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Dynamic instability can occur involving pitch and yaw degrees of freedom of the propeller and the engine supports leading to an unstable precession of the propeller. [13] Failure of the engine supports led to whirl flutter occurring on two Lockheed L-188 Electra aircraft, in 1959 on Braniff Flight 542 and again in 1960 on Northwest Orient ...
For an unstable aircraft, a disturbance in pitch will lead to an increasing pitching moment. Longitudinal static stability is the ability of an aircraft to recover from an initial disturbance. Longitudinal dynamic stability refers to the damping of these stabilizing moments, which prevents persistent or increasing oscillations in pitch.
Most aircraft trimmed for straight-and-level flight, if flown stick-fixed, will eventually develop a tightening spiral-dive. [2] If a spiral dive is entered unintentionally, the result can be fatal. A spiral dive is not a spin; it starts, not with a stall or from torque, but with a random perturbation, increasing roll and airspeed.
The longitudinal stability of an aircraft, also called pitch stability, [2] refers to the aircraft's stability in its plane of symmetry [2] about the lateral axis (the axis along the wingspan). [1] It is an important aspect of the handling qualities of the aircraft, and one of the main factors determining the ease with which the pilot is able ...
Flight dynamics in aviation and spacecraft, is the study of the performance, stability, and control of vehicles flying through the air or in outer space. [1] It is concerned with how forces acting on the vehicle determine its velocity and attitude with respect to time.
The vertical positioning of the wing changes the roll stability of an aircraft. An aircraft with a "high" wing position (i.e., set on top of the fuselage) has a higher roll stability. For example, the Cessna 152. An aircraft with a "low" wing (i.e., underneath the fuselage) has less roll stability. The Piper Pawnee uses a "low" wing.
When an aircraft encounters a horizontal gust of wind, yaw stability causes the aircraft to turn into the wind, rather than turn in the same direction. [26] Fuselage geometry, engine nacelles and rotating propellers all influence lateral static stability and affect the required size of the stabilizer. [27] Not all aircraft have a vertical ...
The way in which particular vehicle factors affect flying qualities has been studied in aircraft for decades, [3] and reference standards for the flying qualities of both fixed-wing aircraft [4] and rotary-wing aircraft [5] have been developed and are now in common use. These standards define a subset of the dynamics and control design space ...