Coaxial rotorcraft control system

Abstract

A control system for a coaxial rotorcraft comprises a coaxial rotor set, further comprising an upper rotor actuated by a first drive shaft and a lower rotor actuated by a second drive shaft, the lower rotor having a direction of rotation counter to a direction of rotation of the upper rotor. A collective blade pitch control is configured to: collectively control pitch of only one of the upper rotor and the lower rotor and not another of the upper rotor and the lower rotor; and create an unbalanced torque force which acts on the rotorcraft and which enables a yaw attitude control input through said collective blade pitch control.

Description

[0001] This is a continuation-in-part of U.S. patent application Ser. No. 09 / 782,941, filed Feb. 14, 2001, the disclosure of which is hereby incorporated herein by reference for the teachings consistent herewith: but to the extent inconsistent herewith, this disclosure shall control.BACKGROUND [0002] 1. Field of the Invention [0003] The invention relates to rotorcraft flight control systems. More particularly, the invention relates to a flight control system arrangement for a coaxial helicopter vehicle. [0004] 2. Description of Related Art [0005] Coaxial helicopters have been known for many years. However, because of difficulties involved in the control of cyclic and collective pitch of rotor blades in a coaxial configuration, development of this type of aircraft has heretofore been limited. Conventional coaxial designs provide roll, pitch and yaw control by providing control input linkages for cyclic and collective pitch to both an upper rotor and a lower rotor of a coaxial rotor s...

AI Technical Summary

Benefits of technology

"The patent describes a control system for a rotorcraft with a coaxial rotor set. The system allows for independent control of the rotors for thrust and yaw, while also providing a yaw attitude control input through a collective control input to one rotor. The system can be simpler and more cost-effective than providing a differential collective where one rotor's blade pitch is increased while the other rotor's blade pitch is decreased. The system can also include a control link within a drive shaft and a small tail rotor for yaw control. The technical effects of the patent include improved performance and potential cost savings."

Problems solved by technology

However, because of difficulties involved in the control of cyclic and collective pitch of rotor blades in a coaxial configuration, development of this type of aircraft has heretofore been limited.

Pitch is increased in one rotor, and decreased in the other, to unbalance torque.

Common to these is that a yaw attitude control input is provided by enabling a different blade pitch magnitude for the first rotor as compared to the second rotor, thereby unbalancing the torque forces in the coaxial rotor set.

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