SpudFiles

I am planning to build a pneumatic launcher that can launch a 400 grams cabbage (average 6 inches diameter) at least 15 meters (does not matter how high it goes). The thing is, I am not very mechnically inclined and this will be one of my first technical projects. However, I do understand the concepts of how the launchers work.

What pneumatic launcher would yall think would work the best.

I believe a piston valve would suit you the best!!!!!!

gonna have to be big though, with my 1 1/2 port i put golf balls 600 yrds but for cabbage you are gonna have to make a big sucker!!!

Best bet at this bore size is, IMO, a burst disk.

Seeing as you require minimal distance, I would suggest a large (4" or more) ball valve or butterfly valve, perhaps with a spring attached the to handle for faster opening times.

All that would be required is a decent sized chamber and a decent barrel length, it shouldn't be too difficult to construct even for a first cannon. You could use a large (100 litre?) propane/compressor tank with low pressure (30PSI and below) or a smaller chamber with higher pressure (50PSI+). Depending on your budget, I'd go for a large chamber, butterfly valve and low pressure.

Edit: Actually, what I suggested would probably launch a cabbage well past 15m. You probably could hit 15m with a chamber as small as 20litre and low-ish pressure.

jsefcik wrote:I believe a piston valve would suit you the best!!!!!!

gonna have to be big though, with my 1 1/2 port i put golf balls 600 yrds but for cabbage you are gonna have to make a big sucker!!!

@ jsefcik:: I would bet every cannon I have that your cannon has never even shot 300 yards!! So stop with the dreams, we all know you are full of shizzznitt and you are making yourself look like a moron. So, stop the madness!! Not tryin to be a dick, but the laziness and trolling gotta stop!!

I would recommend a burst disc as well like gun freak said.

Matty seriously, you're the one who needs to lay off a bit. His cannon with my valve is perfectly capable of 600 yards and beyond. Maybe he's never actually done it but he can.

Gun Freak wrote:Matty seriously, you're the one who needs to lay off a bit. His cannon with my valve is perfectly capable of 600 yards and beyond. Maybe he's never actually done it but he can.

As I said, I will bet every cannon I have, not gonna happen, not with the cannon as it is now!!

It can certainly manage 300.

never said it couldnt, just said it hasnt, unless the basement is 300 yards long, that is all, not tryin to argue with you, of all people!! sorry to lastxdeth, did not mean to hijack your thread!

Enough off topic. My GB results are posted in another tread so no need for one upmanship. Lobbing a golf ball over 300 yards on only 50 psi is not difficult.

Back on topic. I do not recommend a QDV simply because at higher pressure and larger diameter, they become hard to fire. A 6 inch would need a hydraulic or air cylinder to actuate it. I have plans for a 4 inch piloted version, but this is not built and tested yet, so I can not recommend one at this time.

As others mentioned, for best performance, use a big valve. Don't use any valve smaller than 2/3rds the barrel diameter. In clocking projectiles on a 2 inch valve using 2.5, 3, and 4 inch barrels, the effect of the valve size becomes very noticeable for barrels over 3 inches.

In consideration of a burst disk, reload time becomes the main issue as the disk needs replaced for each shot.

The second issue is control of the timing of the shot. A single burst disk is difficult to trigger reliably. A dual disk to pilot it is an option.

The third issue with a burst disk is the operating pressure ranges are fixed related to the burst disk material.

For those reasons burst disks are not very popular. The main issue is cycle time sucks.

Thanks for the advices, guys! They were really helpful, despite the "friendly" competition between yall. I will use MrCrowleyand and use a butterfly valve to accomodate the large projectile that I will be launching. Also, thanks for the valve size tips, Technician1002.

Also, is it reccomended to use metal pipes or PVC pipes when constructing the barrel for this particular project?

No sense in using metal here, I'd go with PVC.

PVC Pressure rated pipes would be most suitable i believe, metal pipes in 6" diameter can be quite costly, not to mention the weight also....

If the cannon is to be used at a public event such as a pumpkin patch, care must be taken for liabilaty issues with the spectators. Insurance requirements may limit your choices in materials. Pumpkin Chukin has eliminated plastic barrels for safety reasons.

Is the cannon for personal rec use, or will it be part of a public event such as a harvest festival?

mattyzip77 wrote:

Gun Freak wrote:Matty seriously, you're the one who needs to lay off a bit. His cannon with my valve is perfectly capable of 600 yards and beyond. Maybe he's never actually done it but he can.

As I said, I will bet every cannon I have, not gonna happen, not with the cannon as it is now!!

Matty the black valve works great!!!!!!!!! fired it out of my window and gun freaks works works just as good

my combustions i have gotten well beyond 300 yrds!!! using a range finder!!!