Battering ram piston design

[pat123]

Do you think this will work

[Hotwired]

So you let it charge up then whack it into a door, causing the piston to slide down, squashing the propane finally tripping a switch, igniting the compressed mix and blasting the piston out again with more force.

Could work but I'm sure theres a reason why the police stick to swinging a bloody great lump of steel at your door instead.

Quieter and less dangerous p'raps.

*edit whahaha first post by seconds

[goose_man]

Well, for starters, the valve would have to let air is as well, not just propane. Also, the piston would have to connect to a cam-shaft like in a car (I'm assuminig you want to make an engine-style device) in order to push down after the combustion stroke is over.
I also see a potential fuel loss problem when the piston is up because the exhaust port and the fuel valve are open at the same time.
I suggest moving the exhaust up to the very end of the piston's stroke (up in your diagram), and putting the propane/air valve at the bottom your cylinder.
Another idea would be to use a peizo-electric igniter as the spark. Think about this: when the piston hits the igniter's button as it ends its compression stroke, then it will cause the spark.
It looks like perhaps you are going with an electric valve? I suggest making it mechanical so that the top "touch valve" pshyically pushes open the propane/air valve via an external shaft.

Hope this helps,
-goose_man

EDIT: Damn, beaten to first post!

[pat123]

thanks for the help i might try to build it soon i'll post pics when it's finished

[lukemc]

if you get it to work you shold hook it up to a kind of piston that pushes air though a 6mm barrel and you got a airsoft. machine gun [/b]

[frankrede]

Why not use a solid propellant?
[ugh forum rules]
Alot easier in my opinion

[From_Hamsterdam]

If you make it i bet you end off worse then the door. The recoil of the piston/ram hitting something solid will be insane. Be very careful when testing this you could do your self some damage.

You are better off building a normal pneumatic or combustion and shooting out the door handle.

[spudzinger]

check out the design of the Tippmann C3 it has some of the aspects that you are interested in (i.e. propane combustion)