Well, communication satellites are very expensive ways of covering a wide area, and they seem to have caught on rather well. Suppose you had a “satellite” that couldn’t cover all of England, but could cover the entire London metro area, and at a tiny fraction of the cost of a real satellite. Might there not be some interest?
Helicopter pilot checking in.
Helicopters are very inefficient and complex. Take the very-popular Robinson R-22, for example. Using basically the same engine as a Cessna 172, its top speed is about 80% of the Cessna. It can carry half the number of people for about half the distance, and has very little space for carrying luggage. A Schweizer 300CB has no stowage at all, except for a small ‘glovebox’. However, helicopters are extremely good at what they do. If you want to rescue someone from the wilderness or haul an air conditioning unit to the top of a building, the ability to hover is rather handy. But if you want to travel a long distance, it just doesn’t make sense to use a helicopter. Fixed-wing aircraft are much better suited to that mission.
There’s another efficiency issue, too. The higher a fixed-wing aircraft flies, the more efficient it is. Air pressure at altitude is lower than at sea level, yet it takes the ‘same amount of air’ at altitude to generate the ‘same amount of lift’ as at sea level. So the aircraft has to fly faster. Given that the engines operate at a more-or-less constant fuel consumption rate, going higher means you’re going faster on about the same amount of fuel. (Note that I’m leaving out the fuel required to reach the altitude in the first place, and that different aircraft have different altitudes at which they’re most efficient.)
A helicopter’s ‘wings’ go round and round. This means that in forward flight (or any-direction flight, for that matter – that’s the great thing about helis, the ability to fly in any direction 
) one blade is going in the opposite direction of the direction of travel. This is called the ‘retreating blade’. In directional flight, the retreating blade has a lower airspeed than the advancing blade. This is compensated for by ‘flapping’ and by altering the pitch of the blades. I think you can see the problem coming up…
At some airspeed, the retreating blade will not be able to compensate for its lower airspeed and the airfoil ‘stalls’. You don’t want to get into retreating blade stall because Bad Things can happen. For example, mast bumping may cause the rotor system to depart the aircraft, or you might experience ‘tail boom chop’ where the rotor strikes the tail boom and causes it to depart the aircraft. The Robinson POH supplements (excellent reading, BTW) uses the word ‘doomed’ (Supplement: Retreating Blade Stall Can Be Fatal).
So the higher a helicopter flies – and the less dense the atmosphere is – the slower it must fly in order to provide enough lift to the retreating blade. This is opposite to what happens in a fixed-wing.
Then there’s the maintenance issue. While a fixed-wing aircraft have… erm, 'fixed wings – wings that are bolted onto the airframe, rotary-wing aircraft have wings that go round and round, flap up and down, speed up and slow down due to the Coriollus effect, and continually change pitch. Plus, there’s the tail rotor that’s doing the same thing, or another rotor system (in the case of ‘twin rotor’ helicopters) that is doing the same thing. Mechanically, there’s a lot going on. Many parts have to be replaced after a certain number of hours in service. For example, the rotor blades on an R-22 have to be replaced after 2,000 hours, and 4,000 hours on the Schwiezer. The bigger and more complex the machine is, the more expensive the maintenance is.
Helicopters have important roles in aviation; but fast and efficient long-distance travel isn’t one of those roles.
Correction: Low Rotor RPM Can Be Fatal.
There was interest in a nuclear aircraft at one time (“It’ll fly forever without refueling!”), but they had problems with shielding (Lead is heavy, but you need it for shielding against radiation. This makes it heavier, so you up the power requirements, which makes the reactor bigger, which means more shielding… and you can see where that goes), plus the worry about spreading radioactive waste all over the landscape if it crashed. I don’t think it ever got past a planning stage. see Henry Patterson’s book Nuclear Power.
For anything else, such a design would use up fuel at a prodiguious rate. Even modern, lightweight helicopters don’t stay up all that long. Something like this wouldn’t even get up before it started coming down.
By the way, no one’s mentioned Jules Verne’s stories Robur the Conqueror and Master of the World, which used the same idea. (Reade preceded Verne, however, and Verne acknowledged him). The adventures in RtC resemble those of the Nasutilus, so the parallel is c,loser than people in this thread seem to realize.
One of the more interesting aspects of Verne’s craft (I don’t know about Reade’s – I never read his) is that the heavier-than-air Albatross is constructed not of wood, not of light metal (Verne correctly preduicted an aluminum space capsule in From the Earth to the Moon, but of composites!Combining great strength and light weight, composites were the ideal material for aircaft, much as the Gossamer Condor, Gossamer Albatross, etc. used. Verne’s composites were basically paper fibers plus binder mixed and cured under high pressure. A reviewer in the 1960s called this “a kind of plastic”, whicvh isn’t really correct, and misses the point.
Not only that, but you’d only need a dozen high-altitude platforms to cover all of UK. It may be a viable solution for mobile communications and digital broadcast.
You may need a few hundred to cover the US, but even then the cost may be comparable to satellites. High-altitude platforms have the added advantage of easy repair, upgrade and replacement.
High-altitude platforms may also be useful for surveillance and geological observations.
For a couple of pictures of Robur’s ship as Verne described it, look here (scroll to the bottom) or here.
Well, where else is Nick Fury going to keep his cigars? We need to get working on fusion power for this very purpose, people!
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- Okay–correction: I don’t know for certain if the Mi-26 is the largest helicopter in production, but it is among the very-largest, and they all originated in the former USSR/bloc countries. My reference books mention several, but I have not been able to turn up any English info on them. That site says the Mi-26 has twin 10,000 HP engines, where one book mentions for example that the largest of that family of rotorcraft was rated for twin 11,400 HP engines.
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- Okay–correction: I don’t know for certain if the Mi-26 is the largest helicopter in production, but it is among the very-largest, and they all originated in the former USSR/bloc countries. My reference books mention several, but I have not been able to turn up any English info on them. That site says the Mi-26 has twin 10,000 HP engines, where one book mentions for example that the largest of that family of rotorcraft was rated for twin 11,400 HP engines.
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Here is a view of the version used in the 1961 movie with Vincent Price and Charles Bronson - a bit different from the original-publication views, but more photogenic.
These remind me a lot of the giant flying machines that show up in Hayao Miyazaki’s works – I’m thinking specifically of Laputa: Castle in the Sky, but my favourite more maneuverable machines are from Nausicaa of the Valley of Wind. Many elements of his works are borrowed from historical, mystical, or literary sources; for example the outfits the characters wear in Nausicaa resemble those of the Russian peasantry of the 1800’s, and Laputa takes its name from the flying realm Swift described in Gulliver’s Travels.
All mechanical difficulties aside, I think it goes back to a problem of practicality. What can you use a giant rotor-borne platform for that makes it worth the time and money to overcome the technical hurdles and build the darn thing?
Sure, the flying fortresses in Sky Captain were marvelous for such a pulp-tastic movie set in or around the 1940’s, but would be terrifically vulnerable to even 1970’s era aircraft, not to mention the more advanced varieties that even poorer countries have available to them (some which no doubt date from the 1970’s, but…) today. It’s one thing to close off a compartment on a naval vessel to avoid sinking – lose a rotor or two and the sky platform could be in real trouble!
Similarly, when something goes horribly wrong with a satellite, it might possibly sit up there in space for a while, break up on re-entry, and land somewhere out in the middle of the ocean. A rotor-driven transmitter station over London that suddenly experiences catastrophic mechanical failure, OTOH, can only land on top of something in London!
Space satellites have latency issues (it takes time fior the signal to go up and down), so aren’t ideal for internet traffic. A stationary flying widget would cut down on the travel time considerably. But I think a fixed wing craft going in circles is probably the best solution for this.
Brian
Is that euphemistic flight-engineer speak for “bust off”?
No, it´s the euphemistic flight-engineer speak for “kiss your arse goodbye”
As for the nucler powered plane/air platform, a B-36 bomber was actually fitted to and actually carried an experimental reactor, a honest to goodness nuclear bomber. The plans to make that into a truly nuclear powered plane involved running liquid sodium out of the reactor through a heat exchanger to heat and expand air, which in turn would turn a turbine and the rest would be more or less like your average jet engine.
Check this cite for more references.
Now, one thing is jumping voluntarily out of a perfectly flyable airplane, that I can accept, but to jump into a freshly made nuclear disaster it´s way too whacky even for my standards.
I seem to remember a story about an experimental airship…essentially a blimp with four helicopter rotors with engines; it was being tested as a flying crane for the logging industry, IIRC…which unfortunately crashed, killing the pilot, when the thrust of the rotors could not be synchronized.
Nope. The last thing London needs is more provision of internet access - the places losing out are rural ones. (And there’s the slight issue of flight paths to several airports to contend with.)
You may be thinking of the Cargolifter project, in Germany in the 90’s. In short, it didn’t do any jobs better than conventional heavy helicopters could, but was more complex and riskier. The crash you refer to didn’t happen because it didn’t get built, but it could have been a regular occurrence.
The company folded when its seed capital (and eastern-zone German investment subsidies from the government) dried up and no plausible market appeared.
Enola is thinking of the Piasecki Heli-Stat which crashed on a test flight at Lakehurst NJ in July 1986. It used a surplus Navy blimp envelope attached via framework to four helicopters.
The Heli-Stat was built under contract to the US Forest Service to test the idea of using such an aircraft to lift timber out of difficult to reach areas. After the crash Piasecki was willing to try again, but the Forest Service was no longer interested.
Might anyone be interested in, say, twice the speed at half the price? My basic point is that Londoners already make considerable use of satellite-based communication services. So if & when someone offers a cheaper/faster alternative, there may well be a market.
They may have to rely on old-fashioned communication methods, if there are not enough potential users to justify the cheaper alternatives.
Give that a very few airborne relay stations (in very predicatable locations) would be needed, this is manageable.
ADSL is capable of 8Mb. No satellites needed. So you’re offering 16Mb, and you’re claiming it’ll cost half as much?!
Maybe not in the 1st world but theres plenty of potential in the 3rd world. It’s horrifically, horrendously expensive to try and wire up a city that isn’t already wired. You need to dig up roads and rip holes in building etc. The only reason the first world has been doing it is because it has no other alternative.
The 3rd world doesn’t even have basic infrastructure like fixed telephone lines so it looks much more appealing to go for the highest tech that you’ve got since you only need to upgrade the infrastructure once rather than several times.