules were followed but they also absolved Beling of responsibility for the disaster. None the less he was removed from command and transferred to staff duty.
Admiral Ephraim P. Holmes, Commander-in-Chief of the U.S. Atlantic Fleet disagreed the Navy's report into the Forrestal disaster and had Beling assigned to his staff so he could issue a letter of reprimand. Holmes attached the reprimand to the final report, but when Admiral Moorer Chief of Naval Operations endorsed the report, he ordered Admiral Holmes to rescind and remove the reprimand. Nonetheless Beling's career was over.

mikewint said:

It's a line of dominoes ready to fall that may or may not do so. The "Fat Boy" bombs were stored incorrectly to begin with and the age instability of Composition B well known IN 1953. Once stored and time passed the bombs were forgotten UNTIL Vietnam and massive bombing campaigns depleted the store of Mark 83. Then some pencil-pusher notices all this neat left-over WWII and Korean ordinance just sitting around...might as well use it...right.
The Zunis had well known problems, thus a double safety system, i.e. a pigtail wire to connect the missiles electrical system to the launch pod AND a TER safety pin. Written Naval procedure required the pigtail to be attached when the aircraft was on the catapult and then the final safety pin was pulled. The pigtail was a PIA to attach and launches were often delayed while launch crews fiddled with the wire. In addition the safety pin were loose fitting and known to, at times, be blown out by high winds on the flight deck.
Four weeks before the fire the Forrestal's Weapons Planning Board and Weapon Coordination Board had met and agreed to allow the pigtail to be installed before taxi. Captain Beling was never notified though again by regulations he was required to be notified and approve the departure from standard procedure.
So, were the "Pumpkins" a danger to the ship?...Beyond a doubt. Would they have detonated with the shock of a catapult launch?...Open question...who knows. Possibly but it would have involved one aircraft being thrown off the ship.
Without the Zuni launch a fuel tank would have never been ruptured and the initial fire never ignited.
The Naval Investigation Board found that Beling knew of the Zuni problems and therefore should have made more effort to insure that proper safety rules were followed but they also absolved Beling of responsibility for the disaster. None the less he was removed from command and transferred to staff duty.
Admiral Ephraim P. Holmes, Commander-in-Chief of the U.S. Atlantic Fleet disagreed the Navy's report into the Forrestal disaster and had Beling assigned to his staff so he could issue a letter of reprimand. Holmes attached the reprimand to the final report, but when Admiral Moorer Chief of Naval Operations endorsed the report, he ordered Admiral Holmes to rescind and remove the reprimand. Nonetheless Beling's career was over.

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Jeez, talk about being screwed over by your boss. I get that Berling was perhaps not quite to speed on the dangers that the Zuni may have represented at the time but he's ONE guy in charge of / and responsible for the ops/safety of a (then) supercarrier. It's impossible to predict every little thing that can go wrong on a US navy warship, much less a chain reaction that you very well detailed. It's like any of the IJN carrier skippers at Midway going "should have thought of this scenerio". When things go bad , they go REALLY bad and very quickly. Now when Admiral Ephraim P. Holmes had this guy reassigned it sounds (to me) that he was covering the Navy's and/or his own ass and that a scapegoat was needed. Thus the blame game begins back to the point of 1.why were the bombs stored there in the first place 2. who issued the orders to put place them there 3. who approved those orders 4.who wrote the procedures on the storage of said bombs 5.who approved the lifespan of said bombs... and downward until the second monkey bashes in the skull of the first monkey with a mastodon bone.
Now that being said, I have never serviced in the military. I can't even begin to imagine the dedication, loyalty, and bravery that all our vets have displayed now and in the past But to me to load a ship with bombs , fuel and flammable airplanes and to NOT have something go wrong seems like a good day to me. Love to hear from those who have served, am I wrong? We've all had bad bosses, but the one that will get you killed because of stupidity, that's a special SOB.

To provide a perspective on the size difference between "Little Boy" and "Fat Man", here's Little Boy on it's loading trolley in the loading recess, directly below the B-29:


Here's Fat Man on it's trolley and for scale, the tires on both trollies were the same size.

My point was that the bombs that went off on the Forrestal were not "pumpkin bombs", there was no pumpkin bombs on the Forrestal, they were AN-M65A1's.
You couldn't even get a bomb 5 foot in diameter mounted under a F-4, or A-4, you have to more than duck your head to walk under a F-4 wing, and a A-4 is about the same height.

Plus I doubt the Forrestal could have survived a explosion from a 10to11,000 lbs bomb, with 6000 lbs of high explosive in it, even if the bomb supposedly only "low ordered".

As to why such old bombs were stored, or used is just the way it was during the cold war era.
During my time in the USAF 1965-69, we renovated and used lots of ordinance left over from WW2 and the Korean war.
All, or most of it had been stored in the many bomb storage dumps constructed during WW2, Guam, The Philippines , Hawaii, west coast, etc. , and sometimes not under the best conditions.
But during the ramp up of the bombing campaign during the Vietnam war there was a shortage of munitions, so we were forced to be a little/lot less particular on what we chose to use.
I can remember several episodes of old bombs not exploding when dropped , ( which tends to piss off the pilots), or over sensitive bombs going off prematurely ( which tended to kill us)

tyrodtom said:

The bomb or bombs that exploded and caused the Forrestal fires and explosions was AN-M65A1

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Tyro, you are of course 110% correct and it is my total screw up. I was going by something that I remembered (should know better by now), i.e.: the nick name "Fat Boy" and that was linked to the old Composition B, RDX and TNT. I had read sometime back about the test Fat MAN test bombs both concrete and the Composition B loaded actual bombs. Sooo...putting 2 and 2 together to get 5, I linked the Fat BOY AN/M65A1 Composition B bombs that caused so much destruction on the Forrestal with the Fat MAN Composition B loaded WWII bombs totally ignoring the weight difference.
The term "Pumpkin" was new to me.
Just as an aside, did you know that even though the bomb bay of the B-29 had been modified to hold it, the Fat Man bomb was still too big to fit under the B-29 to be loaded into the bomb bay. The crews had to pull down on the B-29's tail to lift the nose wheel off the ground, push the bomb under the bomb bay and then lower the nose over the bomb. Eventually bomb pits were constructed. The Fat Man-type bombs were placed into the pit and the B-29 was backed over the pit and the bomb was then lifted into the plane.
I have correct my inaccurate postings...Es tut mir Lied

mikewint said:

...Just as an aside, did you know that even though the bomb bay of the B-29 had been modified to hold it, the Fat Man bomb was still too big to fit under the B-29 to be loaded into the bomb bay. The crews had to pull down on the B-29's tail to lift the nose wheel off the ground, push the bomb under the bomb bay and then lower the nose over the bomb. Eventually bomb pits were constructed. The Fat Man-type bombs were placed into the pit and the B-29 was backed over the pit and the bomb was then lifted into the plane.

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Mike, look at the first photo in my post (#11), that's one of the loading recesses used to bomb-up the B-29s with either Pumpkins or the Atom bombs.

Eventually they constructed those pits BUT initially no one thought to measure the tarmac to bomb bay height and the height of the Fat Man bomb.

Charles Sweeney, War's End. New York: Avon Books, 1997.
Charles Sweeney discussed this issue with the ground crew and the weapons engineer and they finally concluded that the only thing they could do at the moment was raise the nose and slip the bomb under the front of the B-29. A new base at the time, Wendover, really didn't have the cranes needed to lift up the front end of a plane, so the crew threw tarps over each of the rear horizontal stabilizers on the B-29, and put several men (six to eight), pulling down on each tarp. The strength of these men tipped the tail of the B-29 down, which lifted the nose up in the air, providing the clearance for the ground crew to slip the pumpkin below the bomb bay. (The length of the plane pivoted on the main wheels like a seesaw). When they set the nose back down again, they lifted the bomb into the bay and secured it to the aircraft

Army engineers found a long term solution to bomb loading by designing and building bomb pits. However, the ground crew had to keep using this tipping method for bomb loading of the B-29s for two months before the bomb pits were completed.
In my reading, I have come across another time a crew used the weighting down of the rear stabilizers to lift the front end of the aircraft. In that case, P-38 Lightning crews needed work on the front landing gear for maintenance, particularly in the Pacific, which tended to lack adequate maintenance facilities.The P-38 has twin booms and a single stabilizer, which connects those two booms in the rear. But when they needed to work on the front end of the P-38, on the landing gear in particular, men sat on the back end of the stabilizer, in enough numbers that their weight tipped the back end of the Lightning down and front end up. At that point the crew could perform the necessary maintenance. So it's an interesting concept to use this technique to solve an access problem, and although not a very common technique, it was one that worked.

mikewint said:

Eventually they constructed those pits BUT initially no one thought to measure the tarmac to bomb bay height and the height of the Fat Man bomb.

Charles Sweeney, War's End. New York: Avon Books, 1997.
Charles Sweeney discussed this issue with the ground crew and the weapons engineer and they finally concluded that the only thing they could do at the moment was raise the nose and slip the bomb under the front of the B-29. A new base at the time, Wendover, really didn't have the cranes needed to lift up the front end of a plane, so the crew threw tarps over each of the rear horizontal stabilizers on the B-29, and put several men (six to eight), pulling down on each tarp. The strength of these men tipped the tail of the B-29 down, which lifted the nose up in the air, providing the clearance for the ground crew to slip the pumpkin below the bomb bay. (The length of the plane pivoted on the main wheels like a seesaw). When they set the nose back down again, they lifted the bomb into the bay and secured it to the aircraft

In my reading, I have come across another time a crew used the weighting down of the rear stabilizers to lift the front end of the aircraft. In that case, P-38 Lightning crews needed work on the front landing gear for maintenance, particularly in the Pacific, which tended to lack adequate maintenance facilities.The P-38 has twin booms and a single stabilizer, which connects those two booms in the rear. But when they needed to work on the front end of the P-38, on the landing gear in particular, men sat on the back end of the stabilizer, in enough numbers that their weight tipped the back end of the Lightning down and front end up. At that point the crew could perform the necessary maintenance. So it's an interesting concept to use this technique to solve an access problem, and although not a very common technique, it was one that worked.

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Reminds me of how the steam catapults operated on the small RN carriers HMS Hermes and Victorious. Because the cats were short and they were launching heavy Supermarine Scimitars the tail was pulled down to increase the wing angle of attack

Not as hard to sit a nose dragger on it's tail as one might think, though pulling down on the horizon stab might not be the optimal structural solution. I was sitting in the cockpit of a 747 freighter in LAX and a new fueler reversed the tank filling order and filled out to in. All of a sudden all the relays below the cockpit started clicking and "gear tilt" was displayed on the EICAS. I virtually "ejected" from my seat and flew down the ladder to the main deck, at the L1 door it was 4' down to the top of the ground stairs! I hesitated a microsecond wondering if the plane would go, before I jumped. Order got restored before we became a national news item...

Anybody know what the comparative dimensions of the "Earthquake" bombs carried by the Lancasters?

The British TALL BOY bomb
Weight 12,000 lb (5,400 kg)
Length 21 ft (6.4 m)
Diameter 38 in (97 cm)
Filling Torpex D1
Filling weight 5,200 lb (2,400 kg

British GRAND SLAM bomb
Weight 22,000 lb (10,000 kg)
Length 26 ft 6 in (8.08 m)
Length Tail 13 ft 6 in (4.11 m)
Diameter 3 ft 10 in (1.17 m)
Filling Torpex D1
Filling weight 4,144 kg (9,136 lb)

The American FAT MAN bomb
Weight 5.26 long tons (11,782 lbs 5,356 kg)
Length 10 feet 8 inches (3.25 m)
Diameter 60 inches (152 cm)
Filling Composition B
Filling weight 6,300 pounds (2,900 kg)

mikewint said:

The British TALL BOY bomb
Weight 12,000 lb (5,400 kg)
Length 21 ft (6.4 m)
Diameter 38 in (97 cm)
Filling Torpex D1
Filling weight 5,200 lb (2,400 kg

British GRAND SLAM bomb
Weight 22,000 lb (10,000 kg)
Length 26 ft 6 in (8.08 m)
Length Tail 13 ft 6 in (4.11 m)
Diameter 3 ft 10 in (1.17 m)
Filling Torpex D1
Filling weight 4,144 kg (9,136 lb)

The American FAT MAN bomb
Weight 5.26 long tons (11,782 lbs 5,356 kg)
Length 10 feet 8 inches (3.25 m)
Diameter 60 inches (152 cm)
Filling Composition B
Filling weight 6,300 pounds (2,900 kg)

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tyrodtom said:

My point was that the bombs that went off on the Forrestal were not "pumpkin bombs", there was no pumpkin bombs on the Forrestal, they were AN-M65A1's.
You couldn't even get a bomb 5 foot in diameter mounted under a F-4, or A-4, you have to more than duck your head to walk under a F-4 wing, and a A-4 is about the same height.

Plus I doubt the Forrestal could have survived a explosion from a 10to11,000 lbs bomb, with 6000 lbs of high explosive in it, even if the bomb supposedly only "low ordered".

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Follow this link concerning Pumpkin https://www.osti.gov/opennet/servlets/purl/16135500.pdf