SpudFiles

Hello there, thought I would sign up and share my recent(ish) aircannon build.

As much as I enjoy seeing the large pvc builds, or rifle-type copper pipe guns, I decided to go a slightly different route and use a pressure-washer gun and some hydraulic fittings in order to achieve much higher pressures than normal. My inspiration for this build was the following project:

http://www.spudfiles.com/airsoft-pellet ... 7-105.html

Ideally I wanted a 12/24v solenoid valve as the trigger, but finding one that can handle upwards of 1000PSI is hard to say the least- most use weird thread styles or cost as much as a good 2nd hand car. Regardless, I ended up using the pressure washer gun which has a 3/8" BSP inlet, and coupled that with various fittings including a ball valve and a quick-release connector to act as the filling port ( being filled via a PCP airgun pump rated for 3000PSI ).

The cannon was designed with versatility in mind, so as such I can change barrels easily- each one is mounted/mated to a 1/2" BSP fitting with epoxy and grub screws, with a small magnet acting as a de-tent. All projectiles are a very nice fit in their barrels so O-ring de-tents are not necessary, air loss or blow-by is minimal, with a very nice loud crack upon firing.

At present I have 3 barrels, a 7mm brass tube for 16" crossbow bolts, a 19mm aluminium tube, and a 22.5mm aluminium tube; the larger two barrels chamber steel ball bearings, empty Co2 cartridges, and an old Brushless motor rotor/magnet.

Power levels vary depending on ammo type, but with the current set up I can achieve upwards of 60ft/lbs of power and 130fps with my heaviest slug, or 30ft/lbs and 200fps with the lightest. Nothing record breaking but pretty respectable for a very compact cannon- I have just ordered some 1" BSP fittings to build a new air chamber that will hold roughly double the air capacity of the current set up, will do some testing once those arrive in a few days hopefully.

I won't bombard you with too many pictures- I have a project page on my WEBSITE, so here are just a few highlights:







I also have graphs showing recorded weights, velocity and power of various projectiles and differing air pressures- currently I use 1000PSI, but in principle I can go upto 3000PSI... if I was that brave. 1500 is as high as I can go at present as there is a small leak in my cobbled together 'aircylinder', between the T piece and the first male to male adapter- PTFE tape can only do so much it seems. I will have more Dowty seals in my improved set up, and may replace the T with a 90 degree elbow if I can find one with nice large mating surfaces- Dowty seals simply won't work with the more slim-line fittings.

Anyway, this is my Cannon, hopefully you liked it and I will keep this thread updated as I make improvements. Cheers.

To clarify...the pressure washer handle IS the valve? Might look into using it as a pilot for a piston valve...performance should increase noticeably.

Blue loctite makes a REAL good thread sealant...let it sit over night before using. Can take it apart with hand tools if needed..no heat required. Use it on pcps/booster pump @3000psi and my N2 fill setup @4500psi.

Ayyyy still inspiring people! Nice build!

Gippeto wrote:To clarify...the pressure washer handle IS the valve? Might look into using it as a pilot for a piston valve...performance should increase noticeably.

When you're using high pressure even a manual valve like this is pretty darn effective, especially if you use some sort of detent at the breech to delay the launch.

Yeah, the pressure washer is the valve- I really don't have the equipment or patience to machine or build a piston valve assembly- so long as I squeeze the 'trigger' sharply without jerking the whole cannon off target, it is extremely effective at dumping the air instantly vs a slower release of pressure.

I do have some blue thread lock as it happens ( r/c car enthusiasts should never be with out it, lol ), will have to try it if I still get a leak during future testing.

Anywho, I made a larger cylinder for more destructive goodness:







Now using 1" BSP fittings for most of the cylinder, holds roughly 3 times as much air ( 30 pumps vs 10 pumps to reach 1000PSI )- fitted a Picatinny rail to the side of the cylinder rather than the barrel to mount the horizontal grip; next job is to knock up a small mounting plate on top of the plastic body of the cannon to mount the lazer pointer permanently ( gonna use an L shaped piece of Aluminium glued to the top and side, with a short piece of Picatinny rail screwed and glued to that for the laser to mount onto ).

Was planning on doing some testing last week but that fell through ( I like it when people agree to call you and confirm plans, then you don't hear anything ), so hopefully I'll be able to do something sooner or later at any rate- this little monster demands shooting!

Those photos look very professional

Ianbuckwell wrote:Those photos look very professional

Nothing like a plain white or black background and a few lights to really improve the quality of photos.

In other news, I've been watching Yoerg Sprave's videos on his insanely powerful air bow launchers- I'm gonna change my sketchy little ~150psi fill valve for a nice 3000psi check-valve, that way I know it won't fail on me and I don't have to deal with a giant handle sticking out any more. I'll pick up one of those in a week or so after pay day...