Vol.3, No 11, 2001 pp.251-259
UDC 534.012+531.565:629.7(045)

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QUASILINEAR LONGITUDINAL STABILITY OF AN AIRCRAFT
Michael Damianov Todorov
Technical University-Sofia, Faculty of Transport, Dept. of Aeronautics
BG-1756, Sofia, Darvenitza

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Abstract. The equations of the longitudinal motion are usually solved in the literature, using the method of linearization about a mean state of steady flight, to obtain the frequency and damping of the phugoid and short-period modes.
In the present paper the quasilinear differential equations are obtained for constant air density and constant thrust along the flight path. The exact balance of lift, drag, weight, and inertia force is taken, together with the pitching moment equation, under the assumptions of flight at low Mach number. Three numerical examples are given: of a statically stable fighter, a statically unstable fighter and a large transport aircraft.

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KVAZI LINEARNA LONGITUDINALNA STABILNOST LETILICE Jednačine longitudinalnog kretanja uobičajeno prikazane u literaturi, su rešene metodom linearizacije oko srednjeg stanja ustaljenog leta, radi dobijanja frekvencije i prigušenja i kratko-periodičnih modova.
U ovom radu kvazilinearne diferencijalne jednačine su dobijene za konstantnu gustinu vazduha i konstantan potisak duže putanje leta.
Egzaktno uravnoteženje uzgona, otpora, težine i sila inercije je uzeto u račun, pod pretpostavkom da je let režimu makovog broja.
Tri numerička primera su dobijena: statički stabilnih flater, statički nestabilni flater, kao i za transportnu letilicu.