Indigo, just watched a natgeo video on helium flight on YouTube with dd and it was AWESOME! Thank you for your recommendation. I did take a video of dd explaining how her machine is going to work. The good news is dd really does not get disappointed with her failed attempts. She has been coming up with different ways to fly for almost a year now and the ideas just keep evolving. In fact after watching the video she declared that maybe helium was not going to work and she needs propellor fans instead. "Mom do you think we can find an old helicopter and rip its propellers for my flying machine?" Sure honey, anything for you smile