posted on Apr, 30 2019 @ 07:57 PM
a reply to:
Phantom423
The peed a rocket can reach is determined by 2 factors, ISP or specific impulse and mass ratio
Specific Impulse if the amount of energy a given propellent gas, the higher the Specific Impulse faster the rocker can travel on given fuel load
By multiplying the ISP by acceleration of gravity ( 32 feet per second, or 9.8 meters second) gives exhaust velocity of the jet
example ISP of 300 seconds 300 x g (32.1 feet/second) = 9630 feet per second exhaust velocity
Second factor is Mass Ratio , ratio of full load weight divided by empty weight
For a rocket to reach its exhaust velocity needs mass ratio of 2.72
To double its exhaust velocity , mass ratio must be squared as carrying weight of extra fuel or 7.3
That is why rockets are staged, the mass ratio of a single stage would need to be tripled or mass ratio of 20 to reach orbital velocity on single
stage . Having each stage allows rocker to build velocity in increments