The reason they use “winglets” on airplane wingtips and not wind turbine blade tips is:
As they pointed out, the aerodynamic effective advantage of a winglet versus just making the blade or wing longer is about the same.
Airplane wingspan is limited by ground taxiing traffic patterns and clearance between aircraft, so for that application, the winglets make sense and the advantage is better clearance from other aircraft on the ground.
Unlike airplanes, the major force on a blade tip is centrifugal force. Imagine the whacky centrifugal forces on a blade tip caused by a winglet protruding toward the wind, trying to bend outward. The bending moment would want to delaminate the composite structure on the inside of the curve, while pushing the blade back toward the tower. It would take a lot of extra material to handle those loads. Then the whole blade would have to be stronger (heavier, more expensive) to support all that extra weight at the tip. So for wind turbines it is better to just make the blades longer.
Whale bumps? I guess we’re still waiting, after 1000 magazine articles. Discussed on the old forum for maybe ten years. I don’t have to tell you who on the old forum thought they were a great idea. Some people can only reason as deep as a slogan that will fit on a bumper-sticker. In the case of whale-bumps, the single-word slogan was “biomimicry!” As discussed, from a layup standpoint, they would have to be an add-on, but without any real advantages. Whalebumps - sounds like a cellulite chafing issue for thunderthighs. Be careful what you believe. There are a lot of crazy half-truths floating around out there.
Looks as if some flexible kites have no limit of scaling. By approximate calculations according to the image, we would have an inner diameter of about 40 m, i.e. a total annular surface of about 2000 m².
Perhaps this bol kite type could lead to gigantic rotary architectures, including Daisy type.
There are material limits on scaling soft kites.
If I remember @kitefreak correctly…
Weight per square metre of material has to increase with higher wing loading of larger kites. Unless you break them out into cells which use shared loadpath lines to create an overall larger kite form from the cells
The development originated as an Advanced Concept Technology Demonstrator research program from Natick Soldier Systems, whereby iteratively heavier weight requirements were levied (0.25 ton, 1 ton, 2.25 tons, 4.5 tons, 13.5 tons, and finally 19 tons). The wing sizes were 36 m2, 102 m2, 250 m2, 350 m2, 900 m2, and 1,040 m2, respectively.
That said, some shapes (such as bowl kites or parachutes) could perhaps suffer a lower weight penalty when scaling up.
Here it is used to test a kite plane: TX-8.2 Flight - YouTube. And new videos from the same channel of a kite plane riding up and down a tether: WindiVator 1.0 - YouTube and a kite plane controlled by flight software: - YouTube
Its Pablo Casals or like playing prelude from Bach´s Cello Suite No. 1
WindiVator is a classic old-school model-aviation (~80s) hacker. There does not seem to be too much novel in his tethered devices, given so much prior art, but a nice representative of tethered model glider tinkering.
Kite Messenger: “a kite (element) riding up and down a tether”
I’ve for the last few week been seeing references to sand batteries. now the bbc have waded in. It seems Finland is finding a use for these batteries. As energy storage is a topic most green engineers are interested in. i thought I share this one. Complementary systems will definitely be advantageous in the coming years. As heat is a primary loss in energy production. capturing the heat loss, to me would see like a good idea. May bump efficiency by a few points. As in many awes have systems that would benefit. I couldn’t help myself. Thought it rude not to share. So there we go sand batteries.
