Fuel Air Explosions

Quote: Originally posted by Asthenia

Can someone explain what exactly it is? What it requires to create them. I have been blowing stuff up for a while(ANFO TATP etc) but I just ran into this concept. I want to understand this more and wanna hopefully do it. [Edited on 8-10-2012 by Asthenia]

Good ol' whoosh jug demo My favorite example of this is what is termed, "ethanol cannons".

You take a bottle, drill two screws into it, opposite each other and leaving a small gap between them, and then vaporize some ethanol in there, sealed with a rubber stopper. You than touch a tesla coil to one end, creating a spark between the screws, which ignites the mixture and BOOM! Instant cannon!

Kids love this demo Remember, safety first! Cover your ears!

about that ehanol canon enjoy
http://www.youtube.com/watch?v=Jw5mmJ__o8U&feature=plcp
I've been interested for a while about that FAE's but I think it's too complicated to be done well. For me one volume egdn in metal will give better shock wave at any distance then same volume of something that may or may not detonate and is expected to simply deflagrate. All that can be done at home I think is conventional explosive with termobaric effect. May be the easiest way is adding Al to stuff like nitromethane.

That is the most amazing cannon ever! I can't believe he just fires it with one hand all nonchalant!

Quote: Originally posted by sargent1015

That is the most amazing cannon ever! I can't believe he just fires it with one hand all nonchalant!

Quote: Originally posted by Asthenia

Okay guys thanks! I thought that is what it was! But does the gases that are spread out in the air really have THAT much power when they ignite??? I have seen high speed cameras shooting fuel air explosions and it was amazingly powerful!

Quote: Originally posted by Asthenia

Actually... If it goes into a fire ball does that mean I have achieved FAE?

No.... FAE is much more that a simple fireball... A FAE is pretty much a secondary explosive that use air as is source of oxidizer. The real big difference is that the fuel/air mixture is not initiate by the flamme, but by the shockwave of the second charge. Yes, it create a fireball, but it is so fast that you almost dont see it (if all detonate).

There is multiple thing you need to think before you have a complete setup for creating a FEA:

A complete fuel mixture --> You need a detonation promoter and a volatil, energetic and a big range of explosive limit fuel
ex: Iso-propyl nitrate / Ethylene oxide

A good fuel disperser charge--> You need something that will disperse all your fuel and dont prematurly ignite it (explosive that produce almost no flame) and if possible you dont want to create low oxygen spot, so try to use OB possitive explosive.
ex : Nitroglycerine/ammonium nitrate

A good fuel initiation charge--> Well the principle is as simple a a detonator, but the shockwave need to be strong enought to initiate, lets say, 4 square meter of explosive. The size of the charge depend of your detonation promoter, so you need to test or calculation if you want to be sure.
Ex : C4

A precise delay timer--> The delay depend of how good is your dispersion systeme, the temperature and how volatil is you fuel. It always change from desing, but the delay is roughly 100ms. So you need a delay timer that have a millisecond precision (really easy to make).
ex : microchip and two transistor


This is the really big line of fuel/air explosive, but you will find that even the delay that poorly made det cap create is enought too lower you detonation efficiency by 50%... You can try it yourself, but it is not a weekend trip, it is a project in itself.


I hope it help to clarify, even if my english is not perfect!

Good luck

That's why I'd take the EGDN. You can rely it'll do decently Specially per unit weight it's superb compared to all other explosives.

Following on the preceding citations , further resources _

Fuel/Air