The basic principle of a rocket

Résumé du document

At first sight, a rocket seems to be about fire, noise and smoke. The basic principle of rocket is the famous Newtonian principle which says that "To every action, there is an equal and opposite action". A rocket throws mass in one direction and benefit of an equal reaction in the opposite direction. The first man who invented the rocket is the famous Mao Yuanyi in 1621. He wrote eighty books about that subject. (Visual). Indeed, those rockets were used for war. However, there is another famous man that usually use rocket, and here he is…. (Visual). This is the Coyote and he wants above all to catch Beep Beep. So, in order to achieve that goal, he decided to use a rocket. He put some gunpowder inside the tank, he jump on it and he lights the candle. Why his rocket exploded? Solid fuel has to burn very quickly but not explode.
GUNPOWDER: gunpowder is made up 75% nitrate, 15% carbon and 10% sulphur. Therefore, we may change the mix into 72% nitrate, 24% carbon and 4% sulphur. Instead of getting gunpowder, we get a solid-fuel that does not explode and burn during a long time (2 to 5 minutes).

Extraits

[...] The strength of the rocket is measured in "pounds of thrust". One pound of thrust is the thrust needed to keep a one pound object stationary against the force of gravity of Earth. The advantages of solid-fuel engines are: Solid fuel is easy to make. They are cheap. They are safe (well not for the Coyote) The disadvantages are shown by the Coyote The strength of the thrust can not be controlled. There is no way to stop the burning process, once the "candle is lighted". [...]

[...] Therefore, the thrust will be provided by the acceleration of the plasma outside of the rocket. Besides, fusion engine will be able to provide thrust about 300 times longer than thrust provided by conventional rockets. The strength of those kinds of rockets is measured not in pound of thrust, but in a specific impulse. A chemical rocket has a 450 seconds specific impulse which means that they can produce 1 pound of thrust with a 1 pound of fuel during 450 seconds. [...]

[...] Indeed, the fuel required is less than one seventh the fuel the rockets need. The upper limit of speed is theoretically above the speed required to get a rocket into space. However, Air breathing vehicle can't provide enough thrust for lift-off. They have to be combined with liquid fuel engines which are able to bring the rocket to Mach 2 or 3. At this speed, enough air is sucked in for the combustion. Air breathing vehicles also need very little liquid-fuel rockets to provide a little thrust in space. [...]

[...] Throwing Fire: Projectile Technology through History. Cambridge: Cambridge University Press, 100–103. Frank H. Winter, "The `Boun Bang Fai' Rockets of Thailand and Laos:," in Lloyd H. Cornett, Jr., ed., History of Rocketry and Astronautics - Proceedings of the Twentieth and Twenty-First History Symposia of the International Academy of Astronautics, AAS History Series, Vol (Univelt Inc.: San Diego, 1993), pp. 3-24. Johnson W., "Contents and commentary on William Moore's a treatise on the motion of rockets and an essay on naval gunnery", International Journal of Impact Engineering, Volume 16, Number June 1995, pp. [...]

[...] They are expelled under high pressure through the nozzle in order to accelerate the rocket. However, these rockets are more complicated to build. In fact, pumps have to generate high pressure to overcome the pressure created by the fuel in the combustion chamber. Currently, it cost $10,000 per pound to put an object in orbit. At that price, it would cost $1,500,000 to send a 150 pound person. The only way to reduce this cost is to replace the oxidiser tanker ( 3.1 million pounds for the space shuttle) by something lighter. [...]