1. 3, 2, 1, Blast Off!

2. Process Read and understand the rules Research Design Build Test
Analyze
Fix

3. Important Rules Build up to 2 rockets before the tournament
Rockets will use 2 liter carbonated bottles
MUST WEAR SAFETY GLASSES
Nothing within 5 cm of the nozzle
Launched at 75 psi
Can use any recovery system
Best single rocket time will win

4. What makes it work? Water is poured into the pressure chamber
Air is then pumped into the bottle.
When the rocket is released, the air forces the water out of the bottle.
Newton’s Third Law of Motion kicks in

5. Parts of the Rocket and Forces

6. Pressure Chamber 2 Liter soda bottle
Do not cut or scratch the pressure chamber.
Can glue fins to pressure chamber with silicone or polyurethane glues.
If pressure chamber is damaged it will not be launched

7. Fins Fins keep the rocket stable in flight There must be at least 3
Fins must be rigid
Backswept fins work best

8. Fin Shapes

9. What does it mean to be stable?
Stability: the tendency of the rocket to return to equilibrium
This means if the rocket begins to veer, it will straighten back up on its own.
To be stable, the center of mass must be closer to the top of the rocket than the center of pressure

10. Nose Cones Popular types: Nose cones reduce drag
Conical
Blunted Conical
Elliptical
Spherical
Nose cones reduce drag
Conical are easy to make but can be difficult to get straight.

11. Recovery Systems
A recovery system is something that slows the rockets descent.
The two most popular at the parachute and the back-slider

12. Recovery Systems
The velocity of a falling object can be shown as follows
where v(t) is velocity, g is acceleration do to gravity, c is the coefficient of air resistance, t is time, and v(0) is initial velocity.
C is much larger for a parachute than a backslider; therefore, it will fall much more slowly

13. Parachute
Parachutes work best but are harder to get to work consistently
The size needs to match the rocket.
It should have 8 to 10 strings
Fold it like an accordion and then wrap extra string around it to keep it folded

14. Making a Parachute
Cut Here

15. Making a Parachute

16. Backslider
Backslider is made by making the center of gravity close to the center of pressure
This prevents the rocket from turning over at apogee and instead floating down on its side.
Fins on this type of rocket should be larger to help slow it down.
Acceleration down = (m*g – v*b)/m

17. Example Backslider

18. Examples