Propulsion Cheat Sheet
The core ideas of Propulsion distilled into a single, scannable reference — perfect for review or quick lookup.
Quick Reference
Thrust
The forward force produced by a propulsion system, generated by accelerating a working fluid or reaction mass in the opposite direction according to Newton's third law.
Specific Impulse (Isp)
A measure of propulsion efficiency defined as the thrust produced per unit weight of propellant consumed per second. Higher specific impulse means more thrust per kilogram of fuel.
Tsiolkovsky Rocket Equation
The fundamental equation of rocket propulsion relating a vehicle's change in velocity (delta-v) to the exhaust velocity of the propellant and the ratio of initial to final mass.
Combustion Chamber
The enclosed space in an engine or rocket motor where fuel and oxidizer react exothermically to produce high-temperature, high-pressure gases that generate thrust.
Nozzle Design (Convergent-Divergent)
A de Laval nozzle with a converging section that accelerates subsonic flow to sonic speed at the throat, followed by a diverging section that further accelerates the gas to supersonic speeds.
Propellant
The chemical substance or working fluid that is expelled by a propulsion system to generate thrust. Propellants can be solid, liquid, or gaseous and may include both fuel and oxidizer.
Turbofan Engine
A type of air-breathing jet engine that uses a large fan driven by a turbine to produce most of its thrust by bypassing air around the engine core, improving fuel efficiency and reducing noise.
Electric Propulsion
A class of propulsion technologies that use electrical energy to accelerate a propellant, typically an ionized gas, to very high exhaust velocities. These systems offer high specific impulse but low thrust.
Bypass Ratio
In a turbofan engine, the ratio of the mass flow rate of air passing through the fan duct (bypass stream) to the mass flow rate passing through the engine core.
Staging
The practice of dividing a rocket into multiple sections (stages) that are jettisoned sequentially after their propellant is expended, reducing the mass the remaining engines must accelerate.
Key Terms at a Glance
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