Create a solar blimp that uses the power of the sun to heat the air and make it float.
This is not a new idea. However what if you also include a RC box to the bottom, and use it to control the blimp via small solar panels.
If you include a small air pump to the blimp, you can also easily replace loss of air.
This shall allow you to create an autonomous or RC blimp without needing to fill it with helium.-- mofosyne, Feb 12 2011 Solar balloons. dot com. http://www.solar-balloons.com/howto.html [afinehowdoyoudo, Feb 16 2011] I am surprised that no one has done this yet. May I suggest Vehicle: aircraft: airship: solar as a category?-- 2 fries shy of a happy meal, Feb 12 2011 //This shall allow you to create an autonomous or RC blimp without needing to fill it with helium.//
But it will have to come back down to the ground every night while designs which use a burner or hydrogen/helium can stay aloft for weeks or longer.
It will also have to be bigger for a given amount of lift and will thus encounter more drag. Which means it may require more energy to travel than H/He/burner designs even if it can ascend for zero energy.-- Bad Jim, Feb 12 2011 Ah, but could a solar balloon collect enough solar radiation during the day, while above cloud cover, to focus an uv light through an underside aperature overnight long enough to keep it aloft until morning? I'd think it would be down to a size/lift/weight ratio thing.-- 2 fries shy of a happy meal, Feb 13 2011 Perhaps it could be a double bagged sort of thing? One transparent outer skin, and a black inner balloon.
That way you reduce heat loss.-- mofosyne, Feb 13 2011 I like this, and am also surprised it's not been done. I am pretty sure that, with a decent-sized blimp, you would be able to harvest more than enough energy by day to keep it aloft by night. The whole thing would need to be fairly large (since efficiencies of blimps increase with size, and particularly so when they have to carry hardware).-- MaxwellBuchanan, Feb 13 2011 //with a decent-sized blimp, you would be able to harvest more than enough energy by day to keep it aloft by night//
By decent sized, I assume you mean an enormous ocean liner sized thing that costs hundreds of millions and therefore gives no real advantage to radio control over a blimp with a pilot.-- Bad Jim, Feb 13 2011 //no real advantage to radio control over a blimp with a pilot// It might be a real advantage for a robotic probe exploring a planet with 1) an atmosphere 2) not too much cloud cover 3) sufficient sunlight. Mars, maybe.
What (you ask) would be the advantage over an orbiter? Maybe the ability to parachute robotic land rovers more gently (and perhaps with greater precision) onto selected terrain features than an orbiter could do.-- mouseposture, Feb 13 2011 // assume you mean an enormous ocean liner sized thing //
Au contraire. I suspect that something the size of a bus would do the trick. It would have an insolation of about 50kW in daylight, of which perhaps half could be captured as heat, or 12kW recoverable averaged over a 24hr period.
Given a double-skin envelope, this is amount of energy should be way more than is needed to keep the balloon aloft with a payload of a few kilos. The payload needs to include the radio control and propulsion, and also a means of storing sufficient heat to see it through the night against losses. One option would be some phase- transitioning liquid/solid, but it might be more effective to use a smallish heatpump to store hotness more densely.
Another option *might* be to line the bottom-inside of the balloon with photovoltaics. These would generate enough electrical power to be storable for overnight heating (but, at considerable and perhaps unreasonable weight cost), but they are sufficiently inefficient that most of the insolation would still warm the balloon during the day.-- MaxwellBuchanan, Feb 13 2011 The best overnight energy store might simply be hot air, if you don't mind wild fluctuations in lift and therefore altitude. It could slowly descend during the latter part of the night, as long as the sun comes up before it touches down. Extra energy is stored during the day as altitude, and the duration it needs to maintain positive buoyancy is reduced.
Do you need the air pump? Doesn't a solar balloon self-inflate, like a conventional hot air balloon, if it has a small opening at its lowest point?
I thought at first that this was something you took out and flew during the day, then packed away. The requirement to stay aloft during the night adds a whole extra difficulty level!-- spidermother, Feb 14 2011 Ah, yes. Just what we need. A night sky full of Bladerunner-esque, advertising blimps. No thank'ee!-- DrBob, Feb 14 2011 Yes thank'ee! [+]-- BunsenHoneydew, Aug 09 2016 random, halfbakery