Rockets vs. The Campanile

Rocket Science and Physics

Background and HypothesisFunctions of rocketry were developed

through many years of trial and error

Hypothesis:

If we make a rocket that will fly higher than the Campanile, then the rocket’s center of mass will have to be located higher than the center of pressure.

What makes rockets fly?Thrust: Solid or liquid combustion must travel

straight down for rocket to fly straight up. This applies Newton’s Third Law of Motion

Newton’s Third Law of Motion: For every action, there is an equal and opposite reaction

What makes rockets fly?Newton’s Second Law of Motion also applies

to rocketry

Newton’s Second Law of Motion: F=ma (Force=mass*acceleration)

In rockets, propellants make up to 90% of a rocket. In flight propellant is lost (m), so that acceleration increases(a)

What makes rockets fly?Flight Control:

Fins help stabilize rockets during flight, giving them direction. 3s and 4s (symmetrically separated) are most effective. 5 is too much drag.

Rocket Launcher:

Gives rocket initial direction and

thrust

MethodThe rocket launcher was built using following materials:

Wood

Corner Brace

Mending Plate with screws

Galv FLR Flange 

Rubber stopper

MIP Hex Nipple (brass

High pressure air hoseDowelCast Female Pipe Tee

(brass)

Hook and Loop Cable Tie

Barb Splicer 

Rubber Bands

Pan head metal screws

Drill

Bicycle pump

Launch string

Steps for Launcher  

Screw flange into wooden base

Attach each brass nipple to each end of the tee

Insert pressure air hose so that it goes through each end of the tee 

Insert barb splicer into hole

Drill and stand wood block to base (use braces to sustain)

Drill wooden block on opposite end

Insert rod in wooden block

Attach clamps (should tighten bottleneck)

Wrap rubber bands on back end of the clamps

Wrap hook and cable tie to other end of clamps (after bottle is inserted)

Tie launch string to cable 

Connect hose to a pump 

Materials for Rockets

2-Liter empty plastic bottle

CardboardHot Glue GunTapeScissors Clay Water

Steps for Rocket1) Cut out and tape cone to bottom end of

bottle

2) Cut out and attach (use hot glue gun) fins into upper end of the bottle

3) (Ran “string test” to test stability and direction of rocket)

Running the ExperimentThese were the steps taken in running our

experiment:

Place rocket launcher right in front of Berkeley Campanile

Fill up rocket with different amounts of water

Insert Rocket into rocket launcher

Insert different quantities of pressure

Detach string from hook and cable tie

Record (very roughly) how high each rocket went (based purely on eyesight)

ResultsRocket Launch#1:

Volume: 70% total mass of bottle

Pressure: 50 psi

Height: 4th Window of the Campanile

ResultsRocket Launch #2:

Volume: 75% total mass of bottle

Pressure: 80 psi

Height: Clock

ResultsRocket Launch #3:

Volume: 75% total mass of bottle

Pressure: 90

Height: TOP OF THE TOWER!!!!!!

ResultsRocket Launch #4:

Volume: 65% total mass of bottle 

Pressure: 90

Height: HIGHER THAN THE TOWER!!!!!!

AnalysisBecause our (Juan and Luis’) rocket had its

center of mass more obviously located above the center of pressure than the other rocket, our experiment supports the notion that this rocket setup is best.

Conclusion A rocket whose center of mass is higher

than the center of pressure is more likely  to fly higher than one that is very roughly positioned equally or in which the center of pressure is located higher than the center of mass.

And the winner is…