Airborne Lidar for Automatic Feedforward Control of Turbulent In-Flight Phenomena

TLDR: In this article, a forward-looking Rayleigh/Mie Lidar sensor is used to measure the airspeed in front of the aircraft for automatic control of turbulence in-flight phenomena.

Abstract: Design, development, installation, and flight test of a novel airborne forward-looking lidar sensor are presented, aiming at accurately and remotely measuring the airspeed in front of the aircraft for automatic control of turbulence in-flight phenomena. The development is driven by the stringent requirements of the capability of measuring airspeed at cruise altitude, in clear air, and at all weather environments with the required precision. The sensor was installed in an A340-300 testbed for flight testing, inside a dedicated fairing in a forward-looking configuration. The flight-test measurements proved that the direct-detection Rayleigh/Mie lidar is capable of detecting the wind speed under flight-test conditions up to 39,000 ft in clear air, rain, dense clouds, and ice rain. A measurement range of 50 m is achieved for the ultraviolet lidar at a 60 Hz update rate and at a standard deviation of line-of-sight speed as low as 1.0―1.5 m/s. Those parameters, as required for forward-looking automatic control sensors, are a unique basis for the usage of such a remote sensor for automatic turbulence control.