John Mclaughlin

John McLaughlin

Lucien Filip

Dan Hill

Manuel Boria

Percentage of Contribution

John McLaughlin

· Design

· Acquiring materials

· Construction

· Written report

· Testing

· Engineering notebook

Lucien Filip

· Design

· Acquiring materials

· Construction

· CAD drawings

· Testing

· Engineering Notebook

Dan Hill

· Design

· Acquiring materials

· Construction

· Website design and maintenance

· Testing

Manuel Boria

· Design

· Acquiring materials

· Construction

· Testing

Table of Contents

Abstract, Introduction, Background, Methodology 1

Methodology cont. Alternative solutions 2

Alternative solution sketches one and two 3

Alternative solution sketches three and four 4

Alternative solution sketch five 5

Final design 6

Final design CAD Drawing 7

Conclusions and Recommendations 8

Materials used 9

Construction Procedure 10

Record of Testing 11

Bibliography 12

Gant Chart 13

Sample emails 14

Instructions for use 15-17

Engineering Notebook 18-28

Abstract

Our goal is to design and construct a ping pong ball launcher that will launch a single ping pong ball two meters into a receiver. The ping pong ball must stay in the receiver for it to be considered successful. If the ball bounces out of the receiver it is considered half credit. The ping pong ball must travel two meters and over a one meter wall. The launcher must be able to fire five ping pong balls in one minute. The launcher cannot be over one meter high and must also be safe to use. When firing the launcher has to be at least one meter away from the wall and the front edge of the receiver must be one meter from the wall.

Introduction

Building a ping pong ball launcher is not as easy as it may seem. The launcher takes time to design and construct. The launcher must be tested and evaluated. Improvements on the launcher must be made or if the design fails a whole new design must be made and a new launcher must be constructed. Everything must be recorded in an engineering note book so others can understand what is going on and how the design works.

Background

There are many different types of catapults including the trebuchet and ballista. Catapults were originally used as siege weapons. They were designed to destroy fortress walls and to eliminate many enemies with one strike. Catapults have even been used as biological weapons; catapults would be loaded with dead bodies and fired into the enemy’s strong hold causing illnesses among the people. Catapults were most notably used by the Greeks and Romans. The Greeks and Romans designed many different catapults and projectiles. The most widely used catapult is the trebuchet. It has been used all over Europe and Asia. The trebuchet is also the most accurate and has the largest range out of all of the catapults. It is the most accurate because it uses a counterweight the projectile leaves the catapult with the same amount of force every time. Using our background from this course as well as the other courses we have taken at Wentworth we will design and construct a catapult like the ones once used as siege weapons to fire ping pong balls.

Methodology

The first step in the design process is needs assessment were the need for a solution, and who benefits from the solution is established. For our project the need is to launch ping pong ball into a bucket two meters away in the most efficient manner possible. We are the people that benefit from the solution because our grade depends on how many ping pong balls make it into the bucket. The second step of the design process is problem formulation. For this particular project the problem statement was given to us. It states that we must fire five ping pong balls into a bucket that is two meter away and over a wall at least one meter away in one minute or under. Abstraction and synthesis is the next step in the design process. During this stage abstract ideas of how to solve the problem are synthesized. For this step we came up with six possible designs to use. The designs included a trebuchet, a sprig loaded launcher, sling shot, air cannon, pendulum, and a traditional catapult. The fourth step in the design process is analysis. During this stage we compared our two main choices witch where the spring loaded launcher and the traditional catapult. The last step of the design process is implementation. During this stage the product is fabricated and tested. We constructed our spring loaded launcher and tested it. The launcher could not propel the ball far enough into the bucket. We decided to go with our second design which was the traditional catapult.

Alternative solutions

There were five alternative solutions that we considered using if the first design didn’t work well. The first alternative solution was the traditional catapult design. This design uses and arm that springs forward releasing the ping pong ball. The second alternative design was a pendulum. This design would use a hammer that would swing on an axis launching the ball into the bucket. The third alternative design was a trebuchet. A trebuchet works with a counterweight that drops and launches the ball. The fourth alternative design was a cannon that uses compressed air. The ball would roll down a pipe then a measured amount of air would be released launching the ball out of the tube. The last alternative design was a slingshot. This design uses an elastic band that would be pulled back and released launching the ball over the wall and into the bucket.

Final Design Solution

Our final design solution was not our original solution. Our original solution didn’t work as well as we thought it would. It couldn’t launch the ping pong balls far enough to get into the bucket. We turned to our first alternative solution. We redrew our original drawings of this solution and modified it to include some of the materials we already obtained from constructing our original design. This cut down on cost, with this new design we only had to spend five dollars more. This alternative solution became our final solution because it did well in testing. On average the ball landed in the bucket about eight out of ten times.

Conclusions

We obtained the best results with our second design. The first design didn’t work well because the ping pong balls are not perfect spheres and the PVC pipe that the spring was enclosed in was no perfectly round. As a result the ping pong ball had a slow velocity when leaving the tube if it left the tube at all. We tried to overcome this problem by redesigning the tube. A hole was cut out down the side of the tube to widen it and allow air to flow around the ball. The results improved but were still not good enough. We decided as a group to change the design to our second choice which was the traditional catapult design. We obtained much better result with the second design. We used our second design as our final design and used it for our final test. Our second design was much easier to calibrate so the shots were more accurate and was over all a better design than the spring loaded launcher.

Recommendations

For the next class that does this project we would recommend to start early. This project takes a lot more time than expected and there are many parts that have to be completed. Most time should be put in it the design so that it when the ping pong ball launcher is built it will work as expected. We would also recommend taking trips to the hardware store while considering designs so materials can be considered because some materials that may be need might not be obtainable. The only thing the design is restricted by is the availability of materials. Having an alternate design is a must in case the first design doesn’t work. There is not much time to complete this project so work must be started right away. The most important thing is keeping a well organized engineering notebook so that anyone can pick it up and know what is going on with the project.

Materials Used

First design

· Two feet of one and a half in diameter PVC pipe

· One end cap for a one and a half diameter PVC pipe

· One six inch bolt

· One five inch compression spring

· Two one and a half inch diameter steel washers

· Three one quarter of an inch diameter steel washers

· One four inch hinge with six screws

· One 1 and a half to two inch pipe clamp

Second design

· Plywood base three feet by two feet

· Three eye screws

· One wall hook

· One three by five inch piece of quarter inch wood

· Two three by 12 inch pieces of quarter inch wood

· One quarter of inch diameter five inch long round bar

· One twelve by one and a half inch pieces of wood

· Five feet of duck tape

· One shoelace

· One four inch hinge with six screws

· One and a half feet of latex tubing

· Six one inch wood screws

· Six one inch nails

· One six inch bungee cord

· One end cap for a one and a half diameter PVC pipe

Construction procedure

First design

· Assemble spring loaded mechanism using the two one and a half inch diameter steel washers , end cap for a one and a half diameter PVC pipe , the six inch bolt ,the five inch compression spring , and three one quarter of an inch diameter steel washers.

· Cut the two foot PVC pipe to one foot using the ban saw.

· Cut a grove out of the one foot PVC pipe using the milling machine with a quarter inch four flute end mill.

· Attach the four inch hinge with the pipe clamp.

Second design

· Cut the plywood base down to the correct size.

· Layout the position of all the elements of the catapult out on the base with accurate measurements that have been determined earlier.

· Cut the piece of wood for the arm down to ten inches long.

· Attach the arm to the four inch hinge using duck tape.

· Nail the Two three by 12 inch pieces of quarter inch wood two the bottom of the plywood base to be used as legs .

· Screw the hinge and the arm assembly to the base.

· Nail the One three by five inch piece of quarter inch wood to the plywood base.

· Tape the round bar to the top of the One three by five inch piece of quarter inch wood.

· Nail in the wall hook centered one inch from the front of the base.

· Attach one eye screw to the arm five inches from the bottom.

· Cut the PVC pipe cap down so it holds the ball better.

· Attach the PVC pipe cap to the top of the arm with duck tape.

· Attach the other two eye screws on the sides of the arm five inches from the side.

· Loop the shoelace through one eye screw.

· Adjust the length of the shoelace so it will stop the arm at the needed angle.

· Tie the latex tubing to the arm

· Tie the other end of the latex tubing to the arm.

Record of Testing

Test Number: 1

Trial Number / Results
1 / Miss
2 / Hit
3 / Hit
4 / Hit
5 / Hit
6 / Bounce out
7 / Hit
8 / Hit
9 / Miss
10 / Hit

Test Number: 2

Trial Number / Results
1 / Hit
2 / Hit
3 / Hit
4 / Hit
5 / Miss
6 / Hit
7 / Hit
8 / Hit
9 / Hit
10 / Bounce out

Test Number: 3

Trial Number / Results
1 / Hit
2 / Hit
3 / Hit
4 / Bounce out
5 / Hit
6 / Hit
7 / Hit
8 / Hit
9 / Miss
10 / Hit

Bibliography

"How to Create a Ping Pong Ball Canon." Wikihow.com. 2009. WikiHow. 22 Feb. 2009 <http://www.wikihow.com/Create-a-Ping-Pong-Ball-Cannon>.

"Ping Pong Ball Launcher Project." Video.google.com. 2009. Google. 20 Feb. 2009 <http://video.google.com/videoplay?docid=3934962892276786929>.

"Ping Pong Launcher." Youtube.com. 2009. YouTube. 18 Feb. 2009 <http://www.youtube.com/watch?v=q-AEG4y0h_8>.

SeeS. Sooner Elementary Engineering and Science Clubs. 12 Feb. 2009 <http://www.coe.ou.edu/sees/Unit%20Pages/Launchers.htm>.

"SG^2 Â± J - Ping Pong Ball Launcher V. 1.2." Youtube.com. 2009. YouTube. 15 Feb. 2009 <http://www.youtube.com/watch?v=TYQYrAwYmDQ>.

Voland, Gerard. Engineering By Design. Second ed. Upper Saddle River, NJ: Pearson Education, Inc., 2004.

Sample emails

That’s ok I just got back from testing it, the catapult did very well it got all five shots one trial, four out of five a another trial, and four and a half out of five in the last trial.

-----Original Message-----

From: McLaughlin, John

Sent: Tuesday, March 03, 2009 10:14 AM

To: Filip, Lucien

Subject: RE: stuff

I can’t today/tonight. But we have two days to test so it will be good.

-----Original Message-----

From: McLaughlin, John

Sent: Tuesday, March 03, 2009 10:14 AM

To: Filip, Lucien

Subject: RE: stuff

The drawings are good but I think he wants them dimensioned. I you can print out all of the emails or send them to me and I will. Do you have any free time today to test the catapult I am free after 2

-----Original Message-----

From: Lucien Alexander Filip [mailto:

Sent: Monday, March 02, 2009 10:41 PM

Subject: stuff

Here is the AutoCAD I did for our launcher. the top view is done with the arm all the way down to show the cup better.