What will happen to thrust and specific impulse as the rocket is propelled to higher altitudes?

Thrust decreases, specific impulse increases

Thrust increases, specific impulse increases

Thrust increases, specific impulse decreases

Thrust decreases, specific impulse decreases

Correct Answer : Thrust increases, specific impulse increases

Explanation : Atmospheric pressure decreases with increasing altitude. So the pressure thrust part of the total thrust increases and hence the total thrust increases. Specific impulse is impulse per unit weight of the propellant and proportional to thrust, so it too will increase.

Recently Updated in Rocket Propulsion Questions

In which of the propulsion systems is the maximum temperature achieved?

Nuclear

Chemical

Arc heating

Solar heating

Correct Answer : Option (C) : Arc heating

Explanation : Arc heating can lead to temperatures of about 20,000 deg C. Chemical propulsion systems have a maximum temperature ranging from 2500-4100 deg C, while nuclear fission leads to temperatures of about 2700 deg C.

What is the propulsion duration of resistojets?

Few weeks

Few days

Few minutes

Few seconds

Correct Answer : Option (B) : Few days

Explanation : Resistojets have a propulsion duration spanning a few days. The chemical rocket engines have a propulsion duration lasting a few seconds to a few minutes, while for ion-electrostatic engines, it lasts for months.

Which of the following engines can achieve the maximum specific impulse of 5000 s?

Hall effect

Ion-electrostatic

Solar heating

Nuclear fission

Correct Answer : Option (B) : Ion-electrostatic

Explanation : Ion-electrostatic engine has a specific impulse of 1200-5000 s. Nuclear fission type engines have Isp of 500-860 s, while solar heating engines have it around 400-700 s.