Finalising the Ball Launching Device!

After reviewing my old Blog Post with several ideas for a Ping-Pong Ball Launcher, it seems like I was really not thinking the right things so far and therefore I got nowhere ! But it’s fine we are coming up with something now …

{{ Professor McGinn, Thank You for showing me your idea, I am so sorry that I have now stolen it - why I couldn’t come up with something so simple will always be a mystery to me, however we will move on and make the most of our idea…}}

The items I used were some empty cylindrical bottles / cans cut out on either sides - diameter of the bottle and Ping-Pong ball must be in perfect co-ordination, some very very stretchy balloons to hold the largest volume of air possible, and some zip-lock clips to work as valves.

As the clip is unfastened, air is displaced from the balloon, and it rushes into the cylinder. Upon the sufficient building up of pressure in the cylinder, the Ping-Pong ball is launched outwards.

One of my Lucky Times — so happy I had the camera rolling at the time!!!

However sometimes, it does not work ! This could be because the valve was poorly opened - a slower flow of air hugely decreased the exerted force (Low Flow Rate [Q = v.a] due to the low velocity (v) of air, and low Force [F = ma] due to the low acceleration (a) of air), and subsequently reduced the Pressure [P = F/a] - which is ultimately responsible for displacing the Ping-Pong Ball.

Did Not Work !

But fingers crossed hopefully I am able to improve my technique and make it work for my complete run-through!

As my older Pong-Ping Ball Launcher idea took a little rain-check, I also had to think of a new Ball-Reloading mechanism to still comply with the instructions. Therefore, I made 3 prototypes - so that each one could have a full energy source and Ping-Pong Ball loaded at the beginning, with no requirements for a refill of either through time. I sealed 3 balloons with zip-lock clips, attached them onto the ends of the cylindrical cans, and with some of my trusty double-sided sticky tape, stuck the cans, side by side, onto a mounting board.

Ball Launcher Setup! (Balloon 1 and 2 shoot out confetti alongside the Ping Pong Ball !!!)

CALCULATIONS

It is hard to precisely measure the volume of air in each balloon, and maintain a consistent rate of operating the valve - making it hard to compute exerted Forces and Flow Rates. However, I did revise some old Leaving Cert Applied Maths notes to understand the approximate force required to clear the vertical height of a Water Bottle (24 cm) and achieve a vertical distance of close to 50 - 55 cm.

Upon reviewing the results using a standard ‘air-escaping-balloon’ velocity, I could adjust the variable parameters, such as initial Ping-Pong Ball launch angle and starting Ping-Pong Ball height.

We are OK regarding this !

And here, either we are wrong in calculation because we must cover the distance computed x50 ! OR we must alter some parameters ASAP!

Reflecting on Mistakes

Now, I am relived to have a mechanism that works (fingers crossed) - at least more than my original ideas… ! Nevertheless, I do believe that it is only right to look back on some of my mistakes, try see what went wrong and maybe have a laugh at my outrageous- very wrongful-optimism :

Failed Idea !

1. My understanding of Boyle’s Law (P ∝ 1/V), and my impression that minimising the air-pipe diameter would maximise exerted air pressure was so wrong ! I was mistaken for weeeeks and like magic, I made considerable progress just by incorporating a tube of a larger diameter into the design, which is adequately allowing the large gust of air from the balloon to travel in it’s entity, displacing the Ping-Pong Ball.
2. I also thought that my former idea would be a success because it was tested using a very strong source of compressed air from an engineering workshop - however, my home-made energy sources did not prove to be of such power, leading to a very anti-climatic result.. (no Ping-Pong Ball launched!).

All in all, I am happy to have conjured up a Ping-Pong Ball Launcher in time before the Obstacle Course showcase (nothing like a fast approaching deadline to get us going right ..) ! By using the power of the compressed air within a balloon, a pneumatic force is produced - which propels the Ping-Pong Balls from the launcher into the Robot’s collection tub. And we are complying with the rules !!

Thank You for reading up on my idea ! Although it’s not the next-big-thing, it does have balloons with confetti in them so it’s quite nice nonetheless シ