The rides

Getting off Earth and crossing the solar system are two different problems, and they want two different machines. The gravity well only yields to brute chemical fire; the road beyond rewards patience and fuel mileage. Both fleets are below, with a working calculator underneath.

A note on the numbers. An engine's fuel mileage is its specific impulse: how much push each kilogram of propellant buys. A kick engine shoves hard for minutes; a patient engine pushes like a resting sheet of paper for months and wins anyway. The push dial on the launch windows page is bought with exactly these machines.

Leg one: climbing the well

From the ground to orbit costs about 9.3 km/s and must be paid in minutes, which is why every rung of this ladder burns chemical propellant. Patient engines never leave the pad.

Leg two: the road

Once free of the well, thrust matters less and mileage matters more. Pick the engine for the destination and the errand.

The delta-v calculator

The rocket equation, live. Pick an engine, load propellant, read off the speed change the stack can buy. The bars below show what common errands cost.

350 kg

Speed change bought
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How it arrives
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What the errands cost

Costs are one-way speed changes beyond Earth's orbit, from the same transfer model as the launch windows page. A patient engine delivers its total slowly, so it suits the cruise; the hard braking of an insertion still wants a kick stage or a very early start.