phugoid

(redirected from Plughoid)

phugoid

[′fü‚gȯid]
(aerospace engineering)
Pertaining to variations in the longitudinal motion or course of the center of mass of an aircraft.

phugoid

phugoidclick for a larger image
A pitching motion in which kinetic and potential energy (speed and altitude, in this case) are traded. Each cycle typically lasts about 60 s and may continue for many minutes. The motion resembles a roller coaster in which, as the aircraft nose pitches up, the air speed decreases, and as the nose drops, the air speed increases. There is, however, little or no change in the load factor if the aircraft has a neutral pitch stability. The pitching motion is usually damped, and the degree of damping is dependent upon the aircraft's design characteristics (i.e., the amount of positive pitch stability).