Fail-operational multiple lifting-rotor aircraft

Abstract

A rotorcraft having multiple rotors, and wings that provide lift in forward flight, has mechanical coupling between rotors that can be disengaged and optionally reengaged, during flight. The coupling can, which can prevent a failure of one rotor from interfering with rotation of the other rotor(s), can be accomplished using many different types of devices, including for example, dog clutches and friction clutches, and collapsible clutches. Disengagement can range from being completely under control of an operator, to partially under operator control, to completely automatic. Among many other benefits, designing, manufacturing, fitting, retrofitting or in some other manner providing an aircraft with a device that can disengage rotation of one of the rotors from that of another one of the rotors during flight can be used to improving survivability in an emergency situation.

Description

[0001]This application claims priority to U.S. Provisional Application Ser. No. 60 / 713,683 filed Sep. 2, 2005.TECHNICAL FIELD[0002]The field of the invention is multiple lifting-rotor aircraft.BACKGROUND[0003]Any rotor system, its mounting or controls, or the drive connection including shafting and direction-changing gearboxes can suffer from impending or catastrophic failure. The failure cause can be internal, typically a component failure, or external by the sustaining of battle damage. In any event, the method of monitoring the loads, vibrations, temperatures and rotational speeds will determine whether the failure is progressive or instantaneous, and whether the drive disconnection should be elective or automatic.[0004]When in forward flight, the likelihood of secondary damage to an aircraft structure due to severe vibration from, for example, the loss of a rotor blade must be minimized. Aircraft with multiple lifting-rotors always have a mechanical linkage between the rotors to...

AI Technical Summary

Benefits of technology

[0011]The current invention provides methods and apparatus in which a rotorcraft having a mechanical coupling between rotors can be disengaged and optionally reengaged, during flight, and thereby prevent a failure of one rotor from interfering with rotation of the other rotor(s). This can be accomplished using many different types of devices, including for example, dog clutches and friction clutches, and collapsible clutches.

Problems solved by technology

Any rotor system, its mounting or controls, or the drive connection including shafting and direction-changing gearboxes can suffer from impending or catastrophic failure.

The failure cause can be internal, typically a component failure, or external by the sustaining of battle damage.

The problem with that arrangement, however, is that the safety benefit in vertical flight becomes a liability in forward, wing-borne flight.

Until very recently, the range / payload capability of a tilt-rotor or compound aircraft was so limited that attention was not focused on this problem.

During hover and conversion to forward flight, all known tilt-rotor and tilt-wing aircraft cannot continue flight to a safe landing when a rotor (not an engine) fails.

However, as previously noted, these two flight regimes occupy a small and decreasing percentage of the total flight time as the utility of the aircraft improves and it becomes predominantly a transportation machine and not a lifting device.

In order to render tilt-rotor and tilt-wing aircraft acceptable for large scale transportation of passengers, it must be possible to continue wing-borne flight, in airplane mode, to a safe landing with a damaged or disabled rotor, and not to allow this single point failure to unduly compromise flight safety.

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