DER EINFLUSS GESCHWINDIGKEITSABHAENGIGER NICKMOMENTE AUF DIE LAENGSSTABILITAET.

The effects of speed-dependent pitching moments (C//m//V) on longitudinal stability are investigated. The speed ranges are subdivided as follows: hovering flight (VTOL aircraft), low-speed flight (including the aerodynamically borne STOL flight) and high-speed flight (high subsonic speed and supersonic speed). For the hovering flight range, the basic behavior of pitch rate and pitch attitude systems is considered. In regard to the low-speed range, the influence of C//m//V on the eigenvalues is investigated and it is shown how the effect of C//m//V on phugoid damping changes with angle-of-attack stability (C//m//a). The investigation of the stability boundaries considers the case where the effect of C//m//V leads to an aperiodic divergence in spite of static stability. In addition, it is shown which range of destabilizing C//m//a values (C//m//a greater than 0) can be stabilized by C//m//V. From this, the stability limits for the application of downsprings can be determined. For the high-speed range, the effects of the density gradient on the influence of C//m//V on longitudinal stability are shown. It is demonstrated that the combination of speed- and height-dependent pitching moments is of particular significance.