Tsiolkovsky
Δv = Isp · g₀ · ln(m₀ / m_f)
The rocket equation says your delta-v capability is logarithmic in mass ratio. That logarithm is unforgiving — doubling your Δv roughly squares your mass ratio requirement.
Mass ratio intuition
- 90% propellant → mass ratio 10 → ln(10) ≈ 2.30
- 95% propellant → mass ratio 20 → ln(20) ≈ 3.00
- 99% propellant → mass ratio 100 → ln(100) ≈ 4.60
Use the calculator to see how Isp and mass ratio trade against each other.