HAP-alpha solar aircraft clears ground tests, preps for flight trials

Germany’s German Aerospace Center (DLR) has achieved a significant milestone with its HAP-alpha solar-powered unmanned aerial vehicle (UAV), designed for long-duration, high-altitude Earth observation missions. The ultra-light aircraft, weighing just 304 lbs (138 kg) with an 88-foot (27-meter) wingspan, completed a comprehensive series of ground tests at the National Experimental Test Center for Unmanned Aircraft Systems in Cochstedt by autumn 2025. These tests verified the functionality of its systems, including lightweight high-resolution cameras and synthetic aperture radar, and confirmed its structural stability through static vibration testing. The HAP-alpha UAV is engineered to fly at very low speeds to conserve power, relying on solar cells to continuously supply energy for propulsion and onboard systems. During ground trials, it operated solely on onboard power and responded to commands via radio link, simulating real flight conditions. The aircraft was supported to prevent wing and tail flexing and used a patented mechanism for controlled automatic takeoff