Disclaimer

Delta-V Desk provides orbital mechanics calculators and articles for education and general interest. Please read this disclaimer before relying on any result.

A Simplified Model by Design

Every calculator uses the two-body model: one spacecraft and one central body, with gravity acting as if all the body’s mass sat at its centre. Burns are treated as instantaneous changes in speed. Transfers assume circular orbits in a single plane. Real spaceflight differs in ways that matter. Earth’s equatorial bulge, described by the J2 term, makes orbits precess by several degrees a day in low orbit. The Moon and Sun perturb high orbits. Atmospheric drag lowers orbits below roughly 600 km over months to years, and much faster during periods of high solar activity. Finite burn times, steering and gravity losses make real Δv larger than ideal values. Planetary orbits are eccentric and inclined, so real launch windows shift by weeks from the idealised dates.

Not for Operating Real Hardware

Results from this site must not be used to plan, command, certify or insure the flight of any satellite, spacecraft, launch vehicle or payload, or to predict collisions, re-entries or debris hazards. Those tasks require precise orbit determination, numerical propagation with current ephemerides and space weather data, and review by qualified flight dynamics engineers. Published orbital elements of real objects change constantly; use official sources for any operational purpose.

Amateur and Model Rocketry

The rocket equation calculator gives the ideal Δv of a stage in empty space. It does not predict the altitude, stability or safety of a model, amateur or high-power rocket, which depend on drag, thrust curves and the position of the centre of pressure. Follow the safety code of your national rocketry association, use certified motors, fly only where permitted and observe local laws and airspace rules.

Educational Use and Coursework

Our constants are standard published values, stated on each page, but your textbook or instructor may use rounded ones, such as Earth’s mean radius of 6,371 km or g = 9.81 m/s². That can change answers in the third or fourth significant figure. Use the values your course specifies and treat our results as a check, not as a replacement for showing your own working.

Accuracy

We check formulas by back-substitution and against published reference values, but we cannot guarantee that every result is free of error. Mistyped inputs, such as an orbit radius entered where an altitude is expected, produce wrong but plausible-looking answers. If something looks surprising, check the inputs and the stated assumptions first.

External Links and Advertising

Links to other websites and advertisements shown on the site are provided for convenience and to fund the site. They are not endorsements, and we are not responsible for their content.

Questions

If you think a result is wrong, write to logan.luo@adsnova.cn with the inputs you used. See also our Terms of Service.