Bottle Rocket Contest Group C KMSO 2005 NY-Metro Chapter Lehman College, CUNY, Bronx, NY, 2005 Nov. 19

Part I Build your own rocket

Materials Note: two persons share one duct tape. Corporation between two recommended.

Water Rocket Parts Nozzle

Sample Nose cone Label Fins Write down the amount of water in percentage!

Design factors

Design Rules

Launch Rules

Tips 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. Derek Wheeler, 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: 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 II Analysis of Thrust - why water rocket?

Two major explosions 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 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 Impulse Why water is pushed out? How water helps acceleration?

3. 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 rally 88p 51p 51p 88p 88psi He+air He+air air air air Note the fog formation

Speed analysis

Summary2

Why water rocket? It has almost everything. Compare with stomp rockets, model rockets, and real rockets.

Von Brown quotes Bob Goddard

Part III Predict 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. Aerodynamic stability

Pinch motion Roll motion Any rocket will rotate about its center of gravity.

2. 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)