All right! Another biggie!
The FlyMill has been a big big part of my life for years. Here’s a 30-second video about it that I made for my Google Project 10^100 application:
The result of many years of crazy-person-esque obsession and anguish, the FlyMill was (and perhaps still is) the very best I could do at coming up with a quite-scalable scheme that would need as little physical strength per watt as conceivably possible, so as to deliver super-cheap renewable electricity in the ballpark of 2 cents/kw-hr (if all of its many engineering, mass-production and logistical challenges were solved).
(It also has some very serious problems, even as an idea, which I’ll save for last.)
So it’s basically a set of “electric airplanes,” with direct-drive windmills for propellers, booking around in a circle.
The planes are made of metal or plastic, and not cloth like some other kite-power schemes I’ve seen. I just can’t believe in anything that’s not clothless, because no cloth lasts very long in the open air 24-7 (without maintenance).
Super-genius autopilot flight control lets the planes bias their tether up above horizontal, and thus not crash into the ground.
When there’s no wind at all then the tether points straight up and the airplanes consume electricity to stay aloft, because the idea of landing and then taking off is just too horrifying for me to think about. They consume some fraction as much electricity to stay aloft in dead air as they produce when there’s a decent wind.
(A windmill, when driven instead of driving something, makes a crappily-inefficient but still somewhat-functional propeller. That’s how the electric airplanes can theoretically propel themselves at low speed.)
Since it’s tethered, it could be deployed out to sea. Chains get linearly more expensive with length=depth, while with windmill towers it’s something like the third power of length=depth.
The abiilty to cheaply work in deep water is a big big deal. There’s a lot of wind and a lot of real estate out there, and that real estate is far from most authorities with the power to sue. Out of city waters, out of county waters, out of provincial waters, etc. This is important! Terrestrial wind power is basically illegal in France, for instance, because there are so many grounds (environmental, eyesore etc.) upon which someone can sue to keep a wind farm from being built.
Another key idea: The last 20% of a regular windmill blade’s length is where 50% of the power is, but is also the cheapest 20% of the blade’s length. A regular windmill blade must get stronger and stronger the closer it gets to the hub, which is where the material=weight=expense is. The FlyMill has blade tips only!
So on a per-watt basis, this tips-only property is why I believe that a FlyMill needs less material/physical strength per watt than a conventional windmill. If everything else about it can be made to work and Detroit-scale mass production (hopefully not involving carbon fiber or even aluminum if possible) can make the planes, then this lower material-per-watt ratio would be the ultimate key to the FlyMill’s low cost.
The FlyMill is also gearless. The “propellers” direct-drive the motor-generators. This is important because the gearboxes on regular windmills are frightfully complicated, expensive, and still keep breaking down! The FlyMill has no gears! Yes!
So. It can be installed over more real estate, in better winds, while using much less material strength than regular windmils. So, why aren’t they all over the place by now?
Well, dammit, because of some very ugly apparent showstoppers. Showstoppers I just haven’t found a way around, even in the imagination:
Showstopper 1: The autopilot control algorithm of the planes will be super complicated. Just one crash into the ground and it’s all over.
Showstopper 2: The electric airplanes have many actuators. They have rudders, ailerons, tail flaps, etc. So how oh how could they keep on actuating, day in day out, for 10+ years without being serviced? And if not, how could they be serviced? I don’t know!
Showstopper 3: The power electronics needed to speed-control the many “propellers” on the planes and combine their outputs into a single high-voltage cable to the ground would not be free. Furthermore, the power cable coming down along the tether will be prohibitively heavy unless the electricity is upped to many thousands of volts. That’s not free either.
(Am I making any sense here?)
Longshot City 
November 18, 2008 at 3:04 am
I like it, and I don’t think it is as crazy as you think it is.
First off, as scary as it sounds, people have been attaching long cables to airplanes for quite some time now. My dad was into soaring (in sailplanes) and in that sport, you drag the sailplane behind a regular plane with a long cable. And surely you’ve seen those big “Eat at Joe’s” signs trailing behind an airplane at the beach.
What I don’t understand is why you are envisioning more than two planes attached to the “flymill.” Sure, maybe three+ is more efficient, but then yes, I see many issues with control, etc. With two planes, the control seems simpler (but maybe it is still really difficult).
I think you are going to have to be able to land the thing regularly for it to ever work. You’ll need to land it when a big storm comes through. And yes, you’ll need to land it for periodic maintenance. The most difficult thing I envision is the transition between “free flying” and a taut cable. I guess you’ll have to reel it in and out with a winder on the ground, or something.
Rather than starting out “detroit-scale” why not envision something on a “model airplane scale”?
November 18, 2008 at 3:06 am
> Rather than starting out “detroit-scale” why not envision something
> on a “model airplane scale”?
Oh of course, it would have to start that way, yes. And it would be made from RC airplane parts.
November 18, 2008 at 3:14 am
> What I don’t understand is why you are envisioning more than
> two planes attached to the “flymill.” Sure, maybe three+ is more
> efficient, but then yes, I see many issues with control, etc. With
> two planes, the control seems simpler (but maybe it is still really
> difficult).
Well, see here’s the thing.
From 6-o-clock to 12-o-clock, the planes end up doing a very fast rate of climb. I convinced myself (which is a far cry from “I was told my God himself”) that no airplane or glider made form attainable materials could do that rate of climb under wind power alone.
So the upward-traveling plane can’t go up towards 12-o-clock all by itself. The wind power pushing up on the thing isn’t enough to raise it that fast. It’s as if one were to make a single-bladed windmill without any kind of counterweight. I don’t think it could ever make it up to 12-o-clock.
So. Ergo. With 3/4/5+ planes going at once, there’s always a top plane that:
o Is being pulled down by the other planes
(which is another way to say:)
o Is pulling up on the other planes.
So that’s why I can’t see less than three planes. There has to be a “top plane” at all times.
(Does this make any sense at all? If not please say so, because trying to explain this stuff helps me learn it.)
November 18, 2008 at 3:18 am
> And yes, you’ll need to land it for periodic maintenance.
(scratches head…)
Shit, what if they’re seaplanes? What if they take off and land like seaplanes do, only not in straight line but booking around a circular path? Wow. I have no idea whether that significantly adds to the “crazy quotient” or not. Man.