h a l f b a k e r y
Fewer ducks than estimates indicate.
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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
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
Possibly a clever kind of nozzle could
allow the rising air to be used as a
jet, and pointed out the back to
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
This would be a strictly recreational
vehicle for sunny days.
[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.
||I think this is somewhat baked (link). Adding a special tube for increasing solar absorption could increase efficiency.
||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.