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You might have better luck finding things if you could spell them ;) See link for ballons solaires. |
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But that's a French solar balloon. The present implementation is neutral w/r/t French-ness. |
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Ahem. That's a Freedom Balloon to you. |
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Whats so free about potatoes? They grow trapped underground? :) (freedom fries) By the time they're fried, I guess they have been freed... Hmm this is starting to sound like an analogy of current events... |
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It's a great idea on the surface, but you'll need to address the following problems: |
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(1) The balloon has a large surface area and you need to trap enough heat to balance the heat loss to the surroundings. |
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(2) You need to be able to add enough heat to rapidly trim or climb the balloon. Solar energy will have to be, as you say, a top-up measure only. |
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The bigger question to address if you want to enhance the sport is how to make a lighter source of heating than the current burner systems. |
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BTW, [DrCurry]'s link is fabulous! |
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Why mess with troublesome solar energy when a plentiful supply of hot air is available right here? |
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It is a great link from Dr Cury. I wonder if this solar balloon would be able to lift more if you sprayed a mist of water in it. This should evaporate and being more boyant than air (molecular mass 18 compared to about 30 for air) provide increased lift. The experimental balloon looks good too. It has a transparent 'greenhouse' top surface. i imagine this is to increase the warming effect of the suns rays. I wonder what %age of water vapor you could have in the envelope and whether as you gained height this would increase due to the drop in pressure or whether it would decrease because of the drop in temperature (due to the surrounding air being colder) |
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[tobyp] Vapor pressure of water at 20C is 18Torr. Atmospheric pressure is 760Torr. If you try to fill the balloon with just water vapor the water will condense and the balloon will collaps. But you yould use methane (CH4, mass 16). You wouldn't even need a gas bottle, just a few cans of beans for the pilot. |
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[kbecker] so does that give us 18/760*100 (2.37% water) at 20 deg C at sea level? |
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at 30C = 31.8 Torr =4.2% water |
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at 40C = 55.3 Torr = 7.3% water |
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at 60C = 149.4 Torr = 20% water |
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at 80C = 355.1 Torr = 46.7% water |
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at sealevel. At altitude these figures will rise as the pressure will fall. unfortunately so will the surrounding air temperature and I guess the internal temperature of the balloon too. |
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Large inflateable mirrors could be used to collect extra energy. |
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