Naked Science Forum

Non Life Sciences => Chemistry => Topic started by: Curious Cat on 23/08/2021 13:50:07

Title: Did they really use Cordite in Little Boy, AB?
Post by: Curious Cat on 23/08/2021 13:50:07

 .

Title: Re: Did they really use Cordite in Little Boy, AB?
Post by: Bored chemist on 23/08/2021 14:39:53

Because it was a "gun type" nuke and cordite is good for that sort of thing.

https://en.wikipedia.org/wiki/Gun-type_fission_weapon

Title: Re: Did they really use Cordite in Little Boy, AB?
Post by: evan_au on 23/08/2021 22:33:13

Quote from: curious cat

It was hot burning, and they wanted to maximise the heat?

Once the explosive nuclear chain reaction starts, mere chemicals can't hope to compete with the heat.

Title: Re: Did they really use Cordite in Little Boy, AB?
Post by: Bored chemist on 23/08/2021 22:56:47

Quote from: Curious Cat on 23/08/2021 15:05:27

Thanks, BC. Are U saying that Yanks also used Cordite, for artillery!?

Wiki tells me it was Canadian.
I suspect Cordite  may have become a
https://en.wikipedia.org/wiki/Generic_trademark
like Hoover.

Title: Re: Did they really use Cordite in Little Boy, AB?
Post by: alancalverd on 24/08/2021 11:06:22

The value of cordite as a propellant is that it is a fast "low" explosive, unlike its constituent nitroglycerine which is a "high" explosive. That is to say that the flame rate does not exceed the speed of sound inside the charge so the product gases are released at a smoothly increasing rate, accelerating the missile very predictably without shattering it (or the gun barrel).   

Apparently it is a British invention

Quote

A United Kingdom government committee, known as the "Explosives Committee", chaired by Sir Frederick Abel, monitored foreign developments in explosives and obtained samples of Poudre B and Ballistite; neither of these smokeless powders was recommended for adoption by the Explosives Committee.[citation needed]

Abel, Sir James Dewar and W Kellner, who was also on the committee, developed and jointly patented (Nos 5,614 and 11,664 in the names of Abel and Dewar) in 1889 a new ballistite-like propellant consisting of 58% nitroglycerine, by weight, 37% guncotton (nitrocellulose) and 5% petroleum jelly. Using acetone as a solvent, it was extruded as spaghetti-like rods initially called "cord powder" or "the Committee's modification of Ballistite", but this was swiftly abbreviated to "Cordite".

Title: Re: Did they really use Cordite in Little Boy, AB?
Post by: alancalverd on 27/08/2021 22:45:42

Practically everyone.

Title: Re: Did they really use Cordite in Little Boy, AB?
Post by: alancalverd on 29/08/2021 15:35:00

I thought that nitrocellulose had been generally replaced by cordite after WWI for reasons of stability and consistency. Certainly the case in civilised countries (UK) and probably in the colonies (USA).

Title: Re: Did they really use Cordite in Little Boy, AB?
Post by: alancalverd on 29/08/2021 22:44:21

Cordite was a British invention but widely available as it was manufactured in quantity in Canada. If I was designing a one-off bomb based on wholly new physics, I'd want the least number of engineering unknowns, so a stable, off-the-shelf propellant that has been around for 50 years is a good start. Remember a fair number of Commonwealth citizens were involved at Los Alamos and if you can turn the gun design over to a guy who has done it a hundred times before, let him choose the chemistry he is familiar with, for the best chance of it working first time.