Definition System and Criteria Related to the Static Stability of Airplanes. (First Report). Definition System, Static Flight Speed Stability, and Static Angle of Attack Stability.

This paper discusses the static stability concepts of airplanes. The definition of static stability has not been systematically discussed. For example, although “Cmα<0,” “Clβ<0,” and “Cnβ>0” are merely the aerodynamic criteria corresponding to each static stability, they are used just like the definition of static stability. Moreover, “flight path stability” is well known as the static stability concept on one translational motion, but the stability concepts in regard to the heaving and sliding motions of an airplane are indefinite. And though “tuck under” and “flight path divergence” are also static stability problems, they are treated not systematically but individually as special problems. So, this paper proposes a definition system consisting of six static stability concepts. Moreover, in the first report of this paper, “static flight speed stability” and “static angle of attack stability” are discussed in detail, and their stability criteria in terms of the aerodynamic characteristics of an airframe are obtained.