# Rocket Propulsion Questions and Answers – Liquid Propellant Rocket Engine – Propellant Tanks

This set of Rocket Propulsion Multiple Choice Questions & Answers (MCQs) focuses on “Liquid Propellant Rocket Engine – Propellant Tanks”.

1. Which of the following materials of the propellant tank requires a thin inner liner of metal to avoid leakage?
a) Titanium
b) Aluminum
c) Stainless steel
d) Fiber-reinforced plastics

Explanation: Fiber reinforced plastics can have tiny pores through which the propellant can escape easily. In order to prevent that, it is coated with a thin layer of some impervious metal.

2. What is ullage?
a) The volume of propellant stored inside a tank neglecting its empty volume
b) The extra volume of gas above the propellant in a tank
c) The ratio of the volume of extra gas to that of the propellant after 50% of the propellant has been consumed
d) The ratio of the volume of the propellant to that of the extra gas after 50% of the propellant has been consumed

Explanation: Ullage is the extra volume of gas that lies above the propellant in a sealed tank. It is necessary for this extra volume to exist as it takes into account the thermal expansion of the propellant fluid.

3. Determine the amount of propellant trapped in pipe, fittings, and valve corners and lost by other means, if the initial mass of the propellant was M and it had an expulsion efficiency of 97%.
a) 0.97M
b) 0.03M
c) 0.06M
d) 0.48M

Explanation: Expulsion efficiency is the ratio of the amount of propellant available or expelled to the amount of propellant initially present in the tank.
So, 0.97 = mexpel/M
Then mtrapped = M – Mexpel = 0.03M.

4. What happens to the vehicle mass ratio (Initial mass / Burnout mass) when the residual propellant is not available for combustion?
a) Decreases slightly
b) Increases slightly
c) Increases rapidly
d) Decreases rapidly

Explanation: Residual propellant when not available for combustion is treated as inert mass. Since the inert mass increases, the burnout mass will also increase. The residual fuel amount is typically small. So the vehicle mass ratio (Initial mass / Burnout mass) will slightly decrease.

5. A good propellant tank must ensure that sloshing is ___________ and vortexing is ____________
a) minimized; maximized
b) maximized; minimized
c) maximized; maximized
d) minimized; minimized

Explanation: Both sloshing and vortexing need to be minimized. This becomes significant when the tanks are near empty. Sloshing refers to the movement of a liquid inside another body. Vortexing is also similar to sloshing, but the movement is circular in nature.

6. When does the slosh-dynamics problem become useful?
a) When the liquid has a free surface
b) When the liquid has no free surface
c) When the liquid is non-Newtonian
d) When the material stored inside the tank is thixotropic

Explanation: The liquid stored inside the tank needs to have a free surface for slosh-dynamics to be applied. Propellant slosh in aircraft and rocket tanks are some examples of slosh dynamics problems.

7. Who is the innovative rocket designer who created Atlas ICBM?
a) Stewart Powell
b) Karel Bossart
c) John von Neumann
d) Bernard A. Schriever

Explanation: Karel Bossart was the mind behind Atlas ICBM. It was first launched in June 1957. Atlas later was used for the first stage of satellite launch vehicles and served for about 5 decades.

8. Which component of the external tank of Space Shuttle served the main purpose of distributing thrust loads from SRBs?
a) LOX tank
b) LH2 tank
c) Intertank
d) Contractor

Explanation: In addition to the distribution of thrust loads from SRBs of the Space Shuttle, intertank also transferred the loads between other tanks. It is a structural connection between both the LOX and LH2 tanks. It also acts as a protective cover for accommodating some operational instruments.

Sanfoundry Global Education & Learning Series – Rocket Propulsion.