DeHavilland Twin Otter
June 1998 Featured Platform
NOAA
has two DeHavilland
Twin Otter aircraft (N57RF and N48RF) that support a wide range of
scientific missions. Considered to be the most versatile platforms in the
NOAA aircraft inventory, the highly modified Twin Otters are ideal platforms
for operations requiring low altitude, slow speed maneuvers.
In support of NOAA's National Marine Fisheries Service, the Twin Otters are an essential part of habitat protection and restoration programs, including the protection of endangered marine mammals. These aircraft are used to study abundance and distribution of marine mammals in near shore and offshore waters of the United States. Convex plexiglass bubble windows are installed on either side of the forward end of the cabin allowing forward, lateral, rear, and downward visibility. The Twin Otters have been modified with camera and equipment ports to allow several methods of photography and data collection to occur concurrently. Internal auxiliary fuel tanks enable flights of increased duration of up to 7.5 hours, 6.5 hours normally. The reliability of the Pratt/Whitney turbine engines allowing over-water operations to be conducted with confidence.
The Twin Otters are used to support a joint effort by NOAA's Coastal Services Center and NASA's Wallops Flight Facility. An Airborne Oceanographic Lidar III instrumentation package was installed on N57RF to measure surface layer phytoplankton chlorophyll, phycoerythrin pigments, and chromophoric dissolved organic matter. An Airborne Topographic Mapper (ATM) instrumentation package has been installed repeatedly on N48RF to support laser mapping of Atlantic and Pacific coastal regions. The laser altimetry data collected during these mission flights is used to develop coastal area baseline maps that are accurate to within 10 centimeters vertically and 1 meter horizontally. Baseline maps provide an accurate and timely assessment of erosion conditions and storm impacts that are needed to assist decision making on land use, beach renourishment, erosion calculations, insurance compensation, and property value estimation. To provide a baseline map, the Twin Otter modified with the ATM package conducted laser beach mapping in California, Oregon, and Washington prior to this year's winter El Niño storms. In April, the aircraft repeated the same laser mapping mission in an effort to accurately quantify the impacts of the El Niño storms. For these missions the aircraft was modified with camera and equipment ports, scientific power upgrades, and auxiliary fuel tanks. The aircraft must fly at airspeeds as slow as 110 knots for increased data resolution, thus making this aircraft a safe, effective and efficient platform for this project.
NOAA's Air Resources Laboratory developed extensive modifications to the Twin Otter, a configuration referred to as the Mobile Flux Platform, to measure eddy fluxes and concentration gradients through the atmospheric mixed layer, thus allowing for the sampling of rates of exchange of several atmospheric properties throughout the lower atmosphere and between the atmosphere and the surface. The aircraft, with its fast response temperature, water vapor, and carbon dioxide sensors, in conjunction with the GPS, provides routine data on vertical eddy fluxes of temperature, water, and carbon dioxide allowing its research capabilities to contribute to the improvement of predictions of storm formation and movement, precipitation, and air quality. All air-surface exchange studies call for extremely low flight altitudes, some as low as 100 feet above ground level, thus utilizing the low altitude capabilities of the Twin Otter. These Twin Otters are the only aircraft nationwide outfitted with this type instrumentation package.
N48RF Aircraft Specifications
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