Sealed hub and shaft fairing for rotary wing aircraft

Abstract

An aircraft includes an airframe; an extending tail; a counter rotating, coaxial main rotor assembly including an upper rotor assembly and a lower rotor assembly; a translational thrust system positioned at the extending tail, the translational thrust system providing translational thrust to the airframe; an upper hub fairing positioned at the upper rotor assembly; a lower hub fairing positioned at the lower rotor assembly; and a shaft fairing disposed between the upper hub fairing and the lower hub fairing; wherein a geometry of at least one of the upper hub fairing and the lower hub fairing progressively blends from a circle to a series of curved elliptical surfaces in an inboard direction.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims the benefit of U.S. provisional patent application Ser. No. 62 / 058,424, filed Oct. 1, 2014, and U.S. provisional patent application Ser. No. 62 / 058,153, filed Oct. 1, 2014, the entire contents of which are incorporated herein by reference.BACKGROUND[0002]The subject matter disclosed herein relates generally to rotary wing aircraft and, more particularly, to a dual rotor, rotary wing aircraft.[0003]Typically, aerodynamic drag associated with a rotor system of a rotary wing aircraft is a significant portion of the overall aircraft drag, commonly 25% to 30% for conventional single-rotor helicopters. The rotor system drag increases for a rotary wing aircraft having a counter-rotating coaxial system primarily due to the additional rotor hub and the interconnecting main rotor shaft assembly between the upper and lower rotor systems. For high speed rotary-wing aircrafts, the increased drag resulting from the counter-rotat...

AI Technical Summary

Benefits of technology

The patent is about a device that can be attached to a shaft and help reduce friction. This can be useful for improving the performance of the device.

Problems solved by technology

The rotor system drag increases for a rotary wing aircraft having a counter-rotating coaxial system primarily due to the additional rotor hub and the interconnecting main rotor shaft assembly between the upper and lower rotor systems.

For high speed rotary-wing aircrafts, the increased drag resulting from the counter-rotating coaxial rotor system may cause a relatively significant power penalty and / or limit aircraft speed.

The drag contributions may be approximately 40% for each of the rotor hubs, and 20% for the interconnecting shaft assembly; however, the effects are highly interactional, i.e., flow separation over one component may result in more significant flow separation and higher drag on another component.

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