1. Rocket Science and Orbital Mechanics Academic Decathlon Preparation for San Fernando HS by Dr. Muller

2. Action and Reaction One of the basic principles of rocketry is that a force creates an equal and opposite force in the other direction. F = m a “pounds of thrust” in British units Newtons in metric 4.45 N = 1 lb of thrust

3. Ramifications The Space Shuttle has a massive weight to get a 65,000 lb payload into space: 20x more fuel by weight than the Orbiter! PoundsEmptyFuel Orbiter165,000NA Ext. Tank78,1001,359,000 + 226,000 Boosters185,000 x21,100,000 x2

4. SRBs Burn for 2 min and generate 3.3M lb of thrust Fuel made of ammonium perchlorate (69.6%), aluminum (16%), iron oxide (.4%) Also contains a polymer binder (12.04%) + a curing agent (1.96%) By changing the mixture, you change explosion to high-thrust burn (see p23) Has an 11-point star inside to increase burning area; evens out to circle as it burns SRB +: simplicity, low cost, safety SRB -: thrust not controllable, burn can’t be stopped

5. Liquid-Propellant Rockets Fuel tanks contain a fuel and an oxidizer, which is pumped at controlled rates into a combustion chamber; gases have high acceleration. Typical liquid fuels include liquid gases; the cooled gases are used to cool the combustion chamber as they head to it. Combinations for different rocket experiments appear on p24-25.

6. Next-Generation Rockets Small rocket thrusters use pressurized nitrogen to correct orbital decay. Current experiments seek to use high- acceleration ions or atomic particles at high acceleration to drive rockets; dangerous for use on Earth.

7. Physics Thrust = mass exhaust velocity (T = mC) By extension, C = T/m Impulse = how long a pound of propellant can deliver a pound of thrust (Isp) C = g Isp ∆V is the change in velocity. Mass ratio of a fuel-laden vehicle is (M + P)/M, where M is empty vehicle weight and P is propellant weight.

8. More Physics Rocket equation: (M+P)/M = e ∆V/C Increasing ∆V means that the mass ratio will go up – this makes the combined mass heavier, which is bad. Increasing C means that the mass ration will go down – this makes the combined mass lighter, which is good.

9. Satellites Orbit is a circular or eliptical path: apogee, perigee, geo- synchronous Sputnik was first in 1957. Lasted 92 days. Laika was launched in 1958. Lasted 30 days. Difference of Earth’s rotation at equator makes shots from there easier. Escape velocity is to get into space: 25,039 mph. Orbital velocity is required to create circular orbit: 17,000 mph at 150 mi. Geosynchronous orbit is 7,000 mph at 22,223 mi. Polar orbits are lower and are used for photography.