An optimally expanded rocket engine operates with unchanged mass flow and exhaust speed. Its flight speed is doubled. Find the ratio of the new thrust to the original thrust.
Rocket thrust is $F=\dot mV_e+(p_e-p_a)A_e$. Optimal expansion makes the pressure term zero. With mass flow and exhaust speed fixed, thrust is unchanged by the vehicle’s flight speed. The ratio is 1.
More Rockets: thrust equation, specific impulse, multi-staging, solid and liquid propellant rockets questions
GATE 2019 AE Q56– A rocket has initial mass 1720 kg, final dry mass 1000 kg and specific impulse 3000 N…
GATE 2024 AE Q57– A chemical rocket with an ideally expanded flow through the nozzle produces 5 106 N thrust…
GATE 2025 AE Q32– An ideal two-stage rocket has identical specific impulse and structural coefficient for…
GATE 2025 AE Q63– A monopropellant liquid rocket engine has 800 injectors of diameter 4 mm each, and with a…
GATE 2026 AE Q39– An ideal rocket has characteristic exhaust velocity of 1200 m/s, mass flow rate of 75…
GATE 2026 AE Q41– Consider a launch vehicle of mass 10 tons being launched vertically. The vehicle has 8…