Physics · ~7 min read

Launch a rocket

How much Δv does a stack actually deliver — and is that enough for a useful orbit?

Tools Rocket equation · Orbital mechanicsPhysics Tsiolkovsky + two-body orbits

Budget the Δv

The Rocket Equation tool stages propellant mass, dry mass, and exhaust velocity (or Isp). Each stage adds Δv; gravity and drag losses are not free, so real missions need margin beyond the pure vacuum sum.

Rule of thumbΔv = ve · ln(m₀ / m_f). Doubling propellant does not double Δv — mass ratio is logarithmic.
Open rocket equation →

Ask what orbit that buys

Orbital Mechanics turns altitude (or semi-major axis) into period, speed, and escape comparisons for Earth, Moon, Mars, and more. LEO is cheap in time, expensive in Δv from the ground; GEO is the opposite in period.

Rule of thumbCircular orbital speed ≈ √(GM / r). Higher orbits are slower, not faster.
Open orbital mechanics →Projectile / golf flight

Match budget to destination

Compare your staged Δv to the orbit’s required speed plus realistic losses. If the stack is short, add a stage, raise Isp, or lower payload — the tools make those trade-offs visible without a spreadsheet.

Rule of thumbEarth LEO is roughly 9+ km/s from the ground including losses; vacuum Δv alone understates the job.
Adjust the stack →Re-check the orbit →

Snapshot the stack

When the Δv and orbit line up, snapshot both tools. A pair of cards — total Δv and orbital period — is a clean share for a class, a design review, or a curious friend.

Snapshot Δv →Snapshot orbit →

Δv is the currency; orbits are what you buy

Two calculators, one mission narrative — and still zero accounts, zero analytics on the numbers themselves.

All stories All storiesBuy a house
Reference only. Stories chain real tools — verify numbers before relying on them.