Variable pitch rotor assembly for electrically driven vectored thrust aircraft applications
An aircraft employs articulated, variable-position electric rotors having different operating configurations and transitions therebetween, as well as variable-pitch airfoils or blades, for generating vectored thrust in the different configurations. Control circuitry generates rotor position signals and blade pitch signals to independently control rotor thrust, rotor orientation and rotor blade pitch of the variable-position rotors in a manner providing (i) the transitions among the operating configurations for corresponding flight modes of the aircraft, which may include both vertical takeoff and landing (VTOL) mode as well as a forward-flight mode, and (ii) commanded thrust-vectoring maneuvering of the aircraft in the different configurations, including tailoring blade pitch to optimize aspects of aircraft performance.
1. An aircraft, comprising:
an airframe;
a plurality of articulated electric rotors attached to the airframe, at least some of the rotors being variable-position rotors having a plurality of operating configurations and transitions between the operating configurations based on rotor position signals, the rotors generating respective magnitudes and directions of vectored thrust in respective operating configurations as the result of the coordinated actuation of one or more degrees-of-freedom relative to the aircraft, the variable-position rotors being further configured for variable pitch of respective rotor blades in response to respective blade pitch signals;
a source of electrical power for powering the rotors; and
control circuitry configured and operative to generate the rotor position signals and blade pitch signals to independently control rotor thrust, rotor orientation and rotor blade pitch of each of the variable-position rotors in a manner providing (i) the transitions among the operating configurations for corresponding flight modes of the aircraft, and (ii) commanded thrust-vectoring maneuvering of the aircraft in the different configurations,
wherein each of the variable-position rotors includes a respective arrangement having a blade pitch actuator coupled to a variable-pitch mechanism, the variable-pitch mechanism configured and operative to translate a rotational output of the blade pitch actuator to corresponding variable-pitch rotation of the rotor blade,
wherein the variable-pitch mechanism includes a rotational interface, push rod and cross arm, the rotational interface translating between the rotational output of the blade pitch actuator and corresponding linear movement of the push rod, the cross arm being coupled between the push rod and a flange of the rotor blade to translate the linear movement of the push rod to the variable-pitch rotation of the rotor blade,
and wherein the variable-position rotors have an outrunner configuration in which an outer motor portion rotates about an inner motor portion fixed to the airframe, and the push rod extends axially through the outer motor portion and does not rotate with the rotor.
2. The aircraft of claim 1 , wherein the variable-pitch mechanism further includes a housing directly coupled to the outer motor portion to function as a heat sink for heat generated by the motor in operation, the housing facing an oncoming airstream to provide for dissipation of the generated heat.
3. The aircraft of claim 2 , wherein the housing has external cooling fins providing increased surface area of the dissipation of the generated heat.
4. The aircraft of claim 1 , wherein the rotors include front rotors located forward of a center of the aircraft and rear rotors located rearward of the center of the aircraft, the front rotors having either an upward or downward orientation and the rear rotors having an opposite orientation to the orientation of the front rotors.
5. The aircraft of claim 4 , wherein the rotors having upward orientation are configured to provide tractor propulsion and the rotors having downward orientation are configured to provide pusher propulsion.
6. The aircraft of claim 1 , wherein the rotors include front rotors located forward of a center of the aircraft and rear rotors located rearward of the center of the aircraft, the front rotors having either an upward or downward orientation and the rear rotors having the same orientation as the orientation of the front rotors.
7. The aircraft of claim 1 having a symmetric configuration in which front and rear rotors are the variable-position rotors and are operated (1) in a VTOL and hover mode, with the front and rear rotors positioned for vertical lift, (2) in a transition mode, with the front and rear rotors positioned for lift and transition assist, and (3) in a forward flight mode, with the front and rear rotors positioned for forward thrust.
8. The aircraft of claim 1 having an asymmetric configuration in which front rotors are full-variable-position rotors and the rear rotors are limited-variable-position rotors, and the front and rear rotors are operated (1) in a VTOL and hover mode, with the front and rear rotors positioned for vertical lift, (2) in a transition mode, with the front and rear rotors positioned for lift and transition assist, and (3) in a forward flight mode, with the front rotors positioned for forward thrust and the rear rotors being deactivated.
9. The aircraft of claim 1 having an asymmetric configuration in which front rotors are the variable-position rotors and the rear rotors are fixed-position rotors, and the front and rear rotors are operated (1) in a VTOL and hover mode, with the front rotors positioned for vertical lift along with activation of the rear rotors, (2) in a transition mode, with the front rotors positioned for lift and transition assist with activation of the rear rotors for lift assist, and (3) in a forward flight mode, with the front rotors positioned for forward thrust and the rear rotors being deactivated.
10. The aircraft of claim 1 , wherein the variable-position rotors are configured for variable angular position about a tilt axis relative to a direction of motion of the aircraft.
11. The aircraft of claim 10 , wherein the variable-position rotors are further configured for variable angular position about a yaw axis relative to a direction of motion of the aircraft, a combination of the variable angular positions about the tilt axis and yaw axis providing a resultant rotor orientation having respective angular components about the tilt axis and the yaw axis.
12. The aircraft of claim 1 , wherein the variable-position rotors include respective servo control mechanisms for commanded positioning thereof.
13. The aircraft of claim 12 , wherein the servo control mechanisms are parallel tandem servo mechanisms.