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- Princliples
- Rockets run on the principal of Isaac Newton's third law of motion that states "for every action there is an equal and opposite reaction." In this case the "equal and opposite" reactions are the exhaust velocity of the rocket engine and the pull of the earth's gravity. The minimum altitude for a stable orbit about Earth is about 160 km. At lower altitudes, air resistance slows the spacecraft and causes a rapid deterioration of the orbit. The spacecraft must attain a velocity of about 7.8 km per second to reach this altitude. However, in order to overcome the slowing effect of Earth's atmosphere the total velocity must be at least 9.0 (NASA Space Mathematics).
- Assumptions
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- We have made the following assumptions in this project:
- . The structure weight of each stage is 10 percent of the fuel weight; the remaining weight being payload;
- the gain in velocity is divided equally among the states, each contributing 4.5 km/s to the required final velocity of 9.0;
- all stage us the same propellant with an exhaust velocity of 3.7 km/s; and,
- the fuel will be burned to completion by the time the rocket reaches orbit.
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