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Black Powder Ejection at High Altitude

I taped the Discover Channel Rocket Challenge when it aired a year or two ago and still watch it (too often, I'm told). The one thing that really bothers me has to do with the Aurora Project - the use of black powder for ejection at 30K feet.

I expect that there is some empirical evidence that supports the problem of BP at altitude, but the claim that it is due to lack of air drives me nuts. Is it not true that BP is self oxidizing? Estes and Quest motors are sealed, as are things like the Defy Gravity Tether. Even most ejection canisters in electronic deployment systems pack the powder in with a wadding cap and are essentially sealed. Black powder rifles would not work because they too would suffocate themselves. If they depended upon the presence of atmosphere to burn, then BP motors would ignite then quickly go out as the initially burning surface consumes the air as it recedes into the motor.

Where does this premise come from and is technically sound.

Reply to
Thomas Koszuta
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Check this out;

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Might not be the answer your looking for but it could offer some insight.

Ted Novak TRA#5512 IEAS#75

Reply to
tdstr

The Rouse-Tech CD3 manual at

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says that you need enough air molecules to transfer the heat in between the BP particles. If your ejection charge completely combusts inside your ignition container you should be fine. (Although the CD3 manual says that a second issue is the additional cooling because of the lower ambient pressure.)

I think this is similar to the BP vs. Pyrodex argument. If you contain Pyrodex until it is consumed it works fine. If your container ruptures before that point you'll not get complete combustion. BP is sensitive enough that it will continue to combust as it sprays out of the container.

Some of the high altitude airframes are sealed and rema> I taped the Discover Channel Rocket Challenge when it aired a year or two

Reply to
Will Marchant

Based on this article it sounds like the real problem is that the first part of ignition blows the wadding out too quickly and just scatters the rest of the BP because of reduced back pressure. Interesting.

The medthod presented at the website below looks like a very elegent solution..

I'm not planning on flying over 20K yet, but I really could not stand the thought that the lack of air made the black powder stop burning.

Reply to
Thomas Koszuta

Reply to
Roktluver

I've only done ground testing with BP and some smokeless powders.

All I have to add is that I use paper 1/4" launch lugs as the cannister and had varying amounts of unburned powder after ejection. Until I lit the cannister from the "open end". Moving the ignitor to the top (away from the sealed end) of the powder column seems to allow a more complete burn (the remaining powder is not blown out of the cannister by the initial pressure???).

I've wondered about the 20,000ft effect as well. Maybe an actual gas generator (BP rocket motor) would be more effective in pressurizing the airframe than loose powders.

Reply to
Gary

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