PROJECT 4.2.3 PROJECTILE MOTION 1

Project 4.2.3 Projectile Motion

Sunny, Althea, Divya, Natalie

Principles of Engineering Block 2

Due Date: 10 January 2016

PROJECT 4.2.3 PROJECTILE MOTION 2

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

PROJECT 4.2.3 PROJECTILE MOTION 3

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 4

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.

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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.

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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 8

Construction

Skeleton

Inside Mechanisms

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Final Design

Physical Sketch:

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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 11

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).

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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

0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 1 0 002468

1012141618

Test ResultsDistance Polynomial (Distance)

Firing Angle

Dist

ance

in F

eet

Video Link: https://youtu.be/miHDaIG__fw

PROJECT 4.2.3 PROJECTILE MOTION 13

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.

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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?)!