DLR: Unmanned solar aircraft HAP-alpha passes ground vibration test

Aerospace DLR: Unmanned solar aircraft HAP-alpha passes ground vibration test

2025-07-31 From Stefanie Eckardt I Translated by AI 2 min Reading Time

The German Aerospace Center has taken an important step in the development of its own unmanned high-flying solar-powered aircraft and carried out a static vibration test. Further tests and an initial flight test at ground level are planned, depending on ideal weather conditions.

The high-flying unmanned platform HAP-alpha should be able to ascend into the lower stratosphere in the future.(Image: DLR) — The high-flying unmanned platform HAP-alpha should be able to ascend into the lower stratosphere in the future.
(Image: DLR)

High-flying unmanned platforms can remain in the lower stratosphere for long periods of time and perform a variety of tasks in the field of earth observation and communication - from monitoring shipping routes to disaster management or providing internet access. The German Aerospace Center (DLR) has now taken an important step in the development of its own high-flying solar aircraft: a ground vibration test was recently carried out on the high-flying HAP-alpha platform. The ground test took place at DLR's National Test Center for Unmanned Aircraft Systems in Cochstedt.

The HAP-alpha is a highly elastic, solar-powered flight platform in lightweight construction, which was manufactured at the DLR site in Braunschweig with a total weight of 138 kilograms and a wingspan of 27 meters. The aim of DLR's own project is to develop, build and operate a high-flying unmanned solar-powered aircraft. It is to fly as a test platform up to the lower stratosphere at an altitude of around 20 kilometers. There, sensor systems and system technologies are to be tested for long-term use on a high-flying platform.

Detect critical vibrations quickly

The ground vibration test (GVT) is an important test for investigating the vibration behavior of aircraft. The aim is to identify critical vibrations that can occur during flight or during the take-off or landing cycle. This determines whether the aircraft is safe and therefore airworthy. The completed GVT is therefore an important step on the way to the first flight tests, which are planned for next year, depending on ideal weather conditions, and will involve the first basic flight maneuvers at low altitude.

Various sensors were used during the static vibration test to record the dynamic properties of the platform. The platform was excited with electro-mechanical oscillators so that its vibration characteristics could be identified. A particular challenge of the GVT on the High Altitude Platform aircraft was its lightweight and therefore flexible design.

The data obtained will now be used to update the simulation models and predict flight behavior even more precisely - especially with regard to maneuvers, turbulence and wind gusts.

Know-how for the development of high-flying solar aircraft

With HAP-alpha, DLR is pursuing the goal of building up comprehensive expertise for the development of high-performance, high-flying solar aircraft. Furthermore, HAP-alpha is a carrier platform for testing sensor systems and system technologies under real operating conditions in the lower stratosphere. In addition to the platform itself, DLR is developing two sensor systems for use on the HAP-alpha as well as optimized evaluation procedures. These are a high-resolution camera system and a radar with synthetic aperture. (se)

Der Clean Sky 2 Technology Evaluator untersuchte Potenziale neuer Flugzeugtechnologien für CO2-Reduktion, Lärmminderung und europäische Wettbewerbsfähigkeit. (Bild: DLR)

Der offene Lüfter kombiniert den Kraftstoffverbrauch eines Turboprops mit der Leistung eines Turbofans. Es hat das Potenzial, die Treibstoffeffizienz eines zukünftigen Flugzeugs erheblich zu steigern. Das wollen Airbus und sein Partner CFM demonstrieren. (Bild: Airbus)

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