Abstract: A moving-vane angle of attack probe is provided. The moving-vane angle of attack probe comprises: a vane having opposed first and second vane surfaces that define a leading edge and a trailing edge, the first and second vane surfaces, each extending between the leading edge and the trailing edge; a first vane opening located on the leading edge; at least one exhaust opening; a vane conduit extending between the first vane opening and the exhaust opening such that the first vane opening and the exhaust opening are in fluid communication, the vane conduit defining at least an interior chamber between the first and second vane surfaces; and a pitot-tube located within the interior chamber such that in use it receives air that enters the interior chamber via the first vane opening.

Abstract: An ultrasonic airspeed and direction sensor system comprising an ultrasonic sensor array including an elongate base member for mounting to a vehicle, such as a helicopter, so as to extend outwardly from the vehicle. A number of radially extending support members are connected to the base member. The support members carry ultrasonic transducers arranged to define at least four bidirectional ultrasonic paths between respective pairs of the transducers, the ultrasonic paths being arranged into at least three non-coplanar sets. A processing system monitors the passage of ultrasonic signals along the paths to generate corresponding time of flight data, making a weighted selection containing at least one path from each of at least three sets, and processing the time of flight data for the selected paths, proportionate to the determined weighting, to generate airspeed and direction information.

Abstract: A moving-vane angle of attack probe is provided. The moving-vane angle of attack probe comprises: a vane having opposed first and second vane surfaces that define a leading edge and a trailing edge, the first and second vane surfaces, each extending between the leading edge and the trailing edge; a first vane opening located on the leading edge; at least one exhaust opening; a vane conduit extending between the first vane opening and the exhaust opening such that the first vane opening and the exhaust opening are in fluid communication, the vane conduit defining at least an interior chamber between the first and second vane surfaces; and a pitot-tube located within the interior chamber such that in use it receives air that enters the interior chamber via the first vane opening.

Abstract: An ultrasonic airspeed and direction sensor system comprising an ultrasonic sensor array including an elongate base member for mounting to a vehicle, such as a helicopter, so as to extend outwardly from the vehicle. A number of radially extending support members are connected to the base member. The support members carry ultrasonic transducers arranged to define at least four bidirectional ultrasonic paths between respective pairs of the transducers, the ultrasonic paths being arranged into at least three non-coplanar sets. A processing system monitors the passage of ultrasonic signals along the paths to generate corresponding time of flight data, making a weighted selection containing at least one path from each of at least three sets, and processing the time of flight data for the selected paths, proportionate to the determined weighting, to generate airspeed and direction information.

Abstract: A helicopter rotor includes a rotor head having, for each of a plurality of rotor blades, an elastomeric bearing and a damper that is arranged to provide controlled restraint of rotor blade movement in both the flap and lead/lag planes. The damper can be arranged to exhibit either substantially equal stiffness in both operational planes or any desired stiffness ratio. In a preferred embodiment of the latter arrangement, the desired stiffness in the respective planes are provided by separate components incorporated in the single damper. The damper may be situated either inboard or outboard of the elastomeric bearing.