q1werty2

On 11/24/2004 at 9:04 AM, blike said:

I need to make a homemade CHEAP ejection charge for my rockets. I'd prefer not to have to buy any BP.

 

Yesterday I mixed KNO3 and Powdered charcoal 80/20. Then I made a small electric ignitor using a christmas light bulb. I packed the KNO3/Charcoal mix into a straw and put the light bulb in one end. Then I sealed both ends with hot glue and connected the lightbulb to a 9-volt. There was a small pop and the powder burned well. The pop was enough to eject the nosecone off a small estes rocket, but I'm sure it wouldn't be strong enough to push out a large nosecone with a camera on board.

 

What can I do to increase the *bang* without increasing the buck! The lightbulb, straw, and chemicals added up to something like 10 cents per charge.

You can easily get under 10 cents per charge.  I use Pyrodex P.  It is unregulated and a bottle will last years.  I assume you have an altimeter that will trigger the charge.  I use this methos for both the drogue chute at apogee and the main chute at 300 feet.

This is so simple, but it works.  I use a 1/2 cpvc endcap with a hole drilled in it.  I glued a holiday light (xmas light) receptacle in the hole and have it wired to the altimeter.  I then use the bulbs with the tip of the glass sniped off.  Insert bulb, fill with Pyrodex, then tape it up.

It doesn't yield a large "bang", but that is not what you are after.  It does generate enough expansion to pop the nose cone and shear the pins.

I have yet to have a failure.

Xavier