by: alexandro perez greg desrosiers laura berg tara hodgetts

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By: Alexandro Perez Greg Desrosiers Laura Berg Tara Hodgetts

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Page 1: By: Alexandro Perez Greg Desrosiers Laura Berg Tara Hodgetts

By:

Alexandro Perez

Greg Desrosiers

Laura Berg

Tara Hodgetts

Page 2: By: Alexandro Perez Greg Desrosiers Laura Berg Tara Hodgetts

1. Problem Definition

2. Previous Design

3. Current Design

4. Performance Statistics

5. Performance Cont.

6. Performance Cont.

7. Design Improvements

8. Conclusion

9. Special Thanks

Page 3: By: Alexandro Perez Greg Desrosiers Laura Berg Tara Hodgetts

The main objective of this project was to design a trebuchet that, while using the most efficient design, that maximized its launch distance while minimized its weight.

The size of each trebuchet, fully assembled shall be submitted 2 days prior to the competition. When fully assembled with the swing arm in a horizontal position, the entire trebuchet must fit within a 4 x 3 x 2.5 foot container. There is no weight restriction, only a penalty as stated above. The time needed to fully prepare the trebuchet prior to each hurl will be measured. Teams will be given 60 seconds to prepare their device; teams requiring more than 60 seconds of set-up time will be penalized 1 point per second. Each design team will select two operators who will be allowed to set up, load, and activate the trebuchet.

 

Page 4: By: Alexandro Perez Greg Desrosiers Laura Berg Tara Hodgetts

Our first design used lighter wood for the joints where a high amount of stress was present. Due to this the design failed. Further research was needed before the counterweight was added with a faulty release mechanism. This caused undue stress and the design failed.

Page 5: By: Alexandro Perez Greg Desrosiers Laura Berg Tara Hodgetts

Design StatisticsDesign Statistics

• Constructed of 2x2 pine woodConstructed of 2x2 pine wood

• Base dimensions: 3ft.x1ft. Base dimensions: 3ft.x1ft.

• Height: 2.5 ft.Height: 2.5 ft.

• Weight: 10.5 poundsWeight: 10.5 pounds

• Fastened with #6 6x1-1/2`` Fastened with #6 6x1-1/2`` screwsscrews

Page 6: By: Alexandro Perez Greg Desrosiers Laura Berg Tara Hodgetts

Sling Length 6 10 14Launch Avg. Distance 25 16 5

Sling Length vs. Distance

y = -x2 - 6x + 32

0

5

10

15

20

25

30

6 10 14

Sling Length (Inches)

Lau

nch

Dis

tan

ce (

Fee

t)

Page 7: By: Alexandro Perez Greg Desrosiers Laura Berg Tara Hodgetts

Hurl Distance vs. Swing Arm Ratio

0

0.51

1.5

2

2.53

3.5

233 248.8 260.5 266.7 273 276.1 277.8

Distance

Sw

ing

AQ

rm R

atio

Hurl Distance vs. Pivot Height

0

0.5

1

1.5

2

2.5

3

196.3 206.4 233.4 242.4 250.2 256.6 259.2 262.2

Distance

Pivo

t Hei

ght

Hurl Distance vs. Counterweight Length

0

0.2

0.4

0.6

0.8

1

1.2

1.4

198.8 214.1 228.8 240 248.6 256.7 264.4 270.9 276.3

Distance

Co

un

terw

eig

ht

Len

gth

Page 8: By: Alexandro Perez Greg Desrosiers Laura Berg Tara Hodgetts

Launch number 1 2 3 4 5 6 7 8 9 10Launch Avg. Distance 60 10 7 19 25 26.5 26 31 29 20

Launch Distances

0

1020

30

40

5060

70

1 2 3 4 5 6 7 8 9 10

Launch Number

Dis

tan

ce (

Fee

t)

Page 9: By: Alexandro Perez Greg Desrosiers Laura Berg Tara Hodgetts

Possible changes in design

1. More accurate construction of joints. This will greatly reduce wobble and hence increase accuracy.

2. Use lighter wood where a high amount of stress is absent.

3. Move the axle forward hence optimizing the throwing arm lengths.

Page 10: By: Alexandro Perez Greg Desrosiers Laura Berg Tara Hodgetts

 

During the computer simulations, we found that our design should launch a hacky sack 62 feet. When we actually built the trebuchet and tested it, it launched 60 feet on the first trial and about 35 feet for every trial after that. There were significant differences because of wind. During the competition, we had to launch against very strong winds. This made the launch distance extremely short. For future trebuchet builders, we recommend researching what type of wood you are planning to use to build it. The lighter wood is best. Also, careful consideration must be used during construction because the designs may be very fragile do to their lightweight. This project showed how communication is crucial even for the smallest of projects. This gave us insight to the problems we may encounter in the engineering world and showed us many things we cannot learn from a textbook.

Page 11: By: Alexandro Perez Greg Desrosiers Laura Berg Tara Hodgetts

Special thanks to Professor Litton and Professor Golanbari, Professor Turpin,and all the people that woke up early in the morning to attend the launching. Also a really special thanks to Home Depot for being open at all the right times.