Download Rocket Review - CHMS-Technology

Rocketry
Stages of Rocket Flight
1. Ignition - 10,9,8,7,6,5,4,3,2,1 -- Blast Off
2. Lift Off - Then Burnout - Engine thrust pushes rocket until propellant
burns out, then momentum carries rocket upward.
3. Apogee - Peak altitude of rocket - Highest point in the rocket flight.
4. Ejection - Charge pushes out the parachute.
5. Landing - Rocket descends slowly landing undamaged for another
flight.
Rockets have existed for over 700 years.
Rocket Recovery Systems
1. Parachute
4. Boost Glide Recovery
2. Streamer
5. Drag Recovery
Drag is Increased When:
The speed of the rocket is increased.
The density of the air is thicker.
The size of the rocket is increased.
The rocket is made rougher.
The relative wind is increased.
Drag is Decreased When:
The rocket is made smoother.
The density of the air is thinner.
The relative wind is slower.
The rocket is made smaller.
You use a smaller thrust engine.
3. Tumble
The colder the air.
The rocket is fatter.
A longer nose cone is used.
The rocket is skinnier.
The Formula for Drag
D=C D A 1/2pV2
D is the drag force.
CD is the aerodynamic drag coefficient.
A is the crossectional area of the rocket
p (Greek letter “rho”) is the density of the air through which the rocket is
moving.
V is the velocity or the speed of the rocket
The air moving over a smooth surface is called Laminar Flow.
The air moving over a rough surface is called Turbulent Flow.
The center of all the mass of the rocket where it is balanced is called the
Center of Gravity (CG).
When a rocket has an engine the CG is towards the rear.
The symbol for the Center of Gravity looks like:
The point where all the aerodynamic forces come together is called the
Center of Pressure (CP).
The symbol for the Center of Pressure looks like:
The large surface area of the fins usually causes the CP to be near the
back of the rocket.
Adding canard fins (fins that are near the nose cone) moves the CP
towards the front of the rocket.
If your rocket is going to fly straight the Center of Gravity
must be in front of the Center of Pressure.
A Stable rocket has the CG in front of the CP and will fly straight.
A simple way to test the stability of a new model rocket is by the
String Test.