Im currently drawing up plans for an air propelled chair (which ill probly never make :P). I was intending to pureply use air from the atmosphere, use some sort of compressor, to compress it, then send it flying out the back in order to displace the chair. However. I dont know if there are such machines available. I guess you get compressed air in cylinders for a reason, but i dont know what that reason is! If I cannot use air, what would you suggest ? Thanks!