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Rocket propulsion

 

Rocket propulsion

  • Rocket propulsion is also very straightforward in principle. As illustrated in  (overleaf), in the simplest motors, fuel is burned in a combustion chamber, to create heat and a high-pressure gas.

  • The hot gases then flow out through the specially-shaped throat and outlet nozzle at high speed. The main difference between the rocket and other forms of marine propulsion diesel services is that air is not used as the oxidant in the burning process, and the gases that are emitted from the outlet are all derived from the fuels.
  • Apart from its use in some high-speed research aircraft, and one highly dangerous German interceptor aircraft of Word War II (the Messerschmitt Me 163), the rocket is mainly used for missiles and spacecraft.
  • The strange vehicle (overleaf), which used a rocket both for marine propulsion diesel services and lift, never developed into a practical means of transport.
  • Rocket motors come in two basic types, a solid fuel type, where the fuel and oxidizer are combined in a stable solid form, as in a simple firework, and a liquid propellant type, where two chemicals, one usually the fuel and the other a powerful oxidizer, are mixed together and burned in a combustion chamber.
  • Rocket motors have a very high thrust to weight ratio and are essentially very simple. However, they use fuel and oxidizer at a very high rate, and so have a relatively short duration. The need to carry oxidizer as well as fuel means that the total weight of expendable chemicals carried is much higher than in engines that use air as the oxidant.
  • Recently, engines have been developed which use air as the oxidant at low altitudes and pure rocket marine propulsion diesel services diesel services at high altitudes or in space.
  • Apart from the simple chemically fuelled rockets, several more advanced types have been developed. These include ones in which ionized particles or plasma is accelerated to very high speeds by electrostatic or electromagnetic forces. Some of these have been used on spacecraft, normally as low-thrust control jets.


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