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Rockets

Rockets. Tuesday : Rocketry Wednesday : Meet in my room 601: hydrogen demo and Quiz over rocketry. Thursday : Satellites and Orbital Mechanics Friday : Satellites, Orbital Mechanics and Tsiolkovsky Q uiz. Vacuum of space Heat Reentry Orbital mechanics Debris Restrooms

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Rockets

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  1. Rockets Tuesday: Rocketry Wednesday: Meet in my room 601: hydrogen demo and Quiz over rocketry. Thursday: Satellites and Orbital Mechanics Friday: Satellites, Orbital Mechanics and TsiolkovskyQuiz

  2. Vacuum of space • Heat • Reentry • Orbital mechanics • Debris • Restrooms • Getting off the ground What are the seven obstacles?

  3. Russia (USSR) • China • United States Three Countries that have put people in orbit are…

  4. What type of energy does a motor use? • How is that different from a rocket engine? • What principle does a rocket engine use? Rockets Overview

  5. Newton’s 3rd Law? Rocket Propulsion

  6. Measured in Newton’s. WHY? Thrust How do we overcome this problem??

  7. An elephant weighs 1 ton, how much thrust is necessary to hold its weight at a constant level but not send it into orbit? 1 TON Lets try a practice problem…

  8. In order to be launched however, the thrust must be greater than your weight. In other words you must have extra thrust. • That extra thrust make you ACCELERATE upwards. • In other words, “the greater the thrust the faster your rocket will accelerate.” Is it really that easy?

  9. 2nd Law: f = ma • When mass increases, acceleration decrease. So which Newton’s law are we talking about now?

  10. On a frictionless surface you want to measure acceleration of a rocket moving horizontally. (we don’t want to fight gravity just yet). If the rocket produces 50lbs of thrust and weighs 10 kgs, what is the acceleration? Another problem you say… Sure

  11. Lets add gravity into the mix. This time the same rocket is launched upward. What is the acceleration?

  12. The book’s example

  13. More balls • Bigger ball • More acceleration So what must be done to change the thrust?

  14. The fuel, that they use to create thrust weighs something. (like adding an extra space suit to the rocket) but more of course. So what is the funny problem that rockets have?

  15. How many main sections of the shuttle are there? • How much does the shuttle weigh at launch? • What is the shuttle’s main engine fuel? • For how many minutes did the Space Shuttle’s two solid boosters burn at launch? 3 4.4 million Liquid oxygen and hydrogen 2 Just some statistics…

  16. Solid Fuel Liquid Fuel Lets compare and contrast the two types of rockets…

  17. The fundamentals of rocketry rest on Newton’s laws. Thrust = (propellant mass flow) x (exhaust velocity) T= mC Propellant mass flow = how much “fire” come out. Exhaust velocity = It represents the force with respect to the amount of propellant used per unit time Now its time for the fun part…

  18. It is a way to describe the efficiency of rocket and jet engines • Measured in ISP = number of seconds a lb of propellant can deliver a lb of thrust. C= g (ISP) C = Exhaust velocity g= gravity ISP= impulse Lets explore exhaust velocity…

  19. velocity = to get where you want to go. • This is the fundamental currency of astronauts. • Measure in units of speed. • The ROCKET EQUATION shows how big a velocity the system can generate. In order for all this to matter…

  20. (M + P) / M = e V/C e= 2.71828 (M + P) = M= DRY mass at lift off, P= Propellent M = DRY mass in orbit V/C = shows the velocity change a rocket can generate . The ROCKET EQUATION

  21. Because of the exponent there small changes make big differences. • Increase in V or decrease in C can be bad. It is desired to have a have V down and C up.

  22. Since the mass of tanks, engines and most other vehicles increase in proportion to the propellent load, it can be described as 1 factor. • DRY MASS FRACTION = F • Takes into account system design and lightness of the materials used in construction. F x Propellent mass = dry mass ** this is not counting payload***

  23. For example: If F = 0.1 and it is carrying 90 tons of propellant what would the dry mass of the ship? What if the mass ratio of the system had to be 10 to perform a certain V? Then there would only be allowed a 1 ton payload. However, if the F increases to .12 the dry mass of the vehicle would be 10.8 and there would be no lift off!! 9 tons

  24. We chop the V into stages and then drop the dry mass of that stage. How do we fix this?

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