Calculate total velocity change (ฮv) a rocket can achieve. Uses the Tsiolkovsky rocket equation โ the most fundamental equation in spaceflight.
Delta-V (ฮv) is the total change in velocity a rocket can achieve by burning all its propellant. It is the single most important number in spaceflight planning โ it determines exactly what orbits a spacecraft can reach and what missions it can complete.
The natural logarithm in the rocket equation means that adding more fuel gives diminishing returns. To double your delta-v, you need to square your mass ratio. This is why rockets are almost entirely propellant โ the Saturn V was about 85% fuel by mass at launch.
Isp measures how efficiently an engine uses propellant โ higher is better. Kerosene/LOX engines (Merlin) reach ~311s. Hydrogen/LOX (RS-25) achieves ~452s. Ion thrusters exceed 3,000s but produce tiny thrust โ only practical in deep space.
Multi-stage rockets drop empty tanks as they ascend, dramatically improving mass ratio. A single-stage rocket to orbit is extremely difficult โ almost all orbital rockets use 2-3 stages to discard dead mass and maximise delta-v.