Pasta Rocket

First rocket motors were made from gun powder tamped inside a tube. Tamped gun powder had several disadvantages:
Nowadays gun powder is no more used inside rocket motors. Solid rocket fuel is made of a mixture of a high yield oxidizer (ammonium perchlorate for example) instead of potassium nitrate and a high yield fuel (a plastic or rubber) instead of charcoal and sulfur.

The plastic allows to mold the fuel block any shape and makes it be very strong. The boosters of the Space Shuttle and the Ariane 5 space rocket are powered that way.

A lot of receipts exist and additives are most often added to regulate the burning speed versus pressure and to increase the yield. Part of the plastic can be replaced by aluminum powder which is a better fuel. A very satisfactory solid fuel is a mixture of nitroglycerin and nitrocotton, two high explosives.

During my experimentation with solid fuels, I used mixtures of an oxidizer powder and viscous fuels like glycerin or paraffin. The result is a more or less fluid paste. Maybe paste fuel can be used for big high yield rocket motors. One way would be to mix an oxidizer powder with an excess of paraffin in order to get a rather fluid paste and a high yield. The paste would flow inside a burning chamber. The paste reservoir would be a long silo above the burning chamber.

It is possible to let the reservoir be under low pressure and let a pump inject the paste inside the motor chamber at huge pressure. Yet I'm not quite sure this would be very effective. Probably the best solution will be to let the reservoir be at the same pressure as the motor chamber or higher. That can be achieved through a tube going from the motor chamber towards the top of the reservoir or by using gas generators. The reservoir must be able to resist that pressure, just like a common solid fuel rocket motor envelope does.

The paste will flow inside the motor chamber through one or more holes at the bottom of the silo. It is essential electric motors are used to crumble the paste in very small pieces. Those pieces will light easily and power the motor.

Such a rocket motor would have several advantages:

Please do not experiment with rocket fuel if you are not part of an authorized laboratory. Avoiding accidents is not possible. Every person I know who did private experiments got a severe accident and was awfully hurt. One person lost his brother. Another person got a friend's hand exploded. Yet another got several months in hospital and bad sequels. Although having a very good understanding of whatever I was doing, I got accidents too. Luckily, because I followed strictly a lot of tight security rules and never made any exception, I did not get injured severely and the cost of the destruction was not too high. Most effective rules are to keep cans always closed, store oxidizers and fuels far apart, use only very little quantities at a time and make very little rocket motors, use no metal or glass parts and only cardboard, glue and soft plastic, be patient, have a bucket of water at hand, always use an electric ignition system with a very long wire, stop working when tired and especially avoid unresponsible people. Authorized laboratories have insurances, own different kinds of security and protection equipment and every experiment is checked beforehand by trained people. At least ask a Chemistry teacher.

I wish to thank Bob Russell for reading and correcting the text.

Eric Brasseur  -  October 28 1998  till  February 18 2003