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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.
English: Note that aircraft can also by statically unstable. Diagram showing the three main cases for aircraft pitch dynamic stability. Here all three cases are for a statically stable aircraft. Following a pitch disturbance, three cases are shown: Aircraft is dynamically unstable (although statically stable);
In flight dynamics, longitudinal stability is the stability of an aircraft in the longitudinal, or pitching, plane. This characteristic is important in determining whether an aircraft pilot will be able to control the aircraft in the pitching plane without requiring excessive attention or excessive strength.
The missile is characterised by only three stability derivatives, and hence provides a useful introduction to the more complex aeroplane dynamics. This diagram shows lift as perpendicular to the longitudinal body axis. In most technical usage, lift is perpendicular to the oncoming flow. That is, perpendicular to the longitudinal stability axis.
Flight dynamics is the science of air-vehicle orientation and control in three dimensions. The critical flight dynamics parameters are the angles of rotation with respect to the three aircraft's principal axes about its center of gravity, known as roll, pitch and yaw.
In steady level longitudinal flight, thrust counterbalances drag and lift supports the aircraft's weight. Lift and drag are components of the aerodynamic force. Steady flight, unaccelerated flight, or equilibrium flight is a special case in flight dynamics where the aircraft's linear and angular velocity are constant in a body-fixed reference ...
The distribution of forces on a wing in flight are both complex and varying. This image shows the forces for two typical airfoils, a symmetrical design on the left, and an asymmetrical design more typical of low-speed designs on the right. This diagram shows only the lift components; the similar drag considerations are not illustrated.