The Tiny Rocket Project

The goals of the Tiny Rocket Project are:

1. Build tiny rockets, no larger than 6“ tall.
2. Use cheap and readily available supplies.
3. Engines and rockets should be made in a few hours time (after the design phase).
4. Fly the rockets to a height of 300' or out of sight.
5. Use tumble recovery, at least initially.
6. Experiment with multi-stage designs.

1. 01/14/2008 - Successful engine test

• Tiny Engine EX01

1. Small rockets are inexpensive
   1. Paper tubes
   2. Clay nozzles
   3. Small amounts of fuel
2. Rocket fuel is safer in small quantities
3. Tiny rockets are safe in small areas such as the local park.
4. Small designs can use tumble recovery, requiring no recovery loads or parachutes.

Engine tubes will be made from standard 20# copy paper. Initial designs will be made with white glue, while (cleaner) glue sticks will be tested later.

Several engine tube designs will be built and tested. Each tube will be designed around the coring tool, a round toothpick that is about 1/16” thick.

Initial tube designs will have an inside diameter of 3/16“ or 1/4”, a core and nozzle of about 1/16“, and lengths of 1” to 1-3/4“.

Note: I suspect that the 2” core size will explode the paper tubes. This is slightly over the maximum size that can be made with a toothpick (it will taper slightly at the top end). Small kabob skewers may be an alternative if longer core lengths work.

3/16“ Tubes

End Burner
1” Core
1-1/4“ Core
1-1/2” Core
1-3/4“ Core

1/4” Tubes

End Burner
1“ Core
1-1/4” Core
1-1/2“ Core
1-3/4” Core

Nozzles will be made from ground kitty litter (which is usually made of mostly bentonite clay).

Two packing methods will be tried; packing the nozzles then drilling, and packing around a toothpick or nail.

Initial nozzles will be 1/4“ long. After different tube and core sizes are tested, several nozzle lengths will be tested with the best tube performer.

Each engine will be capped with a small amount of epoxy resin. Initially, 1/8” caps will be used. There are currently no plans to test other cap sizes.

Igniter's will be made using paper matches, phone or cat5 wire, and coarse steel wool.

I will use candy propellants. Initial tests will be done with 65/35 KNSU. I will use the KNSU in melted form, initially, because I believe it will burn much better. I will also try packed powder after my initial tests.

After several trials at cooking inert material, I decided that cooking was too risky at this point.  Instead, I found that 15% (by weight) of 70% Isopropyl Alcohol could be used to cold mix the propellant.  The result is easy to mold and dries hard.  Fired first successful test with this propellant.

My KNO3 will be made from “Grants Stump Remover” purchased from Home Depot. It will be ground into a powder and then “milled” to a finer powder in a rock polisher with glass marbles.

Milling is not necessary and does not seem to improve the texture.  KNO3 ground in a coffee grinder seems to work well.  WARNING: DO NOT GRIND KNO3 AND SUGAR IN THE SAME GRINDER.

Grants Stump Remover is said to be 98% Potassium Nitrate, but has known impurities (a coating of some type). I will use it anyway, because I already have it and it's easy to obtain. It is possible to remove the impurities, but I will not try to do so since that requires extra time and chemicals.

The fine KNO3 will be mixed with table sugar then cooked according to Richard Nikka's instructions. I will not use powdered sugar since it includes corn starch.

Scratch that.  Powdered sugar works well.  Haven't tried ground table sugar, since I don't have multiple grinders. SEE WARNING ABOVE.

The fuel will be rolled and then cast in paper tubes of the correct length. The core will be pressed through the center, by hand, with a toothpick. The paper will be carefully removed when they are partially dry.