Work out rocket thrust to weight instantly with clear inputs, formula shown and shareable results.
Thrust to weight must exceed one to leave the pad, and practical launchers use 1.2-1.6 at lift-off. 7.6 MN against a 550 tonne vehicle gives 1.41, so net acceleration is 4.03 m/s2 - about 0.41 g of felt acceleration once gravity is subtracted. Too low a ratio wastes propellant fighting gravity; too high wastes it on drag.
Thrust to weight ratio
TWR = thrust / (mass x g)
Net acceleration
a = (thrust - weight) / mass
Because drag losses grow with the square of speed low in the atmosphere, and structural loads rise. There is an optimum around 1.3-1.5.
Sharply. As propellant burns off, mass falls while thrust holds, so acceleration climbs until engines are throttled back.