The mass of a vehicle (usually a rocket) at lift-off, divided by the mass of the empty vehicle without propellants. Mass ratio is often used as an indicator of a rocket's performance. The greater the mass ratio, the more propellant the rocket can carry, resulting in a better lifting performance from the vehicle. The ratio can be increased by the use of more lightweight materials on the rocket and improvements to the method of introducing the propellants to the combustion chamber. The choice of propellants is also a factor: some are much heavier than others. Typical mass ratios range from 5:1 for boosters using pressure-fed liquid hydrogen propellant, to 17:1 for pumped hydrogen peroxide.
Subjects: Astronomy and Astrophysics.