Bottle Rocket ContestBottle Rocket Contest Group CGroup C

KMSO 2005KMSO 2005NY-Metro ChapterNY-Metro Chapter

Lehman College, CUNY, Bronx, NY, 2005 Nov. 19

Part IPart I Build your own rocket Build your own rocket

MaterialsMaterialsNote: two persons share one duct tape. Corporation between two recommended.

Water Rocket Water Rocket PartsParts

Nozzle

SampleSample

Nose cone

Label

Fins Write down the amount of water in percentage!

Design factorsDesign factors

Design RulesDesign Rules

Launch RulesLaunch Rules

TipsTips

1. Aerodynamic stability

2. Maximum thrust

Note: today’s rocket launch cancelled.

• KMSO’s outdoor activity was approved by Dept. of Public Safety in Lehman college. 11/9/05

• The Vice President for Administration, Mr. DerekWheeler, has overruled the Bottle Rocket portion of the program. 11/14/05

• KMSO’s continued effort to get it back was unsuccessful so far. 11/19/05

What we will do:What we will do:

Contestants:- Build your rocket (<1hr)- Put the label (name, ID, Water%) on the rocket- Submit the rocket with answer sheet- Do a virtual test & make your own prediction- Share wisdom to get bonus points

Committee:- Bring your products out of NY- Do an off-line test in NJ- Inform the result on the web

Part IIPart II

Analysis of ThrustAnalysis of Thrust- why water rocket?- why water rocket?

Two major Two major explosionsexplosions

• 3rd impulse (when water goes out) - reaches maximum acceleration

• 2nd impulse (when the bottle gets out of tube) - sudden increase of acceleration

• 1st impulse (while tube is within the bottle) - linear increase of velocity

1. Launch Impulse1. Launch Impulse

• A launch tube acts as a piston.

• Small explosion at the end of the launch tube.

• This burst comes from the compressed air stored in the launch tube. Water thrust then initiates.

2. Water Impulse2. Water Impulse

• Why water is pushed out?

• How water helps acceleration?

3. Air Impulse3. Air Impulse

• The exit of the pressurized gas at high velocity

• The air dramatically impacts the previously expelled water, creating a large cloud burst.

Bottle Bottle rallyrally

88p 51p 51p 88p 88psiHe+air He+air air air air

Note the fog formation

Speed analysisSpeed analysis

Summary2

Why water rocket?Why water rocket?

• It has almost everything.• Compare with stomp rockets, model

rockets, and real rockets.

Von Brown quotes Bob Goddard

Part IIIPart III

PredictPredict Your Score Your Score

Goal: “The maximum flight distance will win this contest. However, the rocket must not deviate from a designated area.”

1. The greater the “thrust,” the faster your rocket will accelerate.2. Aerodynamic stability and guiding

Four forces: -Thrust-Weight-Aerodynamic force-Drag

1.1. Aerodynamic stabilityAerodynamic stability

Pinch motion Roll motion

Any rocket will rotate about its center of gravity.

2. Water – Air Ratio2. Water – Air Ratio

Your score:

Q1. Why do we have to use water, or will it fly without water?

Q2. If a little water works well, will a lot of water work better?

Q3. What type of fins, fin size matter to help keep the rocket most stable?

Flight performance +

Thank you!

Group C of KMSO 2005

See KMSO webpage for the score.

Group leader: Jeongwoo Lee (NJIT)