PRELIMINARY INVESTIGATION OF A STICK SHAKER AS A LIFT-MARGIN INDICATOR

摘要

An exploratory study was node to determine whether a pilot could use Titration of the control stick, in which either the amplitude or the frequency, or both, varied with lift or angle of attack, as a means of maintaining a desired lift margin below the stall. The study was made in the laboratory with several subjects, both pilots and nonpilots, by using an apparatus consisting of a control stick, a shaker, and shaker control equipment which provided varying amplitude and frequency with stick displacement. The tests consisted of having a subject attempt to maintain a given frequency and amplitude of vibration by moving the stick to compensate for an arbitrary change in frequency and amplitude imposed on the system by an operator independently of the stick motion. A brief study was also made to determine the minimum change in frequency or ampli¬tude a subject could detect.nThe results of these tests indicated that, once established, a given flight condition could probably be maintained by sensing variations in stick vibrations at least over the period of time covered by the tests (35 seconds), provided that the allowable variations from the desired flight conditions produced changes in amplitude of vibration of about 100 percent or changes in frequency of about 40 percent, or both. In the ranges of amplitude and frequency covered in the tests, sensitivity to amplitude changes increased with increase in amplitude and frequency; sensitivity to frequency changes did not appear to be materially affected by amplitude.