The Molecular Optical Air Data System (MOADS) is a compact instrument designed to measure aircraft airspeed as well as the density of the air surrounding the aircraft. Other air data products provided by the instrument include density altitude, angle of attack (AOA), angle of side-slip (AOS), and Mach number. MOADS is a direct-detection LIDAR that measures these air data products from fringe images derived from a Fabry-Perot etalon. Determination of airspeed and direction is achieved through three telescopes that view a fixed air volume ahead of the aircraft turbulent flow field. This method reduces the measurement error as compared to traditional measurements made from within this turbulent region. As a direct detection LIDAR instrument, MOADS is capable of collecting both molecular and aerosol LIDAR returns, which allows operation in clear air as well as in aerosol-filled atmospheric regions. A second prototype was designed, built and tested. This MOADS prototype has been validated in a laboratory wind tunnel. Presented here are the airflow velocity measurement results from ground testing and vibration test measurements.
The Molecular Optical Air Data System (MOADS) is a compact optical instrument that can directly measure aircraft velocity, as well as the density of the air surrounding the aircraft. From these measurements, many air data products can be determined. Successful MOADS operation has been demonstrated in the laboratory using a wind tunnel. Recently, a MOADS prototype was designed and built in order to complete an upcoming flight experiment aboard a Beechcraft King Air 300. This flight program will be a significant milestone for direct detection lidar systems configured as an air data system aboard an aircraft. The background of the technology, ground experimentation summary of results, flight experiment approach, flight prototype design, and flight experiment planning are discussed.
The Molecular Optical Air Data System (MOADS) is a compact optical instrument that can directly measure wind speed and direction, density, and temperature of the air surrounding an aircraft. From these measurements, a complete set of air data products can be determined. Single-axis wind tunnel testing of wind speed and density has just been completed for the current prototype. These wind tunnel measurements have shown that the current prototype meets wind speed accuracy predictions and initial results from density testing indicate a high level of correlation with absolute pressure transducer measurements. A preliminary design for the next generation instrument, the Joint Optical Air Data System (JOADS), has been completed and is intended to meet Joint Striker Fighter (JSF) requirements. Work is also underway to evaluate the application of MOADS to Unmanned Air Vehicles (UAVs), Reusable Launch Vehicles (RLVs), helicopters and weapon systems. Extensions of MOADS technology to wind shear, gust alleviation, and clear air turbulence detection for commercial aircraft are also being pursued. The basic instrument operation, preliminary ground testing (wind tunnel) results, comparison of these results to simulations, next generation instrument capabilities, and plans for a flight demonstration are discussed.
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