first try 3" shell

[superspike23]

hi,

 

today I received my mortar 3 "

I immediately built two shells to try.

 

I used the same black powder for shell 2 "and 3".

 

shells 3 "have not flown while the two" yes

 

Here is the video

 

http://www.youtube.com/watch?v=IDkV82sPQEM

[The504]

It's a good start!

[PyroAce]

How much lift (grams) did you use for each 3" shell?

When you slid the shells into the mortar what kind of fit was it, it shouldnt be too lose, but at the same time not tight either, the shell should slide freely down the mortar to the bottom, even with the quickmatch attached. If the shell is too lose the lift gas will escape around the shell far too easily and you won't get an airborne shell.

 

And what kind of BP are you using as lift, is it home made or commercial, and what grain size?

 

 

[Mumbles]

I can't see the ground so I have no point of reference for how high the 2" shells were going. They seemed to lift and break alright though. I've always found 3" to be a tricky size. 3" ball shells almost always seem to end up undersized for me, however that all depends on what kind of hemis you start from. To properly lift them I was using a finer granulation, and using plenty of it. I would generally use 4FA or 2Fg.

 

Your problems seem fairly consistent. There are really two options. Find a way to make or buy better BP, or use more of what you have. You could also use a finer granulation, but I suspect that isn't the issue here. Some also have success with lift cups.

[superspike23]

How much lift (grams) did you use for each 3" shell?

When you slid the shells into the mortar what kind of fit was it, it shouldnt be too lose, but at the same time not tight either, the shell should slide freely down the mortar to the bottom, even with the quickmatch attached. If the shell is too lose the lift gas will escape around the shell far too easily and you won't get an airborne shell.

 

And what kind of BP are you using as lift, is it home made or commercial, and what grain size?

 

 

the shell weighed 120g and 112g

I used 16 and 15 g of lift.

The black powder is homemade.

The grain size is 1 mm.

 

I tried this afternoon with a false shell.

I put the cocoa powder and couscous.

It weighs 104g and I used 20 g of the same bp for lift.

 

Here is the video

 

http://youtu.be/L4psU959rUU

Edited August 15, 2012 by superspike23

[ryanlg95]

Well there's your problem. For your dummy shell you used 1/5 the weight of the shell in black powder, but for your functional shells you used 2/15 the weight of the shell in blackpowder. It may not seem like much difference but it is 6% less black powder between your dummy and functional shells which I say is your problem.

-Ryan

[superspike23]

new test:

 

3 shell 2 inch

1 shell 3 inch

 

http://youtu.be/4g3c8uITN3M

[ivars21]

Your lift sounds too violent for my liking. Are these canister or ball shells?

[superspike23]

it's paper hemisphere shell

 

new test with new star:

 

http://youtu.be/HzQDojmMBO0