With the increasing automation of rotorcraft (eVTOL and helicopters), the needs and desires of passengers are coming into focus more than before. Passenger acceptance of these aircraft is strongly linked to the individual perception of safety and comfort. It is therefore in the interest of manufacturers to design safe and comfortable rotorcraft. To increase flight comfort, helicopter manufacturers in particular have invested many years of work and time to reduce the high rotor vibration levels. With the successful reduction of rotor vibrations, other sources of vibration are becoming more and more perceptible by the passengers. In particular, the vibrations caused by the flight control system's response to atmospheric turbulence are perceived as uncomfortable by passengers. Since these vibrations have not been systematically considered so far, new opportunities for optimizing flight comfort arise here.
Atmospheric turbulence can occur during a flight and negatively affect the comfort of helicopter occupants. To quantify the discomfort contribution of turbulence, wind speeds must be recorded with a special in-flight measurement device. Indirect methods are needed to determine wind speeds during flights without this measuring device. For this purpose, the IFR is developing methods for reconstructing wind speeds with the aid of common measuring instruments in helicopters.
The counter-reactions of the pilot as well as the reactions of the flight control system to the determined wind speeds lead to low-frequency, broadband vibrations. The IFR, together with partners such as Airbus Helicopters Germany, is analyzing and developing the applicability of existing as well as internally developed comfort models to predict passenger comfort based on these vibrations. These models are used to develop comfort-optimized flight control systems at the IFR to systematically improve flight comfort.
The goal of the activities at iFR in the area of helicopter comfort are:
- Design a comfort metric for helicopter application considering turbulence-induced vibration & rotor-induced vibration.
- Design of a development tool to consider flight comfort in early helicopter development phases.
- Design of flight control system for systematic improvement of flight comfort.
- Modeling and reconstruction of atmospheric disturbances.
 Özkurt, S., Rath, T., Fichter, W., Dieterich, O., Priems, M., Nooij, S. A. E., & Bülthoff, H. H., From Helicopter Vibrations to Passenger Perceptions: A Closer Look on Standards. Proceedings of the 76th Annual Forum, 2020
 Rath, T., & Fichter, W., Flight Control Design for the Systematic Improvement of Ride Qualities. Journal of the American Helicopter Society, 2020
 Rath, T., & Fichter, W., A Closer Look at the Impact of Helicopter Vibrations on Ride Quality. Proceedings of the 73th Annual Forum, 2017