Help Request New Member

[Esna69]

Been researching bait line launcher compressed air cannons and have made one but it didn't perform up to par. Hoping the smart people here could steer me in the right direction and answer some questions.

Initial build:
2" pvc, sch80, 60" long; reducer to 1 1/4"; 1 1/4" brass butterfly valve; various diameter barrels from 1/2" to 1", all 5 to 6.6 feet long. Max air pressure I could get from my compressor was 140 psi. Max object (with 65 pound fishing line attached) was a carbon fiber arrow with 2-3 ounces of weight on the tip; max distance was 115 yards.

I need to get about 250 yards with the fishing line.

I have the following mods, but can't test them for about a week (going on vacation). New tank 70" long, sch80 CPVC, 4"; same reducer and valve setup; ready with various larger diameter barrels all 6 foot or longer. Also now have a friend's scuba regulator that lets me dial down the 3,000 psi in the bottle to an output of 0 to 500 psi. So now I can fill the new tank to much higher than 140 (though I only want the minimum needed to get the required distance).

QUESTIONS:

Any rough estimates of whether this new tank/pressure/barrel increase will get me the distance?

Any suggestions on optimum alternative missile (like a potato or lead weight with some type of wadding?)

And, hypothetically, if I do get the distance, could someone help me figure out if it would be possible to go to a much smaller tank (like a mini scuba tank) with much high pressure and go to a smaller valve barrel to get the same distance?

I have looked over the great program that is posted elsewhere, but I am not as smart as the computer.

Thanks!!!!!!

[jackssmirkingrevenge]

Welcome to the forum!

I have looked over the great program that is posted elsewhere, but I am not as smart as the computer.

That's a shame, because it really is the best way to estimate performance before you start your build. Is there anything in particular you need help with?

1 1/4" brass butterfly valve

Are you opening it manually? If so this could be the literal choke point preventing better performance.

Ideally you want something like a sprinkler valve for a more sudden and consistent burst of air, though it would not be useful at higher pressures. On the other hand, I'm not sure higher pressures would be beneficial as they would tend to destroy the line bearing projectile - although it depends on the projectile.

Let's say you managed to cast a lead weight in more or less this shape:



You could get away with high pressures in a smaller barrel, which would help with costs too because larger valves that can take high pressures will get expensive fast.