Aircrafts tail section drag compensating for nose-down pitching moment
AssigneeThe Boeing Company
InventorArmand Sigalla
Life of this patent
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Abstract
In an aircraft exhibiting an undesirable nose-down pitching moment due to a rearward shift of the wing lift acting aft of the characteristic pitch axis of the aircraft as speed increases in a certain speed regime, the vertical member of the tail section is configured to develop an increasing drag. The increasing tail member drag acts in elevation above the horizontal plane that contains the pitch axis so as to develop a counteracting nose-up pitching moment that mitigates the unwanted nose-down pitching component associated with changing wing lift characteristics.
Claims9
An aircraft comprising the combination of a fuselage, swept wings mounted near mid-body of the fuselage and a tail section, and having a characteristic speed-dependent, nose-down pitching moment due to rearward movement of the center of lift pressure on the wings as the aircraft while in level flight increases speed in a predetermined speed regime, said tail section having a vertical tail member rising from a root connected to said fuselage and terminating at a tip, said vertical tail member being so configured between said root and tip to provide a passive means for developing a compensating drag component that increases as the speed of said aircraft increases in said predetermined speed regime and acts on said tail member above its root so as to produce a speed-dependent, nose-up pitching component that substantially matches in magnitude versus speed, said characteristic speed-dependent, wing associated, nose-down pitching moment of the aircraft, so as to passively counteract said characteristic nose-down pitching moment.
In an aircraft having a fuselage, swept wings mounted near mid-body of the fuselage and a tail section including a vertical tail member, and exhibiting a characteristic speed-dependent, wing-associated, nose-down pitching moment due to rearward shifting of a center of lift pressure on the wings as the aircraft while in level flight increases speed in a predetermined speed regime, the combination therewith of passive means associated with said vertical tail member of said tail section for developing a compensating drag characteristic that increases as the speed of said aircraft increases in said predetermined speed regime and has a magnitude and acts on said vertical tail member so as to produce a speed-dependent, nose-up pitching component selected to substantially match in magnitude versus speed, said speed-dependent, wing associated, nose-down pitching moment of the aircraft.
Dependencies are inferred from the claim text.