When are the tanks with cryogenic propellants pressurized?

After the engine start

10 sec after the engine start

10 sec before the engine start

Just before the engine start

Correct Answer : Just before the engine start

Explanation : This is done to ensure that the propellants are at its lowest possible temperature. Else they might evaporate within the tank and may lead to devastating results under wrong circumstances.

Recently Updated in Rocket Propulsion Questions

Use of solenoid valves increases power consumption for a cold gas propellant system.

True

False

Can Not Say

None of the above

Correct Answer : Option (B) : False

Explanation : In order to decrease power consumption, one can use solenoid valves. It requires an electric pulse to open and close and hence can be easily controlled with lesser power expended.

For a short period of operation (lasting few minutes), the gas expansion in cold gas systems is ________

adiabatic

isothermal

homogenous

heterogeneous

Correct Answer : Option (A) : adiabatic

Explanation : Since the operation lasts only a short period of time, the expansion can be taken as adiabatic. It means that there is no heat absorption or release by the gas.

Thrust in RCS is produced by the momentum exchange between exhaust and the _______

pump

injector

payload

spacecraft

Correct Answer : Option (D) : spacecraft

Explanation : Thrust generation is due to the exchange of momentum between exhaust and the spacecraft. The thrust is given by Newton’s second law F = mV_e.