Black powder at 30K?

What altitude is black powder no longer effective as an ejection charge? Is it still ok to use at 30,000 feet?

Yes, but you need to contain it more than at lower altitudes. See this thread.

I had a successful deployment at 35K at Balls this year.

About 1.5in of CPVC pipe plus end cap (epoxied on).
Starter epoxied through the end cap.
The rest of the pipe filled with wadding and about 4 layers of masking tape sealing the open end.
I upped my normal 1.5g charge to 2g (3in diameter x 12in long bay).
I installed the assembly at the bottom of my chute bay pointing up so it would blow everything out.

JohnCoker said:

Yes, but you need to contain it more than at lower altitudes. See this thread.

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My charges are tightly packed (almost compressed loads; I'm a reloader) and contained in small test vials. My vials are glued closed. From what I've gathered from the link your provided, I might need to add a little more BP for higher altitude flights. My question still, is how much more BP and at what altitude should I start adding more........ I did PM tfish who made a comment that suggested he had some experience/knowledge about this. Thanks for the link and your reply.

So that's about a 33% increase in bp? Good to know. Thanks for your reply!

Zebedee said:

I had a successful deployment at 35K at Balls this year.

About 1.5in of CPVC pipe plus end cap (epoxied on).
Starter epoxied through the end cap.
The rest of the pipe filled with wadding and about 4 layers of masking tape sealing the open end.
I upped my normal 1.5g charge to 2g (3in diameter x 12in long bay).
I installed the assembly at the bottom of my chute bay pointing up so it would blow everything out.

Click to expand...

Walldiver7 said:

So that's about a 33% increase in bp? Good to know. Thanks for your reply!

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You can adjust for altitude using either a better containment approach or more powder. I use the better containment approach, and the amount of powder is the same regardless of altitude (for my rockets, about 1 gram in a 3" rocket and 1.25 grams in a 4" rocket). For uncontained charges, 30-50% increase in powder at 30K would be fine. Above that, I'd recommend moving towards better containment.

Jim

"...the amount of powder is the same regardless of altitude..."

Jim, This is what I needed to know. Thanks for the response! Pat

Walldiver7 said:

"...the amount of powder is the same regardless of altitude..."

Jim, This is what I needed to know. Thanks for the response! Pat

Click to expand...

Whoa, that's not quite what I said. The amount of powder is independent of altitude if it contained in a manner that causes it all to burn. I use the approach in the pic, where the powder is at the base of the tube and the empty part of the tube is what causes the powder to burn (by "containing" the combustion gases). If forced, I can post the article that describes this, but it can be found by a quick search. With this approach, the BP all burns and would do so in space (if I could just get there).

Now, if the containment is something different, and I would include surgical tubes, glove tips, large-diameter containers, etc., then you need to increase the amount of powder to compensate for it not all burning. 30-50% is what I would use at 30K, although I think there is a limit to the benefit of this as you go higher.

Jim

Well,... That is what you said, otherwise I wouldn't have quoted you. LOL! But, I did understand that you meant it had to be contained... as in a barrel. I reload, so I understand the concept that the powder completes its burn down the "barrel". (A slower burning powder, of course, would require a longer barrel for a bullet to reach its max velocity before exiting the muzzle. In the case of black powder (as you know, classified as a low explosive), the burn rate is extremely high/quick and won't need much of a barrel/containment to complete its burn. )

I sometimes use spent straight walled shell cases as my charge holders.. What are you using in your picture? How long are those? I do appreciate you making sure that I understood what you were saying.... and if I'm still not getting it, please say so.

JimJarvis50 said:

Whoa, that's not quite what I said. The amount of powder is independent of altitude if it contained in a manner that causes it all to burn. I use the approach in the pic, where the powder is at the base of the tube and the empty part of the tube is what causes the powder to burn (by "containing" the combustion gases). If forced, I can post the article that describes this, but it can be found by a quick search. With this approach, the BP all burns and would do so in space (if I could just get there).

Now, if the containment is something different, and I would include surgical tubes, glove tips, large-diameter containers, etc., then you need to increase the amount of powder to compensate for it not all burning. 30-50% is what I would use at 30K, although I think there is a limit to the benefit of this as you go higher.

Jim

Click to expand...

Walldiver7 said:

Well,... That is what you said, otherwise I wouldn't have quoted you. LOL! But, I did understand that you meant it had to be contained... as in a barrel. I reload, so I understand the concept that the powder completes its burn down the "barrel". (A slower burning powder, of course, would require a longer barrel for a bullet to reach its max velocity before exiting the muzzle. In the case of black powder (as you know, classified as a low explosive), the burn rate is extremely high/quick and won't need much of a barrel/containment to complete its burn. )

I sometimes use spent straight walled shell cases as my charge holders.. What are you using in your picture? How long are those? I do appreciate you making sure that I understood what you were saying.... and if I'm still not getting it, please say so.

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I think you get it just fine. Good comparison, too, as I've referred to the method as deployment by shotgun. My charge containers are specially designed, hand crafted equipment from, ahh ... Lowes. There is specific information in my article on high altitude deployment, which I've posted here many times before.

Jim

Have you a link to your article? I'd like to read it. Almost mistook your charge holders as brass .410 shotshell cases. They look very similar to your Lowes charge holders. What are they and what their lengths? Thanks for your help.

JimJarvis50 said:

I think you get it just fine. Good comparison, too, as I've referred to the method as deployment by shotgun. My charge containers are specially designed, hand crafted equipment from, ahh ... Lowes. There is specific information in my article on high altitude deployment, which I've posted here many times before.

Jim

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Walldiver7 said:

Have you a link to your article? I'd like to read it. Almost mistook your charge holders as brass .410 shotshell cases. They look very similar to your Lowes charge holders. What are they and what their lengths? Thanks for your help.

Click to expand...

https://www.rocketryfiles.com/files/Technicalarticles/Jim_Jarvis_Highaltitude_deployment_2013.pdf

JimJarvis50 said:

https://www.rocketryfiles.com/files/Technicalarticles/Jim_Jarvis_Highaltitude_deployment_2013.pdf

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Thanks!

I've flown to 30,000' twice. I used black powder in surgical tubing, secured with zip ties. Worked perfectly.