Thursday, June 4, 2015

Gas Powered Cannon

The Youtube Channel Back Yard Scientist has come up with a interesting invention that points the direction to the practicality of building a feasible gas powered projectile weapon that does not rely on factory ammunition.

First lets start with this video:

Seeing this video and seeing these rough plans posted below reminded me of something else.

This combustion cycle of a pulse jet.

From Wikipedia:

Do you notice the similarities?

Now combine this with another discovery I came across related to combustion chambers via Mythbusters TV show:

The key is and you dont see the results at the end of this video, but the debris actually increases the power of the deflagration several fold.

 So, if you combine the valveless pulse-jet that works because the exhaust is larger and offers less restriction than the smaller sized intake for exit, and the debris inside the combustion chamber, and using a similar method as the backyard scientist did with a very long intake and small diameter hose/tube, one could create a high powered weapon.

Now for the ammo:

I found this video years ago, and for the life of me I could not figure out exactly how he did it.

The video shows a young guy in Scandinavia basically shooting gasoline filled aluminum cans at distances of a few hundred yards/meters with then they exploded in large balls of flame.

Finally I found buried deep online using the Google-Fu.

The soda cans have steel wool attached to the bottom.  Steel wool is flammable. 

Add in some sugar to the mixture and you got something interesting.

The designs depicted in the videos are quite crude, however the initial results point towards the possibilities of something much more advanced.


Tucanae Services said...

A little more advancement might include a series of fuel injectors timed along the barrel just behind the flame front to maintain the gas pressure. Temp sensor, uproc, battery and wire would seem to do it.

admin said...

Adding extra fuel during the burn will only serve to make it more rich and change the stoiciametric ratio, not to add the crazy technical challamce vs a larger combustion chamber.

As a side note, gas cannons using acetylene come out to somewhere around 500fps per a NASA study.

The point is to develop a device that uses as few parts as possible and not have to resort to fancy complicated valves, etc.

The long intake tube serves to isolate the intake from the exhaust ie barrel. Possibly a reed valve mighty also serve there.

My past experiments with spud cannons consisted,of a m1 bazooka replica with a 33cubic inch combustion chamber, and a 3/4 inch smooth bore barrel. I was easily able to penetrate 1/2 inch plywood at 50 feet using stainless steel wire mesh inside the combustion chamber. The projectile being potato. It was unable to penetrate metal sheeting at the distance.

admin said...

Sorry for the misspellings, replying via phone. The text is mouse sized.

Anonymous said...

You might consider a flash back arrester (I think it's called) that prevents flame from traveling back to the fuel source thru the fuel line. These are used in acetylene torches for safety. And perhaps the high pressure in an oxygen bottle might be useful to drive a piston.