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Three cases for static stability: following a pitch disturbance, aircraft can be unstable, neutral, or stable. If an aircraft is longitudinally statically stable, a small increase in angle of attack will create a nose-down pitching moment on the aircraft, so that the angle of attack decreases.
Some swept-wing aircraft have an unstable Dutch roll. If the Dutch roll is very lightly damped or unstable, the yaw damper becomes a safety requirement, rather than a pilot and passenger convenience. Dual yaw dampers are required and a failed yaw damper is cause for limiting flight to low altitudes, and possibly lower Mach numbers, where the ...
Longitudinal stability refers to the stability of an aircraft in pitch. For a stable aircraft, if the aircraft pitches up, the wings and tail create a pitch-down moment which tends to restore the aircraft to its original attitude. For an unstable aircraft, a disturbance in pitch will lead to an increasing pitching moment.
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.
Aircraft (usually not missiles) operate at a nominally constant "trim" angle of attack. The angle of the nose (the X Axis) does not align with the direction of the oncoming air. The difference in these directions is the angle of attack. So, for many purposes, parameters are defined in terms of a slightly modified axis system called "stability ...
If the spiral mode is stable, the aircraft will slowly return to wings-level, if it is unstable, the aircraft will slowly diverge from wings-level. Dihedral effect and yaw stability are the two primary factors that affect the stability of the spiral mode, although there are other factors that affect it less strongly.
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.
An unstable approach is an approach during which an aircraft does not maintain certain essential flight parameters within reasonable limits. [1] [2] This usually includes at least one of the following variables stable: speed, descent rate, vertical/lateral flight path and in landing configuration, or receive a landing clearance by a certain altitude.