IGNITERS 'r' US

Following are reader contributed tips and suggestions on subject of rocket motor igniters. Many thanks to all of you, who sent your input to me, via the e-mail. If you don't see your article here, than it is probably because I still didn't get to it...

I am posting all the articles on 'as is' basis, the only editing being the spell checking, and the removal of extraneous subject matter. <BlueSky>

Subject: Igniter pyrogen
Date: Fri, 6 Sep 1996 16:25:12 -0500
From: Mckinney <anarchy@comteck.com>
To: bluesky@tiac.net

I don't know if you will consider this as being useful, but I make my own igniters using 65% AP, 20% willow charcoal, 10% 425 mesh flake AL and 5% iron oxide. I use Duco cement and acetone as a binder. Magnesium can be substituted for the AL. Rubber cement can be used as a binder and so can nitro cellulose lacquer, MC powder, and believe it or not, PVC glue thinned with acetone. The igniters burn very hot and have a fireball approx. 1-1.5 inches in diameter. I make the igniter head about 1" long and 1/8" in diameter. So far they have ignited every propellant I have tried them on.

Following is an exert from a private communication with Wilfred van Bergen from NERO:

I've been working on some igniters during the last few days. These little things have always bugged me till a few days ago. I got the FireStar bottles shipment, and as soon as I opened one bottle and smelled the acetone, I knew what to do.

First attempt was to dissolve some 'single base' smokeless powder into acetone and use that as a binder. It works, but not well enough for my taste. Now I've made the first test using 'nitro dope', used by RC modelers (me) to cover the wings with the silk cloth. This is pure, dissolved nitro cellulose and is thinable with regular household thinners like toluene rather then more nautious acetone.

Mix 20 parts carbon powder (I use active coal) with 10 parts aluminium (#325) and 5 parts red iron oxide. Then add enough dope until you get a mixture that's fluid enough so that it flattens out by itself. Then add 65 parts of AP (<77 micron). Finally, add more toluene until the mixture is very smooth.

Now dip bridge wires into this mix and give them a try. They really surprised me. I test-fired a 10 mm Bates grain with a 5 mm hole with one of these. Instant ignition.

Cheers, Wilfred

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