http://apcnasa3ozl2j74htizuzba5b6nhugbg2qze2nrz43siunkct555fpid.onion
The real importance of I sp (and exhaust velocity) becomes apparent when we consider the relative proportions of the rocket mass before and after a propellant "burn" used to impart some D V to the rocket. Since propellant is used continuously during the burn, and thus the mass of the rocket decreases accordingly, it is necessary to use calculus to derive the desired relationship between D V, I sp , the total mass of the rocket before the burn, M 0 , and the mass of the rocket...