 Let me show you a very, very short video. Have you heard of this gentleman called Arvind Gupta? He makes fantastic toys from trash. So he uploaded a video very recently of a hot air balloon. So this is the hot air balloon. So basically it is a thin wire ring with a wax in the center for burning. There is a light weight ring and then there is this simple paper which is used for the kites. There you go. They claim it can go up to 100 meters. So the height given to you in the convo in this fire is much, much lower than 100 meters and they have not done any course on LTA systems and all that. Still they are able to make it. So I expect a much higher. In this case there is no payload, they are just lifting themselves. The challenge to you is in designing a system which can lift more payload. So the winning team will be the one which can carry the highest payload fraction. If you make a bigger balloon, you will have more buoyancy but then you will have more self-weight. So the challenge in this assignment is how do you decide the dimension so that you get the highest payload fraction. And if you make your calculations properly, you will come across one dimension beyond that the gain in the payload is less than, payload fraction is less than the weight. So you have to stop at that point.