|Balloon is born|
So here we are, stuck with 340 birthday cake candles, some used cans of cat food and a coat hanger. A seemingly random collection of devices to a casual bystander, but not to a member of the chemical engineering core of the yellow team! Our task was clear – to produce the ultimate combustion engine for the balloon from these various apparatus.
After the initial briefing on the subject, we made our way down to the workshop. Straight away, J got busy doing the mathematical equations, the other members of the team decided to play about with candles and matches. After initial “experimentation” it was discovered that larger amounts of candles give much more heat and burn faster then lesser amounts of candles. The main concern of our team was that too many candles increase the weight, which despite increased power, would not give overall increased lift.
However, it was later discovered by J and R, via a means of a brainstorm session on a “compulsory” juice break, that the candles would actually burn off most of the wax before the balloon actually lifted off. Therefore, if we would add more candles, the net weight change would not be effected, but the power increased dramatically. As the saying goes: “the bigger the better”. We decided to fit as many candles as we could in the tin can. This ended up being a rather high number – roughly about 120 candles. This gave us a significant advantage over other groups, who had roughly 80 candles in the burner unit.
|The next design challenge was to design the air
hole system so that the large amounts of candles would combust continuously.
This was handled brilliantly by L, who designed a system of ventilation,
which not only provided enough air, but also directed the flame upwards due
the draft in from the regular structure. Of course some other teams copied
us, realising the brilliance of our burner design. However they FAILED.
Next, via a joint effort of the chemical strand, the system of supports was created, J using her trigonometry skills to figure out lengths with L and R doing the hooks and cutting the things out of the coat hanger. That was fun.
As part of the construction of the balloon, one of the prototype burner vessels (used can of cat food) was damaged and could no longer serve its primary function. However there would be more glories for this piece of tin! Originally created to satisfy your cat’s hungry stomach and later destined to become the engine of the balloon… its future was clear. It was going to be the new team mascot – the SMILEY CAN!
And now over to the Mech Eng!
At first we had to strain our brains with numerous calculations that were vital to the success of the balloon both, being built correctly, and helping the Electronics strand and the Chemical Engineering strand, with their calculations so that it would be successful in flight and its goal to take airborne photos.
These calculations were controlled by the weights involved with the design of the candle burner by the Chemical Engineers, so that we calculated lift and volume correctly for flight times to be confirmed.
Once the exhausting calculations were out of the way, we were able to get on with the structural engineering to make the holding structure for the mini camera. First we had to consider the main design points which went smoothly, with consideration of security, stability, a lightweight frame and good camera positioning.
|However, when it came to actually constructing
our cradle from lightweight but strong fuse wire, we were caused great deals
of worry and bickering between strands as the Electronics strand delayed us
by not having final dimensions of the camera PCB system so that we could
accurately make the cradle prototype for it.
Luckily they pulled through in the last hour with final dimensions of a well designed system and we proceeded to make the cradle with a mock up of the camera system and attach it to the burner so that it was ready for the camera to be added.
As we pulled into the final half an hour of construction, we began installing the camera system which fitted nicely in our cradle, but there were still a few things to finalise, such as the cradle and parts of the circuitry coming in to contact with each other so we had to cover connections with blue tack (very technical technique) and covered the whole circuit with a protective layer of cardboard.