AspireSpace
				The British Amateur Space / Rocket Programme

Hybrid motors combine good features of both Solid and Liquid Fuelled rockets. They are controllable, semi storable, cheap and simple. They are based on the principle of a solid propellant and a liquid oxidiser, and have a number of features which make them ideal for use in a rocket such as ASPIRE II, namely:

1. Cheapness - Neither the oxidisers (Liquid Oxygen, Hydrogen Peroxide or Nitrogen Dioxide) or most polymers are particularly expensive, thus fuel costs are kept to a minimum. The flow lines are also considerably cheaper than those in a liquid fuelled rocket due to the simpler arrangement required (since you only have one liquid in the system, not two).

2. Simplicity - Although more complex than a solid rocket motor, a hybrid motor is considerably simpler to implement than a liquid fuelled engine, since there is only one set of plumbing required.

3. Safety - A hybrid rocket motor offers very safe usage characteristics over both a solid rocket motor and a liquid fuelled rocket engine. Combination of the two components, fuel and oxidiser will not cause an explosion, as can be the case with a liquid fuelled rocket engine, and the hybrid can be turned off at any stage of the flight or on launch. This is most certainly not possible with a solid rocket motor.

4. Environmentally Friendliness - The hybrid motors under development by AspireSpace burn their propellant at extremely high temperatures. The result of this is that the only major byproducts in the rocket's exhaust are Water (in the form of steam), Carbon Monoxide and Carbon Dioxide (similar to a car exhaust).

   Hybrid Motors in general, use non toxic propellants and have fairly benign exhaust products, which are cleaner than those of solid fuelled rockets, and similar to those of most liquid fuelled engines. The exception to this is when maximum performance is required from a hybrid rocket motor, and every last drop of propellant is squeezed out of the motor, in which case the exhaust is less environmentally friendly.