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Rocketry principle

Thrust-to-Weight Ratio

The ratio of an engine's or vehicle's thrust to its weight. To lift off, a launch vehicle's thrust must exceed its weight — a thrust-to-weight ratio above one — while efficient upper-stage and in-space engines can operate well below one. It is the counterpoint to specific impulse: high-thrust engines often trade away efficiency, and vice versa.

Highlights

  • Must exceed one to lift off the pad

Knowledge connections

Sources

The primary and reference sources this topic draws on.

  • NASANational Aeronautics and Space Administration

    Mission data, planetary science, space telescopes, and public-domain imagery.

    Most NASA-produced imagery is in the public domain; individual items are checked for usage terms before publication.