Pneumatic Launcher Science Project

[Lentamentalisk]

do those cost a fortune? are there affordable ones that are about 2"-1.5"? by affordable i mean less than $50.

[DYI]

If you look at sites like eBay you may get lucky, but from what I know, your average 3" sprinkler valve retails for considerably more than $50. DR built a gun with two of them once, so they must be available, it's just a case of finding them. Kind of like pressure rated ABS.

[Lentamentalisk]

would a 1" modded sprinkler be good enough to shoot a golfball quite some distance? Or should I go for 2?

[jackssmirkingrevenge]

would a 1" modded sprinkler be good enough to shoot a golfball quite some distance?

A 2" valve would obviously give better performance but given a say 4 foot barrel and 1:1 C:B ratio you'd certainly get a very impressive launcher using a modded 1" valve.

[Lentamentalisk]

i have been leaning towards a 3' barrel, as i want to keep it portable and non-dangerous for PR reasons, and a 2" valve is about $3k beyond my budget (even a 1.5" seems to be quite expensive...) So Jack, I take it you are voting for a 1:1 C:B ratio, is that the ideal Bang:Buck ratio, because i want a relatively fast refill, but still want some power.

[clide]

With a 1" modded sprinkler a 3' GB barrel and a 2"x12" chamber at 120 psi I've launched golf balls over 300 yards.

[jackssmirkingrevenge]

You'll be fine with 1:4 powerwise, I'd keep that as the bare minimum ratio.

[Lentamentalisk]

omg! 300 yards off that little of a spudgun?
wow, my taters only went 400' out of my hairspray combustion cannon, with a 1.5 in barrel ~4' long and a 3"x18" chamber.
I am probably going to have to shoot off the golf balls at only like 60psi so i don't lose them...

[DYI]

Golf balls are specifically designed for range, so they can go pretty far even at low speeds. You may want to consider something like tennis balls for a science project cannon, some people get scared when you start shooting golf balls (usually something to do with richocheting and killing someone).

Anyone know what the drag coefficient of a golf ball is?

[Lentamentalisk]

there was a post that i saw somewhere here on the forums that had the terminal velocities, from which you could probably calculate the drag coefficient.

[jackssmirkingrevenge]

Anyone know what the drag coefficient of a golf ball is?

According to this study, around 0.4