Fins Which Is Better
Physical Science
Angela Vanderwey
Statement of problem:
Which shape of fin works better on a bottle rocket?
Project Overview:
This project will show which shape of fin will help keep a bottle rocket in the air the longest.
This problem is clearly testable because a bottle rocket will be using different shapes of fins to see which
shape of fin helps keep the bottle rocket in the air the longest.
Research:
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The most common fins are round fins and small triangular fins.
The fin that is best for a rocket is a triangular fin.
Bigger triangle fins are used on a space shuttle.
Bigger triangle fins are used more on buildable rockets.
Bigger triangular fins are also used more often.
Variables:
Independent variable: The shape of fin will help keep the bottle rocket in the air the longest. The fins are
a medium sized triangular fin, a bigger triangular fin, and a medium sized curved fin.
Dependent Variable: The amount of time the bottle rocket is up in the air from when it leaves the
launcher to the time it hits the ground.
Controlled Variable: The controlled variable in this experiment is the amount of fins put onto the bottle
rocket, the amount of air presser put into the bottle rocket, the type of bottle rocket, and the amount of
water put into the bottle rocket. The fin placement will be straight on the bottle rocket.
Control Group: The controlled group in this experiment are the original fins they are the medium sized
triangles, which are being put on to the bottle rocket.
The reason for why the type of fin is the control group is because the type of fins is what is being
changed.
Hypothesis:
The hypothesis is the smaller triangle original fins would work the best by helping the bottle rocket go
higher in the air which will take it longer to come down, and because they seem to be used more often,
and because of previous trials.
Materials:
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Card board (1 big piece)
Party hats ( 1)
Tennis ball (1)
2 litter soda bottles (3)
Duct tape (about 2 rolls)
Air compressor (1)
Launcher (1)
Water (about 3 quarts full each launch)
Writing materials (2)
Stop watch (1)
Ruler (1)
Paper (1)
One pair of safety goggles pure person
Procedure:
1. Build one bottle rocket
a. Cut two 2 litter bottles in half
b. Take labels off
c. Tape the 2 bottom sides stacked on top of each other on top of a whole 2 litter bottle
d. Make 3 different types of fins in pairs of 3(curved, medium triangle, large triangle)
e. Attach fins equally separated a part (use ruler if wanted)
f. Tape the tennis ball directly on top of the last bottle
g. Tape party hat on top of tennis ball
h. Rap party hat up with duct tape
2. Attach fins equally separated a part (use ruler if wanted)
3. Put on goggles
4. Put three quarters of water into the bottle rocket
5. Put bottle rocket onto the launcher with air compressor ready to put in 75 psi
6. Put in 75 psi into the bottle rocket
7. Launch the bottle rocket
8. Time it from the second it leaves the launcher to the second it hits the ground
9. Repeat steps 4-8 each launch
10. Repeat steps 2-8 after each different shape of fin was launched three times
Photos:
Observations:
The observations are the different things that the rocket did with the different fins, and the amount of
time the rocket stayed in the air.
Times
Type
1 (medium
triangles)
2 (large
triangles)
3 (curved)
Time 1
4.7
Time 2
5.4
Time 3
5.4
Average
5.167
6.14
6.08
6.00
6.073
6.34
6.26
7.28
6.627
Average Times
7.00
Time in seconds
6.00
5.00
4.00
3.00
2.00
1.00
0.00
1 CG Medium Triangle
2 Large Triangle
3 Curved
Fin Type
The curved fins made the bottle rocket spiral which made it go higher which made it take longer to
come down.
Conclusion:
The data did not support the hypothesis because it was wrong by a lot the medium triangle fins did the
worst, and the curved fins did the best.
Possible Experimental Errors:
Some possible experimental errors are wrong timing and if the bottle rocket hit or got stuck in a tree.
Applications and Recommendations:
When anyone does this experiment do it away from buildings and away from trees.
Works Cited:
http://home.comcast.net/~timhesterberg/WaterRockets.html
http://www.tclauset.org/21_BtlRockets/BTL.html
http://www.waterrocketmanual.com/bottle_profiles.htm