PROBLEM STATEMENT Which factor affects the efficiency of a rocket’s hang time, the placement of its fins, above or below the center of gravity or the size of its fins?

HYPOTHESIS . . . will have a for the longest amount of time. If different water rocket designs are tested for their efficiency, then the rockets with (student responses)… will have the greatest hang time. (2)…Smaller fins (5)…Larger fins (6)…Fins placed above the center of gravity (1)…Fins place below the center of gravity (6) Then neither of the designs will make a difference . . . will have a for the longest amount of time.

BIBLIOGRAPHY Sciencesaurus: a student handbook. Wilmington, MA: Great Source Education Group/Houghton Mifflin, 2005. Print. Convention, and the single. "Rocket Aerodynamic Forces." Space Flight Systems Mission Directorate. N.p., n.d. Web. 24 Nov. 2012. http://exploration.grc.nasa.gov/education /rocket/rktaero.html cyenobite. "Soda Bottle Water Rocket." Instructables - Make, How To, and DIY. N.p., n.d. Web. 24 Nov. 2012. <http://www.instructables. com/id/Soda-Bottle-Water-Rocket/>.

ABSTRACT The purpose of this experiment was to investigate Which factor affects the efficiency of a rocket’s hang time, the placement of its fins, above or below the center of gravity or the size of its fins? used in a capsule, as propellant to thrust a rocket, would affect how long the rocket is airborne? It was hypothesized by 2 students that 25% of water in the capsule, would maintain the rocket airborne for the longest amount of time. 6 students hypothesized that it would be 50%, 5 students that it would be 75% and 3 students that it would be 100%. Four water rockets were made using 2 liter bottles, the capsule was filled with water then secured to the launching pad and air was pumped into the bottle using a bicycle pump. A timer was used to record the amount of time the water rocket was airborne. In conclusion, the data supported the hypothesis that the least amount, 25% or 500ml. of water as a propellant would maintain the rocket airborne for the longest about time. The average aloft time for the rocket with 25% water capacity was 5 seconds, as opposed to the average aloft time for the rocket filled with 75% water which was 1 second, barely leaving the ground because it was too heavy. Improvements to this experiment would be a harder cone, less water volume testes and harder fins. Future test variables could be to test different levels of air pressure or different placement for the fins. This experiment is useful information for scientists, astronauts and engineers because model rockets and real rockets both have a rocket propulsion system. One of the advantages of this study helps test how much liquid fuel would be the best propellant for a variety of rockets. The investigation of water and air pressure as a propellant is useful in the study of aerodynamics for green energy because water pollutes less than other chemicals. Finally, testing models help future scientists, engineers and NASA researchers develop launching technology before applying it to real rockets.  

MATERIALS (8) 2liter soda bottles (4) birthday hats (1) clear packing tape (4) manila folders permanent marker (1) Water source (1) rocket Launcher launch pad (1) bicycle pump (4) timers

EXPERIMENTAL PROCEDURES Once water rocket is constructed, fill capsule (bottle) with 25% (500 ml.) capacity of water. Insert the stopper into the mouth of the bottle. invert the bottle so that the cone is facing up and the bottle sits on the rocket launcher. Attach bicycle pump connector to the valve stem in the stopper. The launch tube is connected to an air pump by a hollow feeder line. The pump is used to pressurize the inside of the body tube to provide thrust for the rocket. Attach the plastic apparatus to secure bottle, the rocket will take off when the triggering mechanism is pulled. Using timer, record the amount of time water rocket is airborne. Repeat steps 1 through 6 for three additional trials. Repeat steps 1 through 6 filling capsule (bottle) capacity with 50% (1L), 75% (1.5L), 100% (2L) and complete four trials for each water capacity.

PROCEDURES TO MAKE ROCKET Gather two (2 liter soda bottles) and remove labels. Remove the top from one of the soda bottles and invert the bottle so that the bottom of the bottle becomes the top of the rocket. Place 2 newspaper pages in the top of the bottle and secure by placing the section that was cut off from the previous bottle. Insert the bottom part of the second soda bottle upside down into the opening of the top part of the first soda bottle and tape together. Using a birthday paper hat, create a cone for the top of the rocket and tape to bottle. Use file folders and a template to cut 3 exact fins to tape to the bottom of the body tube for stability during the flight. Attach fins equally around the rocket body by measuring the bottle’s circumference, divide by three to find the distances the fins should be separated, then mark fin guides on the bottle. Tape both sides of each fin around the rocket body. Repeat steps 1-9 to create 3 more water bottle rockets.

VARIABLES Independent variable: The design of the bottles Large fins compared to small fins Placement of fins above center of gravity Placement of fins below center of gravity Dependent variable: The amount of time the water rocket stays a loft. Controlled variables: The bicycle pump (air pressure 40psi), the size of the rocket, the amount of water in capsule (?ml.)the rocket launcher and launching pad used.

DATA

GRAPH

RESULTS The capsules of 4 water rockets were filled with different amounts of water and tested for airborne time, the result of 25% capacity for trial one was 4.73 seconds aloft, trial two 4.3 seconds, trial three 6.99 seconds and trial four 4.95 seconds. The results for 50% capacity for trial one was 2.5 seconds aloft, trial two was 3.31 seconds, trial 3 4.15 seconds and trial four 3.3 seconds. The result for 75% capacity trial one was 2.98 seconds aloft, trial two 3.31 seconds, trial three was null because the rocket landed on the roof and never came down, and trial four was 3.53 seconds. Finally the results for 100% capacity was 1.56 seconds aloft, trial two 0.74 seconds aloft, trial three 0.57 seconds, and trial four 1.56 seconds aloft. The averages for each volume of water were as follows: 25% was 5 seconds, 50% was 3 seconds 75% was 2 seconds and 100% was 1 second.

CONCLUSION In conclusion, the data supported the hypothesis that the least amount, 25% or 500ml. of water as a propellant would maintain the rocket airborne for the longest about time. The average aloft time for the rocket with 25% water capacity was 5 seconds, as opposed to the average aloft time for the rocket filled with 75% water which was 1 second, barely leaving the ground because it was too heavy. Improvements to this experiment would be a harder cone, less water volume testes and harder fins. Future test variables could be to test different levels of air pressure or different placement for the fins.

APPLICATION This experiment is useful information for scientists, astronauts and engineers because model rockets and real rockets both have a rocket propulsion system. One of the advantages of this study helps test how much liquid fuel would be the best propellant for a variety of rockets. The investigation of water and air pressure as a propellant is useful in the study of aerodynamics for green energy because water pollutes less than other chemicals. Finally, testing models help future scientists, engineers and NASA researchers develop launching technology before applying it to real rockets.

The fins must be rigid. They must be able to “push” against the wind, even when the rocket is travelling at speeds over 80 MPH. 2. The fins must be located behind the center of gravity of the rocket. Otherwise, they will have the opposite effect, making the rocket less stable and decreasing the height.

A good rocket design can be summarized in five words: reliability, rigidness, precision, weight, and drag. There is no perfect rocket, but the following five critical factors will ensure that your design is as successful as possible. The factors are listed in their order of importance. For example, do not add weight (#4) to a rocket to decrease drag (#5), and do not select a material that is weighs less (#4), unless it is strong (#2).

The researcher chose this topic because in his class they are doing the bottle rocket project and he wanted to find out which rocket was more efficient for hang time. S