Laserfiche WebLink
<br />C. Icing rate detectors <br /> <br />The icing detector, designed by Rosemount, Inc., was originally designed to <br />d~tect icing on .board ari aircr~ft. A similar sensor was developed fo~ ground. <br />use and described by Tattleman (19132). Over the course of the years the ground- <br />based icing detector went through several significant modifications leading to <br />the unit used in SCPP which was the Rosemount 872B Icing detector. <br /> <br />The detector is aerodynamically designed and detects icing from any wind <br />quadrant. The instrument operates on the principle of magnetostrictive oscilla- <br />tion. The sensing element vibrates at 40,000 Hz in no-ice conditions. The fre- <br />quency decreases as ice forms on the sensing element. When the frequency <br />decreases below 39,867 Hz an ice signal output and deicing heaters are activated <br />for 90 seconds. The ice detectors were calibrated at the factory to emit an <br />icing signal when 0.4 to 0.6 mm of ice had accumulated on the sensing element. <br />One occurrence of the icing signal output defines one trip. For more details <br />concerning this device, see Tattleman (1982). <br /> <br />Data from two icing stati~Rs will be discussed in this paper. The first was <br />sited atop the Sierra Nevada crest at Squaw Peak (SQP in Fig. 2). The other <br />station was locate 30 km northwest of SQP at Signal Peak (SIG). The icing sta- <br />tions were linked to a Handar 540 data collection platform, on which tempera- <br />.ture, relative humidity, wind speed, and wind direction were recorded every <br />5 minutes. Once an hour the data were transmitted through satellite and down- <br />linked to a local computer where it could be displayed. <br /> <br />5 <br />