The Radio Control Engineer

"RCENGR"

CO2 Cannons

Spurt cannons have a smaller magazine than regular cannons (15 vs 50 rounds) and instead of firing one BB at a time, all BBs are fired at once.  Spurt cannons are only legal on Class 1 ships, which helps the builder save weight for these smaller ships.

You can make a spurt cannon by simply removing the interrupter piston from a regular cannon, but this doesn’t give you any weight savings.  Since I have not found an article on how to build a purpose built spurt gun, I made one on my own.

I started with a 1/4" compression fitting and drilled it for a 4" tight tolerance barrel. I soldered 2.75" of 1/4" copper tube on the other side of the fitting to be the 15 BB magazine. To the magazine I soldered a piece of 3/8 brass drilled and tapped 10-32 for a Clippard fitting. The total weight of the gun with a MAV-2 valve was 2.5 oz, versus 4.5 oz for a standard 50 round gun without a valve.

I loaded the gun muzzle-loader style and took several practice shots. According to my chronograph I was able to achieve 165 ft/sec velocity at a rate of 115 rounds/sec (10 rounds in 0.09 sec) on 100 psi. That was enough to get one or two rounds through 2" foam.

Most of the weight of a gun system is in the CO2 bottle and regulator.  Small 12 gram CO2 bottles are available, but the lightest regulators are about 3 oz.  So to get the most weight savings, I planned to eliminate the regulator and just use a fixed tank (accumulator) filled with CO2 at 150psi. I experimented with different sized accumulators to get the right size for a 15 round spurt gun. The total accumulator volume needed comes out to 1.95 cuin. With this size, I was able to shoot all 15 BBs at a velocity of 192 ft/sec. Success!  You can make your own accumulator from 4” of 3/4 PVC pipe, or buy a 2.0 volume chamber from Clippard for less than $10.

Overall I'm very pleased with the total gun system. Depending on the accumulator used, the total weight should be about 6 oz and the volume small enough to put in either a submarine or destroyer.

Spurt gun with remote valve

Spurt Cannons

Spurt gun with fixed valve (works better)