An aircraft

Abstract

An aircraft 201 has a wing with port and starboard sides, a fixed wing portion and an aileron and flap on each side of the wing. A method of controlling roll of the aircraft comprises initiating a rol

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a method of controlling roll of an aircraft, and an aircraft. BACKGROUND OF THE INVENTION

[0002] Aircraft are expected to perform a variety of manoeuvres during flight, such as take-off and landing to ensure efficient operation of the aircraft. One such movement performed by the aircraft is rolling (turning of the aircraft either left (port) or right (starboard) around the longitudinal axis of the aircraft).

[0003] The aircraft controls and operates several flight control surfaces to execute these manoeuvres. In the instance of rolling, the aircraft operates ailerons that are located outboard of each wing to create a difference in lift between the port and starboard sides of the aircraft, causing the aircraft to roll in the desired direction.

[0004] It is desirable to improve the manoeuvrability of an aircraft during flight. This is especially true for rolling manoeuvres, which not only help the aircraft to change direction, but also to maintain balance and stability during flight.

[0005] However, modifying existing aircraft wings to include additional ailerons is difficult because this adds complexity to the architecture and actuation systems within the aircraft wing, It is therefore desirable to maintain or improve the manoeuvrability of an aircraft without introducing additional complexity to the flight control surfaces and wings. SUMMARY OF THE INVENTION

[0006] A first aspect of the invention provides a method of controlling roll of an aircraft, the aircraft having a wing with port and starboard sides, a fixed wing portion and an aileron and a flap on each side of the wing, the method comprising: initiating a roll manoeuvre of the aircraft by: moving the aileron on one side of the wing in an upward direction with respect to the fixed wing portion; and extending the flap on the other side of the wing with respect to the fixed wing portion.

[0007] Optionally, moving the aileron and moving the flap are both initiated simultaneously.

[0008] Optionally, initiating the roll manoeuvre comprises moving the aileron from a first angular aileron position to a second angular aileron position with respect to the fixed wing portion, and extending the flap from a first angular flap position to a second angular flap position with respect to the fixed wing portion, wherein the angular movement of the aileron between the first and second aileron positions is larger than the angular movement of the flap between the first and second flap positions.

[0009] Optionally, the flap and aileron each have a neutral position with respect to the fixed wing portion, and wherein initiating the roll manoeuvre is from the neutral position, or is from a deflected position relative to the neutral position.

[0010] Optionally, the wing has a plurality of flaps spaced spanwise across the wing, and the method comprises extending the most outboard flap or flaps when initiating the roll manoeuvre.

[0011] Optionally, the wing has a plurality of flaps spaced spanwise across the wing, and the method comprises extending more than one flap when initiating the roll manoeuvre.

[0012] Optionally, the aircraft further comprises a spoiler on each side of the wing, and initiating the roll manoeuvre further comprises moving both the spoiler and the aileron on the same side of the wing in an upward direction with respect to the fixed wing portion.

[0013] Optionally, the flaps are arranged as a pair of flaps with one flap of the pair located on each side of the aircraft, and the pair of flaps has a neutral position with respect to the fixed wing portion, and wherein an angular difference between the flaps of the pair of flaps during a roll manoeuvre is at least 3 degrees as measured relative to the neutral position.

[0014] A further aspect of the invention provides an aircraft having a wing with port and starboard sides, a fixed wing portion and an aileron and a flap on each side of the wing, and a flight control system for controlling roll of the aircraft, the flight control system comprising a roll demand input, an aileron position output coupled to an aileron actuator for moving the aileron, and a flap position output coupled to a flap actuator for extending the flap, wherein the flight control system is configured to process the roll demand input, provide the aileron position output to the aileron actuator, and provide the flap position output to the flap actuator, so as to initiate a roll manoeuvre of the aircraft according to the roll demand input by moving the aileron on one side of the wing in an upward direction with respect to the fixed wing portion, and extending the flap on the other side of the wing in a downward direction with respect to the fixed wing portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Embodiments of the invention will now be described with reference to the accompanying drawings, in which:

[0016] Figure 1 shows a plan view of an aircraft;

[0017] Figure 2 shows a plan view of a wing of the aircraft shown in Figure 1;

[0018] Figure 3 shows a schematic arrangement of a flight control system;

[0019] Figure 4A shows a method of rolling an aircraft;

[0020] Figure 4B shows another exemplary method of rolling an aircraft. DETAILED DESCRIPTION OF EMBODIMENT(S)

[0021] Figure 1 shows an aircraft 1 with a wing 2, a fuselage 5 and a nose end 6 and a tail end 7 including horizontal and vertical stabilising surfaces 7a, 7b. The wing 2 has a port side 2a and a starboard side 3 a. The port side 2a of the wing 2 has a leading edge 2b and trailing edge 2c, while the starboard side 3a also has a corresponding leading edge 3b and trailing edge 3c. In this example, the wing 2 is a continuous wing 2 that extends through the fuselage 5. The wing 2 in this example is an aft swept transonic wing. In other examples, the wing 2 may be formed as two separate wing structures that extend away from the fuselage 5.

[0022] The aircraft 1 is a typical jet passenger transonic transport aircraft but the invention is applicable to a wide variety of fixed wing aircraft types, including commercial, military, passenger, cargo, jet propeller, general aviation etc. with any number of wings attached to the wings or fuselage.

[0023] The axes shown in Figures 1 and 2 represent the usual reference orthogonal axes of the aircraft 1. The X-axis defines the longitudinal fore-aft direction of the aircraft; the Y-axis defines the spanwise direction and the Z-axis (not shown) defines the vertical up-down direction of the aircraft.

[0024] The wing 2 will be described in relation to each respective side, i.e. the port side 2a and the starboard side 2b. Each side 2a, 2b of the wing 2 has a cantilevered structure with a length extending in a spanwise direction from a root 12 to a tip 13. The root 12 is joined to the aircraft fuselage 5. The wing portion near the root 12 is the inboard region. The wing portion near the tip 13 is called the outboard region. Each side 2a, 2b of the wing 2 also has a chord extending in a chordwise direction from a leading edge 2b, 3b to a trailing edge 2c, 3d.

[0025] The wing 2 has a fixed wing portion 4 with an outer aerodynamic surface. The fixed wing portion relates to the main structural part of the aircraft that is rigid and is not actively moved (e.g. by an actuation arrangement) during flight. The fixed wing portion 4 of the wing 2 is primarily formed by the aerofoil structure of the wing 2.

[0026] The wing 2 also has several aerodynamic flight control surfaces 10. The flight control surfaces 10 are moveable surfaces that can be adjusted during flight to adjust the aircraft flight attitude or wing performance. There are several flight control surfaces such as ailerons, elevator, rudders, spoilers, flaps, slats and air brakes. These are typically located on the wing 2 or on the horizontal stabiliser 7a or vertical stabiliser 7b of the aircraft 1. The wing 2 has mirrored arrangements of the flight control surfaces on the port side 2a and the starboard side 2b of the wing 2.

[0027] Figure 2 shows a plan view of the starboard side 3a of the wing 2 in more detail. The starboard side 3 a of the wing 2 has several flight control surfaces 10 in the form of flaps 20, an aileron 30 and a spoiler 40. In the example shown in Figure 2, the starboard side 3a of the wing 2 has three flaps 20, one aileron 30 and one spoiler 40. However, it will be understood that any number and arrangement of flight control surfaces 10 may be provided on each side 2a, 3a of the wing 2. It will also be understood that the wing 2 may have several other flow control devices 10 that have been omitted from Figure 2 for clarity.

[0028] As described above, the starboard 3 a side of the wing 2 has a plurality of flaps 20 that positioned along the span of the wing 2. The flaps 20 are located on the trailing edge 3c of the wing 2. The flaps 20 are positioned proximal to the inboard region 12 of the wing 2 and are therefore closer to the fuselage 5 than the outboard region 13 of the wing 2.

[0029] The flaps 20 are shown in a neutral, undeployed orientation 20a in Figure 2. The neutral position of the flaps 20 is taken with respect to the fixed wing portion 4. In the neutral position, the flaps 20 are flush with an upper surface of the wing 2 and do not protrude from the outer aerodynamic profile 3 of the wing 2. The flaps 20 are configured to be deployed from the neutral position 20a through to a deployed position (not shown) in which the flaps 20 extend downwardly and / or outwardly away from the aerodynamic profile of the wing 4. In the deployed configuration, the flaps 20 alter the airflow over the wing 2. More specifically, the flaps 20 are deployable so as to extend outwardly and / or downward away from the wing 2 to increase the wings’ 3 surface area to provide additional lift during take-off and landing of the aircraft 1.

[0030] The starboard side 3a of the wing 2 also includes an aileron 30. The aileron 30 is positioned proximal to the outboard region 13 of the wing 2 and is therefore distal from the fuselage 5. As shown, the aileron 30 is positioned on the trailing edge 3c of the wing 2. The aileron 30 is shown in a neutral, undeployed orientation 30a in Figure 2. In the neutral position, the aileron 30 is flush with the upper surface of the wing 2 and does not protrude into the oncoming airflow over the wing 2. The aileron 30 is configured to move from the neutral position 30a to a deployed configuration (not shown). In the deployed position, the aileron 30 are deployable up into the oncoming airflow over the starboard side 3 a of the wing 2. The aileron 30 affects the lift generated at the starboard side 3a of the wing 2 and can be used in conjunction with an aileron on the port side 2a of the wing 2 to roll the aircraft 1. More specifically, one aileron 30 will be deflected upward relative to the fixed portion 4 on one side of the wing 2 (e.g. starboard side 3a), while the aileron on the opposite side (e.g. port side 2a) will be deflected downward relative to the fixed portion 4. This creates an imbalance of lift over the wing 2 on the port side 2a or the starboard side 3a, which causes the aircraft to roll (around a longitudinal axis of the aircraft 1 from the nose 5 to the tail 7) either towards the port side 2a or the starboard side 3a. While the aileron 30 is described as being moved between the neutral position 30a to a deployed configuration, it will be understood that during flight of the aircraft 1, the ailerons 30 may move continuously or periodically through a variety of angled positions relative to the fixed portion of the wing 4. As described in more detail below, the neutral position 30a of the aileron 30 may be taken to be an initial position of the aileron 30 that is not flush with the upper surface of the wing 2.

[0031] The wing 2 also includes a spoiler 40. The spoiler 40 in this example is located on the upper surface of the wing 2 and midway between the leading edge 3b and the trailing edge 3c. While the spoiler 40 is shown in Figure 2 to be located in the mid-span of the wing 2, the spoiler 40 may be at any suitable position along the span of the wing 2. The spoiler 40 shown in Figure 2 is in a neutral, undeployed orientation 40a. The spoiler 40 is configured to move between the undeployed position 40a through to a deployed configuration (not shown), where the spoiler 40 disrupts the airflow over the wing 2, which reduces lift and increases drag, thereby slowing down the aircraft 1. While only one spoiler 40 is shown in Figure 2, it will be understood that the wing 2 may have several spoilers 40 arranged on the wing 2.

[0032] As the port side 2a of the wing 2 is in similar construction with the starboard side 3 a of the wing 2, the wing 2 has similar flight control surfaces 10 on both sides for symmetry of the wing 2. In this example, the wing 2 preferably has at least one flap 20, aileron 30 and spoiler 40 on each side of the wing 2. Preferably, the flaps 20 are arranged as a pair of flaps 20, with one flap of the pair located on each side of the aircraft 1 (i.e. one on the starboard side 3a and one on the port side 2a).

[0033] The aircraft 1 also includes a flight control system 100, shown schematically in Figure 1. The flight control system 100 is an electronic control system within the aircraft 1. The flight control system 100 may be coupled to multiple other systems within the aircraft 1. The flight control system 100 may also be coupled to an interface which allows an operator to control the operation of the control systems coupled to the flight control system 100.

[0034] The flight control system 100 is in electronic communication with the flight control surfaces 10 on both the port side 2a and starboard side 3a of the wing 2. The flight control system 100 is operable to control the operation of the flight control surfaces 10. Each flight control surface 10 shown in Figure 2 can therefore be moved between a neutral position and a deployed position to disrupt the airflow over the wing 2 using the flight control system 100. The flight control system 100 may also be used to deploy each flight control surface 10 independently from neighbouring flight control surfaces. Alternatively, the flight control system 100 may be used to deploy each flight control surface 10 in conjunction with neighbouring flight control surfaces 10. Each flight control surface 10 may therefore be deployed simultaneously or independently.

[0035] While the flight control system 100 can control each flight control surface 10 on the wing 2, the operation of the flight control system 100 to roll the aircraft 1 is described in more detail in relation to Figures 4A and 4B. In this example, the flight control system 100 operates a flap 20 on one side of the aircraft (e.g. port side 2a or starboard side 3a) and an aileron 30 on the opposite side of the wing 2 (i.e. the starboard side 3a or the port side 2a) to assist the aircraft 1 complete a roll manoeuvre. The flap 20 is therefore extended by the flight control system 100. The flap 20 may therefore be extended relative to the fixed wing portion 4 of the wing 2. The flap 20 is therefore moved to the desired position. The flap 20 may be moved downwardly relative to the fixed portion 4 of the wing 2. Additionally, or alternatively, the flap 20 may be moved outwardly relative to the fixed portion 4 of the wing 2. By using a flap 20 on the opposite side of the wing 2 to the aileron 30 to roll the aircraft 1, the flap 20 can increase the lift generated on the respective side of the wing 2 (i.e. port 2a or starboard 3a). Using the flap 20 in this manner creates a larger lift imbalance across the wing 2 compared to when the aircraft 1 executes a roll manoeuvre by only using an aileron 30, and even when a spoiler 40 is additionally used. This is because the flap 20 is typically has a larger surface than the aileron 30 and the spoiler 40. Therefore, even a small flap 20 deflection will contribute to the rolling moment of the aircraft 1.

[0036] The architecture of the flight control system 100 is shown schematically in Figure 3. The flight control system 100 may be used with the flight control surfaces 10 to roll the aircraft 1. As shown, the flight control system 100 is configured to receive a roll demand input 110, to move a flap 20 to a desired flap position output 120 and to move an aileron 30 to a desired aileron output 130 through respective flap drive systems 124 and aileron drive systems 134. As shown the aileron position output 130 is coupled to the aileron 130, and the flap position output 120 is coupled to the flap actuator 122.

[0037] The roll demand input 110 initiates a roll sequence in the aircraft 1 and communicates to the flight control system 100 to begin a roll manoeuvre of the aircraft 1. The roll manoeuvre may turn the aircraft 1 towards the port side 2a or starboard side 3a of the aircraft 1. The degree of roll (i.e. how much the aircraft 1 turns) may also be determined by the roll demand input 110. The flight control system 100 is therefore operable to control the extent of roll exhibited by the aircraft. The roll demand input 110 may be provided by any suitable input, such as a pre-programmed flight signal to the control system 100, or from an operator-input (such as a joystick operated by a pilot).

[0038] In order to achieve the desired roll output (determined by the roll demand input 110), the flight control system 100 calculates what the final position of the flap 20 and the aileron 30 need to be to achieve the desired rate of roll of the aircraft 1. The flight control system 100 therefore calculates the flap position output 120 and the aileron position output 130 in response to the roll demand input 110. The flap position output 120 and the aileron position output 130 are therefore variables that change depending on the roll demand input 110.

[0039] Once the flap position output 120 and the aileron position output 30 have been determined, the flight control system 100 operates a flap actuator 122 and flap drive system 124 to deploy the flap 20 to the desired position. Similarly, the flight control system 100 operates an aileron actuator 132 and aileron drive system 134 to deploy the aileron 30 to the desired position. The flight control system 100 can therefore control the position, or deployment, of the aileron 30 through the aileron position output 130. Similarly, the flight control system 100 can control the position, or deployment, of the flap 20 through the flap position output 120.

[0040] The flight control system 100 therefore moves the flap 20 / aileron 30 from a first position 202 to a second position 208, 210 (described in more detail in relation to Figure 4A). The first position 202 of the flap 20 and / or the aileron 30 may be a neutral undeployed orientation 20a, 30a as shown in Figure 2. In other examples, the first position 202 of the flap 20 and / or the aileron 30 may be a first angular position and the second position 208, 210 may be a second angular position. For example, the aileron 30 may already be deflected upward or downwardly by a certain angular degree relative to the fixed portion 4 of the wing 2 when the roll manoeuvre is initiated 110. Similarly, the flap 20 may also be deflected downwardly or extended backwardly (towards the tail end 7) by a certain angular degree relative to the fixed portion 4 of the wing 2 when the roll manoeuvre is initiated 110. In this instance, the flight control system 100 will move the flap 20 and aileron 30 to the desired position outputs 120, 130 using the relative actuation systems 124, 134.

[0041] The flight control system 100 therefore is operable to control the deployment of the flap 20 and aileron 30 on the wing 2 based on the roll demand input received, as described in more detail below. The flight control system 100 is therefore configured to process the roll demand input 110 and provide the aileron position output 120 to the aileron actuator 122. The aileron 30 is then moved into position by the aileron drive system 134. Similarly, the flap position output 130 is provided to the flap actuator 132, which is then moved into position by the aileron drive system 134. This initiates a roll manoeuvre of the aircraft 1, as the aileron 30 is moved upwards on one side of the wing 2 (with respect to the fixed wing portion 4) and the flap 20 is moved downwards on an opposite side of the wing 2 (with respect to the fixed wing portion 4).

[0042] The aileron position output 130 and / or the flap position output 120 may be a manually inserted value or may be automatically pre-set from the roll demand input 110. The actuators 122, 132 may be any suitable conventional actuation system, and the drive systems 124, 134 may be any suitable drive system capable of changing the position of the flap 20 and aileron 30, respectively. The position outputs 120, 130 may be determined as angular rotations of the flap 20 and aileron 30 relative to the fixed portion 4 of the wing 2, or as relative angular positions of the flap 20 and aileron 30 to each other.

[0043] A method 200 of controlling the roll of the aircraft 1 is described below in relation to Figures 4A and 4B. At step 201, an aircraft 1 is provided as described, with a flap 20 on one side of the aircraft (i.e. port 2a or starboard 3a) and an aileron on the opposite side. The flap 10 and / or aileron 30 are provided in a first position at step 202. As described above in relation to Figure 3, the first position 202 may be a neutral position of each flow control surface 10, where the flap 20 and / or aileron 30 are provided flush against the surface of the wing 2. In other examples, the first position 202 may be in a deployed position, where the flap 20 and / or aileron 30 are already actuated into the oncoming airflow over the wing 2.

[0044] The flap 20 and aileron 30 may be in different first positions when the roll manoeuvre is initiated at step 204. The roll manoeuvre 204 may be pre-programmed into a specific flight path programming within the flight control system 100 or may be a manual input (e.g. by displacing a joystick within the aircraft 1). Once the roll manoeuvre has been initiated, the flight control system 100 processes the roll demand input at step 206 before moving the aileron to a second position at step 208 by using the relevant aileron drive system 134 and aileron actuator 132.

[0045] The second position at step 208 of the aileron 30 may be upward relative to the fixed wing portion 4 of the wing 2 or may be a different angular position relative to the first position 202. The flap 20 is moved to a second position at step 210 using the relevant drive system 124 and actuator 122. The second position at step 210 of the flap 20 may be downward relative to the fixed wing portion 4 of the wing 2 or may be a different angular position relative to the first position 202. When not in the neutral position, the flap 20 and the aileron 30 may be deflected position relative to the neutral position.

[0046] Optionally, the method 200 may also include moving a spoiler 40 that is on the same side of the wing 2 as the aileron 30 that is deployed (e.g. if the port 2a aileron is deployed during the roll manoeuvre, then the port 2a spoiler 40 is also deployed). The spoiler 40 may be deployed from a first position 222 to a second position 232 in relation to the fixed portion 4 of the wing 2. The spoiler 40 is therefore deployed in a similar manner to the flap 20 and the aileron 30 using a spoiler drive system (not shown). The spoiler 40 may be used with the aileron 30 to create a greater lift on the relevant side of the wing 2, allowing for a greater difference in left between each side of the wing 2 and resulting in a tighter turning circle of the aircraft 1.

[0047] Figure 4B shows another exemplary method 200’ of rolling the aircraft. Identical steps are provided with an additional dash and will not be explained in further detail again. As shown, the flap 20 and aileron 30 are provided in a first angular position 212. As described above, the angular position of the flap 20 and aileron 30 describe the position of the flap 20 and aileron 30 when they are deflected into the oncoming airflow over the wing 2. After the roll manoeuvre is initiated at 204’, the flight control system 100 processes the roll demand input at step 206’ and determines the flap position output 120 and the aileron position output 130. Finally, the flight control system 100 moves the flap 20 and aileron to the second angular positions respectively 214, 216.

[0048] Due to the architecture of the wing 2 and the flap drive system 124 and aileron drive system 134, the angular movement of the aileron 30 between the first position 202 and the second position 208 is larger than the angular movement of the flap 20 between the first position 202 and the second position 210. This is typically because the aileron 20 are positioned near the outboard region 13 of the wing 2 and are designed to withstand larger ranges of angular movement than the flaps 20, which are located inboard 12 of the wing 2.

[0049] Optionally, the method 200’ may also include moving a spoiler 40 that is on the same side of the wing 2 as the aileron 30 that is deployed (e.g. if the port 2a aileron is deployed during the roll manoeuvre, then the port 2a spoiler 40 is also deployed). The spoiler 40 may be deployed from a first angular position 242 to a second angular position 252 in relation to the fixed portion 4 of the wing 2. The spoiler 40 is therefore deployed in a similar manner to the flap 20 and the aileron 30 using a spoiler drive system (not shown).

[0050] In both the method 200 in Figure 4A, and the method 200’ in Figure 4B, the roll manoeuvre results in upward deflection of the aileron 30 and a downward deflection of the flap 20 relative to a fixed portion 4 of the wing 2. While the examples described in Figures 4A and 4B show the flap 20 and aileron 30 both in the neutral position 202 or in a first angular position 212, it will be understood that the flight control system 100 operates in a similar manner even if the flap 20 or the aileron 30 is in the neutral position 20a, 30a and the opposite flap or aileron 30 is in a first angular position 212.

[0051] While both method 200 and method 200’ describe the flight control system 100 deploying only one flap 20, it will be understood that any number of flaps 20 may be moved between a first position 202 and second position 210 when the roll manoeuvre 204, 204’ is initiated. Preferably, the most outboard flap 20 (i.e. the flap 20 closest to the outboard region 13 of the wing 2) is deployed when the roll manoeuvre is initiated. The most outboard flap 20 is most preferred because this affects the lift distribution over the wing 2 and therefore has the greatest impact in creating an imbalanced lift across the wing 2 to cause the aircraft 1 to turn. In other examples, more than one flap 20 may be moved when the roll manoeuvre is initiated depending on the roll demand input received by the flight control system 100.

[0052] Similarly, while both method 200 and method 200’ describe the flight control system 100 deploying only one spoiler 40, it will be understood that any number of spoilers 20 may be moved between a first position and second position when the roll manoeuvre 204, 204’ is initiated. Preferably, the most outboard spoiler 40 (i.e. the spoiler 40 closest to the outboard region 13 of the wing 2) is deployed when the roll manoeuvre is initiated. The most outboard spoiler 40 is most preferred because this affects the lift distribution over the wing 2 and therefore has the greatest impact in creating an imbalanced lift across the wing 2 to cause the aircraft 1 to turn. In other examples, more than one spoiler 40 may be moved when the roll manoeuvre is initiated depending on the roll demand input received by the flight control system 100.

[0053] While the method 200 and 200’ in Figures 4A and 4B describe controlling the roll of an aircraft 1 by using only one aileron 30 on one side (i.e. port 2a or starboard 3 a) of the aircraft 1, it will be understood that the flap 20 may be deployed when both ailerons 30 on both sides of the wing 2 are deployed and still have the described advantages. Furthermore, step 208 in method 200 (Figure 4A) and step 214 in method 200’ (Figure 4B) may further include moving the aileron on the opposite side of the wing 2 at the same time that the aileron 30 on the first side of the wing 2 is moved to the second position. In this arrangement, the aileron that is on the same side as the flap 20 on the wing 2 (i.e. port 2a or starboard 3a) is preferably deployed downward relative to a fixed portion 4 of the wing 2. The aileron and the flap 20 therefore work together to affect the lift over one side of the wing 2. The aileron 30 that is on the opposite side of the wing 2 to the flap 20 is preferably deployed upward relative to the fixed portion 4 of the wing 2. This allows the aircraft 1 to roll either in the port 2a or starboard 3a direction.

[0054] The flight control system 100 may initiate the deployment of both the aileron 30 and flap 20 simultaneously, but the aileron 30 will typically deploy faster than the flap 20. This may be because the aileron 30 is smaller than the flap 20, and therefore the aileron drive system 134 can deploy the aileron 30 faster than the flap drive system 124. Furthermore, typical aircraft do not need to move the flap 20 as quickly as aileron 30 and as such they have different actuators and design speeds. It may be desirable to have the flight control system 100 move the flap(s) 20 and the aileron(s) 30 simultaneously. Accordingly, the flight control system 100 may introduce a delay into the initiation of deployment of the aileron 30 so as to move both aileron 30 and flap 20 simultaneously.

[0055] In other examples, the flight control system 100 may initiate deployment of the flap 20 or aileron 30 depending on the roll manoeuvre of the aircraft 100. In other examples, the flight control system 100 may delay the deployment of the aileron 30 so that the aileron 30 deploys later than the flap 20. Therefore, with reference to Figure 4A, step 210 may be initiated before step 208. In other examples, the flight control system 100 may delay the deployment of the flap 20 so that it deploys later than the aileron 30. Therefore, with reference to Figure 4A, step 208 may be initiated before step 208. The delay initiated by the flight control system 100 is preferably a time delay. The delay may be pre-programmed into the flight control system 100 depending on the roll manoeuvre 204, 204’ or may be manually controlled by e.g. the pilot. In other examples, the delayed deployment of the flap 20 and aileron 30 may be caused by the rate of deployment by the flap drive system 124 or the aileron drive system 134.

[0056] Moving the aileron 30 on one side of the wing 2 and the flap 20 on the opposite side of the wing 2 allows the aircraft 1 to utilise smaller flight control surfaces 10. More specifically, because the flap 20 is used to assist in the roll manoeuvre of the aircraft 1, the aileron 30 can have smaller dimensions than conventional aileron 30 arrangements. This is because the aileron 30 is not solely responsible for creating a lift imbalance over the wing 2. Instead, the lift imbalance over the wing 2 is caused by both the aileron 30 and the flap 20.

[0057] While the flap 20 on one side of the aircraft 1 is deployed during the roll manoeuvre, the aircraft 1 still has a pair of flaps 20 across both sides of the aircraft 1 (i.e. one on the starboard side 3a and one on the port side 2a). During the roll manoeuvre, only one flap 20 (or a plurality of flaps) are deployed on one side of the wing 2. As such, when in the second position, the angular difference between the pair of flaps during the roll manoeuvre is at least 3 degrees when measured relative to the neutral position 20a.

[0058] For example, if the aircraft 1 is required to turn right (i.e. towards the starboard side 3a of the aircraft 1), the roll manoeuvre is initiated 110 by any suitable means. In response, the flight control system 100 calculates the degree of deployment (i.e. the angular displacement) required of the aileron 30 and opposite flap 20 to achieve the roll. Then, the starboard aileron 30 is moved from a first position 202 to a second position 208, and the port flap 20 is also moved from a first position 202 to a second position 210. Optionally, the spoiler 40 on the starboard side may be moved upward relative to a fixed portion of the wing 2. The aileron 30 on the port side of the wing 2 may also optionally be moved downward relative to a fixed portion of the wing 2. In this arrangement, the starboard side 3 a of the wing 2 produces less lift (from the aileron 30) and the port side 2a generates more lift (from the flap 20), causing the aircraft 1 to turn towards the starboard side 3a. If the aircraft 1 is required to turn left (i.e. towards the port side 2a of the aircraft 1), the flight control system 100 operates the opposite arrangement of ailerons 30 and flaps 20 (i.e. the aileron 30 on the port side 2a is moved to a second position, while the flap 20 on the starboard side 3a is moved to a second position).

[0059] Where the word 'or' appears this is to be construed to mean 'and / or' such that items referred to are not necessarily mutually exclusive and may be used in any appropriate combination.

[0060] Although the invention has been described above with reference to one or more preferred embodiments, it will be appreciated that various changes or modifications may be made without departing from the scope of the invention as defined in the appended claims.

Claims

1. A method of controlling roll of an aircraft, the aircraft having a wing with port and starboard sides, a fixed wing portion and an aileron and a flap on each side of the wing, the method comprising:initiating a roll manoeuvre of the aircraft by:moving the aileron on one side of the wing in an upward direction with respect to the fixed wing portion; andextending the flap on the other side of the wing with respect to the fixed wing portion.

2. A method according to any preceding claim, wherein moving the aileron and moving the flap are both initiated simultaneously.

3. A method according to any preceding claim, wherein initiating the roll manoeuvre comprises moving the aileron from a first angular aileron position to a second angular aileron position with respect to the fixed wing portion, and moving the flap from a first angular flap position to a second angular flap position with respect to the fixed wing portion, wherein the angular movement of the aileron between the first and second aileron positions is larger than the angular movement of the flap between the first and second flap positions.

4. A method according to any preceding claim, wherein the flap and aileron each have a neutral position with respect to the fixed wing portion, and wherein initiating the roll manoeuvre is from the neutral position, or is from a deflected position relative to the neutral position.

5. A method according to any preceding claim, wherein the wing has a plurality of flaps spaced spanwise across the wing, and the method comprises moving the most outboard flap or flaps when initiating the roll manoeuvre.

6. A method according to any preceding claim, wherein the wing has a plurality of flaps spaced spanwise across the wing, and the method comprises extending more than one flap when initiating the roll manoeuvre.

7. A method according to any preceding claim, wherein the aircraft further comprises a spoiler on each side of the wing, and initiating the roll manoeuvre further comprisesmoving both the spoiler and the aileron on the same side of the wing in an upward direction with respect to the fixed wing portion.

8. A method according to any preceding claim, wherein the flaps are arranged as a pair of flaps with one flap of the pair located on each side of the aircraft, and the pair of flaps has a neutral position with respect to the fixed wing portion, and wherein an angular difference between the flaps of the pair of flaps during a roll manoeuvre is at least 3 degrees as measured relative to the neutral position.

9. An aircraft having a wing with port and starboard sides, a fixed wing portion and an aileron and a flap on each side of the wing, and a flight control system for controlling roll of the aircraft, the flight control system comprising a roll demand input, an aileron position output coupled to an aileron actuator for moving the aileron, and a flap position output coupled to a flap actuator for moving the flap,wherein the flight control system is configured to process the roll demand input, provide the aileron position output to the aileron actuator, and provide the flap position output to the flap actuator, so as to initiate a roll manoeuvre of the aircraft according to the roll demand input by moving the aileron on one side of the wing in an upward direction with respect to the fixed wing portion, and extending the flap on the other side of the wing respect to the fixed wing portion.A

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