19 replies to this topic

[1145climber]

Hey all. I know there are many variables here, but im pretty sure some one could give at least a ball park answer. If it helps, my black powder is just normal black powder. even the height to which my shell flies to doesnt really matter, just looking for a simple, good height. So:

for a two inch PVC mortar, what are some basic lift powder weight (or amount) to shell weight ratios? for example, how much (weight or appx. volume) lift powder would i need for a cylinder shell that weighs about the same as a 2AA maglite, or a duracell D battery? sorry about the crude description, i dont have a scale on hand right now. as always, thanks for any questions/comments/concerns/verbal thrashings.

Edited by 1145climber, 14 April 2005 - 11:34 PM.

[Richard H]

I would say 5g is a good starting point. Of course this depends entirely on the quality and state of your lift powder.

[aapua]

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

For peony I use like Richard says 5 gr. For spider 7-8 gr and for extra long lasting firedust 11-12 gr. The BP I use is not homemade but commertial.

[BlackSky]

Is it worth to use NC instead of lift power ? (Assuming that the load fuse is the same fuse to ignite the NC lift charge)

[paul]

You would need really good NC (highly nitrated)... Otherwise you need a very good confinement. But there is nothing better than black powder in my opinion. Easy to make, cheap and it gives the best and most powerfull lifts.

There is no real option left besides black powder...

[BlackSky]

Thanks paul for the reply.
I do have an excellent NC (highly nitrated).

[Arthur Brown]

Lift is typically a pressed and corned BP, with the corning size being important Large granules will burn slower than fine dust, the right size and the right amount gives you optimum trajectory, Too fine and you may split the tube leaving the shell sitting there fuse burning and you TOO close! Too little and the trajectory will be low. Only by having a good corned BP of known grain size can you do the tests repeatably to determine the best amount. Longer tubes need more and larger grains.

[BigG]

Lift is typically a pressed and corned BP, with the corning size being important  Large granules will burn slower than fine dust, the right size and the right amount gives you optimum trajectory, Too fine and you may split the tube leaving the shell sitting there fuse burning and you TOO close! Too little and the trajectory will be low. Only by having a good corned BP of known grain size can you do the tests repeatably to determine the best amount. Longer tubes need more and larger grains.

Correction to this - Longer tubes need LESS lift of the same size...

[Douchermann]

Well if your not using professional or even corned BP, i'd say 30 grams will do thats what i use for all my shells, some of 2inchers i need to use 60 grams because they are smaller than my tube, so a lot of the pressure escapes.

[RegimentalPyro]

60g of lift for a 2 inch shell - Surely not!

I use 6g of my homemade BP to lift 35g of 2inch shell [also in a loose fitting tube]
I use 17g of my homemade BP to lift 120g of 3inch shell. #

Not yet up to a four inch shell but I reckon the rule of thumb is about one eighth to one tenth shell weight.

[seymour]

All this talkin about NC is gona get someone a warnin. I copy Yugen-Biki and use 25-35g for a 3" ( Yugen, All this time I thought you had the best ever name, but then I got "the Art, Science and Technique" and find out you were just naming yourself after a charcoal streamer!) Would Potassium nitrate/Magnalium/sulphur flash work as a booster in 3" shells?

[Yugen-biki]

seymour

Yugen, All this time I thought you had the best ever name, but then I got "the Art, Science and Technique" and find out you were just naming yourself after a charcoal streamer!)

What? It is the best name ever :-) ,"Mystery of willow". I see you have read the book throughly. For you who have not, you can find it on page 19.
I really like willow effects and thought that Yugen-biki was a perfect name.

Congratulation by the way! I have been waiting for a long time fore any one to mention it. But I guess people doesn't have Shimizu?s book, or just don't read it throughly. That's a shame because it is a very good book!

Would Potassium nitrate/Magnalium/sulphur flash work as a booster in 3" shells?

I think it would, you have to test it to be sure. I don't see why not, if the right ammount is used.

[adamw]

As welcoming as I am of trying alternative compositions and techniques - I really don't suggest trying a different mix (kno3 / mg / s etc), let alone NC (which I don't like the sound of anyway) before you have mastered shells using BP; the way it has, and will probably continue to be done.

[seymour]

NC? when Did I say that i was going to use it? The closest I am ever going to get to Nitrocellulose is at the ping pong table!

before you have mastered shells using BP; the way it has, and will probably continue to be done.

I am can not claim to have mastered shells, but I do know no amount of extra pasting on a 3" will give me a nice spherical and symetrical burst when un-boosted Bp is used as a break. I also know that the common method or incresing the power of the bursts is to boost it with whistle or flash. First up, whistle. I dont want to, and I am sure Adam, you dont want me to, use Picrate or Gallic whistle. I dont have perc so there goes Benzoate whistle. So then there is flash, as I have said, I dont have perc, so there goes 70/30. Chlorate doesnt even exist in this discussion, and nor will it exist, EVER in my possesion. So no H3. I read on Rec.pyro that some people use 50%KNO3/30%Al/20%S flash. As flash grade Al is expensive to get here, in New Zealand, I decided that as magnalium can be made with easy to get solid Mg and Al, and that magnalium is brittle ( so I could quickly and easily mill it down with my soon to get stainless media) it would be a possible alternative. Would 50%KNO3/30%MgAl/20%S realy be that much more sensitive than 70/30 flash? If so should I just remove the sulphur and adjust the ratios acordingly? Oh, and I am not going to use 20g of flash, more like 1g.
YES Yuge...( now I dont know what to call you) I think Yugen Biki IS an awesome name, just think about it, Yugen-biki

Oh, what a crap post. Adam, I am not in any way arguing with you, as it apears. You have my full respect. And I almost forgot! I will be using NC laqueur for e-matches, but those are going to be ping pong balls, so I am safe.

[AmericanRodent]

I actually did a calculation on this before. I ended up using 7.623g of BP for a 43.034g mortar in a 2 inch PVC. Sent it sky-high.