PROJECT 4.2.3 PROJECTILE MOTION
Project 4.2.3 Projectile Motion
Sunny, Althea, Divya, Natalie
Principles of Engineering Block 2
Due Date: 10 January 2016
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PROJECT 4.2.3 PROJECTILE MOTION
Table of Contents
1. Abstract
2. Concepts
3. Design Brief
4. Brainstorming
5. Decision Matrix
6. Construction
7. Final Design
8. Final Program
9. Testing
10. Conclusion Questions
11. Reflection
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PROJECT 4.2.3 PROJECTILE MOTION
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Abstract
This project encourages students to utilize useful skills that can be used in the
engineering field as well as in other aspects of life. Our problem called for a creative solution to
the problems where we had to be able to shoot an object at least 15 feet in an effective way. This
project took our previous knowledge of simple machines all the way from Unit 1 and combined
it with our programming skills to create a an effective machine that solved our problem.
Keywords: engineering, programming
PROJECT 4.2.3 PROJECTILE MOTION
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Concepts
In order to build our machine, we had to use our knowledge of previous concepts to build
certain attributes. We used what we learned about coding and motors to program our machine
and work the way we want it to. We also used our knowledge of simple machines to build the
skeleton of our design, which included gears and the wheel and axle. We also used our
knowledge of what would work the most efficiently when building the cannon part of our
machine.
PROJECT 4.2.3 PROJECTILE MOTION
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Design Brief
Client Company: Hobby Spectacle, Inc.
Target Consumer: Society
Designers: Sunny, Althea, Natalie, Divya
Problem Statement: A leading hobby company is looking to improve an existing launcher
design. The device must launch a projectile using the materials provided. The device must be
adjustable so that projectile launches can be precise at varying distances. The winning design
will receive cash for a patent that can be mass-produced as a kit and sold to the public. Members
from the company will be present during the launching phase of the process.
Design Statement: Improve an existing design, then build and test a device that will launch a
projectile varying distances with precision and accuracy.
Constraints:
1. Must be constructed using the materials outlined by the instructor.
2. Must be adjustable to different angles including: 10, 20, 30, 40, 45, 50, 60, 70, 80
degrees.
3. Must have the same initial velocity at any adjusted angle.
4. Must launch a projectile at least 15 ft.
PROJECT 4.2.3 PROJECTILE MOTION
Brainstorming/Potential Solutions
1. Catapult
2. Cannon
3. Slingshot
4. Rocket launcher
Brainstorming for Inside Mechanisms
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PROJECT 4.2.3 PROJECTILE MOTION
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PROJECT 4.2.3 PROJECTILE MOTION
Construction
Skeleton
Inside Mechanisms
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PROJECT 4.2.3 PROJECTILE MOTION
Final Design
Physical Sketch:
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PROJECT 4.2.3 PROJECTILE MOTION
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Photo:
Our final design resembles a cannon, but since we are not allowed to use water or gunpowder,
we opted for a rubber band mechanism on the inside instead. The machine is programmed to
adjust the angle, and after it is loaded, a pin is pulled out to launch the projectile. The angles are
controlled by two servo motors on either side of the frame, and the rubber bands at attached to a
metal piece that can hold the projectile being fired.
PROJECT 4.2.3 PROJECTILE MOTION
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Final Program
Our final program is extremely simple because it can be adjusted based on the angle. We did
some calculations and testing to figure out what servo positions to set the machine at. The
machine works the best at a 45 degree an angle, which happens to be the starting position of the
servo (0, 0).
PROJECT 4.2.3 PROJECTILE MOTION
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Testing
Angle (degrees)
Distance (feet)
0
4
10
9
20
5
30
10
40
11
45
16
50
14
60
14
70
6
80
5
90
1
TEST RESULTS
DISTANCE IN FEET
Distance
Poly. (Distance)
18
16
14
12
10
8
6
4
2
0
0
20
40
60
FIRING ANGLE
Video Link: https://youtu.be/miHDaIG__fw
80
100
PROJECT 4.2.3 PROJECTILE MOTION
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Conclusion Questions
1. What was the most challenging aspect of this design problem? The most challenging
aspect of this design problem was building the machine that would effectively shoot an
object fifteen feet. We had many obstacles when building, and had to redo and modify over
and over again just to get the proportions of the skeleton right. Creating a rubber band system
on the inside of the cannon was also difficult because it put a lot of strain on the walls of the
cannon, but we needed a lot of tension in order for the object to go fifteen feet.
2. What are some creative changes that you would make to the design solution if you could
start over? If we could start over, we would have thought of a better way to program our
machine to launch the object. It would be more efficient if we could program the entire
machine rather than using human interferences to make the machine launch the object.
3. Suppose that the client wants your ballistic launcher to be guaranteed to hit a target at
least once, given three tries.
a. Would a 34% success rate per launch be good enough? Explain why or why not.
Yes, because if you are given 3 tries and only have to succeed once, that is a ⅓
chance and 34% is greater than ⅓.
b. If a launcher hits the target 34% of the time, what is the probability that it will
miss three out of three tries? 28.7496%
c. If the client defines a “success” as hitting the target at least once, given three
shots, what success rate per launch is necessary to succeed 99 times in 100 groups
of three shots? Explain your reasoning. Yes, because 100 groups of 3 shots is 300
and ⅓ of 300 is 100. 99 is less than 100, so it is pretty much theoretically guaranteed
that it will succeed at least 99 times.
PROJECT 4.2.3 PROJECTILE MOTION
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Reflection
This design problem was very challenging because we had to accomplish the objective of
shooting an object fifteen feet, programming and building a machine that would require only
minimal human interaction, all while combining our creativity and previous knowledge of simple
machines, efficiency, and physics. After brainstorming, we ended up with the creative, yet simple
solution of a cannon that could have adjustable angles (accomplished by servos on each side) and
a rubber band mechanism on the inside. We initially had some challenges deciding on the
proportions of the cannon, and later on, we had difficulty deciding on how to execute the rubber
band mechanism (more specifically, what type of rubber bands to use and how many, in order to
achieve maximum shooting potential). As a team, some of us disagreed on what to do, but we
worked through it by listening to each option thoroughly and deciding on the best course
together. In the end, the final result did accomplish the objective, and we feel like we did our best
to achieve it in the most efficient way possible. Compared to other teams, I feel we are
somewhere in the middle in terms of how well the machine works because ours is very
temperamental. If we could start over, we would have thought of a better way to program our
machine to launch the object. It would be more efficient if we could program the entire machine
rather than using human interferences to make the machine launch the object. We learned that
troubleshooting is a very important part of the design making process, and our knowledge of
machines, their inner mechanisms, and how everything can work together has increased
immensely. In conclusion, although we had a difficult time figuring out how to do everything, we
created a solution that is both effective, creative, and fun (who doesn’t like building cannons?)!