Hanging below your blimp is a very long, lightweight black tube, made of a heat conductive substance, perhaps a metal foil, and held open by a light spring coil wound inside it. I imagine this would need to be a couple of hundred meters in length at a wild guesstimate, with a weight at the lower end to keep it vertical.

Sun-heated air rises inside the tube and rushes up to the blimp. Once there, it can be sent into the envelope to top up the hot air for lift, or it can be directed through a small turbine which in turn powers the propellor.

Possibly a clever kind of nozzle could allow the rising air to be used as a jet, and pointed out the back to provide thrust.

Your blimp would need to be inflated with hot air for takeoff in the traditional manner, but would not need to carry heavy gas tanks and burners aloft.

This would be a strictly recreational vehicle for sunny days.
-- BunsenHoneydew, May 23 2004

Solar balloon http://perso.wanado...olaire/en-index.htm
[kbecker, Oct 04 2004, last modified Oct 21 2004]

Fair points. Perhaps the profile of the tube could be streamlined relative to the direction of movement, and a simple flap valve installed to prevent backdrafts.
-- BunsenHoneydew, May 23 2004


I think this is somewhat baked (link). Adding a special tube for increasing solar absorption could increase efficiency.
-- kbecker, May 23 2004


Solar energy is about a kilowatt a square meter - considering something the size of a solar baloon, that's a awesome ammount of heat, comparable to a propane heated hot air baloon for sure. These things only get better as you build them bigger, as a larger volume of air keeps it's heat better. If you could have a transparent insulating layer on the outside of a solar baloon it'd have some awesome lifting power - might even work when overcast.
-- venomx, Jun 07 2004



random, halfbakery