An air vehicle configured to augment effective drag to change the rate of descent of the air vehicle in flight via propeller shaft rotation direction reversal, i.e., thrust reversal.

The aircraft can include: an airframe, a tilt mechanism, a payload housing, and can optionally include an impact attenuator, a set of ground support members (e.g., struts), a set of power sources, and a set of control elements. The airframe can include: a set of rotors and a set of support members.

The present invention relates to Tetracyclic Heterocycle Compounds of Formula

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and pharmaceutically acceptable salts or prodrug thereof, wherein A, X, R.sup.1, R.sup.2, R.sup.3 and Ware as defined herein. The present invention also relates to compositions comprising at least one Tetracyclic Heterocycle Compound, and methods of using the Tetracyclic Heterocycle Compounds for treating or preventing HIV infection in a subject.

The present invention relates to Tetracyclic Heterocycle Compounds of Formula

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and pharmaceutically acceptable salts or prodrug thereof, wherein A, X, R.sup.1, R.sup.2, R.sup.3 and Ware as defined herein. The present invention also relates to compositions comprising at least one Tetracyclic Heterocycle Compound, and methods of using the Tetracyclic Heterocycle Compounds for treating or preventing HIV infection in a subject.

A rotorcraft includes a rotor hub coupled to a mast and a plurality of rotor extensions. Each rotor extension is configured to secure a rotor blade to the rotor hub and includes a first connector configured to attach the rotor extension to a rotor blade, a second connector configured to attach the rotor extension to the rotor hub; a shaft disposed between the first and second connectors, and a damper mount attached to the second connector. The rotorcraft also includes a fairing enclosing the damper and at least a portion of the rotor hub.

A rotorcraft includes a rotor hub coupled to a mast and a plurality of rotor extensions. Each rotor extension is configured to secure a rotor blade to the rotor hub and includes a first connector configured to attach the rotor extension to a rotor blade, a second connector configured to attach the rotor extension to the rotor hub; a shaft disposed between the first and second connectors, and a damper mount attached to the second connector. The rotorcraft also includes a fairing enclosing the damper and at least a portion of the rotor hub.

The aircraft can include: an airframe, a tilt mechanism, a payload housing, and can optionally include an impact attenuator, a set of ground support members (e.g., struts), a set of power sources, and a set of control elements. The airframe can include: a set of rotors and a set of support members.

Embodiments of the present application relate to the technical field of propellers, and particularly to a folding propeller, a power component and an unmanned aerial vehicle. The folding propeller includes a hub, at least two blades and at least two connecting pieces, the hub being configured to mount the folding propeller to a driving device. The hub includes a first surface and a second surface disposed oppositely, the first surface facing the driving device, and the second surface facing away from the driving device. Each of the blades is mounted on the second surface by the corresponding connecting piece, and each of the blades is capable of rotating relative to the hub. In the above manner, according to the embodiments of the present application, during mold adjustment in injection molding, a rotary damping between the blade and the hub can be adjusted by only adjusting the friction force of one contact surface, which is convenient for mold adjustment, is beneficial to mass production and reduces the production cost.

Various embodiments of an unmanned aerial vehicle are disclosed. In some embodiments, the UAV includes a motor assembly rotatable about a rotation axis and a propeller hub assembly removably engageable with the motor assembly. The propeller hub assembly includes a retainer configured and dimensioned for engagement with the motor assembly such that rotation of the motor assembly causes corresponding rotation of the propeller hub assembly. The retainer includes a pair of deflectable arms resiliently repositionable between a first position and a second position, for engagement and disengagement with the motor assembly, respectively. The arms are movable inwardly towards the rotation axis from the first position to the second position upon application of an external force and movable outwardly away from the rotation axis from the second position to the first position upon removal of the external force.

A rotor system is provided in one example embodiment and may include a first pair of rotor blades comprising a first pitch and a first diameter; and a second pair of rotor blades comprising a second pitch and a second diameter, wherein the first pitch of the first pair of rotor blades and the second pitch of the second pair of rotor blades are different.