3 ms·
Same thrust but less mass as the fuel burns up.
by torpfactory 6y ago
Same thrust but less mass as the fuel burns up.
- Udik 6y agoAh, right!
- m4rtink 6y agoAlso rocket engines are (IIRC) generally less efficient at lower than full thrust, so you want to keep firing them at max as long as possible. On the other hand you also don't want to turn your crew into pancakes or even make your upper stage look like a squashed can. You have a couple options: - throttle the engine - design payload weight, propellant load and trajectory to make g loads bearable till burnout And one more thing related to stage 2 burnout - precise orbit insertion. Rocket engines used to be pretty imprecise at shutdown, delivering a slightly lower/higher impulse at shutdown at random. Due to this many older rockets have also some small & precise engines to correct the orbit insertion once the main one shuts down - many Chinese rockets have that. As far as I know, the Falcon 9 upper stage engine (Merlin 1D Vacuum) is precise enough so this is not needed.