DLR completes ground tests of high-altitude platform HAP-alpha ahead of first flight
Key Highlights
Summary Points:
- HAP-alpha is designed for long-duration missions up to 20 kilometers carrying scientific payloads for Earth observation.
- The aircraft uses solar cells for continuous power and flies at low speeds enabled by its large, ultra-light wing.
- Flight tests will use a trailer-based takeoff system with a patented mechanism to ensure safe lift-off.
COCHSTEDT, Germany - The German Aerospace Center (DLR) has completed extensive ground tests of its high-altitude, uncrewed platform HAP-alpha in preparation for its first flight. Tests ran through autumn 2025 and confirmed that all aircraft systems operate correctly while providing additional data on handling the aircraft. The first low-altitude flight tests are planned for 2026.
HAP-alpha is designed for long-duration missions at very high altitudes, carrying scientific payloads for Earth observation. Its solar cells must generate enough power to supply propulsion and onboard systems continuously. To reduce energy consumption, the aircraft flies at very low speeds, enabled by its large but ultra-light wing.
In spring 2025, the aircraft structure passed a static vibration test. During subsequent ground trials, HAP-alpha left the hangar of DLR's National Experimental Test Center for Unmanned Aircraft Systems in Cochstedt for the first time fully assembled.
Testing under flight-like conditions
DLR researchers preplanned procedures for the deployment, aiming to verify that both the aircraft systems and operational procedures worked correctly under flight-like conditions. The elastic structure was subjected to vibrations similar to those encountered during takeoff or flight, measured by high-precision sensors. The aircraft powered itself and responded only to commands sent over the same radio link used in flight.
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During testing, the wings and tail remained supported to prevent aerodynamic forces from damaging the lightweight structure.
The setup for upcoming flight tests will be similar: HAP-alpha will take off from a specialized trailer using a patented mechanism that secures the aircraft until the proper angle of attack is reached. The aircraft then lifts off automatically and lands gently on skids with the engine off.
Next steps
Before receiving flight clearance, final measurements and integration work are planned for the first quarter of 2026. Although HAP-alpha is designed for altitudes up to 20 kilometers, initial flights at Cochstedt will be limited to 150 meters for safety. Higher-altitude flights are expected over remote areas, including the sea.
A total of 16 DLR institutes and facilities jointly developed HAP-alpha and its ground systems, coordinated by the DLR Institute of Flight Systems.