Talk:Airborne wind turbine

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This concept seems pretty flakey to me. I've split this out from the Wind power article because that article is already too long, and this idea was allocated equal space with onshore and offshore installations, both of which are widely practiced.

If this concept is anything other than a crackpot idea, I'd like to see this article fleshed out to answer several questions:the Wind power article because that article is already too long, and this idea was allocated equal space with onshore and offshore installations, both of which are widely practiced.

  • If the rotor blades are also used as a lift mechanism, then the thing is a helicopter. :I agree. If the tether breaks or there is no wind, the FEG = flying electric generator descends slowly as an autogyro without power. Typically only minor damage occurs when it lands. What is the steering mechanism? :ordinary GPS = global positioning service plus a computer which makes most of the decisions. Ground operators can also pilot by radio control.
  • Are counter-rotating turbines used? If not, what cancels the rotor torque? :The 15,000 foot model will have two rotors spaced a bit more than two rotor radius apart. The later model will have 4 or more rotors spaced a bit more than a rotor radius apart.
  • Are winds aloft any less variable than low altitude winds? Why?
I believe they are very much so. They're driven by global patterns rather than local factors. For example, the equator is always much warmer than the poles, so the basic Hadley cell is always there. dsws 15:57, 26 April 2006 (UTC)
I agree, but much larger scale and typically faster wind. When the wind aloft shifts, The FEG will tyically find a new arrangement that works favorably in about one minute.
  • Identify any patents on this idea, companies/research groups pursuing it, and test articles or prototypes.
see www.skywindpower.com

Iain McClatchie 20:20, 29 September 2005 (UTC)

  • I'd also like to know how much 30,000 feet of wire weigh.:#20 aluminum wire is 930 pounds per 1000 feet and 17.6 ohms per 1000 feet = one million ohms for 60,000 feet. We need two conductors very well insulated from each other. (Three conductors for 3phase ac) If the FEG produces 400,000 volts at 1/5th amp, half the energy is line loss. The wire gets warm, but not hot, which helps keep the the tether dry and ice free. Wouldn't that weigh the thing down, so it would be spending all it's energy to get lift up? Sometimes altitude will lost, but typically altitude will be regained as conditions improve. Reduced power will be delivered briefly and rarely. The 30,000 foot tether will weigh at least 30 tons, unless we develop superconductors and/or CNT = carbon nano tubes for strength and/or think less than 1/5 amp. More than 400,000 volts is likely impractical and well into decreasing returns.
  • Does it get lift from wind blowing over its wings? Or by rotors?
www.skywindpower is thinking rotors, but likely wings are possible

I tried contacting the company via their email form, but have not yet heard back.

my guess is neither company has yet found the extensive funding needed yet, so they are stretch thin for man hours. NeilCcpoodle 12:46, 1 April 2007 (UTC)

A much simpler approach is to have a tethered controllable airfoil. The kite might look like a paraglider or like a glider. The angle of attack control could be via radio, via a conductors in the tether or by an on board computer. Changing its angle of attack in a periodic way would produce a periodic variation in the tension on the tether. This alternating tension could be rectified by a spring and crank apparatus on the ground.

For example, consider 0 to 1000 KG (10,000 N) at 6 cycles /minute along a 500 meter tether. Wire rope is rated at about 1550 N/mm^2 so the wire rope would weigh about 32KG

The sole role of tether (other than optionally carrying some light communication wire) is carrying the kite's wind driven tension. The tether material selection criterion is maximum strength and durability at minimum weight.

The advantage of this scheme is that all the heavy apparatus on is on the ground and only the functional airfoil and light aerodynamic controls are aloft. A lighter kite means that it converts wind into usable energy more efficiently. It can also pull a longer tether and thus reach higher altitudes where winds are steadier and stronger. It can be lofted at lower ground wind speeds and if it comes down to the ground it is less likely to cause serious damage. The kite should be designed to maximize lift at minimum weight subject to durability.

The ground base for the tether has a reel, crankshaft and generator. and can have a fairly small footprint. It would have to be anchored to withstand the peak tether stresses. Many ground bases and kites could be scattered fairly densely over a region.

With more sophisticated controls to avoid kite collisions (and tether tangles) one could have multiple (two in tandem seems reasonable, perhaps more on the same tether at different altitudes) kites tethered to the same ground station. Lou (talk) 20:01, 12 May 2008 (UTC)