|I started this site to document, mostly for myself, the experimental motors
that I have built and tested.
My interest in building my own motors flourished when I started buying big motors and realized how expensive they were. Then I found out how cheaply they could be made. After some dismal tries with Ammonium Nitrate motors, I finally talked to Ted Proseus about his AP motors. A few weeks later, and I was down there casting grains. Alot of people have helped me out:
Ted Proseus - The guy who got me going. The guy I brainstorm with. He puts up with my 10 calls a day.
Jeff Taylor - Makes absolutely fantastic snap ring cases. No more Kosdon for me!
Sean McAndrew - Set me up with some great formulations. If Sean had the chance, he could do this professionally.
Marty Wright - My dad....and a polymer chemist. Not a bad contact to have! He is the buffer between my gray area hobbies and my mother, the eternal worrywart.
John Gustavsen - Another mad scientist. He is my rubber ball...I bounce EVERYTHING off his brain.
Erik Hall - My partner of Ozark Aerospace. He makes all the electronic doohickeys run properly. Another rubber ball for my wild ideas.
The guys on AROCKET list. Man are you a bunch of smart geeks. Heheh. Me too.
So how does one make a motor?
First, a few basic terms:
"Kn" - This is super important. It is the ratio of the burn area to the nozzle area. If your Kn is too low for a certain propellant, it will never come up to pressure. If it is too high, the motor will keep accelerating the burn and eventually overpressurize and CATO.
"Web" - The measurement from the edge of the core to the edge of the propellant.
"Burn Rate" - The rate at which the motor burns. This is measured generally by taking (web / burn time).
"Grain Type" - What the geometry of the propellant is. Most of my motors are Bates Grains.
"Solids Loading" - The % of metal / oxidizer to binder / curative.
Secondly, some equipment:
1. Plastic spoons and cups - Buy them by the millions
2. Tongue Depressors - Work great for scraping. A billion would be a good number.
3. Aluminum Bowls - For mixing.
4. Wooden spoons - again for mixing unless you can afford a....
5. Kitchen Aid mixer - Nice to have.
6. A good scale. I use and Acculab VIR-2400. I could not live without a Tare function, but a triple beam may work ok.
7. Proper liners and casting tubes.
8. Chemicals - More on this later.
So, what goes into a motor?
An AP motor is basically 2 things. Fuel, and an oxidizer. The motors I make use Ammonium Perchlorate (AP) as the oxidizer, and the binder, HTPB, as the fuel. Thsoe 2 things together will burn very nicely. To make the propellant do different things, we add different chemicals to the mix. My basic propellant, Tiger Tail, is a formulation made up by Ted Proseus. It consists of:
Per 100 grams:
HTPB R45-M 18.6g
ISP: about 185 (1.79 NS/g)
This site was last updated 11/02/01