First Compressed gas Cannon (rather technical)

[mrmagoo]

OK heres what I have so far:
Power source: Propane from a Colman 16oz bottle (Its roughly 300psi as I understand) stored in a sealed container filled from an airsoft gbb fill valve. The container will be either PVC or ABS (PVC would be nice because it is cheaper, but if ABS is an overall safer design for the specs, I would go with that.)
Barrel will be roughly 20-25" long
Round will be a tennis ball
Fireing mech with be a Quarter turn ball valve
The Barrel will be 3" piping
the container will be 1.5" piping (have some lying around, so its that small for price sake)

The problem is this thing hast to be shooting a tennis ball below 300 feet per second and above 200. does anyone have an idea of how long my gas chamber should be to give me this result?

[spudthug]

ummm 2 problems...one dont use propane for a pneumatic gun.....two a tennisball fits WAY to loosely in a 3inch barrel to go more than 20 feet....oh and that isnt at all technical that is a basic cannon gone wrong...look up this stuff around here that wont work at all.......

[spudthug]

oh and the container????you mean chamber???you cant power a bigger barrel with a smaller chamber...your gun is a disaster plan...do some research

[WOW!!]

NO ABS!!!!!

Go with pressure rated Sch40 PVC, and don't use propane eather. For a tennis ball barrel use 2.5'' Sch40 PVC.


NO ABS IN PNEUMATIC GUNS. Sorry for the caps but I want to make sure you understand this.

[schmanman]

what do you mean by "the container"?

the chamber needs to be larger than the barrel.

is this a combustion or a pneumatic?

do you mean a 25 foot log barrel?

do you mind explaining better?

and what is a "airsoft gbb valve"?

and what diameter ball valve?




lots of holes in your design.

[zeigs spud]

omg rofl propane??!?!?! roflmfao omg dude i'm sorry but do some research rofl...what a waste of $$ get a bike pump it is safer and cheaper and it uses somthing you have alot of.....AIR!!!!! lol sounds good for a first...besides the Propane!! rofl only time you pressurize an explosive gas for spudding is in a hybrid but you ar nowhere close to safely acomplishing that i'm sorry lol. when u make ur cannon show some pics

[Punstype]

i think he got his barrel and chamber sizes mixed up,and you cant shoot tennis balls out of 1.5" need to use 2.5"
and you might want to make sure you use PVC for your pneumatic gun because ABS is unsafe. alot of guys gave me some advice because i had made that mistake on my first pneumatic.

[spudthug]

exactly guys thats what i explained to him look at my post lol i agree with every one of u

[Hotwired]

300psi from 1.5 into 2.5 with a 25" barrel

...and the dodgy assumption that air is the same as propane ( )

...and some fudging of the valve details

You'd need about the same length of chamber as barrel for over 200fps, probably a bit more, say 30".

You'd first want to get pipe that can actually hold 300psi....

[zeigs spud]

i basicly sugest for ur first penu that u only make a 125psi cannon. for first 300 seems high to me.

[Insomniac]

I thought propane liquifies at around 90psi @ room temp.

And NEVER EVER EVER USE ABS IN A PNEUMATIC!!! It can't cope with the rapid pressurization/depressurisation over and over and over again.

[iknowmy3tables]

300psi of highly flamable gas in a ABS chamber now thats a really safe spud gun lol
man I really hope he ment that the ABS was for just holding the propane tank.

[chaos]

well if you are going to attempt to shoot this please video tape it. i like seeing things explode.

[Insomniac]

Oh and you will need pressure rated fittings, NOT DWV!!!

[MrCrowley]

Yeah well I doubt you like seeing people explode

Dude, download GGDT(dont ask use google) to find out what diameter chamber and the length of the chamber and barrel to get 200-300fps.


I say a 3"(or 4") chamber 36"(24") long.....2.5" barrel 50" long. And a blow gun acuated sprinkler valve. Pressure 125psi.

I doubt you could get 250fps with a 20" barrel easily.