Abstract: A method of operating an electrically powered rotorcraft of the type having a fuselage and a set of N rotors driven by a set of electric motors and coupled to the fuselage, N?4, under a failure condition preventing ordinary operation of the rotorcraft. The method includes entering a failsafe mode of operation wherein autorotation of at least four of the rotors is enabled. The method also includes using electrical braking associated with a selected group of the rotors to control pitch, roll and yaw of the rotorcraft.

Abstract: An improved electrically powered rotorcraft is of the type having a rotor including a rotor hub and a pair of rotor blades mounted to the rotor hub on opposite sides thereof, the rotor being rotatably mounted on a primary drive shaft, and a rotary electric motor coupled to the drive shaft. In this rotorcraft, the improvement includes a common pitch-angle shaft coupled to each of the blades; a limited-angle electric motor, mechanically coupled to the common pitch-angle shaft, and configured to cause rotation of the common pitch angle shaft and therefore adjustment of pitch of the pair of rotor blades; and a controller system in communication with the limited-angle electric motor, configured to provide cyclic control of pitch of the pair of rotor blades.

Abstract: Systems and methods of communication synchronization are described herein. An exemplary system includes two or more radios and a cloud controller. The two or more radios are collocated with one another and they communicate with two far radios over a pair of long range wireless links. The two or more radios are configured to transmit and receive in synchronization with one another on a same channel. An off-axis response for each of the two or more radios is reduced compared to their on-axis response for improved signal to noise ratio.

Abstract: Simultaneous transmission on a shared channel by a plurality of collocated radios is provided herein. The two or more radios are collocated with one another and are communicating with two far radios over a pair of long range wireless links. The two or more radios are configured to transmit and receive in synchronization with one another on a same channel. An off-axis response for each of the two or more radios is reduced compared to their on-axis response for improved signal to noise ratio, and the on-axis response the two or more radios are substantially equal to one another.

Abstract: A contra-rotating electric helicopter utilizes an electric motor having a base and an output shaft and a power source. The helicopter couples the base to a first rotor, thus allowing both the base and the power source to rotate within the frame of reference of the first rotor, while a contra-rotating and coplanar second rotor is coupled to the output shaft of the electric motor.

Abstract: An improved vertical takeoff aircraft of the type having a set of pads that are in contact with the ground when the aircraft is at rest on the ground and a controllable lift and propulsion system. The aircraft includes an array of force sensors coupled to the set of pads. The array has an output providing measurements over time of forces exerted on the pads along at least two independent axes. The aircraft also includes a controller, coupled to the lift and propulsion system and to the array of force sensors. The controller is configured to control the lift and propulsion system in a manner to counteract forces exerted externally on the aircraft that would cause undesired motion of the aircraft when on the ground and transitioning from the ground to flight.

Abstract: A method of operating an electrically powered rotorcraft of the type having a fuselage and a set of N rotors driven by a set of electric motors and coupled to the fuselage, N ? 4, under a failure condition preventing ordinary operation of the rotorcraft. The method includes entering a failsafe mode of operation wherein autorotation of at least four of the rotors is enabled. The method also includes using electrical braking associated with a selected group of the rotors to control pitch, roll and yaw of the rotorcraft.

Abstract: A method of operating an electrically powered rotorcraft of the type having a fuselage and a set of N rotors driven by a set of electric motors and coupled to the fuselage, N?4, under a failure condition preventing ordinary operation of the rotorcraft. The method includes entering a failsafe mode of operation wherein autorotation of at least four of the rotors is enabled. The method also includes using electrical braking associated with a selected group of the rotors to control yaw of the rotorcraft.

Abstract: WiFi repeater devices described provided herein. An example device includes an enclosure that is configured to be mounted to a window that divides an outdoor area from an indoor area. The enclosure houses a 5 GHz WiFi client radio coupled with a high order MIMO (multiple input, multiple output) antenna, the high order MIMO antenna transmitting and receiving data from a 5 GHz access point located in the outdoor area, and a 2.4 GHz WiFi access point radio coupled with a MIMO (multiple input, multiple output) antenna, the MIMO antenna transmitting and receiving data from 2.4 GHz UEs located in the indoor area.

Abstract: An improved rotorcraft of the type having a fuselage and a set of N?4 rotors. The rotorcraft includes a structural support system affixed to the fuselage and mounting the set of rotors. The support system is configured as a set of airfoils that provide lift when the fuselage is in level flight. The fuselage has a central longitudinal axis that defines the direction of forward flight of the rotorcraft. Each of the rotors defines a corresponding rotational plane, that is tilted forward in the direction of the forward flight, when the central longitudinal axis of the fuselage is horizontal. Each airfoil may be positioned so that a majority of its length is disposed beneath the rotational plane of its corresponding rotor. When the rotorcraft is at a cruise speed, the airfoils are configured to provide lift that approximately matches the lift provided by the rotors.

Abstract: Ellipticity reduction in circularly polarized array antennas is provided herein. An antenna array may include a processor that is configured to control a plurality of elements, each of the plurality of elements producing an elliptically polarized wave having an eccentricity value, the elliptically polarized wave traveling along a direction of propagation, wherein at least a portion of the plurality of elements are incrementally clocked around their direction of propagation, so that a combined output of the plurality of elements is substantially circularly polarized.

Abstract: A method of charging a battery system of an electrically powered aircraft that is at a location on the ground. The method moves an Aircraft Charging Unit (ACU) to a position proximate to the location, the ACU having a set of storage batteries, a charge controller, and a connection system. The method further couples the set of storage batteries to the battery system through the connection system of the ACU and causes transfer of energy from the set of storage batteries to the battery system under control of the charge controller. The method then decouples the set of storage batteries from the battery system of the aircraft.

Abstract: Sector antenna arrays and methods of use that provide high main-lobe gain and high side-lobe rejection over a wide range of operating frequencies are provided herein. The example sector antennas provide these outstanding performance and reliability features due to (1) a cross-section profile for the ground plane, (2) a corporate feed for the linear array of patch antennas, and (3) an optimized sub-assembly of parasitic elements for high bandwidth operation with low return-loss.

Abstract: Multi-band antenna arrays and methods of use are provided herein. An example device includes vertical surfaces arranged into a tubular configuration, where each of the vertical surfaces comprising antenna arrays is aligned along the vertical surfaces. The antenna elements are arrayed through a feed network in such a way that antenna gain is increased while elevation beam-width is reduced. The device also includes two or more radios connected to the antenna arrays on the vertical surfaces via the feed network.

Abstract: Multi-band antenna arrays and methods of use are provided herein. An example device includes vertical surfaces arranged into a tubular configuration, where each of the vertical surfaces comprising antenna arrays is aligned along the vertical surfaces. The antenna elements are arrayed through a feed network in such a way that antenna gain is increased while elevation beam-width is reduced. The device also includes two or more radios connected to the antenna arrays on the vertical surfaces via the feed network.

Abstract: WiFi repeater devices described provided herein. An example device includes an enclosure that is configured to be mounted to a window that divides an outdoor area from an indoor area. The enclosure houses a 5 GHz WiFi client radio coupled with a high order MIMO (multiple input, multiple output) antenna, the high order MIMO antenna transmitting and receiving data from a 5 GHz access point located in the outdoor area, and a 2.4 GHz WiFi access point radio coupled with a MIMO (multiple input, multiple output) antenna, the MIMO antenna transmitting and receiving data from 2.4 GHz UEs located in the indoor area.

Abstract: Ellipticity reduction in circularly polarized array antennas is provided herein. An antenna array may include a processor that is configured to control a plurality of elements, each of the plurality of elements producing an elliptically polarized wave having an eccentricity value, the elliptically polarized wave traveling along a direction of propagation, wherein at least a portion of the plurality of elements are incrementally clocked around their direction of propagation, so that a combined output of the plurality of elements is substantially circularly polarized.

Abstract: WiFi repeater devices described provided herein. An example device includes an enclosure that is configured to be mounted to a window that divides an outdoor area from an indoor area. The enclosure houses a 5 GHz WiFi client radio coupled with a high order MIMO (multiple input, multiple output) antenna, the high order MIMO antenna transmitting and receiving data from a 5 GHz access point located in the outdoor area, and a 2.4 GHz WiFi access point radio coupled with a MIMO (multiple input, multiple output) antenna, the MIMO antenna transmitting and receiving data from 2.4 GHz UEs located in the indoor area.

Abstract: A method and system are provided. The system includes a communication system including a first transmitter/receiver operating on a first frequency and a second transmitter/receiver operating on a second frequency. The system also includes a controller monitoring at least one of interference and throughput on the first and second transmitter/receiver and shifting demand based on the monitoring.

Abstract: Wireless access points providing hybrid 802.11 and scheduled priority access communications are provided herein. An exemplary wireless access point may be configured to communicate with a set of standard access clients using an 802.11 mode of communication during standard access phases, as well as communicate with a set of priority access clients during priority access phases, when the wireless access point is not communicating with the set of standard access clients, using a priority mode of communication.