The Launcher
At the end of my last blog I started to describe what the next small project I’m working on is. You can check that out for a little intro if you haven’t seen it but basically I am going to be designing a ping pong ball launcher to fire the balls into a container on top of the Tumbller (if it arrives in time). The project brief states that the launcher should be an energy storage device that converts potential energy into kinetic energy when releasing the balls. Obviously the forces and energy stored by the device should be low, and not present any risk of harm.
There is also an element of competition as the the Tumbller will be allowed to stand still for 20 seconds during which as many balls as possible must be fired into the container (ten points per ball), with extra points going for those with smaller target containers. Naturally I am in it to win it so I’ll be putting some thought into the design of my launcher. I have come up with three initial design concepts which I will go through now.
- Compression Spring Launcher
This first design is very simple and uses a compression spring with a platform fastened to the top of it as well as a handle attached to the same platform. This can be seen in the section view shown above. It works by pulling on the handle at the bottom of the launcher which generates potential energy as the spring is compressed. This built up potential energy is converted into kinetic energy once the handle is released, allowing the spring to extend and fire off the ping pong ball.
2. Tension Spring Launcher
As the name suggests this launcher uses tension rather than compression springs. I chose to fasten these springs externally to the launcher housing for easy of construction if I choose to proceed with this design. The actuation for this launcher is the same as for the previous design although in practice I expect them to perform quite differently. This is because compression springs tend to be a lot more inflexible and would require more force to generate the required potential energy.
3. Pneumatic Launcher
Here the ping pong ball is fired through the use of pressurised air (pneumatics). This air pressure is generated through pulling the plunger out from the launcher housing and then swiftly pushing it back in. There is a stopper in place (visible in the section view) so that a more consistent volume of air can be used to launch the ball. As mentioned before these designs are just concepts for the moment and will be modified and compared in more detail in future blog posts.
There were two other elements I thought would be important to design along with the launcher itself in order to optimise the device. These were a ping pong ball reloading container and a launch angle adjustment device.
These elements could be designed for any of the three design concepts mentioned and are also by no means final designs. The reloading container would work by holding up the ping pong balls until the spring is compressed a certain amount (freeing up enough room for the ball to fall through). The ball would then sit right in front of the spring platform and hold up the remaining balls in the container itself. Once fired the process would repeat. A likely problem I see already is that the force of the spring would cause the other balls to fly out the other end of the reloading container. I’ll have to do a bit more thinking about that. The angle adjustment device is very straightforward with grooves for the horizontal bars to slot into, changing the face direction of the launcher. Obviously the bottom of the launcher would need to be fastened but allowed to rotate up and down in order to achieve a fixed direction.
My hope for these elements is to allow me to be more consistent in where the ping pong balls land and also to be able to fire off more balls within those precious 20 seconds. Those are my initial thoughts and plans for the moment but I have no doubt that they will change a lot once I look into them more and eventually have to physically build the launcher. This may limit me quite a lot depending on what I can get my hands on around the house and within my 5km.
That’s all for now. Thanks so much for taking the time to read through my project blog, I hope you have found it somewhat interesting. If so you might also like to follow my Instagram page where you can find more regular updates and extra details to all that is going on here. You can find a link to it in my bio.
More soon.
