🚀 Rockets: How They Work

What you’ll learn

1. Newton's Third Law: The Real EngineExplain how Newton's third law produces thrust and how thrust and specific impulse are quantified.Rockets accelerate by throwing exhaust backward; the reaction pushes the vehicle forward, working even in vacuum. Thrust equals mass flow times exhaust speed. Newspapers once wrongly claimed rockets need air, mocking Goddard before retracting decades later. Specific impulse rates how efficiently an engine converts propellant into velocity.
2. The Tyranny of the Rocket EquationExplain Tsiolkovsky's rocket equation, the concept of delta-v, and why staging and better propellants are the only escapes.Tsiolkovsky's equation ties velocity gain to a logarithm of the mass ratio, forcing orbital rockets to be 85-90% propellant. Delta-v is the velocity budget every mission spends. The only ways to beat the equation are faster exhaust or shedding empty mass through staging.
3. Propellants: Solid Versus LiquidCompare solid, liquid, cryogenic, and hypergolic propellants and their engineering tradeoffs.Solid motors are simple, storable, and powerful but cannot be shut off. Liquid engines are complex but controllable and restartable. Cryogenic propellants offer high performance but must be kept near absolute zero. Hypergolics self-ignite, prized for the reliability that mattered on the Moon.
4. Engines and the Bell NozzleExplain how a converging-diverging bell nozzle accelerates exhaust and how engines survive the heat.The nozzle converts combustion energy into high-speed directed exhaust. Gas reaches the speed of sound at the throat, then accelerates further in the diverging bell — a de Laval nozzle. Regenerative cooling keeps engines from melting, and nozzles are tuned to the altitude where each stage operates.
5. Staging: Shedding Dead WeightExplain serial and parallel staging using the Saturn V and the cost problem staging historically created.Staging discards empty tanks and engines so the rocket stops carrying dead weight, letting the remainder accelerate efficiently. The Saturn V used three serial stages; many rockets add parallel strap-on boosters. Historically each discarded stage was lost, making spaceflight extraordinarily costly until reusability.
6. Orbital Mechanics: Falling SidewaysExplain orbit as free fall, why sideways speed dominates, and how Kepler and Hohmann transfers govern maneuvers.An orbit is continuous free fall while moving sideways fast enough that Earth curves away beneath you. Height matters far less than the roughly 7.8 km/s orbital speed. Orbits are ellipses; speeding up raises them and slowing lowers them. The Hohmann transfer is the fuel-efficient path between orbits.
7. From Goddard to Reusable BoostersTrace rocketry's history from Goddard through the V-2, Saturn V, Space Shuttle, and reusable boosters.Goddard flew the first liquid rocket in 1926. The wartime V-2 reached space at terrible human cost. Cold War rivalry produced Sputnik, Gagarin, and the Saturn V that landed Apollo 11 on the Moon. The partly reusable Shuttle taught hard lessons, and in the 2010s SpaceX finally landed and reused first stages.

Questions this course answers

Grounded in trusted sources

• NASA
• National Air and Space Museum (Smithsonian)
• Encyclopaedia Britannica
• Royal Aeronautical Society

Every Wunder lesson is built from real, reputable sources — never invented.

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