From afar, wind turbines look like small toys spinning lazily in the wind. But get up close and you realise what huge structures they really are: hundreds of feet tall, blade tips slicing through the air at over 160km/h. And these wind turbines can really scramble airport and weather radars. To solve the problem, engineers turned to the radar-evading pros: stealth fighter planes. When Energies Nouvelles of France builds what will be the country's biggest wind farm ever, they will be using "stealth turbines" inspired by military technology. As Popular Science explains, there are two main strategies for making planes invisible to radar. Ordinarily, planes can be identified by the radar signals that bounce of them. One strategy is a specially formulated coating that turns the radar signals into heat. Another is an oddly angular body that deflects radar in a certain way. The wind turbines in France will likely be coated with the radar-erasing material. Ironically, the need for these coatings on turbines came from the military, too. France's military keeps radar stations all over the country, which can be disrupted by wind farms nearby. In France alone, 6000 megawatts worth of wind farm projects have been blocked for fears of radar interference. In comparison, this new wind farm, which will be France's largest, will have a capacity of 96 megawatts. That's 96 invisible-to-radar megawatts. [Reuters via Popular Science]