19 replies to this topic

[miniskinny]

what is all this talk of NC being ping pong balls?.. explain someone? BTW PVC pipes make shrapnel and are not condoned for mortor uses...

[ProfHawking]

Ping pong balls are made of nitrocellulose. However they are not very highly nitrated, so just burn (albiet quite well).
Try it out. (has to be a proper one, not a cheapo plastic one)

PCV mortars are a bad idea, but can be used safely if they are shelded from any operaters/spectators.
For example they could be set up behind a wall and fired electronically.

Back on topic: My lift troubles
My lift powder is really bad i think. I push damp clumped meal throgh a screen to give granuals about 0.5-1mm aprox diameter. I dunno what mesh my screens are, just random bits ive found.
Anway i have to use about 1/3 of the weight of the projectile, for a loose fitting 3". It burns too slow, not the nice "whump" it should make.
I blame my charcoal...
In tighter fitting candles and stargun it is fine

Edited by ProfHawking, 11 July 2005 - 05:59 AM.

[miniskinny]

off-topic, but what should the ratio be of ping pong/acetone? should I just add until it becomes syrupy?

[LadyKate]

off-topic, but what should the ratio be of ping pong/acetone? should I just add until it becomes syrupy?

That's what I do. The Ping Pong balls I get don't melt all that quickly so I put everything in a clean can (you can get new pint paint cans that will hold this stuff), put the lid on and come back and stir after a few hours. If I don't like the consistency, I add more balls or more acetone. If I don't have more balls, I leave the can open for a few hours and it evaporates down.

Adding 1/2 Meal and 1/2 Ping Pong Acetone Mix makes a dip that is great. I dip the fuses from my shells and garnishes in it and swish in loose BP - dries super quickly and lights every time.

[LadyKate]

For a two inch PVC mortar, what are some basic lift powder weight (or amount) to shell weight ratios?

With commercial powder, start with 5 grams of FFg for a 2" shell. That will probably do it for a 35 gram load. I make a dummy shell and load it with dog food (I think Perigrin mentions that in his book) and test new powder mixes. My homemade BP isn't very hot - but it is just what I want for almost everything else. If I use homemade stuff for lift, I double or triple the amount I would use if it was a commercial blend. I have made hot homemade BP by using the CIA method, drying, ball milling, misting with 35% alchohol, compressing to 1.7 grams per cc, drying, breaking up and sifting, but it is a pain to make. I just double or triple up with the slower homemade for expediency. If I want rock solid results - then I use commercial stuff.

If I am lifting with a bag or lifting by pouring the powder into the tube, the results will be different. It seems to take less powder with a bag - at least that is what a couple of us have deduced. I prefer pouring the powder into the tube - but I use a powder chamber at the bottom of the tube. A powder chamber is just a wooden plug with a hole in it to hold the powder in a smaller confinement. The fuse hole goes through the outer wall of the tube, the wooden plug, and into the chamber. The result is a higher lift - but that is a subjective evaluation so your mileage may vary.

Edited by LadyKate, 16 July 2005 - 04:59 PM.