Part 2: Rocket Principles Module 4 . Rocketry Part 2: Rocket Principles Rev 1, 17 Nov 2003 Steven Esh

What We Will Learn Newton’s three laws Rocket vocabulary Thrust in rockets Rocket stability Page 2, Module 4, Part 2 Rev 1, 17 Nov 2003 Steven Esh

Vocabulary Inertia: the tendency of a body to maintain its same motion if no force is applied to change it Velocity: how fast something moves Acceleration: how fast a body’s speed changes Mass: the amount of substance in a thing Thrust: a “pushing” force momentum: mass x velocity Page 3, Module 4, Part 2 Rev 1, 17 Nov 2003 Steven Esh

Newton’s Laws 1st Law: inertia A body at rest tends to stay at rest. A body in motion tends to maintain that same motion 2nd Law: conservation of momentum The force on a body = change in momentum (momentum = mass x velocity) 3rd Law: balance of forces For every action, there is an equal and opposite reaction Page 4, Module 4, Part 2 Rev 1, 17 Nov 2003 Steven Esh

Rocket Thrust Depends upon how fast momentum is changing (Newton’s 2nd Law) Comes from mass of fuel being pushed out at high velocity Needs nothing to “push against”, so it can work in outer space Page 5, Module 4, Part 2 Rev 1, 17 Nov 2003 Steven Esh

Stability Is the tendency to return to its original flight path after an upsetting disturbance Is Positive (stable) if the rocket tries to stay on its intended path Is Negative (unstable) if the rocket tends to go out of control Page 6, Module 4, Part 2 Rev 1, 17 Nov 2003 Steven Esh

Stability A stable rocket must have it’s Center of Gravity (CG) ahead of it’s Center of Pressure (CP) The distance from the CP to the CG determines how stable it is The fins provide stability through a “weather vane” effect (the CP moves toward the fins) Page 7, Module 4, Part 2 Rev 1, 17 Nov 2003 Steven Esh

The future? The ion engine - for space flight . Page 8, Module 4, Part 2 Rev 1, 17 Nov 2003 Steven Esh

Review What are the properties of rocket thrust? . What are Newton’s three laws? What is required for a stable rocket? Page 9, Module 4, Part 2 Rev 1, 17 Nov 2003 Steven Esh