These conditions can best be met when the expulsion of the masses is obtained by burning suitable substances carried on the vehicle and by permitting the resulting gases of combustion to escape towards the rear"to exhaust." In this manner, the masses are expelled in the smallest particles (molecules of the combustion gases), and the energy being freed during the combustion and being converted into gas pressure provides the necessary "internal power" for this process.
The well known fireworks rocket represents a vehicle of this type in a simple implementation (Figure 15). Its purpose is to lift a socalled "bursting charge": there are all sorts of fireworks that explode after reaching a certain altitude either to please the eye in a spectacular shower of sparks or (in warfare, by way of example) to provide for lighting and signaling.
The continual movement (lifting) of a fireworks rocket of this type takes place as a result of a powder charge carried in the rocket, designated as the "propellant." It is ignited when the rocket takes off and then gradually burns out during the climb, with the resulting combustion gases escaping towards the rear (downward) and as a result by virtue of its reaction effectproducing a continuous propulsion force directed forward (up) in the same way as was previously discussed.
However, a rocket that is supposed to serve as a vehicle for outer space would, to be sure, have to look considerably different from a simple fireworks rocket.
Figure 15. Fireworks rocket in a longitudinal section. The attached guide stick serves to inhibit tumbling of the rocket.
Key: 1. Bursting charge; 2. Propellant; 3. Combustion of the propellant; 4. Reaction of the escaping combustion gases; 5. Guide stick; 6. Escaping combustion gases