The Rocket Delta V Fuel Requirements Estimator converts a delta-v target into an ideal propellant requirement using the Tsiolkovsky rocket equation. It uses initial mass, specific impulse, and required delta-v to estimate the propellant consumed, then adds a separate reserve percentage for planning.
This is most useful for preliminary sizing and trade studies where propulsion performance is known but detailed tank, residual, pressurization, and finite-burn modeling has not yet been completed. Because the rocket equation is idealized, the result should be treated as a first-order estimate. The reserve field is applied to calculated propellant mass and is capped at the entered initial mass in the displayed planning result.
1. Enter initial mass
Use vehicle mass immediately before the modeled maneuver sequence.
2. Enter required delta-v
Use the total velocity-change target in meters per second.
3. Set specific impulse
Enter the effective specific impulse of the propulsion system in seconds.
4. Add propellant reserve
Use the reserve percentage required by your preliminary design convention.
5. Review propellant mass
Compare the result with available usable propellant and tank capacity.
The model assumes constant effective specific impulse and an ideal rocket equation treatment without gravity, drag, steering, boiloff, unusable residuals, or staging effects.
The main result is the ideal rocket-equation propellant estimate after the selected reserve percentage is added.
If reserve pushes the planning value near or above initial vehicle mass, the concept is physically infeasible and should be redesigned or modeled in stages.
Given: 5,000 kg initial mass, 1,800 m/s delta-v, 320 s specific impulse, and 5% reserve.
Calculation: Mass ratio = exp(1800/(320×9.80665)) ≈ 1.775. Final mass ≈ 2,817.5 kg. Ideal propellant ≈ 2,182.5 kg. With 5% reserve ≈ 2,291.6 kg.
Result: The planning estimate is about 2,291.6 kg of propellant.
Use the mass immediately before the modeled burn sequence, including propellant that will be consumed during it.
Use a representative effective Isp for the propulsion mode being modeled. If performance changes significantly, model segments separately.
No. Here the reserve is added to estimated propellant mass as a planning allowance.
The rocket equation is exponential: larger delta-v requirements demand progressively larger mass ratios for the same specific impulse.
Those masses should already be part of the entered initial vehicle mass. The calculator estimates consumed propellant, not propulsion-system dry mass.