Helicopter Icing Spray System (HISS) Nozzle Improvement Evaluation
ARMY AVIATION ENGINEERING FLIGHT ACTIVITY EDWARDS AFB CA
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The U.S. Army Aviation Engineering Flight Activity USAAEFA operates a modified CH-47C helicopter as an airborne spray tanker to create a simulated icing test environment. This Helicopter Icing Spray System HISS was modified in 1979 to improve its spray cloud characteristics with respect to uniformity of liwuid water content LWC and reduction of drop size median volumetric diameter MVD. The existing atomizers on the spray boom assembly were replaced by Sonic Development Corporation model 125-H Sonicore nozzles. A UH-1H helicopter equipped with particle measuring spectrometers conducted in-flight sampling and calibration of the modified HISS spray cloud during Jan - Mar 1980 at St. Paul, Minnesota in conjunction with other helicopter icing tests. Average cross sectional dimensions of the present spray cloud are estimated as 36 ft wide and 8 ft deep. Usable values of cloud LWC in excess of 1 gram per cubic meter with a drop size MVD range of 20 to 35 microns could be generated at a 90 knot airspeed. This represents a vast improvement over the artificial cloud of previous years, and overlaps the MVD range representative of natural icing clouds. Test aircraft ice formations produced with the artificial cloud compared favorably with those seen in the natural environment.
- Snow, Ice and Permafrost
- Machinery and Tools