Squash ball help

[rg123]

Hi all, I am doing a project at uni which requires construction of a 'gun' to shoot a squash ball projectile up into the air with the goal of it coming down and landing in a target area...this is on a small scale so gun to target length is only 2-6metres.The gun has to be fixed to a stand and fired remotely (solenoid or something)..and we have a construction budjet of 20 pounds...Any idea of the pressures we would need and a cheap option for a trigger.
I was thinking construct a pressure vessel out of pvc pipe(capped at both ends) ,oneway valve to bikepump, then pvc barrel (pointing upwards) mounted on a stand..main area of concern is which kind of solenoid to use...must be cheap.
any ideas appreciated, just to note,the whole assembly needs to fit inside a 40cm^3 envelope .
is in effect a mini mortar gun.

[Kensingt0n]

Does it have to be electronic for remote firing? You could keep it plain and simple if the budget wont allow for a solenoid and make an actuated ball valve that triggers via a length of rope or wire.

[rg123]

hi there ,yes it has to be electronic . i can get a 1/2" solenoid for a few quid ,a pressure gauge for a few quid ,and use the rest on materials..

[Kensingt0n]

No worries then, sounds like you have it covered for that. Go the solenoid for sure then id say

[rg123]

basic design at the moment is pressure vessel constructed from pvc pipe (capped each end, bike valve in) then connected to solenoid which is mounted directly at base off barrel..
squash ball is 40mm dia i believe ,and we have a max pressure allowance of 5.5bar..
the solenoid i have got my hands on is only 1/2" ...do you guys think i can get sufficent force on the ball with that pressure limit and the size of solenoid?