DLR simulates the dropping of a UAV from a flying Airbus A400M

The German Aerospace Center (DLR), Airbus, Geradts and SFL have used computer simulations to help design and develop a novel mechanism that enables unmanned aerial vehicles (UAVs) to be dropped off a flying transport aircraft's rear ramp.

Using simulation and the project based on an agile design and development approach, the development and completion of a prototype took place in just six months. The system developed makes it possible to use unmanned aerial vehicles in areas that they cannot usually reach independently. In-flight, the UAVs are set down from the rear of the transport aircraft using the developed mechanism, an example of its intended use, to carry out targeted reconnaissance work from the air.

The DLR researchers' main task was to use numerical simulations to determine conditions that would ensure that the UAV could be safely set down.

The creation of large lift forces on the aerodynamically shaped UAV must be ruled out, preventing a collision between the transport aircraft and the UAV. This is particularly challenging with large transport aircraft, as air turbulence occurs around the large doors. Simultaneously, the UAV should be able to assume a stable flight condition immediately after being set down.

Using complex numerical simulations, the influence of various variables, such as the position of the transport aircraft or the speed and place of the UAV relative to the transport aircraft, was examined. Since the aerodynamic forces and the response behaviour of the UAV to these forces are decisive for a safe landing, multidisciplinary simulations were carried out in which the flow solver was coupled with a flight mechanics tool. DLR used its own previously proven simulation methods for flow and flight mechanics. All partners worked cross-divisionally in the project. Airbus carried out the management of the project and the provision of a full-size A400M loading ramp for the implementation of the lowering mechanism, Geradts GmbH was responsible for the detailed design and the construction of the prototype of the mechanism, and SFL GmbH was responsible for the project-specific modification of the UAV.

The project is part of the "Innovations for FCAS" (I4 FCAS) initiative to bring German non-traditional defence companies, which cover startups, small and medium-sized enterprises (SMEs) and research institutes, into the development of the Future Combat Air System (FCAS). The German Ministry of Defense funds this initiative.