Analysis of short-period longitudinal oscillations of an aircraft--interpretation of flight tests

Abstract

A method is presented of analysing experimental curves obtained in flight when an aircraft is disturbed longitudinally by a suitable elevator input and performs mainly short-period oscillations. Determination of frequency, damping factor, amplitude ratios and phase angles of various oscillatory curves leads to formulae for evaluating stability derivatives. Cases of elevator fixed or oscillating, for tailed and tailless aircraft, are considered and illustrated by numerical examples. The main results of the investigation are listed in section 6.