Search found 3197 matches
- Mon Apr 09, 2007 11:40 am
- Forum: Combustion Cannons
- Topic: Ratio of marble cannon
- Replies: 16
- Views: 4063
Spudblaster put it very well. The Latke spark strip / multiple spark data is of only limited use. Indeed, I looked at his comparison of two versus three sparks on the strip and there is no statistically significant difference in muzzle velocities. http://home.earthlink.net/~jimsluka/_images/Latke_sp...
- Sun Apr 08, 2007 6:04 pm
- Forum: Combustion Cannons
- Topic: Ratio of marble cannon
- Replies: 16
- Views: 4063
If the chamber is too big, the cannon will be too loud, but there's no real negative effect. For this reason, I always tend to go chamber-heavy. This is not true for combustion guns. A too-big chamber will decrease the muzzle velocity of the gun. The maximum muzzle velocity for a combustion gun occ...
- Sun Apr 08, 2007 8:58 am
- Forum: Combustion Cannons
- Topic: Ratio of marble cannon
- Replies: 16
- Views: 4063
If the chamber is too big, the cannon will be too loud, but there's no real negative effect. For this reason, I always tend to go chamber-heavy. This is not true for combustion guns. A too-big chamber will decrease the muzzle velocity of the gun. The maximum muzzle velocity for a combustion gun occ...
- Sat Apr 07, 2007 12:53 pm
- Forum: Ammo & Parts
- Topic: How the heck do you rifle PVC pipe??
- Replies: 32
- Views: 16960
Instead of cutting the grooves into the barrel you might consider building up the lands instead. Wild Ass, Untested, Method 1: Get some, say, 1/8" thick by 1/4" wide plastic (PVC would be perfect) and glue it in a spiral inside the barrel. Wild Ass, Untested, Method 2: Get on old metal slinky. Stret...
- Sat Apr 07, 2007 12:37 pm
- Forum: Off-Topic Hobbies
- Topic: I'm still waiting for a credible answer to this
- Replies: 9
- Views: 2264
The peak chamber pressure in "typical" combustion spud guns (propane + air) has been measured a couple of times. IIRC nobody has ever measured a peak pressure greater than about 60 PSIG. Unfortunately, measuring the peak pressure isn't as easy as it sounds. The pressure peak is so short that many ty...
- Sat Apr 07, 2007 12:02 pm
- Forum: Combustion Cannons
- Topic: propane help
- Replies: 11
- Views: 2275
I don't believe anyone has ever gotten a combustion gun to fire from sparking in a brushed fan. Too bad really, it would have been an primo ignition system. DR regularly uses the "personal fans" from Kmart and has never had a premature firing (of his spudgun anyway). Still, with a brushed fan all th...
- Sat Apr 07, 2007 12:01 pm
- Forum: Ammo & Parts
- Topic: Laser pens
- Replies: 13
- Views: 3595
- Sat Apr 07, 2007 11:37 am
- Forum: BB, Airsoft, and Pellet Guns
- Topic: Backspin
- Replies: 12
- Views: 3190
For BBMG's people have cut a narrow slot perpendicular to the length of barrel a short distance before the muzle. Then use a small rubber band or O-ring around the barrel that fits into the slot as the "hop-up" mechanism. Making the slot deeper allows the O-ring to block more of the barrel. Too chal...
- Fri Apr 06, 2007 11:28 am
- Forum: Off-Topic Hobbies
- Topic: Can E-BAY Sellers Really do this???
- Replies: 8
- Views: 2136
Re: Can E-BAY Sellers Really do this???
... He requested a divers license because he assumes all buyers are under 18, i just dont see where he has the jurisdiction to do this. Can he do this??? ... Of course he can. He can do whatever he f'ing pleases. He can only sell to left handed Martians if he wants. Why would he have to sell to you...
- Thu Apr 05, 2007 2:30 pm
- Forum: Combustion Cannons
- Topic: new way of using camera for ignition
- Replies: 20
- Views: 5334
- Thu Apr 05, 2007 12:15 pm
- Forum: BB, Airsoft, and Pellet Guns
- Topic: legitimate count per second
- Replies: 19
- Views: 4052
Measuring the ROF is pretty easy if you have an old PC or laptop laying around. (I can't believe how backwards this forum is.) Just use the PC to record the sound of the gun firing, or, the sound of the ammo hitting a target. Use any old sound editing software to display the waveform and measure the...
- Thu Apr 05, 2007 11:43 am
- Forum: General How-To & Discussion
- Topic: c:b ratio to destroy the cannon???
- Replies: 12
- Views: 2103
Well, you could make a chamber that wouldn't hold up to the pressure. Since the volume of a cylinder increases much faster than the inner surface area when you increase the size of the chamber, the pressure exerted by the force of the combustion on each square inch increases. I'm not sure how quick...
- Tue Apr 03, 2007 5:40 pm
- Forum: Combustion Cannons
- Topic: peizio wont work!
- Replies: 13
- Views: 2795
If it's an electric arc it is hotter than the surface of the sun, makes no damn difference if the spark is 0.01" or 0.5" long, it is more than enough to ignite the fuel. With aerosol fuels, mixing is often inconsistent, and so an ignitable fuel mixture is often not achieved between the ignition ele...
- Mon Apr 02, 2007 1:46 pm
- Forum: Off-Topic Hobbies
- Topic: Help me with electricity (Making a new taser)
- Replies: 10
- Views: 2271
You really can't wire up several transformers in series and expect them to boost the voltage to an "interesting" level. There are all kinds of limitations; the inductance and saturation of the transformers, resistance ... Besides, when you start getting into the "interesting" voltage range you'll ha...
- Mon Apr 02, 2007 1:42 pm
- Forum: Combustion Cannons
- Topic: peizio wont work!
- Replies: 13
- Views: 2795
If lengthening the spark gap solved the problem then the spark gap wasn't the problem in the first place. A spark is a spark is a spark. If it's an electric arc it is hotter than the surface of the sun, makes no damn difference if the spark is 0.01" or 0.5" long, it is more than enough to ignite the...