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Heliradar: the pilot's eye for flights in adverse weather conditions
In 1992 Eurocopter Deutschland and Daimler-Benz Aerospace started a research program to investigate the feasibility of a piloting radar based on the so-called ROSAR technology: HELIRADAR. While available radar instruments are not capable of guiding a helicopter pilot safely under poor visibility conditions due to lack of resolution and lack of height information, ROSAR technology, a Synthetic Aperture Radar based on ROtating antennas, has been the promise to overcome these deficiencies. Based on ROSAR technology HELIRADAR has been designed to provide a video-like image whose resolution is good enough to safely guide a helicopter pilot under poor visibility conditions to the target destination. To yield very high resolution a similar effect as for Synthetic Aperture Radar systems can be achieved by means of a rotating antenna. This principle is especially well suited for helicopters, since it allows for a stationary carrier platform. Additional rotating arms with antennas integrated in their tips are mounted on top of the rotating rotor head. While rotating, the antenna scans the environment from various visual angles without assuming a movement of the carrier platform itself. The complete transmitter/receiver system is fixed mounted on top of the rotating axis of the helicopter. The antennas are mounted at the four ends of a cross and rotate at the same speed as the rotor. The received radar signals are transferred through the center of the rotor axis down into the cabin of the helicopter, where they are then processed in the PolyCluster type high performance digital signal processor.
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