Cast TNT

[lucas]

A 200g charge of cast TNT (75%) with RDX (20%) and aluminium (5%) was poured into a thick walled cardboard tube, 7mm wall thickness, 30mm ID. 30g blasting gelatin has been added to the charge as a booster. A comercial det will be used for initiation.

Who thinks that's an ideal boster?

Who thinks it'll be fully detonated by that booster?

How far away would YOU want to be for open air detonation.

[Sausagemit]

I would bury it in the ground or put it in something (like a car) and then mount up a camera and then hide in or behind something solid.

An open air detonation for something like this is just a waste.

But if your dead set on an open air detonation I would feel safe at right around 75-100 feet with nothing in between you and the blast, 50 feet with some sort of shield.

[lucas]

Well here are the pics and vid.

http://rapidshare.de/files/31213788/Torpex200g.wmv
http://rapidshare.de/files/31214363/TorpexStills.rar

It was set against a steel reenforced concrete post. The concrete was mashed and the steel slightly bent. Approx 25mm steel rod (X4) inside a 200X120mm concrete post.

[Diabolique]

Back in the 70's, I was tasked to set up and touch off a nuclear weapons simulator - a 55 gal. drum 1/3 full of photoflash powder and a paper mache casket of 20 lb of flake TNT. The Army provided only 30 meters of wire. To keep debris from being thrown, I put it in a shallow pit. I also found out the real reason the old Army fatigue unifor is brown, and one leutenant's pants also became a bit damp.

There are several tables of safe distances available. I'll upload one to tmp's ftp site today.

Lucas, I salute you - having fun, but staying safe. Also, learn as much as possible from what you do.

[lucas]

The pale yellow TNT was placed in a beaker and this into a nearly boiling waterbath. The very fine RDX powder was also warmed in the same manner. The TNT was mixed gently until all melted. As the TNT melted it took on a clear orange appearance. TNT which solidified on the side of the beaker returned to an off white colour. The RDX was added all at once and gently stirred. The RDX easily mixed without showing capture of air. The appearance went from clear to opaque. The mixture remained quite fluid. The fine aluminium power, which was of very low apparent density was also added all at once. The very fine particle size meant some became airborne as it was gently stirred. The powder did not mix easily, largely remaining floating as stirring gradually incorperated it into the mixture. The mixture was now silver in appearance and still quite fluid. It poured easily and remained liquid for a minute or more after pouring.
The whole process took 15 minutes for 200g of 75/20/5 mixture.

Hope this is interesting!

[nbk2000]

I read that anthracene, in 1/3%-3%, prevents cracking in cast TNT compositions.

[Diabolique]

Great, Lucas. From the description, you used high grade of TNT.

The munitions plants use RDX that has been water wet. It helps in the incorporation of RDX into the TNT. They also add the Aluminum flake to the wet RDX, it will help keep down the air fly of aluminum as well as helping in its mixing.

You may want to download ExplosivesPropellants&Pyrotechnics.pdf from the ftp site. Chapter 9 has some information on cast loading explosives into munitions. Also get LLNL_Explosives_Handbook,pdf, and read up on the Gurney equations. Run the equations with the parameters for your mix, and a steel cylinder, and you will quickly see why containers of high density or metal are not a good idea.

Some cautions on the TNT. Molten TNT is a lot more senitive than when solid. Also, the TNT that solidified on the side of the container is likely flake TNT, which I understand can be initiated by a simple black powder squib. Be careful of it.