But flying a device at these altitudes is complex... According to the initial results, these drones flyingat high altitude should have around a thirty meter wing span and weigh around ten metric tons
Existing craft, flyingat low altitude, are particularly suited to long-duration flights at low or zero cruise speed. Stratospheric dirigibles, still to be designed, would constitute an alternative or complementary solution to satellites, for high-altitude observation
Flarm installed above the dashboard of an ASW19. The enlarged view of the Flarm dial indicates that another glider is in front, flyingat a lower altitude, invisible. This firm decision was taken following the tragic crash on May 5 2012 between a glider and a tow plane near Paris
They're especially intrusive when used at the week-end, and when they repeatedly flyat low altitude. "Virtually all the small aerodromes are under pressure from residents associations who demand limits on flights and the noise they generate", says Claude Le Tallec, engineer at Onera and a flying enthusiast with more than 4 000 hours flying experience
