Free wing multirotor transitional S/VTOL aircraft
An improved aircraft design to harness advantages of vertical or short-takeoff and landings (V/STOL) and efficient horizontal flight is disclosed. The aircraft design includes multiple thrust sources and wings which are free to rotate on a spanwise axis, and have their center of gravity aft of the axis of rotation. Wing rotation is decoupled from both the fuselage and the thrust sources. Wings are coupled to each other such that rotation induced in one wing affects rotation in all wings. Thrust sources are directed vertically during hover and some degree forward of vertical for horizontal flight. The disclosed configuration improves aircraft flight stability and efficiency in all flight profiles: vertical flight, transition to/from horizontal flight, and horizontal flight. The aircraft has the possibility of a controlled emergency landing using autorotation of the propellers, wings or a combination of the two.
1 . An aircraft comprising:
free wings having control surfaces;
a fuselage;
a vertical stabilizer;
spars positioned both fore and aft, and on both left and right sides of the fuselage; and
multiple rotatably thrust producing rotors producing both vertical and horizontal thrust vectors,
wherein the free wings are mounted on each one of the spars such that they each are free to rotate about the spar on a span wise spar-centered axis without physical or mechanical coupling to the thrust producing rotors and the fuselage, the free wings are coupled front-to-back and side-to-side with each other such that a rotation induced in one free wing affects all free wings, and
a center of mass of each free wing is located at a distance behind the spar-centered axis of rotation;
the rotatably thrust producing rotors are configured with propellers, are mounted on ends of each one of the spars, and are rotatable from a horizontal to a vertical orientation.
2 . The aircraft of claim 1 wherein the propellers are variable pitch.
3 . The aircraft of claim 1 wherein a relative angle of attack of the fore and the aft wings can be adjusted.
4 . The aircraft of claim 1 wherein a relative angle of attack of the left and the right wings can be adjusted.
5 . An aircraft comprising:
an airframe comprising two or more spars positioned fore and aft on the airframe and extending laterally;
free wings having control surfaces are positioned on the spars such that they rotate about the spar on a spar-centered axis of rotation;
at least three rotatably from horizontal to vertical thrust producing rotors located at outermost ends of each one of the spars;
wherein the free wings are mechanically coupled front-to-back and side-to-side with each other such that a rotation induced in one free wing affects all free wings, and a center of mass of each free wing is located at a distance aft of the spar-centered axis of rotation, and
the free wings rotate about their respective spar without physical or mechanical coupling to a fuselage and the rotatably thrust producing rotors.
6 . The aircraft according to claim 5 , wherein each of the rotatably thrust producing rotors rotate about the respective spar without physical or mechanical coupling to the free wing.
7 . The aircraft according to claim 5 , wherein a relative angle of attack of the fore and the aft wings can be adjusted.
8 . The aircraft according to claim 5 , wherein a relative angle of attack of a left wing and a right wing can be adjusted.
9 . The aircraft according to claim 5 , wherein during horizontal flight, the free wings are positioned horizontally with the airframe and induce lift.
10 . The aircraft according to claim 5 , wherein during vertical flight, the free wings are positioned in a chord vertical attitude.
11 . The aircraft according to claim 5 , wherein the airframe is maintained in a generally horizontal attitude throughout vertical, transitional and horizontal flight modes.
12 . The aircraft according to claim 5 , wherein the at least three thrust producing rotors are configured to provide stability to the aircraft in vertical, transitional, and horizontal flight modes.
13 . An aircraft comprising:
a fuselage comprising a vertical stabilizer, two sides, a floor, and at least two spars coupled thereto and extending laterally therefrom;
four rotatably from horizontal to vertical thrust producing rotors with one positioned on each spar;
free wings having control surfaces positioned on each spar having a spar-centered center of rotation, coupled front-to-back and side-to-side with one another and without physical or mechanical coupling to and between the fuselage and the rotatably thrust producing rotors;
wherein a center of mass of each free wing is located aft of the spar-centered center of rotation of the free wing, and each of the four rotatably thrust producing rotors is located outside of each free wing.
14 . The aircraft according to claim 13 , wherein the thrust producing rotors rotate about the spar without physical or mechanical coupling to the free wing.
15 . The aircraft according to claim 13 , wherein each thrust producing rotor comprises a propeller, and configured to tilt through a range of motion for vertical, transitional, and horizontal flight modes.
16 . The aircraft according to claim 13 , wherein during vertical flight, the free wings are positioned in a chord vertical attitude.
17 . The aircraft according to claim 13 , wherein the four rotatably thrust producing rotors are configured to provide stability to the aircraft in vertical, transitional, and horizontal flight modes.
18 . The aircraft according to claim 9 , wherein the free wings are positioned horizontally aerodynamically.
19 . The aircraft according to claim 10 , wherein during vertical flight, the free wings are positioned gravitationally in the chord vertical attitude.