Search found 113 matches

by GalFisk
Wed Aug 19, 2009 4:03 am
Forum: Pneumatic Cannons
Topic: Triggered burst disk
Replies: 16
Views: 1040

Dudeman: Your link has a period at the end which breaks it. Mike: The pressure between the burst disks should be about half the chamber pressure, and it needs to be more than half the burst pressure of the burst disks (about 70-80% of the burst pressure should be both safe and reliable). As long as ...
by GalFisk
Wed Aug 19, 2009 3:25 am
Forum: Pneumatic Cannons
Topic: compression fittings /pressure rating
Replies: 9
Views: 1095

I don't trust compression fittings, I know of at least two incidents where such a fitting has slipped with ...energetic disassembly as a result. To improve safety, you could fasten the olive on the barrel, brace the barrel so it won't slip, or use sand paper to put radial grooves around the pipe und...
by GalFisk
Thu Aug 13, 2009 4:24 pm
Forum: Combustion Cannons
Topic: Chamber Venting with compressed air.
Replies: 38
Views: 2540

http://www.hostanyimage.com/files/bmy8awmqun9smy41z2ml.gif This is an idea for a venting piston actuated by the combustion pressure. I made the animation long ago, I can see a few ways to improve upon this thing. Operation: the chamber itself is to the right. when the cannon is fired, the blue pist...
by GalFisk
Thu Aug 13, 2009 4:00 am
Forum: General How-To & Discussion
Topic: The Combustion Machine Gun
Replies: 33
Views: 2819

Smiley_666: that is indeed an interesting idea. Experimentation is needed to see if/how enough air can be drawn in through reed valves in the rear of the combustion chamber to support another combustion. If not enough air is being drawn in, the cycle will peter out. C:B ratio will make a major diffe...
by GalFisk
Wed Aug 12, 2009 4:56 am
Forum: Combustion Cannons
Topic: Chamber Venting with compressed air.
Replies: 38
Views: 2540

I don't have the time, tools or materials now, my next project will probably be a big combustion cannon built around a fiberglass tank I got from a water purifier. It may be recoil operated, but that will be a simpler mechanism than what I have drawn up. And I need to get the valved hybrid working p...
by GalFisk
Tue Jul 28, 2009 4:25 am
Forum: Hybrid Cannons
Topic: fuel mixing
Replies: 10
Views: 1718

Your spark plug is a bit "out of the way", so you may have a problem getting a good mixture at the spark (possibly in addition to general mixture issues). I have had similar problems with my hybrid. You could try placing the spark in the middle of the chamber to see if you get more reliable ignition.
by GalFisk
Tue Jul 28, 2009 4:02 am
Forum: Combustion Cannons
Topic: Chamber Venting with compressed air.
Replies: 38
Views: 2540

How about placing a piston inside the chamber, which moves through the entire chamber and pushes out the combustion products? (It can even be powered by a CO2 piston ;) ). Some kind of system is needed to ensure that you don't just push the combustion products into the barrel and then suck them back...
by GalFisk
Tue Jul 28, 2009 3:31 am
Forum: General How-To & Discussion
Topic: share your cannon accidents!
Replies: 328
Views: 27296

I just read the thread, lots of stupid and lots of interesting incidents in here. When I saw a new post by you in it I expected to find a tale of some catastrophic accident that has kept you away for so long :roll: :D Haha, not to worry, I've just been pursuing other interests such as pyrotechnics,...
by GalFisk
Mon Jul 27, 2009 5:39 am
Forum: General How-To & Discussion
Topic: share your cannon accidents!
Replies: 328
Views: 27296

I just read the thread, lots of stupid and lots of interesting incidents in here. These are my cannon accidents, I haven't fired my cannons in a couple of years but I'm thinking of blowing the dust off them and having a go. 1. An unrated 90° PVC elbow exploded on my very early combustion cannon expe...
by GalFisk
Sun Jan 11, 2009 9:52 am
Forum: Hybrid Cannons
Topic: Combustion/burst valve/piston hybrid?
Replies: 14
Views: 1979

Thanks, maing the drawings beforehand is part of the fun :) It also lets me see many problems before even ordering the parts. The wrapped up wire is for 9-12V - underneath the tape is a flyback transformer circuit, you can see the HV wire going of to the right. The long wire is so that the cannon ca...
by GalFisk
Sat Jan 10, 2009 7:16 am
Forum: Hybrid Cannons
Topic: Combustion/burst valve/piston hybrid?
Replies: 14
Views: 1979

It's called a piston hybrid, and I've done it. Twice now, but I haven't completely finished the second one. I think a guy by the name of galfisk also might have a semi-working version. Hey, people remember me :D Yes I still have the cannon, the valve itself works perfectly, it's only the fueling sy...
by GalFisk
Sat Jan 10, 2009 6:56 am
Forum: General How-To & Discussion
Topic: strongest joint copper ?
Replies: 5
Views: 940

Removable as in compression fittings? Those should not be used in cannons at all, they slip. I know of at least one accident with those (no injury fortunately). I've used a female adapter with a screw plug to access the piston in my copper pneumatics. The copper tube handbook is a great resource. Yo...
by GalFisk
Sat Jan 10, 2009 6:36 am
Forum: General How-To & Discussion
Topic: New Combustion Ignition?
Replies: 20
Views: 1207

A few summers ago I used paper caps for igniting my coke-bottle combustion, before I had made a portable electric ignition. I ignited them by focusing sunlight through the chamber wall with a magnifying glass.
Not very practical, just a fun thing to have done.
by GalFisk
Mon Aug 04, 2008 11:37 am
Forum: Hybrid Cannons
Topic: Lardas First Hybrid - HyGaC20
Replies: 323
Views: 95492

Jävlar, Larda! That's one awesome cannon. More damage pics please (would also be interesting to see what sort of damage the sheer pressure from a dry firing can do). About firing >200x mixes, I suspect any liquid propane would diesel when the gas is ignites, so as long as you don't go below the LEL ...
by GalFisk
Fri May 16, 2008 3:34 am
Forum: General How-To & Discussion
Topic: "In the world of spuds today"
Replies: 2412
Views: 170406

That explanation does not make sense, the check valve should open as soon as the pressure inside the pump exceeds the chamber pressure, keeping the pump pressure from rising any further.