Coaxial rotor yaw control

A method includes determining, by a computing device comprising a processor, a value for at least one parameter related to an operation of a coaxial rotary wing aircraft; processing, by the computing device, the at least one parameter to determine control power available from one or more flight controls comprising a differential cyclic; and establishing, by the computing device, a value for the differential cyclic to create a net yaw moment for the rotary wing aircraft based on the determination of the available control power.

BACKGROUND

In an aerospace or rotorcraft environment, coaxial rotors have the ability to provide yaw control by varying a balance of torque between the individual rotors. Torque balancing may be achieved through the application and use of a differential collective. A well-known shortcoming of the coaxial configuration is a reduction, and eventual reversal, of the yaw control authority provided by differential collective when operating in one or more regions of a flight envelope, such as during moderate speed descent conditions. Very large rudders may be used in an effort to compensate for such reduction/reversal.

BRIEF SUMMARY

An exemplary embodiment is directed to a method including determining, by a computing device comprising a processor, a value for at least one parameter related to an operation of a coaxial rotary wing aircraft; processing, by the computing device, the at least one parameter to determine control power available from one or more flight controls comprising a differential cyclic; and establishing, by the computing device, a value for the differential cyclic to create a net yaw moment for the rotary wing aircraft based on the determination of the available control power.

Another exemplary embodiment is directed to an apparatus including at least one processor; and memory having instructions stored thereon that, when executed by the at least one processor, cause the apparatus to: determine a value for at least one parameter related to an operation of a coaxial rotary wing aircraft, process the at least one parameter to determine control power available from one or more flight controls comprising a differential cyclic, and establish a value for the differential cyclic to create a net yaw moment for the rotary wing aircraft based on the determination of the available control power.

Another exemplary embodiment is directed to a rotary wing aircraft including: a first rotor aligned with a second rotor as part of a coaxial configuration; sensors coupled to the first and second rotors; and a computing device coupled to the sensors and configured to: process data provided by the sensors to determine control power available from one or more flight controls comprising a differential cyclic, and establish a value for the differential cyclic to create a net yaw moment for the rotary wing aircraft based on the determination of the available control power.

Additional embodiments are described below.

DETAILED DESCRIPTION

It is noted that various connections are set forth between elements in the following description and in the drawings (the contents of which are included in this disclosure by way of reference). It is noted that these connections in general and, unless specified otherwise, may be direct or indirect and that this specification is not intended to be limiting in this respect. In this respect, a coupling between entities may refer to either a direct or an indirect connection.

Exemplary embodiments of apparatuses, systems, and methods are described for creating a net yaw moment for an aircraft. In some embodiments, a differential cyclic may be used to create the net yaw moment. A phasing of the differential cyclic may depend on the direction of the wind relative to an orientation or direction of travel of the aircraft. Yaw control power may be relatively steady or constant in a range from, e.g., twenty knots to eighty knots, including during descent where control using a differential collective may be lost. In some embodiments, an empirical model may be used to estimate the yaw control power available from the differential collective or other means of yaw control. This information can be used to cue the pilot and/or reconfigure flight controls.

FIG. 1Aillustrates an exemplary vertical takeoff and landing (VTOL) rotary wing aircraft10having a dual, counter-rotating main rotor system12, which rotates about a rotating main rotor shaft14U, and a counter-rotating main rotor shaft14L, both about an axis of rotation A. The aircraft10includes an airframe F which supports the dual, counter-rotating, coaxial main rotor system12as well as an optional translational thrust system T which provides translational thrust during high speed forward flight, generally parallel to an aircraft longitudinal axis L. Although a particular counter-rotating, coaxial rotor system aircraft configuration is illustrated in the disclosed embodiment, other rotor systems and other aircraft types such as tilt-wing and tilt-rotor aircrafts will also benefit from the present disclosure.

A main gearbox G located above the aircraft cabin drives the rotor system12. The translational thrust system T may be driven by the same main gearbox G which drives the rotor system12. The main gearbox G is driven by one or more engines E. As shown, the main gearbox G may be interposed between the engines E, the rotor system12, and the translational thrust system T.

Referring toFIG. 1B, an exemplary computing system100is shown. Computing system100may be part of a flight control system of the rotary wing aircraft10. The system100is shown as including a memory102. The memory102may store executable instructions. The executable instructions may be stored or organized in any manner and at any level of abstraction, such as in connection with one or more applications, processes, routines, procedures, methods, etc. As an example, at least a portion of the instructions are shown inFIG. 1Bas being associated with a first program104aand a second program104b.

The instructions stored in the memory102may be executed by one or more processors, such as a processor106. The processor106may be coupled to one or more input/output (I/O) devices108. In some embodiments, the I/O device(s)108may include one or more of a keyboard or keypad, a touchscreen or touch panel, a display screen, a microphone, a speaker, a mouse, a button, a remote control, a control stick, a joystick, a printer, a telephone or mobile device (e.g., a smartphone), etc. The I/O device(s)108may be configured to provide an interface to allow a user to interact with the system100.

As shown, the processor106may be coupled to a number ‘n’ of databases,110-1,110-2, . . .110-n. The databases110may be used to store data. In some embodiments, the data may include one or more parameters associated with the operation of an aircraft (e.g., a coaxial rotorcraft). For example, the data may include one or more parameters related to airspeed, power supplied to one or more rotors, rotor thrust, descent or ascent rate, and angle of attack. The processor106may be operative on the data to determine or predict control power that may be available using one or more flight controls.

The system100is illustrative. In some embodiments, one or more of the entities may be optional. In some embodiments, additional entities not shown may be included. In some embodiments, the entities may be arranged or organized in a manner different from what is shown inFIG. 1B. For example, in some embodiments, the memory102may be coupled to or combined with one or more of the databases110.

Referring toFIG. 2, a block diagram of a system200is shown. The system200may be used to determine or predict control power that may be available. In some embodiments, the system200may be used as a basis for providing yaw control to rotary wing aircraft10. The system200may be included as part of the rotary wing aircraft10.

The system200is shown as including a rotor202aand a rotor202b.The rotors202aand202bmay be coupled to one another in a coaxial manner or fashion.

The rotors202aand202bmay be coupled to one or more sensors. For example, as shown inFIG. 2, the rotor202amay be coupled to one or more sensors204a.The rotor202bmay be coupled to one or more sensors204b.In some embodiments, at least a portion of the sensors204amay be common to a corresponding portion of the sensors204b.The sensors204aand/or204bmay be configured to measure one or more parameters, such as those described herein.

The sensor(s)204aand204bmay be coupled to a processing unit206. The processing unit206may correspond to the processor106. The processing unit206may correspond to a flight control computer.

The processing unit206may be operative on data provided by the sensor(s)204aand204b.The processing unit206may process the data provided by the sensor(s)204aand204bto determine or predict control power that may be available using one or more flight controls208. In some embodiments, the determination/prediction of the control power may be provided by the processing unit206to one or more I/O devices210(where the I/O devices210may correspond to the I/O devices108). In some embodiments, the determination/prediction of the control power may be based on the actual values or positions for the flight controls208and/or may be based on a range of available values/positions for the flight controls208.

The flight controls208may include a cyclic control208a,a collective control208b,and a rudder control208c.While each of the controls208a-208cis shown inFIG. 2as a single entity, multiple instances of one or more of the controls208a-208cmay be used in some embodiments. For example, two instances of the cyclic208aand the collective208bmay be available, such that the first instance of the cyclic208aand the collective208bmay be applied to the rotor202a,and a second instance of the cyclic208aand the collective208bmay be applied to the rotor202b.Furthermore, the controls208a-208cmay be applied in terms of differential quantities. For example, a differential cyclic may correspond to the difference between the rotor202aand the rotor202bin regards to the cyclic208a.

In some embodiments, based on the determination/prediction of the control power generated by the processing unit206, a value or position for one or more of the flight controls208may be provided. For example, the value or position for the flight controls208may be automatically adjusted. Such automatic adjustment may be used in, e.g., fly-by-wire configurations. Alternatively, output provided by the I/O devices210may direct a pilot or operator to set the state for one or more of the flight controls208. The output provided by the I/O devices210may advise the pilot/operator of an acceptable range for setting one or more of the flight controls208based on, e.g., the region of a flight envelope that the aircraft is operating in.

Based at least in part on the state of the flight controls208, a (differential) moment may be generated between the rotors202aand202b.The moment may be coupled to an airframe212of the aircraft. The moment may correspond to an imbalance in torque that may be harnessed or used to provide yaw control for the aircraft.

Turning now toFIG. 3, a flow chart of an exemplary method300is shown. The method300may be executed by one or more systems, components, or devices, such as those described herein (e.g., the system100and/or the system200). The method300may be used to provide yaw control for rotary wing aircraft, such as a coaxial helicopter. The method300may be used to generate an indication or determination of control power and may provide output regarding positions for one or more flight controls.

In block302, one or more parameters (e.g., airspeed, power supplied to one or more rotors, rotor thrust, descent or ascent rate, and angle of attack) may be determined, sensed, or measured.

In block304, the parameters of block302may be processed to determine a region of a flight envelope that an aircraft is operating in. For example, the determination of block304may indicate that the aircraft is descending and traveling at a rate of approximately thirty to forty knots, wherein yaw control provided by differential collective between coaxial rotors and/or rudders may be limited. Regions of operation within a flight envelope may be established based on simulation results or via the use of flight test data.

In block306, a determination may be made regarding control power that may be available using one or more flight controls (e.g., a differential collective and/or rudders). The determination of block306may be based on the parameters of block302and/or the region of the flight envelope determined in block304.

In block308, an indication of the control power of block306may be provided. For example, one or more audio or displayed outputs may serve to indicate to a pilot the control power that is available. The pilot may provide values or positions for the flight controls on the basis of the indicated control power.

In block310, one or more values or positions for flight controls may be established. The values/positions may be set automatically. Alternatively, the values/positions may be set manually (e.g., via pilot actuated controls). As part of block310, an optimal strategy utilizing the available controls may be applied to create a net yaw moment, which may be used as a basis for providing yaw control for the aircraft. This control strategy may include use of differential cyclic to create a net yaw moment. The optimization may even automatically reverse the direction of application for controls, such as differential collective and rudders, in flight regimes where their yaw moment contribution reverses.

The method300is illustrative. In some embodiments, one or more of the blocks or operations (or a portion thereof) may be optional. In some embodiments, additional operations not shown may be included. In some embodiments, the operations may execute in an order or sequence different from what is shown inFIG. 3.

Embodiments of the disclosure may be used to reduce the size of rudders relative to aircraft in current use. A differential cyclic may be used to provide yaw control.

Embodiments of the disclosure may be used to provide for yaw control without adding considerable complexity to a design or platform. Aspects of the disclosure may be used to enhance situational awareness and/or increase stability margins associated with flight controls.

As described herein, in some embodiments various functions or acts may take place at a given location and/or in connection with the operation of one or more apparatuses, systems, or devices. For example, in some embodiments, a portion of a given function or act may be performed at a first device or location, and the remainder of the function or act may be performed at one or more additional devices or locations.

Embodiments may be implemented using one or more technologies. In some embodiments, an apparatus or system may include one or more processors, and memory storing instructions that, when executed by the one or more processors, cause the apparatus or system to perform one or more methodological acts as described herein. Various mechanical components known to those of skill in the art may be used in some embodiments.

Embodiments may be implemented as one or more apparatuses, systems, and/or methods. In some embodiments, instructions may be stored on one or more computer-readable media, such as a transitory and/or non-transitory computer-readable medium. The instructions, when executed, may cause an entity (e.g., an apparatus or system) to perform one or more methodological acts as described herein.

Aspects of the disclosure have been described in terms of illustrative embodiments thereof. Numerous other embodiments, modifications and variations within the scope and spirit of the appended claims will occur to persons of ordinary skill in the art from a review of this disclosure. For example, one of ordinary skill in the art will appreciate that the steps described in conjunction with the illustrative figures may be performed in other than the recited order, and that one or more steps illustrated may be optional.