Active Dihedral Control System for a Torsionally Flexible Wing

Abstract

A span-loaded, highly flexible flying wing, having horizontal control surfaces mounted aft of the wing on extended beams to form local pitch-control devices. Each of five spanwise wing segments of the wing has one or more motors and photovoltaic arrays, and produces its own lift independent of the other wing segments, to minimize inter-segment loads. Wing dihedral is controlled by separately controlling the local pitch-control devices consisting of a control surface on a boom, such that inboard and outboard wing segment pitch changes relative to each other, and thus relative inboard and outboard lift is varied.

We claim: 
     
         1 . An aircraft characterized by a flight envelope, comprising:
 a laterally extending wing;   a plurality of pitch-control devices, each pitch-control device being mounted at a separate lateral location along the wing, and each pitch-control device being configured to apply pitch-control torque at its lateral location, wherein the wing is characterized by a torsional flexibility adapted to allow the plurality of pitch control devices to control localized pitch at their lateral wing locations to a degree substantial enough to be significant for flight control; and   a control system configured to control the plurality of pitch-control devices based upon the relative localized pitches at the plurality of lateral locations.   
     
     
         2 . The aircraft of  claim 1 , wherein each pitch-control device is adapted to cause a control surface pitch effect and a control surface flap effect, and wherein each pitch-control device includes a boom connecting the wing to a control surface aft of the trailing edge of the wing at a distance adequate to cause the control surface pitch effect to dominate the control surface flap effect. 
     
     
         3 . The aircraft of  claim 1 , wherein the control system is configured to operate the pitch-control devices under a protocol adapted to control and alter wing dihedral based upon the dihedral of the wing. 
     
     
         4 . The aircraft of  claim 3 , wherein the protocol actively provides for dihedral control and alteration that maintains the wing bending stresses within safety limits. 
     
     
         5 . The aircraft of  claim 1 , and further comprising a plurality of motors, wherein the control system is configured to separably control the thrust from the plurality of motors based upon fore-and-aft wing loads between the motors. 
     
     
         6 . The aircraft of  claim 1 , wherein the pitch-control devices include both fixed and controllable horizontal surfaces. 
     
     
         7 . The aircraft of  claim 4 , wherein the protocol is configured to direct outboard pitch-control devices with more downward pitching pitch-control torques than pitch-control torques of inboard pitch-control devices. 
     
     
         8 . The aircraft of  claim 1 , wherein the aircraft is controlled without the use of elevators. 
     
     
         9 . An aircraft characterized by a flight envelope, comprising:
 a laterally extending wing;   a means for separately actuating the pitch of the wing at a plurality of lateral locations along the wing, wherein the wing is characterized by a torsional flexibility adapted to allow the means for separately actuating to actuate localized pitch at the plurality of lateral locations to a degree substantial enough to be significant for flight control; and   a means for controlling the means for separately actuating based upon the relative localized pitches at the plurality of lateral locations.   
     
     
         10 . A method of controlling an aircraft characterized by a flight envelope, comprising:
 separately actuating the pitch of a laterally extending wing at a plurality of lateral locations along the wing, wherein the wing is characterized by a torsional flexibility adapted to allow the means for separately actuating to actuate localized pitch at the plurality of lateral locations to a degree substantial enough to be significant for flight control; and   controlling the means for separately actuating based upon the relative localized pitches at the plurality of lateral locations.   
     
     
         11 . The method of  claim 10 , wherein the step of controlling includes directing the pitch-control devices under a protocol configured to control and alter wing dihedral based upon the dihedral of the wing.