The aerial surveyor diaries
The team
Jonathan Hare's diary about the challenge for the Aerial Surveyor programme, from the BBC/OU series Rough Science 4
Day One
Kathy and I are to make a hot air balloon but it can’t be powered by a heater / burner - it has to be solar heated!
Apparently there are astronomers / physicists that are planning to send payloads to Mars and to get these machines to travel around the surface of the planet using a similar hot air balloon. It works like this: If the equipment lands at night, the air is cold. A dark coloured balloon will be made to inflate from the equipment using compressed gas. The whole thing waits till sunrise. As the Sun rises the gas in the balloon will heat up faster than the air around it. This will make it expand and so will become relatively less dense. This will make it rise.
Ideally this works best in the Polar Regions where there is the greatest difference in temperatures possible. We are to make a similar device. The production team have given us a wireless camera to put on the balloon as a payload.
Kathy and I talk about the science of this and then start to make up a couple of prototypes. We intend to use bin liner bags to make the balloon from. The first was a geodesic design – a spherical (12 pentagons called a dodecahedron) structure while a second quite different design was a sausage shape. As we have no previous experience we need to try out two very different designs. Both the balloons looked great and easily filled up with air by wafting using a board. The sausage was about five metres long while the round balloon was about two metres in diameter.
However apart from the beginning of the day there is always a breeze at the mine and our balloon bellowed and wriggled about far too much. Even when the breeze did die down and we could make sure the balloons were in the Sun nothing happened!
Finally we found out that the bags we had been using were too thick and too heavy. The production team got us some lighter bags and we started again.
next > Page 1 of 3
Content last updated: 19/07/2006
