„Automatic Formation Flight“ is a research project that is funded by the Deutsche Forschungsgemeinschaft (DFG). Goal is to develop a flight control system which enables an automatic formation flight with the following aircraft flying in the near flow field created by an aircraft ahead.
The potential of saving power while flying in formation is used by migratory birds and is long been known. By using this technique airplanes could save 15-20% fuel. Because of unresolved technical and operational issues formation flight of commercial aircrafts is not possible today. In view of stricter economic and ecological conditions, it is gradually becoming interesting to solve the open issues.
The project “Automatic Formation Flight” will perform fundamental research on automatic formation flight where the following aircraft makes use of the energy contained in the near flow field behind the leading aircraft. The focus of the project is on the design of flight control laws. Questions about chances of success, required implementation effort, achievable fuel savings and the safety of formation flight under real operational conditions will be examined later on.
The objective is to develop a flight control system which enables an automatic formation flight with maximum power reduction and to provide the needed methods for its design. To understand the flight-physical mechanism knowledge of vortex-induced wind velocities and the effect on encountering aircrafts is needed. This provides the basis for the choice of the controller structure and for modeling the controlled system (system aircraft – wake vortex).
To gain the maximum power reduction it is necessary that the formation flight control system enables the aircraft to maintain the optimal position in the flow field of the leading aircraft (more precisely the optimal position in the induced upwash) with high precision. The task is challenging because the flow field induces not only the desired lift but also unwanted rolling moments which depend from the distance to the vortex axis in a highly nonlinear way. Classical controller concepts and simple controlled systems are not suitable for the design.
An appropriate model of the complex controlled system “aircraft – wake vortex” will be composed in this project. Based on which the formation flight control system will be designed by means of modern, adaptive and peek-seeking techniques and it will finally be evaluated by pilots in the research flight simulator SEPHIR.
|Definition of scenarios and requirements
|Defining operational procedures for automatic formation flight
|Design of flight control laws
|Flight simulator tests to evaluate the flight control system, analysis and documentation
Technischer Bericht, TN-FMRA-2014-007, Berlin, 01.12.2014