In the 19th Century, the fictional proto-Tom-Swift Frank Reade, Jr. (created by Lu Senarens) flew around the world in giant heavier-than-air airships held aloft by “rotors” (helicopter blades), which could remain airborne for months at a time without refueling. See http://www.iwt.tv/. We saw the same idea used in Sky Captain and the World of Tomorrow, which featured an RAF airborne aircraft carrier held up by copter blades. It seems silly now – a helicopter, even one no larger than a Piper Cub, is just not fuel-efficient! On the other hand, we now have nuclear-powered submarines that can do everything Jules Verne’s Nautilus could do and more. Is there some reason helicopter airships remain impossible, or impractical?
First, I don’t see what the link has to do with the question in, er, question.
As for said question, AFAIK the only reason would be that we already have other means of conveying aircraft, setting up bases, etc. that do the job just fine.
IMO, “Giant Helicopter Airship” would be an excellent name for a band.
What would they do? Submarines have a specific (somewhat outdated Cold War) role. I can’t see any possible purpose for an aircraft that doesn’t land for months, and won’t move very quickly.
Wouldn’t large nuclear powered aircraft flying over cities be a massive safety hazard?
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- Well I may not be following you here but–quite frankly, if you can build a giant lighter-than-air aircraft “held up” by helicopter blades, then what do you need the helicopter blades for? Unless you meant an “airship” to just be “a giant thing flying around”…
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If you want to know why gigantic 500-seat helicopters have never been built, that’s easy: it’s because the gearboxes are not possible to build. The engines spin at a high speed, and they need gearboxes to slow their rotational speeds down to spin the rotors (which turn at a relatively low speed). As you engineer the helicopter larger and larger, the size and weight of this gearbox grows at a faster rate than the overall weight of the rest of the helicopter itself. The Russians built the largest helicopter put into regular use, but they were not used for heavy loads, due to the high wear on the gearboxes. And even this was generally understood to be a matter of nationalistic pride, not a matter of a vehicle that anyone thought would really be practical to produce and maintain. Most of the largest helicopter engines/helilcopters built were done by the USSR, starting in 1953, under the direction of Pavel Solovyev. What research was done in various Soviet-bloc countries has culminated in the Mi-26, the largest helicopter in regular production : http://www.aeronautics.ru/archive/vvs/mi26-01.htm
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Other far larger helicopter designs have been proposed, but these recognized the gearbox problem and sought ways around it in various novel ways such as by directing jet-thrust through the trailing edges of the rotor blades, or by mounting the engines upon the rotor blades themselves. The largest proposed was by Westland in 1950, for a helicopter with a 196-foot diameter rotor lifting a cargo of 206,000 lbs, or about 450 passengers. No government at the time thought it a workable concept, and none were ever constructed or even fully engineered. Westland is still a UK defense contractor, but they don’t build monster helicopters.
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Well, actually **BrainGlutton **said, “heavier-than-air.” Slight nit-pick.
Also, if a nuclear sub goes critical, it’s generally out in the ocean and the mess sinks to bottom of the ocean where we can’t see it. A nuclear airship however poses a much greater threat of nuclear devastation.
Anyways, we don’t need nuclear power. We’re already working on sustainable flight with solar power: Helios. Correct me if I’m wrong, but I think that the farther up you get in the atomosphere the more energy you can get from solar panels.
I don’t know how much of an effect that has - but definitely significant is that solar power doesn’t suffer from the lower athmospheric pressure, unlike jet engines.
Actually, jet engines become signifcantly more efficient with altitude. This is mostly due to decreasing temperature, and the effect levels off at around 35000’, since the temperature stays more or less constant above that. Flying at this sort of altitude has the additional benefit that you are above most weather problems.
At 35000’, you are above approximately 70% of the atmosphere, and probably 99% of particles, moisture and other things that would attenuate sunlight. So there’s not much power to be gained by a solar-powered aircraft flying higher than this.
Of course the Helios aimed to fly much higher - close to 100,000’. But the reason had mostly to do with the desire to store energy in the form of height, so it could remain flying through the night.
One is as a sort of “very low orbit” communications “satellite”. Compared to true satellites, it would be a lot closer to earth and thus need less transmit power. It could easily be a lot cheaper.
Another would be for high-detail terrain mapping and surveillance. Again, it would be competing with satellites that are quite expensive, at least a hundred miles from the points of interest, and which stay within view of their photo targets for only a brief time.
Good point, but why would they need to be manned or anywhere near the size of the airships in SC&WT?
For communications on that scale, how would they be an improvement over surface cables?
I just included it to show where I got the concept the concept. Obviously neither Senarens nor his illustrators were engineers. They just took what everybody understood a “ship” to look like (including a general shape designed for cutting through the water) and attached rotors to the top of it. The result is silly – but don’t these ships look way cool? 
Well, Senarens was writing explorer-adventure stories and his airships were modeled on water-going ships – which didn’t need to land for months, and didn’t move very quickly. Only the Frank Reade airships were not limited to the coasts but go directly into the interior of a savage territory to terrorize/civilize the backward natives. (The Frank Reade stories were horribly racist and imperialist – so I’ve heard; I’ve never been able to find one in a library.) Also, if you’ve got one of those ships you’re independent, like Captain Nemo – just sail around the world and do your own thing, beholden to no one.
As for what use they’d be in a modern setting – well, there does seem to be some renewed interest in lighter-than-air airships (see this GD thread: http://boards.straightdope.com/sdmb/showthread.php?t=277967; and http://en.wikipedia.org/wiki/Zeppelin#Recent_developments), which don’t need to land for long periods, and don’t move very quickly. But that’s not quite the same (see below).
I meant the latter. Obviously LTA ships are more practical, i.e., we already know how to build them. But a LTA ship is mostly gasbag. A Frank Reade airship has a lot more space inside for crew, passengers and cargo than you would find in the gondola of the Hindenberg (which had only 97 people on board on its last voyage). In theory, I suppose, you could make a gasbag large enough to lift a gondola the side of an ocean liner – or could you? If it were possible, it would be awfully unwieldy. And think of the size of the hangar!
There are no helicopter air juggernauts at the site linked, unless they are hiding deeper in the Independent World Television advisory statements.
:o You’re right, I don’t know how that happened. Here’s the link: [urlhttp://www.bigredhair.com/airships/
You might have given credit to Jules Verne for the design of the Albatross in Master of the World.
But anyway, the answer is still that anything such a machine could do, others could do much more efficiently.
Nitpick of my own: a nuclear reactor that is “critical” is a reactor that has a self-sustaining nuclear reaction, in which the rate of fission is neither increasing or decreasing. It does not mean an out-of-control reaction or a meltdown.
They could probably be unmanned and of moderate size.
In much the same way that satellites are: they would be in direct “line of sight” view of millions of homes/businesses/cars/PDAs/mobile phones. You want wide-area high-speed wireless internet access? This might be the way to provide it.
Nope, still don’t see any advantages. Only in a few locations would it provide ‘millions’ with such access - and these would be densely-population areas which already are likely to have multiple methods of high-speed internet access.