27 replies to this topic

[robbstech]

Hi all I have been haveing some problems with my aerial shells...

I have made several shells and loaded them into mortars for testing....

They are 2 inch and they weigh around 35g so I have been using 3.5g BP to launch them. The problem is they are only launching about 6 feet in the air then landing and then exploding.... this happens all the time and I have tried more and less BP still the same results.

I have even tried different tightness shells from really loose to tight where they have to be pushed in the mortar.

I have not been putting lift cups on them I have just been poring the BP in the mortar and There is a 1/8" hole in the bottom of the mortar for the visco.

What is happening?

And before you say it. My black powder is perfectly fine. There is nothing wrong with the speed of the black powder because it burns in a split second.

Can you think of anything else? I need to get this right before I start wasting more chems and shell cases.

Thanks
Rob

[jayden]

Maybe it has something to do with the length of your mortar tube?
That's not such a huge factor in lifting the shell, however - but it's a possibility.

[Creepin_pyro]

Odd - you seem to have most of the variables covered...

How are you granulating your BP?

[robbstech]

when you say its going up 6 feet and it going off, do u mean the shell will only go 6 foot high or would it go higher if it didn't go off early.

so if you used a golf ball would it go upto the full height.

if so then then the flame is getting into the shell some how, maybe posting a picture of how you fused it / pasted it (do u use Chinese time fuse)

The shell is not exploding early. Funny you said gold ball as I tried firing a golf ball and still it only went about 6 feet hight then landed!

The mortar length is around 14 inches if that helps?

[Atom Fireworks]

I know you have said you bp is fine but this is the only variable that can be at fault if you have a tube long enough which i think you have, and a tight fitting shell. Theres also two other possible causes however they arent that probable, one is your fuse hole could be letting too much gas out for the mortar to get enough pressure behind the shell or seen astho you are pouring your bp in the mortar then loading the shell maybe its damp. Ive notice on the mortar tubes used on displays ive been involved with after firing a shell they feel wet inside, cooperman told me this was because the black stuff left behind is hydroscopic. Could this be your problem??

If you can ide make a mortar tube with no fuse hole and make a shell with a lift cup, then fire it out of that tube and see if your result is different. If not its 100% a problem with your bp, maybe granulating it or just its performance in general. I used to think my bp was wicked until i seen another persons of here and his when unconfined make abit of a poof noise let alone behind a shell !!!!
Jay

[robbstech]

well if its going only 6 foot means your bp needs looking into, you may find its a really easy problem to sort out, (i had this problem to start out with and it was my charcoal, serious if i find one more pyro seller (ebay / other websites) selling cheap rubish charcoal and claiming it to be ultra fast willow im going to go mad.

My charcoal is vine from cooperman

[Potassium chlorate]

I think your BP is too weak.

But to comfort you, I can say that before I had a ballmill, I didn't know what good BP was.

[cooperman435]

I hear my name! lol

What process have you used to make your BP Robstech?

[digger]

well if its going only 6 foot means your bp needs looking into, you may find its a really easy problem to sort out, (i had this problem to start out with and it was my charcoal, serious if i find one more pyro seller (ebay / other websites) selling cheap rubish charcoal and claiming it to be ultra fast willow im going to go mad.

Hey not all ebay sellers are the same. Don't tar them all with the same brush. I am aware of a number that do this (I am sure I know who you bought yours from). However there are others that actually source their charcoal from European BP manufacturers (and don't brag anbout it on ebay), so if it is good enough for them then it should be good enough for anyone.

[digger]

Vine should be fine. I do have a vested interest in that for some reasons that may not be obvious. So it goes all the way back to production methods.

So go back to the beginning and let us know exactly how you are producing it.

[robbstech]

I hear my name! lol

What process have you used to make your BP Robstech?

I just ball mill all chemicals for 6 hours add 3% dextrin and granulate by mixing with water/alcohol until it just holds together then press it through a sieve!

BTW cooperman your products are great and I have recieved a great customer service from you!

Also you will know more about the mortar tube as you sold it to me

[digger]

I just ball mill all chemicals for 6 hours add 3% dextrin and granulate by mixing with water/alcohol until it just holds together then press it through a sieve!

Also you will know more about the mortar tube as you sold it to me

No need for more than 5% alcohol in the water just to break the surface tension.

Describe your ball mill to us. How big is your jar? What media are you using? how much of it? What is the rotational speed? Do you have any video of a test sample of your BP?

Edited by digger, 21 September 2010 - 06:23 PM.

[robbstech]

No need for more than 5% alcohol in the water just to break the surface tension.

Describe your ball mill to us. How big is your jar? What media are you using? how much of it? What is the rotational speed? Do you have any video of a test sample of your BP?

The jar is 1.3L and i use half full of ceramic 1" media, the jar rotates at around 75 rpm....

As for the video, I have used the last of my BP so I will post a vid when the batch (currently milling) is done!

Thanks