GB2043562A

GB2043562A - Control surfaces of aircraft

Info

Publication number: GB2043562A
Application number: GB8005928A
Authority: GB
Original assignee: Vereinigte Flugtechnische Werke Fokker GmbH
Current assignee: Vereinigte Flugtechnische Werke Fokker GmbH
Priority date: 1979-02-22
Filing date: 1980-02-21
Publication date: 1980-10-08
Also published as: GB2043562B; DE2906889C2; DE2906889A1; FR2449592A1; FR2449592B1

Abstract

An aircraft has an auxiliary control surface/or canard 2 which normally moves freely in the surrounding flow, but upon the application of a control signal at 14, the surface is coupled to a servo device 11 which drives surface 2 to a desired position. The lever 8 which actuates, surface 2 is coupled to the piston 6 of a hydraulic servo cylinder 5. Cylinder 5 is normally by-passed by a pipeline 12, thus permitting free movement of surface 2. A by-pass valve 13 is provided in pipeline 12 and upon application of control signal 14, valve 13 closes and piston 6 is driven to a desired position by servo device 11 via a control valve 9. <IMAGE>

Description

SPECIFICATION Control surfaces of aircraft The invention relates to an aircraft with auxiliary control surfaces which may be controlled by servomotors.

In modern aircraft there is a trend towards using auxiliary control surfaces. These auxiliary control surfaces make it possible to carry out rapid corrections in the course and to neutralize the effects of movements during flight by means of direct control of buoyancy or lift or direct lateral force control. The use of these auxiliary devices producing driving control force has special advantages for target and landing approach runs and is therefbre particularly valuable in fighter aircraft.

It is known to use the already existing devices for producing driving control force in aircraft for such purposes e.g. landing flaps or transverse rudder controls for controlling elevation and external load carrying devices (py lons) for lateral control. As already mentioned however additional control surfaces namely so-called canards are also used for lateral control which have a stabilizing or destablizing effect on the aircraft---depending on their position with respect to the centre of gravity of the aircraft. A stablizing action is produced for an aircraft if an auxiliary control surface is arranged behind its centre of gravity while an auxiliary control surface has a destablizing effect if arranged in front of the centre of gravity of the aircraft.When setting an auxiliary control surface the balance of moments is disturbed and must be compensated by setting the conventional controls so that the desired flight path is maintained. The resultant driving force or torque of the conventional controls either increases or decreases the effectiveness of the auxiliary control surface depending on whether this surface is in its destablizing or its stabilizing position.

Thus, this stability effect constitutes a disadvantage in an aircraft having auxiliary control surfaces which may be set by servomotors.

According to the present invention there is provided an aircraft having at least one auxiliary control surface, drive means which may be coupled to said surface to position it, and control means responsive to a control signal and connected to said drive means, wherein, in one condition of the control signal, the surface is decoupled from said drive means so that the surface may move with the surrounding flow and, in another condition of said control signal, said drive means is coupled to said surface.

The drive means is preferably a hydraulic servo-cylinder which is bridged by a pipeline including a by-pass valve which constitutes said control means, the valve being open in response to said first-mentioned condition of the control signal and closed in response to said other condition of the control signal.

A preferred embodiment of the present invention will now be described in greater detail by way of example only with reference to the accompanying drawings, in which: Figure 1 shows a general view of a portion of an aircraft in accordance with the present invention; and Figure 2 shows a plan view of the aircraft of Fig. 1.

As Figs. 1 and 2 show, a control surface 2 is arranged on the fuselage of an aircraft 1.

The aircraft may have control surfaces in front of and/or behind its centre of gravity. The control surface 2 is mounted pivotally on the aircraft 1 with a shaft 4. In order to set the control surface 2 there is an hydraulic servo cylinder 5 the piston 6 which actuates servo lever 8 of the control surface 2 via a piston rod 7. The servo cylinder 5 is, as is usual, supplied with hydraulic fluid through a control valve 9, the control piston 10 of which may be set by means of an electrical servo setting device 11. The electrical servo device 11 is settable. The operating spaces of the servo cylinder (5) produced by the piston 6 are bridged by means of a pipeline 1 2 with a normally-open valve 1 3 which is connected therein.Thus under normal conditions the bypass valve 1 3 permits the control surface 2 to move about in dependence on the flow. Thus valve 1 3 provides a free running arrangement. The electric servo device 11 and the valve 1 3 may be triggered by means of an electric control signal 1 4.

When the aircraft 1 is on a mission then for certain manoeuvres especially when fighter aircraft are in air combat, the control action may be applied to the control surface 2. The control signal 1 4 produced or given in this case therefore controls the normally open valve 1 3 and ensures that it is closed. As a result the bypass is removed so that a desired setting of the control surface may be undertaken by adjusting the control valve 9 via the electrical servo device 11.

Thus, the present invention has the advantage that the stability effect of the auxiliary control surface is avoided and that if necessary, especially in fighter aircraft, there are excellent control and steering facilities.

When required, the device provides exceptional control properties as a result of an additional or auxiliary control surface. The stability effect due to the by-pass which would occur at other times is avoided by means of the by-pass valve permitting the control surface 2 to be slowly moved about in dependence on the flow.

1. An aircraft having at least one auxiliary control surface, drive means which may be coupled to said surface to position it, and control means responsive to a control signal

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Control surfaces of aircraft The invention relates to an aircraft with auxiliary control surfaces which may be controlled by servomotors. In modern aircraft there is a trend towards using auxiliary control surfaces. These auxiliary control surfaces make it possible to carry out rapid corrections in the course and to neutralize the effects of movements during flight by means of direct control of buoyancy or lift or direct lateral force control. The use of these auxiliary devices producing driving control force has special advantages for target and landing approach runs and is therefbre particularly valuable in fighter aircraft. It is known to use the already existing devices for producing driving control force in aircraft for such purposes e.g. landing flaps or transverse rudder controls for controlling elevation and external load carrying devices (py lons) for lateral control. As already mentioned however additional control surfaces namely so-called canards are also used for lateral control which have a stabilizing or destablizing effect on the aircraft---depending on their position with respect to the centre of gravity of the aircraft. A stablizing action is produced for an aircraft if an auxiliary control surface is arranged behind its centre of gravity while an auxiliary control surface has a destablizing effect if arranged in front of the centre of gravity of the aircraft.When setting an auxiliary control surface the balance of moments is disturbed and must be compensated by setting the conventional controls so that the desired flight path is maintained. The resultant driving force or torque of the conventional controls either increases or decreases the effectiveness of the auxiliary control surface depending on whether this surface is in its destablizing or its stabilizing position. Thus, this stability effect constitutes a disadvantage in an aircraft having auxiliary control surfaces which may be set by servomotors. According to the present invention there is provided an aircraft having at least one auxiliary control surface, drive means which may be coupled to said surface to position it, and control means responsive to a control signal and connected to said drive means, wherein, in one condition of the control signal, the surface is decoupled from said drive means so that the surface may move with the surrounding flow and, in another condition of said control signal, said drive means is coupled to said surface. The drive means is preferably a hydraulic servo-cylinder which is bridged by a pipeline including a by-pass valve which constitutes said control means, the valve being open in response to said first-mentioned condition of the control signal and closed in response to said other condition of the control signal. A preferred embodiment of the present invention will now be described in greater detail by way of example only with reference to the accompanying drawings, in which: Figure 1 shows a general view of a portion of an aircraft in accordance with the present invention; and Figure 2 shows a plan view of the aircraft of Fig. 1. As Figs. 1 and 2 show, a control surface 2 is arranged on the fuselage of an aircraft 1. The aircraft may have control surfaces in front of and/or behind its centre of gravity. The control surface 2 is mounted pivotally on the aircraft 1 with a shaft 4. In order to set the control surface 2 there is an hydraulic servo cylinder 5 the piston 6 which actuates servo lever 8 of the control surface 2 via a piston rod 7. The servo cylinder 5 is, as is usual, supplied with hydraulic fluid through a control valve 9, the control piston 10 of which may be set by means of an electrical servo setting device 11. The electrical servo device 11 is settable. The operating spaces of the servo cylinder (5) produced by the piston 6 are bridged by means of a pipeline 1 2 with a normally-open valve 1 3 which is connected therein.Thus under normal conditions the bypass valve 1 3 permits the control surface 2 to move about in dependence on the flow. Thus valve 1 3 provides a free running arrangement. The electric servo device 11 and the valve 1 3 may be triggered by means of an electric control signal 1 4. When the aircraft 1 is on a mission then for certain manoeuvres especially when fighter aircraft are in air combat, the control action may be applied to the control surface 2. The control signal 1 4 produced or given in this case therefore controls the normally open valve 1 3 and ensures that it is closed. As a result the bypass is removed so that a desired setting of the control surface may be undertaken by adjusting the control valve 9 via the electrical servo device 11. Thus, the present invention has the advantage that the stability effect of the auxiliary control surface is avoided and that if necessary, especially in fighter aircraft, there are excellent control and steering facilities. When required, the device provides exceptional control properties as a result of an additional or auxiliary control surface. The stability effect due to the by-pass which would occur at other times is avoided by means of the by-pass valve permitting the control surface 2 to be slowly moved about in dependence on the flow. CLAIMS

1. An aircraft having at least one auxiliary control surface, drive means which may be coupled to said surface to position it, and control means responsive to a control signal and connected to said drive means, wherein, in one condition of the control signal, the surface is decoupled from said drive means so that the surface may move with the surrounding flow and, in another condition of said control signal, said drive means is coupled to said surface.

2. An aircraft according to Claim 1, wherein said drive means is a hydraulic servo cylinder.

3. An aircraft according to Claim 2, wherein said cylinder is bridged by a pipeline including a by-pass valve which constitutes said control means, the valve being open in response to said first-mentioned condition of the control signal and closed in response to said other condition of the control signal.

4. An aircraft having at least one auxiliary control surface substantially as herein described with reference to the accompanying drawings.