Static and dynamic flight-path stability of airplanes. Seiteki oyobi dotekina hiko keiro anteisei

When a flying speed of an airplane decreases and enters from the front-side flight region to the back-side flight region, its flight-path stability becomes unstable. In this paper, the flight-path stability in the back-side flight region has been studied. First of all, the flight-path stability based on the conventional stationary balanced flight condition is defined as static flight-path stability, several explanation methods concerning this concept have been shown, and among them, the existing explanation of instability in a compensating loop for maintaining a flight altitude with the elevator has been expanded to the interpretation of instability of a compensating loop for maintaining a constant value of a flight-path angle. Furthermore, the concept of dynamic flight path stability has been introduced into the flight condition deviated from a steady balanced flight, and the compensating amount of the elevator necessary for securing the dynamic flight-path stability set optionally has been obtained. Taking the approach and landing phase of an airplane with no thrust as an example, the above explanation has been applied to it and it has been shown that a dynamically stable flight-path could be maintained even in the back-side flight region. 9 refs., 12 figs.