A central aspect of flight testing a helicopter consists in demonstrating the availability of adequate, so called “residual controls travel” in every flight situation. This represents the reserves available to the pilot through the control stick, allowing him to quickly react to gusts or down drafts during extreme maneuvers, e.g. when hovering over mountainous terrain.
Conventional methods of capturing the control path require the installation of sensors in mechanical elements of the flight control system, which transmit the pilot’s control inputs to the rotor blades. Such add-ons to the flight control system typically entail a huge certification effort.
In close collaboration with DLR, the Design Organization of SII developed a brand new, contactless optical system. This consists of a camera placed above the control stick which records the movements of the control stick during the flight as a video.
The video data is evaluated using a special software, able to detect an element of the control stick in the image and to track it automatically. The data is then post-processed to display both the controls inputs and the maximum control stick travel in a diagram.
The new system was extensively tested in connection with the qualification of an external sensor pod, also developed with SII’s involvement, and has now been filed for patent application.