Question

A hybrid rocket propellant uses:
A.A liquid oxidizer and a solid fuel
B.A complete solid propellant
C. A biliquid propellant
D.None of the above

Answer 1

Hint:To answer this question you must recall the properties of different compounds as fuels. A hybrid propellant represents an intermediate between the solid and liquid propellant.

Complete step by step answer:
In a hybrid propellant engine, one of the substances is a solid while the other is liquid. Generally, the fuel is solid and the oxidizer is present as a liquid. The liquid oxidizer is injected into the solid fuel, whose reservoir is also a site for the process of combustion.

Thus the correct option is A.

Additional information:
Hybrid propellants have two major drawbacks. The first drawback is that the casing around the solid fuel must be built in such a way so as to withstand full combustion pressure and often extreme temperatures as well, like in solid propellant engines. However, through modern composite structures, this problem can be well handled, and when used with nitrous oxide and a solid propellant like HTPB, a relatively small percentage of fuel is needed, and thus the combustion chamber is not large.
The second disadvantage is that in the hybrid engine, the mixing of the oxidizer and fuel happens at the evaporating surface of the fuel. The mixing is not well-controlled and hence, a lot of propellant is left unburned, which reduces the efficiency of the motor.

Note:
The advantage that the hybrid propellant serves is that it has a high performance and unlike the solid propellants, the combustion process can be moderated, stopped or restarted as per the requirements.
It is difficult to practically make use of this concept and thus hybrid propellant engines are very rarely built.