japanese atomic bomb question

[pastafarian]

Sort of a what if question, the other day I was watching something on Japan's effort to develop an atomic bomb. Anyway, someone on the show said that if they had built one, a possible plan was to put it in a kamikaze aircraft and fly it into the invasion fleet and detonate among the fleet to hopefully (from their point of view anyway) wipe out all of the troop carriers and everything else.

Would they likely have used a betty for this or something else? I would guess it would be a betty since you'd need something to carry all that weight. Might be an interesting build to fix up an old betty with a Little Boy in the bomb bay. Could a betty lug something like that around even?

John

[JasonB]

Sort of a what if question, the other day I was watching something on Japan's effort to develop an atomic bomb. Anyway, someone on the show said that if they had built one, a possible plan was to put it in a kamikaze aircraft and fly it into the invasion fleet and detonate among the fleet to hopefully (from their point of view anyway) wipe out all of the troop carriers and everything else.

Would they likely have used a betty for this or something else? I would guess it would be a betty since you'd need something to carry all that weight. Might be an interesting build to fix up an old betty with a Little Boy in the bomb bay. Could a betty lug something like that around even?

John

Looking at the specs for the Betty, I doubt that it could lug an atomic bomb of that era. It looks like its bomb load was about 2200lbs. Even stripped of everything, its not likely it could carry one. Fatman weighed in at 10,200 lbs, Little Boy 4000lbs. Its doubtful theirs would have been in any way smaller. Probably the Nakajima G5N Shinzan would be a better candidate. Maybe the Nakajima G8N Renzan if it had been ready in time.

Edited December 22, 2009 by JasonB

[Jennings]

That's so far out in "what-if" land as to be off the edge of the map. The Japanese had essentially no research into nuclear weapons. What little research there was wasn't supported by the military, mainly I think, because they didn't understand what its potential was. And Japan didn't have the natural resources to even begin to be able to produce fissionable material.

J

[Eli Raphael]

That's so far out in "what-if" land as to be off the edge of the map. The Japanese had essentially no research into nuclear weapons. What little research there was wasn't supported by the military, mainly I think, because they didn't understand what its potential was. And Japan didn't have the natural resources to even begin to be able to produce fissionable material.

J

J, did you get my PM?

[pastafarian]

You're probably right, but "the absence of evidence is not evidence of absence." LOL If you don't know the reference, you should watch this clip from the boondocks: http://www.youtube.com/watch?v=tVQZz8WDRdQ I wouldn't watch it at work because of language though.

Near the end of the war they were supposed to get a shipment of U-235 on a uboat (was diverted to New Jersey). The show made a case for it, but the evidence was so limited that you couldn't really come to any sort of conclusion about the issue.

Now, would it be possible with 1944ish science to build a bomb smaller than little boy? Since that can destroy a whole city, I'd guess a smaller device could hit an invasion force with a decent amount of damage (enough to cause the group to attend to their own causalities rather than landing, so you wouldn't have to wipe out the whole thing).

John

[Matt Roberts]

You watch the program and you could ALMOST be convinced it COULD HAVE happened.....

But then again this network at the time ran a 'documentary' on the Blair Witch....

WHo is to say if they would have had one they would have used it via an aircraft? Bury it near the invasion beaches or put it on a sub. Remember the Japanese were on the defensive and could wait for the Americans to come to them

Matt

[JasonB]

Now, would it be possible with 1944ish science to build a bomb smaller than little boy? Since that can destroy a whole city, I'd guess a smaller device could hit an invasion force with a decent amount of damage (enough to cause the group to attend to their own causalities rather than landing, so you wouldn't have to wipe out the whole thing).

John

Maybe, maybe not. Looking at the Wiki article about "Little Boy", only about 140lb of that 4000lb bomb was the nuclear material. The rest was casing, the "gun", electronics, shielding,etc.. (and I am probably on some watch list now for googling "nuclear bomb" and "Little Boy").

As I recall from reading Tom Clancy :( , there was/is a minimum of material required to achieve critical mass with that design, so there may not have been an option of using less Uranium. I guess they could have went with less shielding and a simpler fuse, thinner casing, etc...but would anyone survive long enough to deliver the bomb without all that shielding? I don't know. The amazing thing to me is that of the 65kg of nuclear material used, only something like 0.6kg of it was actually turned into energy. Thats both terribly inefficient, and efficient, all at the same time.

If I am never heard from again, its probably due to also googling nuclear fission and critical mass. Just waiting for the knock at the door.

Edited December 22, 2009 by JasonB

[pastafarian]

You watch the program and you could ALMOST be convinced it COULD HAVE happened.....

But then again this network at the time ran a 'documentary' on the Blair Witch....

WHo is to say if they would have had one they would have used it via an aircraft? Bury it near the invasion beaches or put it on a sub. Remember the Japanese were on the defensive and could wait for the Americans to come to them

Matt

Right. They do a pretty good job of stirring up the possibility.

The Japanese wanted to use an aircraft because Hobby Lobby has a bunch of 1/48 Bettys with some suicidal plastic pilots. LOL A diorama of a buried nuke in the sand just doesn't seem as interesting. hehehehe

John

[tornado64]

Maybe, maybe not. Looking at the Wiki article about "Little Boy", only about 140lb of that 4000lb bomb was the nuclear material. The rest was casing, the "gun", electronics, shielding,etc.. (and I am probably on some watch list now for googling "nuclear bomb" and "Little Boy").

As I recall from reading Tom Clancy :( , there was/is a minimum of material required to achieve critical mass with that design, so there may not have been an option of using less Uranium. I guess they could have went with less shielding and a simpler fuse, thinner casing, etc...but would anyone survive long enough to deliver the bomb without all that shielding? I don't know. The amazing thing to me is that of the 65kg of nuclear material used, only something like 0.6kg of it was actually turned into energy. Thats both terribly inefficient, and efficient, all at the same time.

If I am never heard from again, its probably due to also googling nuclear fission and critical mass. Just waiting for the knock at the door.

tis an odd world where you will be deemed a bigger danger to society googling little boy than googling nuclear bomb , critical mass etc ..

[tornado64]

way i'd view it is it may have been a possibility

since it's a suicide mission who needs to shield the pilot from radiation as long as it is at a level that he stays alive to target he aint comming back

so that's no shielding

the plane and pilot are the guidance , bomb aiming and delivery system so no weight is needed there in fact systems could be stripped out of the aircraft to minnimalise weight

could use less of the explosive elements as they found nukes were better if exploded above ground level

so with ships at sea there would be no other buildings etc to take the sting out of the blast

the biggest mistake in any warefare is to assume the enemy wouldn't be capable !!

[JasonB]

tis an odd world where you will be deemed a bigger danger to society googling little boy than googling nuclear bomb , critical mass etc ..

I would think the two would be tied together since they were part of the same Google search, but who knows? I could add in a few more phrases and I am sure I could raise some red flags.

way i'd view it is it may have been a possibility

since it's a suicide mission who needs to shield the pilot from radiation as long as it is at a level that he stays alive to target he aint comming back

so that's no shielding

the plane and pilot are the guidance , bomb aiming and delivery system so no weight is needed there in fact systems could be stripped out of the aircraft to minnimalise weight

could use less of the explosive elements as they found nukes were better if exploded above ground level

so with ships at sea there would be no other buildings etc to take the sting out of the blast

the biggest mistake in any warefare is to assume the enemy wouldn't be capable !!

You would need some shielding, otherwise anyone that came into contact with the bomb would likely become so ill from radiation sickness they wouldn't be able to get it to the airfield, loaded on the plane, fly the plane to the target, etc...

Again as far as size, I don't know how much less could be used to achieve critical mass and a usable explosion.

Now I am picturing a Japanese airman riding a bomb down toward the ground ala Slim Pickens in 'Doctor Strangelove', only in this case he would have a hammer in one hand and be acting as the fuse!

Edited December 22, 2009 by JasonB

[Dave Williams]

Uranium and Plutonium are alpha emitters. The only shielding you need is a couple of sheets of paper. The bombs didn't weigh as much as they did due to the need to protect humans from the radiation of the critical material. Fat Man weighed more because it was an implosion type weapon that needed a considerable amount of HE to force the critical mass together.

Edited December 22, 2009 by Dave Williams

[JasonB]

Ah, good info. Now I know more than I did 30 seconds ago. Which ain't sayin' much.

[JasonB]

Ok, this seems to be where a lot of the weight of the Little Boy bomb came from.

http://en.wikipedia.org/wiki/Neutron_reflector

Necessary for every nuclear weapon of that time period? Beats me, I will sleep in a budget hotel tonight and think it over.

[pastafarian]

Ok, this seems to be where a lot of the weight of the Little Boy bomb came from.

http://en.wikipedia.org/wiki/Neutron_reflector

Necessary for every nuclear weapon of that time period? Beats me, I will sleep in a budget hotel tonight and think it over.

huh? I'd have to sleep in an expensive hotel to make sense of that. Math and science are evil.

John

[JasonB]

huh? I'd have to sleep in an expensive hotel to make sense of that. Math and science are evil.

John

Basically sounds like a surrounding container of very dense material that keeps the uranium from flying apart in the very first milliseconds of the explosion, which allows it to continue the chain reaction more efficiently and completely. Otherwise some of the Uranium would simply be blasted to bits instead of adding to the chain reaction. Or something like that. Where's our resident nuclear scientist/atomic weapons expert when you need them???

Edited December 22, 2009 by JasonB

[Dave Williams]

Gun type weapons like Little Boy need a tamper more than implosion type weapons (the explosive shock wave does a lot to keep it together) and according to the Wiki article, it had a heavy reflector/tamper (although strangely, the mass they show for the reflector/tamper is greater than the listed weight of the entire bomb!).

http://en.wikipedia.org/wiki/Little_boy

It's interesting that of the 64kg of U235, only 0.7kg underwent fission and 0.6kg was converted to energy, so 99% of the uranium was vaporized. Still, that 0.6kg of metal yielded an explosive force of about 15kT. The effect of that pesky c-squared multiplier.

Edited December 22, 2009 by Dave Williams

[LanceB]

"The Japanese had essentially no research into nuclear weapons."

They had an active and ongoing program that predated Pearl Harbor by a couple of years. They had working centrifuges, although they were quite inefficient, and the capability to produce enriched uranium although not plutonium as you need a reactor for that (which Japan never built). Japanese scientists who were involved in the program have gone on record as stating they were able to produce enriched uranium, although how much is a big question. Some of the people involved in the program said they had made enough before August 1945 for one bomb - others say they only were able to produce a very tiny quantity. We'll probably never know, as all records were burned at the end of the war before Allied troops landed in Japan.

"What little research there was wasn't supported by the military, mainly I think, because they didn't understand what its potential was."

Again, survivors who were involved in the program have gone on record as stating they were fully backed up by the Navy, who was sponsoring the efforts centered around Amagasaki, and were told the first target if they could have made a workable bomb was Saipan.

"And Japan didn't have the natural resources to even begin to be able to produce fissionable material."

Japan had access to plenty of raw uranium. The north of the Korean Peninsula has plenty of it. And the steel needed to make the centrifuges. This was one instance where natural resources were not as much of an issue for Japan as technical know-how and capability. Mainly capability, as Japanese physicists were on the right path in terms of development, unlike the German program where the head of the program stuck with an impossibly high figure for the minimum amount of uranium needed to achieve critical mass.

[LanceB]

Basically sounds like a surrounding container of very dense material that keeps the uranium from flying apart in the very first milliseconds of the explosion, which allows it to continue the chain reaction more efficiently and completely. Otherwise some of the Uranium would simply be blasted to bits instead of adding to the chain reaction. Or something like that. Where's our resident nuclear scientist/atomic weapons expert when you need them???

Something like that - it contains the neutrons released when critical mass is achieved thereby forcing them to smash into more uranium and make the whole thing go "kaboom" rather than just slowly sizzle.

Little Boy's design used 2 critical masses of uranium, somewhat less than half was on the nose of the device (meaning a bit less than critical mass) surrounded on all but the "gun barrel" side with a neutron reflector. Somewhat more than half (meaning a bit over 1 critical mass) was at the aft end of the "gun barrel", and only had neutron shielding on the side facing the conventional explosives that were to force it down the barrel to slam into the other mass. They couldn't surround the aft mass with a neutron reflector as, since it was over critical mass, doing so would have made it "kaboom" - so it just slowly sizzled away during the flight and first part of the drop.

This is one of the reasons why the Little Boy design was so quickly discarded after the war. It was a very, very dangerous design to handle and store. It was only ever built as a "war expedient device" - it was absolutely guaranteed to go "kaboom", whereas the Fatman design was far, far more technically complex and had more question marks over it. Fatman was the design tested at Alamagordo. Little Boy was not tested prior to use as they were that certain it would work.

[JasonB]

Yes, and for our benevolent internet overlords that currently monitor Carnivore, DCS1000, or whatever they are calling it today, I don't know LanceB at all! :lol:

[A-4Silverfox]

"What if" indeed. So say they got all the material together, test proved everything would work, then they load it into a stripped down Betty and launch. OK so far so good........but then approaching the fleet.......and U.S. radar and air patrols and finally AAA from the fleet if they got past the Hellcats and Corsairs.......

[LanceB]

Yep, that's about what would have happened. If they could not have gotten a stand-off missile like the Ohka within range of the targets very often, one plane with (almost certainly) the one and only nuke on it wouldn't have had a chance. The result would never have been "What if Japan had used a nuke against the US in WWII?", it would have been "What if Japan lost a nuclear bomb-carrying airplane at the bottom of the Marianas Trench?"

[richter111]

From what I have read in the distant past, Japan was working towards the bomb, and had gotten to the heavy water stage, but resources and money were so strapped that they really could not progress as far as they would have hoped.

I do recall the Japanese were fairly far advanced in laser research and hoped to have a device that would blind the eyes of the pilots.

FWIW

Ric

[Cool Hand]

OK, this is going to sound a bit out there, but bear with me.

A couple of years ago a saw a program on the History Channel (considering the source i have some doubts now but it seemed really plausible), that stated the Japan actually TESTED an atomic bomb off the coast of Korea. This occurred between the cease-fire and the signing of the Japanese surrender on Sep 2nd 1945.

This program went into great detail about the men involved in the development programs, there were more than one group of scientists. The army and navy each had their own competing projects with the aim to manufacture atomic weapons to use against Allied forces. The Army program came to an end when its equipment was destroyed during U.S. bombing of Tokyo. The Navy program on the other hand continued uninhibited in Korea until the Soviet Army captured the facility in late Aug 1945.

Well, this is where history ends and speculation begins.

While the History Channel program presented the weapon test as fact, the truth is that the test was only a rumor started by captured Japanese scientists.

But what IS the truth about the Japanese bomb? Was there ever a working device? Probably not.

But if there was, there was plenty of reason to cover up it's existence. The Soviets would not want the U.S. to know it had captured a nuclear facility, and all the equipment and research with it. The U.S. would have kept the Japanese programs existence under wraps, to maintain the stature of being the worlds only atomic power. And remember the old adage: HISTORY IS WRITTEN BY THE VICTOR.

Here is a link to more info. http://en.wikipedia.org/wiki/Japanese_atomic_program

Phew! Is anybody still awake after all that?

Edited December 24, 2009 by Cool Hand

[gmat]

Much of the story probably came from this book.

Wilcox, Robert K. (1985). Japan's Secret War: Japan's Race Against Time to Build Its Own Atomic Bomb. William Morrow & Company. ISBN 9780688041885

I believe that he was a news reporter who followed the story for his book.

I read it during the 80s and it seemed OK. Had Japan really detonated a device, it would be remembered by people who do the sniffing.

Best wishes,

Grant