2" Piston Valve Tennisball launcher

[airpress]

Hi all.

Here's my newest pneumatic launcher.
I've constructed the piston valve by myself.
It's the first time in 7 years making spudguns that I use (important to mention; pressure rated) pvc pipes.

Some more info about the cannon.
Chamber: 1m 75mm PN16 PVC (inside diameter of the chamber is 65mm)
Barrel: 1m 75mm PN16 PVC for tennisballs and 1,50m 50mm PVC for golfballs
Piston: is made of ACULON, a sort of hard plastic
Piston seat: 1 1/4"
Piloting valve: 1/2"
Maximum used pressure so far 5.5 bar.

Piston, seat,... :






Piloting area:


2 different barrels:


golfballs





tennisball

Here my brother holding the launcher.



Videos: VIDEOS ARE UPLOADING AT THE MOMENT

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Around 100 meters with 5.5 bar

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Used pressure 3.5 bar

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Pressurizing the cannon (bicyle pump)

I didn't shoot golfballs yet. That is coming later.

I've ordered fittings for a larger piston valve. 3"

Airpress

[mattyzip77]

That is a really nice build. Well done. Its pretty damn close to perfect in my opinion. Also very clean as well. Wait till you shoot some golf balls you will be amazed. My hats off to you bro, 10 outta 10...

[Mr.Tallahassee]

That Pipe should be rated for 200PSI or 13.7BAR according to the engineering toolbox. I wouldn't take it beyond 5.5 BAR unless you use high pressure rated pvc cement though. Most combination ABS/PVC cements only hold up to 80PSI/5.5BAR because they don't "weld" the pipe together. Maybe change to steel chamber? That would be able to take a lot more pressure. 300PSI+tennis ball=Destruction!!

[airpress]

The glue I used is fine for 16bars of pressure and the pipes are rated to 16bars. When I glued the pipes together I got pain in my head because of the strong fumes and yes it does weld the pipes together. I was told that by someone who's working hole days with these pipes.

But I will not use 16bar. Something around 7 bar maximum.

[MrCrowley]

That Pipe should be rated for 200PSI or 13.7BAR according to the engineering toolbox. I wouldn't take it beyond 5.5 BAR unless you use high pressure rated pvc cement though. Most combination ABS/PVC cements only hold up to 80PSI/5.5BAR because they don't "weld" the pipe together!

I don't think this is ABS pipe, looks more like the European coloured PVC pipe; it should be relatively safe up to 10 bar but I probably wouldn't go over 120PSI.

Great job with the cannon, airpress. Do you think you are you getting good performance from it?

[airpress]

It is abolutely not ABS pipe! Just like mr crowley said European coloured pvc pipe.

Yes, its the first cannon I build that shoots tennisballs.
About the performance. Some days ago we tested the cannon in Vencimont(Wallonië, southern part of Belgium)
Where were tested it constantely with 5.5bar. I was not shooting but I was standing in the field to take the tennisball when he landed. The maximum distance was +- 100m
I also love the sound when the piloting valve is triggered, the sound of the piston sliding back and the air escaping.

The only thing i was thinking of is the piston seat. What if this was bigger?

That why is bought some 3" fittings.
I will duplicate the cannon but then with a 3" piston and larger seat.
And then see the difference.
But maybe i will make the chamber a bit longer and also the barrel.

[MrCrowley]

It would be difficult to make the seat much bigger than it already is for a 2" tee but a 3" tee should give you better performance with tennis balls. If you can afford it, by all means build a larger cannon. But you will also find it less practical when it comes to pumping it up with a bicycle pump so it might be better to use a metal chamber, invest in a fridge compressor, and see what happens to tennis balls fired from a 20bar 2.5" porting piston cannon

[airpress]

20bars behind a piston that is 5cm in diameter.
That's some serious forces. I wonder if the metal reducer will not brake by the piston sliding back at those pressures(forces).

No no.
I will make this cannon again but then with a 3" T piston valve. And a seat so large as possible. But I will know that in a couple days.

Something else. What if I make the barrel 1m longer?

[mattyzip77]

I would invest in a 3/4 inch qev to pilot it. You could cut down alot of dead space in the pilot area and will give you a boost in performance.

[Mr.Tallahassee]

That Pipe should be rated for 200PSI or 13.7BAR according to the engineering toolbox. I wouldn't take it beyond 5.5 BAR unless you use high pressure rated pvc cement though. Most combination ABS/PVC cements only hold up to 80PSI/5.5BAR because they don't "weld" the pipe together!

I don't think this is ABS pipe, looks more like the European coloured PVC pipe; it should be relatively safe up to 10 bar but I probably wouldn't go over 120PSI.

Great job with the cannon, airpress. Do you think you are you getting good performance from it?

I know it's PVC. I made a ball valve cannon with it and I was pretty sure it was just SCH80 PVC pipe.
I see people regularly using a combination cement for both ABS and PVC but all it is is glue. It doesn't actually fuse the two pieces. I used this chart here to find the maximum working pressure for the pipe used in this gun.

[MrCrowley]

I know it's PVC. I made a ball valve cannon with it and I was pretty sure it was just SCH80 PVC pipe.
I see people regularly using a combination cement for both ABS and PVC but all it is is glue. It doesn't actually fuse the two pieces. I used this chart here to find the maximum working pressure for the pipe used in this gun.

Ah, I was confused as to why you mentioned the PVC/ABS glue; is that what he used or something? Perhaps I missed something but I didn't see the relevance in why you mentioned the cannon's working pressure is about 80PSI because that's your estimated working pressure when ABS/PVC glue is used.

20bars behind a piston that is 5cm in diameter.
That's some serious forces. Razz I wonder if the metal reducer will not brake by the piston sliding back at those pressures(forces).

I have ~80bar pushing back a piston 5cm in diameter in my piston hybrid cannon that uses the same metal fittings for the housing

[Mr.Tallahassee]

I based 80PSI off of every can of combination cement I have ever bought. I think I may test the working pressure of various pipe sizes with combo cement. Now I'm kinda curious about the actual bursting pressure.
Anyways, I do like the cannon. It's much cleaner than any of my pneumatics. I need to work on that.

[airpress]

Its not combination cement.

[airpress]

I'm back from vacation in the france alpes. Colmar les alpes in Côte d'azur.

In that time my 3"inch fittings were delivered.
Some pictures this evening. :p

[airpress]

Hoopla, the fittings layed like they should be mounted in a couple days.
The piston seat is 2".


That white painted reducer must be taken of. It just a recycled piece of pipe from something else.