VARIOMETER COMPENSATION DURING ACCELERATED FLIGHT

Abstract

Improvements in the performance of total-energy probes and variometer systems have greatly reduced the errors from these sources and the effects of changes in acceleration now need to be considered. During accelerated flight, changes in the normal acceleration g experienced by the glider result in changes in the polar sink. Since the calibrations of netto and speed-to-fly systems are based on g = 9.81 m/s/s, they will show errors during accelerated flight. To obtain an estimate of the size of errors that can be expected, the approximate incremental changes in polar sink on an ASW-15 for accelerations between 0 and 3 g are presented. They are quoted as knots error rather than as percentage changes, since this is what the pilot observes (1 knot = 0.515 m/s.) Reducing g to near zero has only a relatively small effect on the variometer indication over the normal cruising speed range, although the percentage change may be quite large.