Claim: Kites in a MAWES need to be able to: CLAMP onto the tether and LATCH onto the previous kite + a discussion on how to do this + a first mention of stackable kites + a concept for automatic launch of a soft kite train

[Windy_Skies]

@gordon_sp

The best reference that I found is an article by ALEXANDER BOLONKIN in 2002, where he states that the energy transfer from a high-speed cable drive is more efficient than the energy transfer from an electric cable in the units of energy per kilogram weight. He discusses various cable materials and suggest cable speeds of 300 m/s. Below is an excerpt from Bolonkin’s article for a 20 MW system.

“One of the main innovations of the given invention is the cable transfer (transmission) of energy from the wind rotor located at high altitude to the electric generator located on ground. In proposed Installation it is used a new cable transmission made from artificial fibers. This transmission has less a weigh in thousands times then copper electric wires of equal power. The wire having diameter more 5 mm passes 1-2 ampere/sq.mm. If the electric generator produces 20 MW with voltage 1000 Volts, the wire cross-section area must be 20,000 mm2, (wire diameter is160 mm). The cross-section area of the cable transmission of equal power is only 37 mm2 (cable diameter 6.8 mm for cable speed 300 m/s and admissible stress 200 kg/mm2, see Project 1). The specific weight of copper is 8930 kg/m3, the specific weight of artificial fibers is 1800 kg/m3. If the cable length for6
altitude 10 km is 25 km the double copper wire weighs 8930 tons (!!), the fiber transmission cable weighs only 3.33 tons. It means the offered cable transferor energy of equal length is easier in 2682 times, then copper wire. The copper wires is very expensive, the artificial fiber is cheap.”

Utilization of Wind Energy at High Altitude.pdf (228.7 KB)

RE: rope drive ideas:

A bigger single rotor doesn’t make much sense beyond a certain size I think, because you would need to counteract the torque, among other things.

You’d want to make coaxial counter-rotating downwind rotors. The downwind rotors would probably look like the pyramid or daisy systems, because those allow you to have the arms of the two rotors (1) coaxial, (2) close together to couple to a gearbox and the rope drive components, while (3) putting the airfoils further downwind so they won’t interfere with each other so much, and also (4) concentric with each other.

I don’t think this is such an interesting thing to pursue until after you’ve perfected an idea like the pyramid or daisy. Maybe it makes those ideas more interesting, if you feel you need more altitude.

Edit: Or maybe you can cancel (most) of the rotation of the assembly using the rope drive tension and long lever arms, no need for the counter-rotating rotors.