YAW-enhancing attitude control system for VTOL fixed-wing aircraft
View Patent ↗An unmanned aircraft capable of vertical takeoff, vertical landing, and/or flight in a hovering orientation is presented; its fixed-wing is positively-swept and of low aspect-ratio with suitable airfoils. The unmanned aircraft includes a thruster comprising two contra-rotating motors and propellers forward of the fixed-wing's leading-edge and a rudderless fin aft of the center-of-mass, all of which lie on the aircraft's plane-of-symmetry. Two elevons provide pitch and roll control. The unmanned aircraft can stand upright on its feet. A control system for aircraft with at least one wing is also presented. The control system includes a mount and attached thruster which lie on the plane-of-symmetry forward of the fixed-wing's leading-edge. A hinge axis approximately perpendicular to the aircraft's horizontal plane passes through the mount. The thruster rotates about the hinge axis for aircraft yaw control.
1. A control system for aircraft with at least one fixed-wing ( 1 ), the control system comprising:
a mount ( 8 );
(i) where the mount ( 8 ) is located forward of the wing's ( 1 ) leading-edge ( 101 );
(ii) where the mount ( 8 ) lies on the plane of symmetry ( 114 );
a thruster ( 2 );
(iii) where the thruster ( 2 ) is attached to the mount ( 8 );
a horizontal plane ( 115 );
(iv) where the horizontal plane ( 115 ) is perpendicular to the aircraft's plane-of-symmetry ( 114 ) and coincident with the leading edge ( 104 ) of the wing's root airfoil and the trailing edge ( 105 ) of the wing's root airfoil;
a hinge axis ( 116 );
(v) where the hinge axis ( 116 ) is approximately perpendicular to the horizontal plane ( 115 ) such that the axis angle ( 117 ) between the horizontal plane ( 115 ) and the hinge axis ( 116 ) is between 65 and 115 degrees;
where the thruster ( 2 ) rotates about the hinge axis ( 116 ); and
a fin ( 6 );
where the fin ( 6 ) does not have an attached control surface;
where the fin ( 6 ) does not rotate with respect to the fixed-wing ( 1 );
where the fin ( 6 ) lies on the plane of symmetry ( 114 ), aft of the aircraft's center-of-mass ( 112 ), and within the thruster's ( 2 ) slipstream ( 201 ).
2. The control system for aircraft according to claim 1 , further characterized by:
where the thruster ( 2 ) does not rotate about another axis except the hinge axis ( 116 ).
3. The control system for aircraft according to claim 1 , wherein the thruster ( 2 ) comprises:
(i) two motors ( 3 );
(ii) two propellers ( 4 ), each of the two propellers comprising:
(1) a leading propeller ( 401 ); and
(2) a trailing propeller ( 402 );
(iii) where the two motors ( 3 ) and two propellers ( 4 ) are coaxial;
(iv) where the two motors ( 3 ) and two propellers ( 4 ) are counter-rotating, where the two propellers ( 4 ) are fixed-pitch.
4. The control system for aircraft according to claim 1 , the control system further comprising:
elevons ( 5 );
where the elevons ( 5 ) are designed to deflect symmetrically for pitch-control;
where the elevons ( 5 ) are designed to deflect differentially for roll-control;
where the elevons ( 5 ) are of approximately equal size and shape;
where the elevons ( 5 ) are symmetrically-located about the plane of symmetry ( 114 );
where the elevons ( 5 ) are partially or wholly located within the thruster's ( 2 ) slipstream ( 201 ).
5. The control system for aircraft according to claim 1 , further characterized by:
the aircraft being unmanned;
the aircraft being of a flying-wing design;
the aircraft being of a tail-sitter design.
6. The control system for aircraft according to claim 1 , the control system further comprising:
a gap ( 801 );
where the gap ( 801 ) provides clearance between the mount ( 8 ) and the leading-edge ( 101 ) of the fixed-wing ( 1 ) to prevent interference during mount rotation;
a pin anchor ( 802 );
(i) where the pin anchor ( 802 ) is located near the leading-edge ( 101 ) of the wing ( 1 );
(ii) where the pin anchor ( 802 ) lies on the plane-of-symmetry ( 114 );
a pin ( 803 ), which:
(iii) is oriented along the hinge axis ( 116 );
(iv) is located near the leading-edge ( 101 ) of the fixed-wing ( 1 );
(v) connects the mount ( 8 ) to the pin anchor ( 802 ); and
(vi) whereby the pin ( 803 ) allows the mount ( 8 ) to rotate relative to the pin anchor ( 802 ) about the hinge axis ( 116 ).
7. The control system for aircraft according to claim 1 , the control system for aircraft further comprising:
a servo ( 804 );
a servo horn ( 805 );
a control horn ( 806 );
a push-pull rod ( 807 );
where the servo ( 804 ) is attached to the mount ( 8 ) or to the fixed-wing ( 1 ) near its leading edge ( 101 ),
where the servo horn ( 805 ) is attached to the servo ( 804 ),
where the control horn ( 806 ) is attached to the fixed-wing ( 1 ) near its leading edge ( 101 ) or to the mount ( 8 ),
where one end of the push-pull rod ( 807 ) is attached to the servo horn ( 805 ) and the other end of the push-pull rod ( 807 ) is attached to the control horn ( 806 ).
8. The control system for aircraft according to claim 1 , wherein the mount ( 8 ) comprises:
a forward mount ( 817 ), the forward mount ( 817 ) comprising:
(i) a forward mounting plate ( 831 );
(ii) a forward upper plate ( 818 ); and
(iii) a forward lower plate ( 819 );
(iv) where the forward upper plate ( 818 ) and forward lower plate ( 819 ) are located on the forward mounting plate ( 831 ) and extend rearward with respect to the forward mounting plate ( 835 );
an aft mount ( 813 ), the aft mount ( 813 ) comprising:
(v) an aft mounting plate ( 832 );
(vi) an aft upper plate ( 814 );
(vii) an aft lower plate ( 815 );
(viii) where the aft upper plate ( 814 ) and aft lower plate ( 815 ) are located on the aft mounting plate ( 832 ) and extend forward with respect to the aft mounting plate ( 832 ); and
(ix) where the aft mount ( 813 ) is fixed to the aircraft;
hinge holes ( 816 ), where a hinge hole ( 816 ) is located on:
(x) the forward upper plate ( 818 ),
(xi) the forward lower plate ( 819 ),
(xii) the aft upper plate ( 814 ),
(xiii) the aft lower plate ( 815 ),
(xiv) where the hinge holes ( 816 ) are concentric with each other,
where the hinge axis ( 116 ) passes through the center of the hinge holes ( 816 ), where the forward mount ( 817 ) is designed to rotate with respect to the aft mount ( 813 ) about the hinge axis ( 116 ) to facilitate aircraft yaw control.
9. The control system for aircraft according to claim 1 , the control system further comprising two motors ( 3 );
where the motors ( 3 ):
(i) are coaxial,
(ii) counter-rotating,
(iii) attached to the forward mount ( 817 ),
(iv) are designed to rotate with the forward mount ( 817 ) about the hinge axis ( 116 ), wherein the forward mounting plate ( 831 ) comprises:
(v) a central hole ( 820 );
(vi) where one of the motors ( 3 ) passes through the central hole ( 820 ).
10. The control system for aircraft according to claim 1 , the control system further comprising:
a servo ( 804 );
a servo horn ( 805 );
a control horn ( 806 );
a push-pull rod ( 807 );
where the servo ( 804 ) is attached to the mount ( 8 ) and located within its skin ( 811 );
where the servo horn ( 805 ) attaches to the servo ( 804 );
where the control horn ( 806 ) is located on the forward mount ( 817 );
where one end of the push-pull rod ( 807 ) is attached to the servo horn ( 804 ) and the other end of the push-pull rod ( 807 ) is attached to the control horn ( 806 );
where forces exerted on the push-pull rod ( 807 ) by the servo ( 804 ) cause the forward mount ( 817 ) to rotate with respect to the aft mount ( 813 ).
11. The control system according to claim 8 , further comprising:
a hinge bolt ( 827 );
where the hinge bolt ( 827 ) comprises:
(i) a threaded portion ( 836 );
(ii) a smooth portion ( 837 );
(iii) a head ( 838 );
where the threaded portion ( 836 ) is closer to the head ( 838 ) of the hinge bolt ( 827 ) than the smooth portion ( 837 );
where the threaded portion ( 836 ) has a larger outer-diameter than the smooth portion ( 837 );
where the threaded portion ( 837 ) engages either the forward ( 817 ) or aft ( 813 ) mount by screwing-into its hinge holes ( 816 );
where the smooth portion engages the opposite mount ( 813 , 817 ) by insertion into its hinge holes ( 816 );
where the forward mount ( 817 ) can rotate with respect to the aft mount ( 813 ).
12. The control system according to claim 8 , wherein the fin ( 6 ) is approximately symmetric about the horizontal plane ( 115 ) such that it extends both above and below the fixed wing ( 1 ).
13. A control system for aircraft with at least one fixed-wing ( 1 ), the control system comprising:
a mount ( 8 );
(i) where the mount ( 8 ) is located forward of the wing's ( 1 ) leading-edge ( 101 );
(ii) where the mount ( 8 ) lies on the plane of symmetry ( 114 );
a thruster ( 2 );
(iii) where the thruster ( 2 ) is attached to the mount ( 8 );
where the thruster ( 2 ) does not rotate about another axis except the hinge axis ( 116 ), wherein the thruster ( 2 ) comprises:
(i) two motors ( 3 );
(ii) two propellers ( 4 ), each of the two propellers comprising:
(1) a leading propeller ( 401 ); and
(2) a trailing propeller ( 402 );
(iii) where the two motors ( 3 ) and two propellers ( 4 ) are coaxial;
(iv) where the two motors ( 3 ) and two propellers ( 4 ) are counter-rotating, where the two propellers ( 4 ) are fixed-pitch;
a horizontal plane ( 115 );
(iv) where the horizontal plane ( 115 ) is perpendicular to the aircraft's plane-of-symmetry ( 114 ) and coincident with the leading edge ( 104 ) of the wing's root airfoil and the trailing edge ( 105 ) of the wing's root airfoil;
a hinge axis ( 116 );
(v) where the hinge axis ( 116 ) is approximately perpendicular to the horizontal plane ( 115 ) such that the axis angle ( 117 ) between the horizontal plane ( 115 ) and the hinge axis ( 116 ) is between 65 and 115 degrees;
where the thruster ( 2 ) rotates about the hinge axis ( 116 ); and
a fin ( 6 );
where the fin ( 6 ) does not have an attached control surface;
where the fin ( 6 ) does not rotate with respect to the fixed-wing ( 1 );
where the fin ( 6 ) lies on the plane of symmetry ( 114 ), aft of the aircraft's center-of-mass ( 112 ), and within the thruster's ( 2 ) slipstream ( 201 ).