GB2461051A - VTOL aircraft control - Google Patents

Abstract

A method of controlling directional motion and yaw of a vertical take-off and landing (VTOL) aircraft that comprises an even number of at least four independent thrust devices by tilting each device about an axis defined by a line drawn between itself and a diametrically opposite thrust device. The aircraft may alternatively comprise an odd number of at least five independent thrust devices, the method comprising tilting each device about an axis defined by a line drawn between itself and the centre of gravity of the aircraft. Four thrust devices may be arranged with one at each front and rear corner of the aircraft, or with one at the front, one at the rear and one at each side of the aircraft. The thrust devices may be propellers, ducted fans, jets, turbines, rockets, chemical propellant devices, pressurised gas or other propellant devices.

Description

AN ASPECT OF MULTI ROTOR VTOL AIRCRAFT CONTROL -DESCRIPTION

For the purposes of this document, the word rotor' will be deemed to relate to and represent any appropriate thrust producing device such as jet, turbine, rocket, chemical propellant device, pressurised gas or other propellant device, propeller, ducted fan etc suitable to the purpose of providing a directional source of jilL This document relates to one aspect of control of a multi rotor VTOL aircraft utilising four or more rotors, the most common example of which s the four rotor Quadrotor.

Quadrotor aircraft use four rotors posftioned around the airframe, normaUy, but not necessary, in an even spadng. Most common rotor ayouts are a + shape (front, rear, left, right see FIG2) or an x shape (front left, front right, rear left, rear right -see FIG3), although other combinations have been proposed. In these aircraft it is usual to maintain stability and induce motion through control of the thrust from each rotor. For example, increasing thrust at the rear of the airframe and decreasing it at the front (e.g. FIG2 increase thrust rotor 3 and decrease rotor I & FIG3 increase thrust rotor 2 & 3 and decrease rotor 1 & 4) will cause the airframe to pitch forward and induce a change in the direction of thrust towards the rear, resulting in forward motion, and vice versa. Lateral motion would be induced by equivalent variations in thrust in the appropriate side rotors.

This invention relates to a system of rotors which can be tilted, independently or in combination, around a specific axis to induce motion without the need to change the attitude of the airframe. In applications with an even number of rotors, the axis of rotation of the rotor tilt is defined by a line drawn between one rotor and the rotor diametrically opposite. For example, in FIG2, the axis of rotation of tilt of rotors I and 3 is defined by Line A, and rotors 2 and 4 by Line B, in FIG3 the axis of rotation of tilt of rotors I and 3 is defined by Line C and rotors 2 and 4 by Line D (direction of tilt is represented in FIG2 and FIG3 by the double headed arrows). Rotor tilt will be induced by an actuator mechanism suitable to the nature of the thrust device (or rotor) and the specifics of the design and scale of the aircraft in question. Rotation direction of rotor tilt around any other axis, for example that defined by FIG2 Line E, or FIG3 Line F are not included in the claims of this patent. This patent also makes no claims for rotor tilt systems on aircraft utilising less than four rotors.

On aircraft using an odd number of rotors which may or may not be evenly spaced around the airframe, the axis of rotation of rotor tht is defined by a line between the rotor and the centre of gravity of the aircraft (see FIG4).

Description with reference to drawings:

FIG I shows the most common configuration of rotors for this type of aircraft, the + layout with rotors at the front, back, left and right. Double headed arrows show the direction of rotation of tilt of the various rotors and the axis of tilt rotation is represented in this case by the lines marked X axis and Y axis, which in this case also represent the X and Y axis of the airframe. Rotors can be tilted in various combinations to induce motion, either together in the same direction to induce motion in that direction or in opposite directions to induce yaw etc (rotation of the airframe around its Z axis).

FIG 2 shows a similar rotor configuration as FIG1 but in plan view with the axis of rotor tilt rotation for each pair of rotors marked as Line A for front and rear rotors and Line B for left and right rotors. Double headed arrows show rotor tilt rotational direction.

FIG 3 shows another rotor configuration with the axis of rotor tilt rotation for each pair of rotors marked as Line C and Line D. FIG 4 shows a configuration with an uneven number of rotors configured in a non symmetrical pattern around the airframe. Here the axis of rotation of tilt of the rotors is defined by a line between the rotor and the centre of gravity of the airframe represented by Point V. FIG 5 shows a configuration with an uneven number of rotors configured in a symmetrical pattern around the airframe. In this case the axis of rotation of tilt of the rotors is also defined by a line between the rotor and the centre of gravity of the airframe represented by Point V.

Claims (1)

1. AN ASPECT OF MULTI ROTOR VTOL AIRCRAFT CONTROL -CLAIMSCIams: 1> A method of controffing directiona' motbn and yaw of a VTOL arcraft that comprises an even number of at east four independent thrust devices by thting said devices independenfly or together around an axis defined by a line drawn between each device and the device diametrically opposite to it on the airframe.

   2> A method of controlling directional motion and yaw of a VIOL aircraft that comprises an odd number of at least five independent thrust devices by tilting said devices independently or together around an axis defined by a line drawn between each device and the centre of gravity of the airframe.