# US 10,479,481 B2 · Process and machine for reducing a drag component of a horizontal stabilizer on an aircraft

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- Number: US 10,479,481 B2
- Document ID: US10479481B2
- Status: Granted
- Kind: B2
- Application number: 15/279,414
- Filed: 2016-09-28
- Published: 2018-03-29
- Granted: 2019-11-19
- Earliest claimed: 2016-09-28
- Assignees: The Boeing Company
- Applicants: The Boeing Company
- Inventors: Henry Llewellyn Beaufrere
- Web page: https://patentgrep.com/patent/US10479481B2

## CPC

- B64C 19/00: Aircraft control not otherwise provided for
- B64C 13/16: actuated automatically, e.g. responsive to gust detectors
- B64C 5/02: Tailplanes
- B64C 5/10: adjustable
- B64C 2009/005: {Ailerons}
- B64C: AEROPLANES; HELICOPTERS

## Abstract

A process and a machine for improving a performance of a particular model of an aircraft, via reducing a size of a horizontal stabilizer for the particular model of the aircraft, the process comprising augmenting a nose-up moment, for the particular aircraft model, provided by a reduced horizontal stabilizer for the particular aircraft model, via addition of an ailevatoron mixer.

## Claims

### Claim 1

A flight control system for an aircraft, that comprises:
tricycle configured landing gear that comprises main gear;
wings mounted on, and separated from a horizontal stabilizer by, a fuselage, the horizontal stabilizer configured to generate a moment, about an axis defined by contact points of the main gear of the aircraft with a takeoff surface, in an aircraft nose-up direction;
an ailevatoron, respectively on each wing of the wings, located aft of the axis and configured to generate, about the axis, an ailevatoron moment;
an ailevatoron mixer that comprises a filter and a scheduler configured to:
receive inputs that comprise: a flight control position, rotation speed criteria, aircraft performance, and flight control commands;
determine, based upon the inputs, a rotation moment required to rotate a nose of the aircraft off the takeoff surface for takeoff;
responsive to the moment generated by the horizontal stabilizer being less than the rotation moment, due to the horizontal stabilizer comprising a size reduced from a size originally designed to produce the rotation moment for the aircraft to takeoff with a maximum allowed nose-down take off weight moment without the ailevatoron mixer, determining a magnitude required for the ailevatoron moment, such that a sum of the moment produced by the horizontal stabilizer and the ailevatoron moment equals the rotation moment;
determine a deflection, away from the takeoff surface, required for the ailevatoron, respectively on each wing of the wings, to generate a force that generates the magnitude required for the ailevatoron moment; and
command the ailevatoron, respectively on each wing of the wings, to deflect away from the takeoff surface to the deflection determined.

### Claim 2 (depends on 1)

The flight control system of claim 1, further comprising:
the ailevatoron mixer comprising program code, fixed in a non-transitory medium, configured to blend the deflection, away from the takeoff surface, of the ailevatoron, respectively on each wing of the wings, based upon at least: a deflection of an elevator on the horizontal stabilizer, an airspeed, and a weight-on-wheels signal, of the aircraft.

### Claim 3

A flight control system that comprises an ailevatoron mixer configured to produce an ailevatoron moment for an aircraft at takeoff, such that the aircraft comprises:
a tricycle landing gear configuration that comprises two main gear and a nosewheel;
a tail that comprises a horizontal stabilizer that comprises an elevator;
wings mounted on opposite sides of, and separated from the tail by, a fuselage;
an axis defined by contact points of the two main gear with a takeoff surface;
a center of gravity located between the axis and the nosewheel of the aircraft, such that the center of gravity generates a weight moment about the axis that holds the nosewheel on the takeoff surface;
an ailevatoron, respectively on each wing of the wings, located aft of the axis and configured to generate the ailevatoron moment about the axis; and
the ailevatoron mixer comprising:
a filter configured to receive: a weight on wheels signal, an airspeed, a pitch command, and a deflection of the elevator, of the aircraft;
a scheduler configured to determine, responsive to the pitch command to rotate the aircraft for the takeoff and based upon a magnitude of the weight moment being greater than a magnitude of an aircraft nose-up pitch moment generated by the horizontal stabilizer, due to the horizontal stabilizer comprising a size reduced from a size originally designed to produce the required nose-up pitch moment to overcome the weight moment for the aircraft to takeoff without the ailevatoron mixer:
a magnitude required for the ailevatoron moment; and
a magnitude required for a symmetric deflection, away from the takeoff surface, of the ailevatoron, respectively on each wing of the wings, such that the ailevatoron moment supplements the aircraft nose-up pitch moment generated by the horizontal stabilizer sufficiently to generate a rotation moment that overcomes the weight moment and lifts the nosewheel off the takeoff surface for the aircraft to tho takeoff from the takeoff surface;
a mixer configured to:
receive: a roll command, and the magnitude required for the symmetric deflection; and
mix the roll command with the magnitude required for the symmetric deflection to form a command to the ailevatoron, respectively on each wing of the wings, that generates the ailevatoron moment.

### Claim 4 (depends on 3)

The flight control system of claim 3, further comprising the reduced size horizontal stabilizer designed to produce a stab moment required for the aircraft to generate the rotation moment that overcomes a maximum allowed nose-down weight moment at the takeoff.

### Claim 5 (depends on 4)

The flight control system of claim 4, further comprising the magnitude required for the ailevatoron moment comprising 12-17% of a magnitude of an aircraft nose-up pitch moment generated by the reduced horizontal stabilizer at rotation speed.

### Claim 6 (depends on 3)

The flight control system of claim 3, further comprising the ailevatoron mixer receiving the roll command from an aileron controller.

### Claim 7 (depends on 3)

The flight control system of claim 3, further comprising the pitch command to rotate the aircraft for the takeoff comprising an elevator deflection comprising a magnitude of at least 80% of an elevator deflection limit in a direction that generates an aircraft pitch-up.

### Claim 8 (depends on 3)

The flight control system of claim 3, further comprising the ailevatoron mixer configured to send the command to the ailevatoron, respectively on each wing of the wings, that generates the ailevatoron moment, during a deflection period that begins within 2 seconds a speed of the aircraft being a rotation speed of the aircraft.

### Claim 9 (depends on 3)

The flight control system of claim 3, further comprising the aircraft comprising more than one ailevatoron, respectively on each wing of the wings, and the ailevatoron mixer configured to send the command to each of the more than one ailevatoron, respectively on each wing of the wings, that generates the ailevatoron moment that supplements the aircraft nose-up pitch moment generated by the horizontal stabilizer sufficiently to generate the rotation moment that overcomes the weight moment.

### Claim 10 (depends on 3)

The flight control system of claim 3, further comprising the ailevatoron mixer comprising a washout filter configured to remove the symmetric deflection and the ailevatoron moment after the aircraft lifts off the takeoff surface.

### Claim 11 (depends on 10)

The flight control system of claim 10, further comprising the washout filter configured to remove the symmetric deflection and the ailevatoron moment within 2 seconds after the aircraft lifts off the takeoff surface.

### Claim 12 (depends on 1)

The flight control system of claim 1, further comprising the deflection of each ailevatoron being a symmetric deflection.

### Claim 13 (depends on 12)

The flight control system of claim 12, further comprising a mixer configured to add an input from an aileron controller to the symmetric deflection.

### Claim 14 (depends on 1)

The flight control system of claim 1, further comprising the reduced size horizontal stabilizer comprising a size smaller than a size originally designed for the horizontal stabilizer to produce a stab moment required for the aircraft to generate the rotation moment that overcomes a maximum allowed nose-down weight moment at the takeoff.

### Claim 15 (depends on 1)

The flight control system of claim 1, further comprising the magnitude required for the ailevatoron moment comprising 12-17% of a magnitude of an aircraft nose-up pitch moment generated by the horizontal stabilizer at rotation speed.

### Claim 16 (depends on 1)

The flight control system of claim 1, further comprising the ailevatoron mixer receiving a roll command from an aileron controller.

### Claim 17 (depends on 1)

The flight control system of claim 1, further comprising the ailevatoron mixer configured to receive a pitch command to rotate the aircraft for the takeoff that comprises an elevator deflection that comprises a magnitude of at least 80% of an elevator deflection limit in a direction that generates an aircraft pitch-up.

### Claim 18 (depends on 1)

The flight control system of claim 1, further comprising the ailevatoron mixer configured to send the command to the ailevatoron, respectively on each wing of the wings, that generates the ailevatoron moment, during a deflection period that begins within 2 seconds a speed of the aircraft being a rotation speed of the aircraft.

### Claim 19 (depends on 1)

The flight control system of claim 1, further comprising the aircraft comprising more than one ailevatoron, respectively on each wing of the wings, and the ailevatoron mixer configured to send the command to each of the more than one ailevatoron, respectively on each wing of the wings, that generates the ailevatoron moment that supplements an aircraft nose-up pitch moment generated by the horizontal stabilizer sufficiently to generate the rotation moment that overcomes a weight moment of the aircraft.