On September 2, 2026, the HAP (High Altitude Platform)-alpha, a high-altitude platform developed by the German Aerospace Center (DLR), took off for the first time. The maiden flight took place at the DLR's National Test Centre for Unmanned Aircraft Systems in Cochstedt. During the test flight, the team evaluated the aircraft's flightworthiness at low altitude. The unmanned vehicle completed a safe flight lasting approximately 70 minutes over the airfield, reaching altitudes of up to 180 metres above ground level.

The crew monitored the flight and ensured adherence to all designated processes and procedures. They relied on pre-rehearsed workflows and intensive communication among team members to manage every situation that arose. Additionally, they evaluated various flight manoeuvres to test the behaviour of this newly developed aircraft.

"We are proud to have developed a flying platform from the ground up at the DLR and successfully brought it into the air. This is an impressive achievement by our staff, demonstrating expertise and collaboration across all necessary disciplines, as well as the exceptional skills and dedication of everyone involved."

Dr.-Ing. Markus Fischer, DLR Divisional Board Member for Aeronautics

The tests also aimed to obtain initial validation data for flight dynamics models. Based on this data, researchers can improve the underlying models and bring theory closer to practice. The results are now being analysed to optimise the flight test programme and further refine procedures ahead of the second low-altitude test flight. To gather the necessary data, pre-defined manoeuvres were flown over the test site at varying speeds and altitudes.

Preparing for the maiden flight challenge

For weeks, the flight test team had been monitoring weather forecasts to identify the optimal window for the maiden flight. Strict limits applied to HAP-alpha's maiden test flight, particularly regarding wind speed, which was not permitted to exceed one metre per second. "The greatest challenge during the maiden flight of such a high-altitude aircraft lies in its susceptibility to even minor turbulence, a result of its extremely lightweight construction combined with an enormous wingspan and significant aeroelastic deformation while airborne," explains Dr. Andreas Bierig, Acting Director of the DLR Institute of Flight Systems. Despite a wingspan of 27 metres, the platform weighs only 138 kilograms.

A total of 25 people made up the flight test team that launched HAP-alpha for the first time. The interdisciplinary team was coordinated by the Flight Test Director. Flight physicists and structural dynamics specialists monitored the aircraft's behaviour in the air. It was crucial, especially during takeoff and landing, to ensure the wings did not begin to oscillate (a phenomenon known as flutter) or suffer structural failure. To operate at high altitudes using available solar power, the aircraft must fly extremely slowly; flight speeds range from 30 kilometres per hour near the ground to approximately 50 kilometres per hour at high altitudes. The entire flight was overseen by a remote pilot stationed in the mission control centre, located several hundred metres from the runway, who controlled the unmanned high-altitude platform via a UAV (Unmanned Aerial Vehicle) pilot station. A safety pilot was also positioned directly on the runway, ready to take over flight controls at any moment in the event of an unexpected incident.

Goal: Testing at higher altitudes

Developed for flight altitudes of up to 20 kilometres, HAP-alpha is intended to serve as a flying testbed in the lower stratosphere, testing platform technologies and payload systems for Earth observation. This includes both a high-resolution camera system (MACS-HAP) and a synthetic aperture radar (HAPSAR), which are already being co-developed within the project. Furthermore, through this high-altitude platform, the DLR aims to gain comprehensive expertise for the development of high-performance, purely solar-powered high-altitude platforms.

Following the successful completion of the test campaign, initial flights at higher altitudes over uninhabited or extremely sparsely populated regions, such as over the ocean, are planned. A total of 16 DLR institutes and facilities developed the high-altitude platform and the associated ground systems; the entire team was coordinated by the DLR Institute of Flight Systems. The DLR is the only major research institution in Europe conducting research on such a platform and intending to operate it.