dummy test shells

[vinny1892]

Hello all.

What does every one use for testing their lift charges? Im currently using just a baseball for 3 inch shells, but what are some options for 4 5 and 6+ shells?

[pyrokid]

If the powder works for three inch shells, it should work for 4 and 5 inch shells. If it's hot enough to lift a three, it's hot enough to lift larger shells. Lift powder granule size should increase with shell size. Lift powder should "push" the shell and not "slam" it out of the mortar. More massive shells need more time to accelerate to their muzzle velocity to retain structural integrity.

 

I would build a simple star shell to test lift powder.

[MadMat]

Pyrokid is right, but if you want dummy shells to "dial in" lift charges for various sized shells, the answer is as simple as making a dummy shell. You should know, or at least be close, to an average weight of your various shells, so simply make a shell close to that average. I make cylinders almost exclusively, so thats what I make. I have found that scoopable cat litter makes a fairly close analog for stars and burst charge. If you make rockets you more than likely already have the cat litter in your supply. If the weight starts getting too heavy before the shell is tightly packed, stuff it with crumpled paper until it is tight. If it isn't heavy enough, a lead ball or two from your BP mill will fix that problem easy enough. After your dummy shell is complete, several coats of polyurethane varnish of even a coating of polyester (fiberglass) resin will make your shell last for many firings.

Edited March 27, 2018 by MadMat

[Arthur]

There is much to be said for a test shell that fires! It does not have to land anywhere. The bigger the tube the more area of land the shell may travel. A test 10" shell could land 500 yards away according to the wind -you'd need a big test site, if it fires it doesn't have to land on anything.

[OldMarine]

I built shells filled with cat litter and use a small burst charge. You have to remember not to look up after it pops or you'll get an eye full!

Now I use the baseball test and just extrapolate the data for larger shells.

Edited March 29, 2018 by OldMarine

[MadMat]

Ha! I never thought about shells as large as 10", I guess that would be a problem.

[Mumbles]

If you need to fire a test 10" shell to gauge height, you need to slow your roll at pyro.

[vinny1892]

Never had any intencio

If you need to fire a test 10" shell to gauge height, you need to slow your roll at pyro.

[/quote. Never had any intensons on building one that big. Not enough space..

[tenneyguy]

Pyrokid is right, but if you want dummy shells to "dial in" lift charges for various sized shells, the answer is as simple as making a dummy shell. You should know, or at least be close, to an average weight of your various shells, so simply make a shell close to that average. I make cylinders almost exclusively, so thats what I make. I have found that scoopable cat litter makes a fairly close analog for stars and burst charge. If you make rockets you more than likely already have the cat litter in your supply. If the weight starts getting too heavy before the shell is tightly packed, stuff it with crumpled paper until it is tight. If it isn't heavy enough, a lead ball or two from your BP mill will fix that problem easy enough. After your dummy shell is complete, several coats of polyurethane varnish of even a coating of polyester (fiberglass) resin will make your shell last for many firings.

Would the cat litter be new, or used?

Edited April 23, 2018 by tenneyguy