High Performance Pyrotechnics

[BlazingAngel665]

I've used 4F black powder for all my time in this hobby, but I'm working with a team on a high altitude rocket, and we're looking into a pyrotechnic gas-generator feeding a pneumatic piston for a deployment system, similar to Derek Deville's excellent Qu8k.
Cleaning out the piston after every firing is a drag, and as an engineering student I'm inclined to assume that we can spend money and find an aerospace grade (overpriced and overperforming) solution to the problem. We do have an LEUP, so we can consider a wide range of materials.
We're looking at Black Powder as a baseline material, but we're also considering nitrocellulose. We've eliminated sodium azide (too toxic), and APCP (thermal issues).
Has anyone used anything other than black powder? Does anyone have any advice to share on the subject?

[dhbarr]

How do you feel about co2 systems? Check out cd3 & peregrine for powder activated, or life vest/raft inflators for mechanically activated.

Check out Swiss Null B (0b) powder, it's even finer than 4fg. I don't think anyone still has stock of 5fg since Goex quit bottling it.

Investigate 7fa or Meal XF powder. It's got more surface area per flake and isn't graphite polished, but I believe more susceptible to static and moisture.

My current theory is that a thin layer of double base pistol tucked under a strata of meal xf in a lamp nipple would be an extremely fast and clean burn for a fantastic electronics bay support.

Nobody that I know of has tried any of this; if you don't have an experienced firearms reloader to go with your LEUP you shouldn't try this.

[dhbarr]

Oh, dirty piston. Duplex loads of smokeless pistol under black powder substitutes is where I'd take a look.

Also airbag pellets, not all of them are azide based.

[Steve Shannon]

I looked at gun cotton years ago, which is just nitrocellulose that looks just like cotton. It burns very fast and very clean. Unfortunately it’s affected by humidity over time and breaks down into something that was much less useful. It works well because it exposes so much surface area. Nitrocellulose powder might not work so well. Smokeless powder requires containment and when contained delivers very high pressures in a very short time, much higher than our amateur rocketry components can withstand.
I’ve considered CO2 Systems and I’ve read about spring systems. I keep coming back to 4g black powder. Jim Jarvis had some recent posts on achieving more complete combustion that remove concerns about high altitude use of BP for me.
Almost all of my rockets have used pistons. I have never had a problem simply wiping out the “cylinder”. I have brushes up to three inches and my hand with a rag works above that.


Steve Shannon

[jderimig]

Doesn't AP burn clean (no ash)?

[dhbarr]

Doesn't AP burn clean (no ash)?

Yes, but they mentioned thermal issues there.

[Steve Shannon]

Doesn't AP burn clean (no ash)?

One byproduct is hydrochloric acid.


Steve Shannon

[tfish]

The below links still use BP but use confinement methods for high altitude...

http://www.google.com/url?sa=t&rct=j...k_0G5sFpeX2FXf

http://www.rocketryforum.com/showthr...d-Ejection-Cap

Tony

[ksaves2]

One byproduct is hydrochloric acid.


Steve Shannon

Oh yeah, I forgot about that one. HCl acid might not be kind to the hardware and harnesses. Judging by the "heat blast" of a few pounds of APCP chips, bits and powder on the burn pile from 100 feet away after a group motor "machining" session,
I'd say the thermal effects could lead to the flaming parachute recovery. Or a flaming rocket recovery if a cardboard rocker were tried! Kurt

[rocket_troy]

I've used 4F black powder for all my time in this hobby, but I'm working with a team on a high altitude rocket, and we're looking into a pyrotechnic gas-generator feeding a pneumatic piston for a deployment system, similar to Derek Deville's excellent Qu8k.
Cleaning out the piston after every firing is a drag, and as an engineering student I'm inclined to assume that we can spend money and find an aerospace grade (overpriced and overperforming) solution to the problem. We do have an LEUP, so we can consider a wide range of materials.
We're looking at Black Powder as a baseline material, but we're also considering nitrocellulose. We've eliminated sodium azide (too toxic), and APCP (thermal issues).
Has anyone used anything other than black powder? Does anyone have any advice to share on the subject?

Why even use pyrotechnics

TP

[dixontj93060]

Why even use pyrotechnics

TP

Looks cool! But large, and maybe expensive.

From the Ether...

[rocket_troy]

Looks cool! But large, and maybe expensive.

From the Ether...

Yeah, probably not totally ideal for high altitude attempts where you want to optimise everything. Saying that, I have used it in airframes up to 4.5" diam which provides a modest intrusion to the available volume and mass.

TP