Ping pong ball launcher
Finally, I have arrived at my final design for my ping pong ball launcher(s). The design which can be seen below takes inspiration from a slingshot like mechanism, using the potential energy of an elastic band to shoot the ball out when the trigger is pressed (clothes peg). As it is not allowed in the rules of the assignment to manually reload the kinetic energy before firing each ping pong pong ball, I created 3 identical launchers.
Design
The design is very simple, with every material used found lying around the house. The full list of materials used are:
· Clothes peg x3
· Clothes hanger x2
· 1 large cardboard cylinder
· Elastic bands x3
· 60cm x 2.5cm x 2.50 cm piece of wood
· Glue
· Scissors
· Saw
My initial design was to have one, rather than 3 launchers, with a reloading device (another cardboard cylinder) attached to the top of the cardboard cylinder, with the launcher reloading after one ball is launched. However, for this design, I would need to manually pull back the elastic band each time before shooting the ball, unfortunately this was not allowed in the design rules, so I had to slightly alter my design. Instead, I made 3 identical launchers, and turned them into one much bigger and better launcher, this also meant I would not have to install the reloading device on the launcher as planned.
Making the launcher process
My first step was to cut out the cannon shape from the long piece of cardboard cylinder. Once the shape was created, I then cut out a rectangular shape along both sides of the cylinder to act as a path for the elastic bands to follow when released. I then began to saw the long piece of wood to a length of 12.5cm, this was to act as a handle for the launcher, and once it was cut, I proceeded to glue the piece of cardboard cylinder to the wood.
My next step was to cut up the clothes hangar I had into 2 small pieces to act as a pinpoint on either side of the launcher to hold the elastic band. Cutting up the hangar was a lot harder than I Imagined, but thankfully after some brute force and a lot of elbow grease I was able to pull through.
Once I had all the remaining pieces in order, all I had left was to glue a clothes peg to the top of the wood to act as a trigger, glue the cut up clothes hangar pieces to the cylinder, and finally glue a point on the elastic band to the clothes hangar so the elastic band remained in a fixed position, to give my completed ping pong ball launcher #1.
Like I mentioned, at the time I thought this was going to be my only launcher, but soon I realised that I could not manually reload the elastic band to shoot more balls, so I proceeded to repeat this process two more times to give me three identical launchers.
Testing
As each launcher, was different, it was necessary to test each launcher individually.
Launcher #1
The first launcher shoots the ping pong balls slightly left. This obviously meant the position of the launcher when shooting the balls should be aimed slightly right.
Launcher 1 testing can be seen through the link below.
https://www.youtube.com/watch?v=2qxUduNGCoA
Launcher #2 & Launcher #3
The second and third launchers performed nearly identical. Initially, when they were fired, the elastic bands were sliding under the ball, rather than firing it out.
There was a really simple remedy to this problem. I glued a piece of cardboard just inside the cylinder, and just in front of the cardboard. This meant the elastic band would have to go over this little bump which would prevent it from sliding under the ball.
The trajectory of the launchers were similar to launcher #1, and their flight paths were more straight so were positioned accordingly.
Testing of the final design of launcher 2 and 3 can be found through the link below.
