somewhat-mini golf ball launcher

[grock]

i was thinking of making a small golf ball launcher, something that would fit in a backpack. whats the shortest barrel and smallest chamber you guys think i could get away with to still shoot about 200 yards? (sprinkler valve ~120 psi)

[inonickname]

I'm more of a combustion man....I.M.O go pure H2/O2... If it's on a small enough scale you could use something smaller than a car battery (motorbike ones are alright apparently). But I'm not here to change your mind, so I'd suggest:

Gas gun design tool

A bit of trial and error with that, and you're rolling!

[starman]

It's not that hard to get a golf ball 200 yards. Here's CO2 system that was installed in a golf bag. It could be done with a sprinkler valve with no problem.

[jeepkahn]

you could make a nice little coax for GBs 3" chamber 24" long, sdr21 36", fill it with a bike pump and should net you about 300 yds easy... total length about 40"...