More laddermill / spidermill ideas

Windy_Skies · May 13, 2022, 9:38pm

I don’t know if it was huge. For years the only thing I saw was Bryan Robert’s idea. Then there was Altearos and Magenn and so on. Compared to that the laddermill concept seems to hold much more promise, if the kites are actually moving crosswind. IIRC that wasn’t actually the case, so if I remember that right, it is good that that was abandoned. The text below does mention flight computers though.

TU Delft - Laddermill

Laddermill

There is an enormous amount of energy hidden in the winds over our heads. At an altitude of 30.000 feet, the wind energy is twenty times as large as at sea level. The laddermill is a new and novel idea to harness this immense energy resource.

The laddermill consists of a large number of kites on an upward and downward motion. The kites used are of a breed between regular kites and airplanes. Whereas a kite climbs relatively easy, getting a kite down requires a force pulling in the cable. An airplane, on the other hand, requires large engines to gain altitude. Decreasing altitude is much easier, as the aircraft can glide to the ground. The kites used in the laddermill, generally called “kiteplanes”, combine the ascension characteristics of kites with the descension characteristics of aircraft. By creating a large loop of kiteplanes ascending and descending, a rotation can be created. In turn, this rotation can be coupled to a generator to create energy. The loop of kiteplanes can ultimately go up to 30.000 feet, which would generate approximately 100MW. The cable is an important part of the system and consists of strong fiber materials such as Dyneema. The kiteplanes themselves need to be both large in surface area as well as light in construction weight. Structural principles such as inflatables are being investigated. The control of the kiteplanes can be done by a pressure differential in the inflatable members. Its control will ultimately be automated using flight computers.

Currently, there are several master students, PhD students and PhD graduates working on the laddermill in the fields of ground station mechanics, lightweight structures and flight mechanics. It is our intention to have a working demonstrator 2008. The laddermill project is an extremely multi-disciplinary project and it will lead to a radical change in wind energy doctrine.

Compared to a laddermill, kite-reeling seems better to many people, or at least simpler, for now, so the switch in focus to that. When something better comes along and seems to hold promise people will switch to that.

But that would be rubbish. It would need a lifter kite, it would use high drag soft kites, the kites would not be moving crosswind, barely making power, the generator would not be optimized, and so on. Why bother.

Wind-driven driving apparatus employing kites

US6072245.pdf (198.3 KB)