Search found 270 matches

by kjjohn
Thu Jul 22, 2010 11:26 am
Forum: General How-To & Discussion
Topic: launcher design
Replies: 45
Views: 8778

Well, I thought it would look cooler to have the bullets 6 or 7 cm apart instead of the actual distance. :)
by kjjohn
Thu Jul 22, 2010 11:11 am
Forum: General How-To & Discussion
Topic: launcher design
Replies: 45
Views: 8778

Behold MY genius!

Image

Image

Image

Bushmaster ACR with AK gas tube, grenade launcher, holosight, MP5 retractable stock.
by kjjohn
Wed Jul 21, 2010 2:20 pm
Forum: General How-To & Discussion
Topic: launcher design
Replies: 45
Views: 8778

JSR, did you find that link on the Firearm Blog, because I was just on Pascal's page before I saw this thread! I agree, some of the physics are questionable, not so much for the Thor, but the Epic A1 seems a little too sci-fi. However, a solenoid barrel may be possible in the future, especially cons...
by kjjohn
Tue Jul 20, 2010 11:38 am
Forum: Combustion Cannons
Topic: Powering ignition and chamber fan.
Replies: 10
Views: 2969

I would use a 12v battery (rechargeable NiMH or Lithium RC battery), but use a 9v voltage regulator for your HV supply circuit.
by kjjohn
Mon Jul 19, 2010 4:34 pm
Forum: Combustion Cannons
Topic: 16.4 Ounce Containers for a Combustion Cannon
Replies: 22
Views: 5880

8-10 feet? For the barrel, or just the chamber? Because if you mean the chamber, that's going to be one powerful combustion cannon! Usually these things don't have a whole lot of recoil. At least, not as much as you would expect. You could build a stand out of PVC, but make sure it has a large enoug...
by kjjohn
Mon Jul 19, 2010 1:57 pm
Forum: Combustion Cannons
Topic: 16.4 Ounce Containers for a Combustion Cannon
Replies: 22
Views: 5880

The fan survives the combustion because it is very quick. Although the combustion produces a few thousand degrees of heat, it only does so for a small fraction of a second, so the fan can survive it. The only time a fan won't survive is in high-power hybrids. I would not run your ignitor/chamber fan...
by kjjohn
Mon Jul 19, 2010 1:12 pm
Forum: Combustion Cannons
Topic: 16.4 Ounce Containers for a Combustion Cannon
Replies: 22
Views: 5880

Yes, that should work, but still, I would use a regulator for better precision, plus you would just have to open the valve and the meter would fill with the correct pressure immediately.
by kjjohn
Mon Jul 19, 2010 1:08 pm
Forum: Combustion Cannons
Topic: 16.4 Ounce Containers for a Combustion Cannon
Replies: 22
Views: 5880

Welcome to Spudfiles! I believe Coleman canisters have the same threads as the blue propane tanks, so you could use those. However, I'm not sure, but I think they are a slightly different mixture of fuel. If you just calculate for propane, the Coleman canisters should work. And yes, you could run a ...
by kjjohn
Sun Jul 18, 2010 12:44 am
Forum: General How-To & Discussion
Topic: Water/steam as propellant?
Replies: 8
Views: 2557

Water/steam as propellant?

Could you possibly increase the power of a combustion cannon by loading it with a cartridge containing regular water before the projectile? My theory is that you could possibly use a smaller chamber and still achieve the power of a larger cannon. Upon combustion, that water would (in theory) flash t...
by kjjohn
Thu Jul 08, 2010 8:33 pm
Forum: Hybrid Cannons
Topic: Hybrid Valve design
Replies: 12
Views: 2118

@jhalek90 - I believe you misinterpreted his design. There is no pressure between the two pistons at any time, so it would work. The cone shaped piston at the front is the only piston exposed to the chamber pressure, and upon ignition, it pushes back, uncovering the two openings in the side. The two...
by kjjohn
Wed Jul 07, 2010 5:53 pm
Forum: Pneumatic Cannons
Topic: Pressure rating...
Replies: 7
Views: 2273

This question has been asked before - I asked it. The responses I got were that it could hold well above 150psi, more in the range of 1kpsi, and as theBOOM stated, DYI's cannon was constructed of standard fittings, and I believe he even used a plastic barrel. Pressure ratings usually use somewhat hi...
by kjjohn
Fri Jun 18, 2010 10:28 pm
Forum: Off-Topic Hobbies
Topic: Smart dog and cool machine
Replies: 1
Views: 762

Yes, I have seen this video before. The launcher appears to use a slingshot type design to launch the ball.
by kjjohn
Thu Jun 10, 2010 9:53 pm
Forum: Combustion Cannons
Topic: ignition for my combustion
Replies: 42
Views: 6997

That would be a very sufficient ignition source, however I would advise against it. Neon sign transforms usually wear out eventually, and most, if not all of them require an AC power source, which means you would either have to bring a generator with you wherever you fired the cannon, or you would h...
by kjjohn
Thu Jun 10, 2010 12:38 am
Forum: Pneumatic Cannons
Topic: Pneumatic Cannon
Replies: 4
Views: 1235

In terms of connecting the tank to the sprinkler valve, do you mean the C02 tank, or the chamber? If you are referring to the C02 tank, this will not work. Discharging an entire C02 tank at once through a sprinkler valve will be inefficient, dangerous, and provide mediocre performance at best. You w...
by kjjohn
Fri Jun 04, 2010 8:52 pm
Forum: Combustion Cannons
Topic: "New" Fuel Has anyone seen / used this?
Replies: 17
Views: 4998

Perhaps someone should put it in a vacuum chamber and try to light it, then we will know if it is an oxidizer or not.