Imagine a steam powered hot air balloon so massive that storm clouds form inside the envelope, and lightning rods are required to keep lightning strikes from destroying it. Inside a hot air balloon of this size, smaller hot air balloons can navigate when the weather is calm, and rain isn't precipitating to refill the water tanks.-- rcarty, Jan 06 2013 Moisture build up in VAB on humid days http://en.wikipedia...e_Assembly_BuildingNo lightning though [Brian the Painter, Jan 06 2013] Plausible
The interior volume of the [VAB] building is so vast that it has its own weather, including "rain clouds forming below the ceiling on very humid days", which the moisture reduction systems are designed to minimize
see link-- Brian the Painter, Jan 06 2013 Silver coat the Mylar Balloons inside?-- Brian the Painter, Jan 06 2013 The balloonists inside this huge hot air balloon are not going to like it. They are breathing hot air, after all! And the hot air inside their own balloons needs to be quite a bit hotter....-- Vernon, Jan 06 2013 Bazinga! score 1 for [Vernon]
Interesting how that fact slipped right past us.
So if the internal temp of the enveloping balloon is 120 °C (250 °F) [max] then do the smaller internal balloons need to be an additional 120 °C (250 °F) to float inside? Or would an extra 10 degrees be enough?-- Brian the Painter, Jan 06 2013 I think that's great because the smaller hotter balloons can work at keeping the large volume of the balloon at working temperature. I don't know about the balloonists though, maybe they will be in special self-contained suits, or be remotely controlled balloons.-- rcarty, Jan 06 2013 The "balloonists" will need environment suits … pure water vapour at 100 C has no free oxygen, and would severely damage mucous membranes.
The heat loss through the envelope, particulaarly when it rains, will be considerable. The bigger the envelope, the better.
Condensate will form continuously over the entire inner surface, and will add to the weight of the envelope.
What is the heat source for the inner balloons, since there is no free oxygen to support combustion? Are they to carry hydrogen and oxygen in pressure vessels?-- 8th of 7, Jan 06 2013 Prior art:
"Buckminster Fuller proposes the "Cloud Nine" project, a levitating city of tensegrity spheres, each a mile in diameter. Because the surface-to-volume ratio of such spheres would be vanishingly small, Fuller calculated that if trapped solar energy raised their internal temperature by a mere one degree, they would be able to float like balloons."
So a double hull encapsulating a vacuum would minimize heat loss and the temperatures in the lowest portions of the sphere should be livable. Condensation could be stored as ballast or ejected.-- 2 fries shy of a happy meal, Jan 06 2013 I surmise that a helium balloon inside of another helium balloon would sink within the outer balloon and never rise to the top under any circumstance. But as always, how the laws of physics are applied is always Flying Toasters job to decide.-- Brian the Painter, Jan 07 2013 There's no mention of a helium balloon.-- rcarty, Jan 07 2013 What are you the helium police? I know that. I'm just curious, would a helium balloon float within another helium balloon? Its a thought experiment and I'm bored.-- Brian the Painter, Jan 07 2013 The inner balloon would not float inside the outer balloon.-- rcarty, Jan 07 2013 hmmm, if the outer balloon were inflated to a greater pressure than the inner one it should... shouldn't it?
Now back to the idea...I almost posted this same idea once, that's when I found the Cloud 9 reference, and I would So like to see it built in my life-time.-- 2 fries shy of a happy meal, Jan 07 2013 No the important factor is the lightness of the gas. Helium floats in air because it is lighter than air. It would be interesting to inflate an outer balloon with air, and a smaller inner balloon with helium as a way of saving helium.-- rcarty, Jan 07 2013 But, if the outer balloon were inflated to a greater pressure then the gas would be more dense in the outer balloon than the inner balloon and, the inner one should rise within the outer one shouldn't it?What am I not understanding?-- 2 fries shy of a happy meal, Jan 07 2013 On second thought you might be right. However on third thought the pressure of the inner balloon would be the same as the outer balloon if it is inside of the outer balloon. How could the inner balloon possibly maintain less pressure than a surrounding balloon with greater pressure? The inner balloon would compress equalizing to the same pressure.-- rcarty, Jan 07 2013 rcarty's right 2fries, the pressure of the outer compresses the inner, thus negating the pressure differential required for buoyancy.
We digress however. What about the lightning. We can use hydrogen balloons to float inside a hot air balloon and watch the lightning storms! yeah us!-- Brian the Painter, Jan 07 2013 Ah. I get it. Thanks.-- 2 fries shy of a happy meal, Jan 07 2013 random, halfbakery