The fuel burnt will be mo -m1=(1-0.368)mo=0.632mo, and the weight of the tank and engine to be opped will be 0.0632mo, leaving an initial mass for the second stage, m2, of m2=0.368m0-0.063m0=0.295m0 After burn out The fuel burnt in this stage will be m2-mf =(0.295-0.109)mo=0.186mo and the weight of the tank plus engine will be 0.019mo, leaving for the payload dng=(0.109-0.019)m0=0.090m which is still very small but about twice the size of the payload obtained for the single stage rocket Note Specific Impulse The specific impulse Isp, with units of seconds, is often used in practice to characterize the performance of a rocket engine. The definition of the specific impulse is the magnitude of the thrust divided by the propellant weight flow rate T g 9 Typical values of Isp are around 300 s for solid propellants and up to 500 s for higher energy fuels ADDITIONAL READING J. L Meriam and L.G. Kraige, Engineering Mechanics, DYNAMICS, 5th Edition References [1 M. Martinez-Sanchez, Unified Engineering Notes, Course 95-96The fuel burnt will be m0 − m1 = (1 − 0.368)m0 = 0.632m0, and the weight of the tank and engine to be dropped will be 0.0632m0, leaving an initial mass for the second stage, m2, of m2 = 0.368m0 − 0.063m0 = 0.295m0 . Second stage After burn out, mf = e −1m2 = e −1 0.295m0 = 0.109m0. The fuel burnt in this stage will be m2 − mf = (0.295 − 0.109)m0 = 0.186m0 and the weight of the tank plus engine will be 0.019m0, leaving for the payload m 2stage payload = (0.109 − 0.019)m0 = 0.090m0, which is still very small but about twice the size of the payload obtained for the single stage rocket. Note Specific Impulse The specific impulse Isp, with units of seconds, is often used in practice to characterize the performance of a rocket engine. The definition of the specific impulse is the magnitude of the thrust divided by the propellant weight flow rate, Isp = T mg˙ = c g . Typical values of Isp are around 300 s for solid propellants and up to 500 s for higher energy fuels. ADDITIONAL READING J.L. Meriam and L.G. Kraige, Engineering Mechanics, DYNAMICS, 5th Edition 4/6, 4/7 References [1] M. Martinez-Sanchez, Unified Engineering Notes, Course 95-96. 5