Scientists at the Institute of Flight Systems Technology are researching new methods to make helicopters quieter, more energy-efficient and less vibrating.
The Helicopter Department performs research on various aspects of rotor and flight systems for rotary wing aircraft. Objectives are to support the development of new technologies and their evaluation to improve the handling qualities, safety, economic efficiency, environmental performance and mission effectiveness of rotorcraft. The activities span from system analysis, modeling and simulation of configurations and system components to wind tunnel and flight tests.
As fundamental requirement for the design, development and evaluation of innovative rotor systems and pilots’ supporting technology, rotor and flight dynamics models of different detail and complexity are available. These configurable models are adapted to the needs and validated by comparison with flight test and wind tunnel data. Besides physics’ based modeling for prediction and analysis, system identification methods and parameter optimization techniques are used to develop numerical models for flight control applications.
Handling qualities analysis methods are used to analyze, optimize and evaluate the functions and systems through pilot-in-the-loop simulator and flight tests. This approach has led to the ability to define and specify handling qualities criteria for existing and future rotorcraft.
Systems to support the 24/7 operation of helicopters
Still challenge for the helicopter of the future is the 24-hour usability in all weather conditions. The helicopter department contributes to this goal through the development of necessary pilots’ supporting systems, such as adaptive flight controls, automatic flight including obstacles avoidance and rerouting, and the testing of new sensors and displays.
The easy-to-fly helicopter
In studies on active sidesticks, flight and system states are fed back to the pilot as additional tactile information to indicate the approach to system limitations and to avoid exceeding these limits. Active sidesticks are short pole sticks mounted on both sides of the pilot’s seat instead of a centerstick (cyclic control) and a collective lever. Besides the advantage of tactile cueing, this arrangement of pilot control inceptors is superior to the current arrangement from an ergonomic and fatigue standpoint. Other topics cover the continuous improvement and optimization of rotorcraft handling qualities and the development and evaluation of new concepts how to steer a helicopter, and the facilitation of flying with externally slung loads by automatic damping of load motion and enabling the precise positioning for final delivery.
Flying Helicopter Simulator FHS
An important and in Europe unique facility for flight testing new systems and approaches is DLR’s Flying Helicopter Simulator FHS. The FHS is based on an EC 135 which was substantially modified for use as a research and experimental helicopter. The FHS features an electrical/optical flight control system, a flexible and modifiable programmable experimental system, and is equipped with active sidesticks.
Rotor control
The noise footprint of the helicopter of the future has to be reduced to be widely accepted. In addition, the vibration level must be reduced drastically to reduce the burden on the crew and passengers and the wear of material. At the same time the performance of modern rotors with regard to load, flight speed and economy shall be considerably higher than those used today. With these objectives, systems of the active rotor blade control (higher harmonic control, individual and local blade control) are designed and tested in the wind tunnel and partially in flight. Furthermore, unconventional and promising rotor blade designs are tested and evaluated in the wind tunnel, in close cooperation with industry.
Rotor test rig facility
The Institute operates the rotor test rig, an important and worldwide unique facility for wind tunnel testing of isolated main and tail rotors and fuselage configurations, complete rotorcraft configurations, and new rotor control technology. With this test rig, the effectiveness of new developments can be evaluated reliably in the controlled environment of a wind tunnel, as well as investigating effects at the limit of the flight envelope without risking pilots and a crew in a test aircraft.
Besides DLR’s basic research, these topics in the field of rotorcraft flight systems technology are conducted in close cooperation with industry and with national, European and international research institutes and universities.
FHS in flight test
During the flight tests, the crew practises handling and sensor technology for the rescue hoist.
DLR-Testpilot Sebastian Soffner mit Augmented-Reality-Brille Microsoft HoloLens 2 im DLR-Forschungshubschrauber ACT/FHS (Active Control Technology / Flying Helicopter Simulator). Das visuelle Assistenzsystem soll den Piloten bei anspruchsvollen Flugmanövern unterstützen: Dem Piloten werden wichtige Informationen über den aktuellen Flugzustand sowie die Darstellung von Hindernissen direkt in seinem Sichtfeld eingeblendet.
For the validation of modern numerical analysis methods for the aerodynamics and aeroacoustics of helicopters, it is necessary to conduct wind tunnel tests with helicopter models. The results obtained from these tests contribute significantly to the lowering of development risks and to the reduction of the development time and costs for new helicopter systems.
