Analysis of Three Icing Test Flights Reaching the Aircraft-Referred Icing Degreeof Severe

摘要

Three test flights in icing conditions are discussed: one in the range of a highpressure area, and the other two in the range of warm fronts, where the aircraft-referred icing degree of 'severe' was reached. The ice accretion on the underside of the wing of the Do28 extended (at 50 to 70 cm) beyond the area which can be pneumatically deiced. In the area of the pneumatic deicing boots, the deicing was totally ineffective or incomplete. The mean values of the cloud physics parameters which produced the aircraft referred icing degree of 'severe' were: total water content 0.20, 0.22, 0.30 g/cu m; temperature -1.8, -2.0, -4.5 C; and median volume diameter 20, 180, and 300 microns. The cloud flight paths in the range of the warm fronts were only 1/10 to 3/10 of the cloud flight path in the range of high pressure areas when it came to attaining the maximum icing characteristics achieved in the range of a high pressure area. The reason for this was the considerably higher value of the median volume diameter in the range of the warm fronts.