GB2025341A - Canard wings - Google Patents

Abstract

A canard control surface 10 is forward mounted on an aircraft fuselage 11 and has an inboard fixed strake part 12 with high aspect ratio or sweep back and an outboard control surface part 13 of lower aspect ratio. The part 13 is movable about an axis 15 almost perpendicular to the longitudinal axis 14 of the aircraft. The control surface may be pivotable about the junction line 16 and the strake part may pivot about axis 17 almost parallel to the axis 14. <IMAGE>

Description

SPECIFICATION Aircraft control surfaces This invention relates to aircraft control surfaces which are located in a forward zone in front of the main wings and mostly in the zone of the cockpit.

Control surfaces are known which are positioned in the region of the cockpit and which can be locked in any desired intermediate position between a fully retracted and an extended state.

The surfaces are movable about an axis parallel to the longitudinal axis of the aircraft and also about an axis transverse to the longitudinal axis and are designed so that they can be moved and locked independently. This system ensures that the surfaces can be used both for longitudinal and for transverse control and maintain stability in these directions. In the case of large angles of incidence the system adversely affects the stability and controllability of flight.

It is known also to provide each wing unit pivotable about an axis which lies at an angle to the longitudinal axis of the aircraft and which sweeps back. This arrangement is intended to reduce buffeting or vibration, but does not enable control at large angles of incidence to be effected.

This invention seeks to provide a control surface arrangement on which the,strake air flow is maintained at large angles of incidence.

According to this invention there is provided a forward mounted (canard) control surface arrangement on an aircraft with a high sweep back fixed inboard part and a movable outboard control surface part rotatable about an axis nearly perpendicular to the longitudinal axis of the aircraft.

An-embodiment of the invention is shown diagrammatically in the accompanying drawings by way of example and further explanation. The drawing shows only one half of a forward part of an aircraft.

The fuselage of an aircraft 11 has in the region of the cockpit, a canard control surface 10. One surface is provided each side of the aircraft fuselage. The control surfaces 10 have a greatly swept-back strake part 12 which is fixed in position on the fuselage and a lesser swept-back control surface part 13, which latter is rotatable about an axis 1 5 nearly perpendicular to the longitudinal axis 14 of the aircraft. The sweptback strake 12 continues as far as the trailing edge of the control surface 10 at substantially the same angle and forms a joint 1 6 with the rotatable control surface 13 and lying at an acute angle c4 extending towards the nose of the aircraft.

In a further embodiment the control surface 10 and the strake 1 2 are movable in relation to the fuselage about an axis 17 and through which the control unit 12 and 13 can swing into a vertical position. Since the control surfaces 13 are primarily designed to rotate about an element Yparallel axis 1 5 (transverse or pitch axis parallel), so that two axes 15 and 1 7 are situated perpendicular or at an angle to each other, any desired combination of angles about the x (longitudinal) and Y--parallel axis can be obtained.

The rear edge of the strake part 12 may include an additional control surface 1 8.

This arrangement described provides a canard control system in which the strake air flow is maintained at high angles of incidence when it is necessary to relieve the canard surface for trimming, this being done by a negative setting of the surface in relation to the fuselage. In contrast with known systems of rotatable control surfaces the angle of incidence and the boundary flow of the strake is maintained.

Apart from this, fewer difficulties are encountered in adjusting the part of the control unit which is located on the outside, due to the smaller dimensions and lesser forces occurring.

The preservation of the strake air flow, despite the reduction in the lift of the canard surface, is important for stability and control at high angles of incidence.

1. A forward mounted (canard) control surface arrangement on an aircraft with a high sweep back fixed inboard part and a movable outboard control surface part rotatable about an axis nearly perpendicular to the longitudinal axis of the aircraft.

2. A control surface arrangement in accordance with Claim 1, wherein the junction between the inboard strake part and the outboard control surface part lies at an acute angle (a) -directed towards the nose of the aircraft.

3. A control surface arrangement in accordance with Claim 2, wherein the junction between the strake and the fuselage forms a rotation axis nearly parallel with the longitudinal axis of the aircraft (x-parallel).

4. A control surface arrangement in accordance with Claim 3, wherein the rotation axis of thecontrol surface part and the rotation axis of the strake part can be combined to produce any desired combination of angular adjustments.

5. A control surface arrangement in accordance with any preceding claim, wherein an additional control surface is provided on the trailing edge of the fixed inboard strake part.

6. A control surface arrangement for an aircraft or an aircraft encorporating same, substantially as herein described with reference to and as shown in the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Aircraft control surfaces This invention relates to aircraft control surfaces which are located in a forward zone in front of the main wings and mostly in the zone of the cockpit. Control surfaces are known which are positioned in the region of the cockpit and which can be locked in any desired intermediate position between a fully retracted and an extended state. The surfaces are movable about an axis parallel to the longitudinal axis of the aircraft and also about an axis transverse to the longitudinal axis and are designed so that they can be moved and locked independently. This system ensures that the surfaces can be used both for longitudinal and for transverse control and maintain stability in these directions. In the case of large angles of incidence the system adversely affects the stability and controllability of flight. It is known also to provide each wing unit pivotable about an axis which lies at an angle to the longitudinal axis of the aircraft and which sweeps back. This arrangement is intended to reduce buffeting or vibration, but does not enable control at large angles of incidence to be effected. This invention seeks to provide a control surface arrangement on which the,strake air flow is maintained at large angles of incidence. According to this invention there is provided a forward mounted (canard) control surface arrangement on an aircraft with a high sweep back fixed inboard part and a movable outboard control surface part rotatable about an axis nearly perpendicular to the longitudinal axis of the aircraft. An-embodiment of the invention is shown diagrammatically in the accompanying drawings by way of example and further explanation. The drawing shows only one half of a forward part of an aircraft. The fuselage of an aircraft 11 has in the region of the cockpit, a canard control surface 10. One surface is provided each side of the aircraft fuselage. The control surfaces 10 have a greatly swept-back strake part 12 which is fixed in position on the fuselage and a lesser swept-back control surface part 13, which latter is rotatable about an axis 1 5 nearly perpendicular to the longitudinal axis 14 of the aircraft. The sweptback strake 12 continues as far as the trailing edge of the control surface 10 at substantially the same angle and forms a joint 1 6 with the rotatable control surface 13 and lying at an acute angle c4 extending towards the nose of the aircraft. In a further embodiment the control surface 10 and the strake 1 2 are movable in relation to the fuselage about an axis 17 and through which the control unit 12 and 13 can swing into a vertical position. Since the control surfaces 13 are primarily designed to rotate about an element Yparallel axis 1 5 (transverse or pitch axis parallel), so that two axes 15 and 1 7 are situated perpendicular or at an angle to each other, any desired combination of angles about the x (longitudinal) and Y--parallel axis can be obtained. The rear edge of the strake part 12 may include an additional control surface 1 8. This arrangement described provides a canard control system in which the strake air flow is maintained at high angles of incidence when it is necessary to relieve the canard surface for trimming, this being done by a negative setting of the surface in relation to the fuselage. In contrast with known systems of rotatable control surfaces the angle of incidence and the boundary flow of the strake is maintained. Apart from this, fewer difficulties are encountered in adjusting the part of the control unit which is located on the outside, due to the smaller dimensions and lesser forces occurring. The preservation of the strake air flow, despite the reduction in the lift of the canard surface, is important for stability and control at high angles of incidence. CLAIMS

1. A forward mounted (canard) control surface arrangement on an aircraft with a high sweep back fixed inboard part and a movable outboard control surface part rotatable about an axis nearly perpendicular to the longitudinal axis of the aircraft.

2. A control surface arrangement in accordance with Claim 1, wherein the junction between the inboard strake part and the outboard control surface part lies at an acute angle (a) -directed towards the nose of the aircraft.

3. A control surface arrangement in accordance with Claim 2, wherein the junction between the strake and the fuselage forms a rotation axis nearly parallel with the longitudinal axis of the aircraft (x-parallel).

4. A control surface arrangement in accordance with Claim 3, wherein the rotation axis of thecontrol surface part and the rotation axis of the strake part can be combined to produce any desired combination of angular adjustments.

5. A control surface arrangement in accordance with any preceding claim, wherein an additional control surface is provided on the trailing edge of the fixed inboard strake part.

6. A control surface arrangement for an aircraft or an aircraft encorporating same, substantially as herein described with reference to and as shown in the accompanying drawing.