PHYSICS / ROCKET PROPULSION
Calculate ideal rocket delta-v from effective exhaust velocity and the initial-to-final mass ratio.
METHOD / WORKED EXAMPLE
The equation links propellant-driven mass change to an ideal velocity increment; it does not predict a complete trajectory or mission margin.
WORKED DEFAULT
With 3,000 m/s effective exhaust velocity, 50,000 kg initial mass, and 20,000 kg final mass, the mass ratio is 2.5 and ideal delta-v is about 2,748.87 m/s.
READ THE RESULT
Treat the output as an ideal propulsion budget. Real mission delta-v must also cover gravity, drag, steering, reserve, and performance losses established by the vehicle and trajectory design.
ASSUMPTIONS AND LIMITS
This ideal result excludes gravity loss, aerodynamic drag, steering loss, staging transients, changing exhaust performance, and reserve requirements.
Use internally consistent units and retain extra precision when carrying the result into another calculation.
COMMON QUESTIONS
No. Delta-v is a modeled change in velocity capacity, not a guaranteed final speed. The actual trajectory depends on starting velocity, gravity, atmospheric drag, steering, burn direction, staging, and timing. Mission analysis normally compares an ideal propulsion budget with a separately calculated required delta-v plus reserves.
No. Initial mass includes the vehicle, payload, and propellant before the modeled burn. Final mass is what remains after that burn, including dry structure, payload, residuals, and any unburned reserve. Entering propellant mass alone changes the mass ratio and produces the wrong result. Confirm both values against one burn state.
Not accurately as one ratio when stages have different exhaust velocities or discarded hardware. Calculate each stage or burn with its own initial mass, final mass, and effective exhaust velocity, then add the ideal delta-v increments. Keep staging losses and mission reserves as separate engineering allowances.
RELATED TOOLS
Use boundary
Apply the Tsiolkovsky rocket equation to one burn represented by a constant effective exhaust velocity. The page evaluates the displayed equation from your supplied values and presents both symbolic and substituted KaTeX working so the arithmetic can be checked.
Delta v = u ln(m0 / mf)