(19)
(11)EP 3 816 041 A1

(12)EUROPEAN PATENT APPLICATION

(43)Date of publication:
05.05.2021 Bulletin 2021/18

(21)Application number: 19382940.5

(22)Date of filing:  29.10.2019
(51)International Patent Classification (IPC): 
B64C 9/00(2006.01)
B64C 9/30(2006.01)
(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR
Designated Extension States:
BA ME
Designated Validation States:
KH MA MD TN

(71)Applicant: Airbus Operations, S.L.U.
28906 Getafe (Madrid) (ES)

(72)Inventors:
  • BALSA GONZALEZ, Alberto
    28906 Getafe (ES)
  • KOBIERECKI, Robert
    28906 Getafe (ES)
  • SANCHEZ RUIZ, Juan Antonio
    28906 Getafe (ES)
  • MÉNDEZ RODRÍGUEZ, Miguel Ángel
    28906 Getafe (ES)

(74)Representative: Elzaburu S.L.P. 
Miguel Angel 21, 2nd floor
28010 Madrid
28010 Madrid (ES)

  


(54)CONTROL SURFACE FOR AN AIRCRAFT AND CONTROL STRUCTURE FOR AN AIRCRAFT WITH ANTI-FLUTTER BALANCE WEIGHT


(57) Control surface (1) for an aircraft and control structure (11) for an aircraft. The control surface (1) for an aircraft (as an elevator or a rudder) comprises a leading edge (3) and a trailing edge (4) and is able to rotate around a spanwise hinge line (5) when assembled in the aircraft, and additionally comprises a balance weight (6) completely installed ahead of and adjacent to the most frontal portion (7) of the leading edge (3). The control structure (11) for an aircraft comprises a control surface (1) for an aircraft and a stabilizer (2) that supports the control surface (1), the control surface (1) being able to rotate with respect to the stabilizer (2) around a hinge line (5), the stabilizer (2) comprising a leading edge, a trailing edge and a torsion box, such that at least part of the leading edge (3) of the control surface (1) and the balance weight (6) completely installed ahead of and adjacent to the most frontal portion (7) of the leading edge (3) of the control surface (1) are inside the trailing edge of the stabilizer (2). This arrangement allows to have an anti-flutter balance weight without any impact in aerodynamic drag.




Description

Field of the invention



[0001] This invention refers to a control surface for an aircraft, such as an elevator or a rudder, and to a control structure suitable for installing anti-flutter balance weight with minimal aerodynamic drag.

Background of the invention



[0002] Flutter is a phenomenon caused by aerodynamic forces which can damage elastic structures such as aircraft, bridges or buildings, for example.

[0003] Flutter in aircraft causes oscillations in stabilizers and wings. The amplitude of these oscillations can become so large that it can damage such structures.

[0004] As a consequence, flutter must be avoided. For this purpose stabilizers and wings in aircraft are thoroughly designed.

[0005] Most of the solutions of anti-flutter balance weight installations have aerodynamic drag penalty or big mass impact.

[0006] There are different ways to install balance weights that change the control surface centre of gravity to avoid structural configuration that leads to flutter. Some examples are: external mass balance, mass balance inside fuselage or balance weight in aerodynamically balanced surface.

[0007] Currently one solution is to locate an additional weight ahead of the hinge line in a horn-shape housing on the leading edge of a control surface (elevator or rudder), as shown in Fig. 1.

[0008] This solution generates an important aerodynamic drag when the control surface is not aligned with the corresponding stabilizer.

[0009] It is very difficult to find the best place where to install the balance weight. In effect, some limitations are the problems with clashes due to control surface kinematics, geometrical restrictions and ergonomic requirements.

[0010] WO2008127482A2, referred to "Structural Dynamic Stability for an Aircraft", discloses an improvement and method for improved structural dynamic stability for 20 and 30 Series Learjets. The improvement includes a redistribution of the elevator mass balance to uncouple the elevator rotational motion from the stabilizer translation motion for the higher order horizontal frequencies having node lines in the proximity of the mass outboard counterbalance weights. The original tail section includes a rudder, and a horizontal stabilizer supporting an elevator mounted adjacent the rudder. The improved elevator includes a proximal end adjacent the rudder and a distal end that includes a counterbalance portion. The improvement further includes replacement of an original mass counterbalance weight from within the counterbalance portion with new mass counterbalance weights of less mass, and the inclusion of the additional mass counterbalance weights disposed within the elevator and interposed between the proximal and distal ends, and the counterbalance portions.

[0011] US2859925A, referred to an "Automatic Balancing Arrangement for Aircraft Control", discloses an automatic balancing arrangement for aircraft control surfaces, which is essentially constituted by at least one counter-weight arranged at the extremity of a lever-arm of sufficient length for the mass of the said counter-weight to be as small as possible, this lever not being rigidly connected to the control but pivotally-mounted upon it, and being operated by a suitable device in such manner that, when the control-surface pivots in a given direction, the lever pivots in the opposite direction, whereby, for every angular position of the control-surface, there will correspond a position of the balancing lever which is always contained within the limits of space in the wing or other member within which this lever is housed.

[0012] U2980367A, referred to a "Linked inertial balance for tab", discloses, in a control surface for an aircraft, a tab pivotable about a hinge line on said control surface, first and second counterweights having independently selectable masses-carried at opposite ends of a bar, said bar being rotatable about a pivot having the first and second counterweights onto opposite sides of the pivot axis, means linking said bar to said-tab including an arm extending downward midway between the counterweights and a push rod connected between the arm and tab for transferring motion of said bar to said tab to provide independently selectable amounts of dynamic balance and static balance to said tab as determined by the selected masses of said first and second counterweights.

[0013] US2930550A, referred to "Aircraft flight controls", discloses an elevator that has a nose portion of elliptical section projecting forwardly of its hinge axis and serving as a partial aerodynamic balance for the elevator and also serving to house weights to mass balance the elevator. The aerodynamic balancing of the elevators is substantially completed by a horn balance at the outer end of each elevator. Part of the balancing mass in each elevator is constituted by a torsion bar spring arranged near the tip of the nose portion and with its axis parallel to the hinge axis. One end of the spring is anchored to the elevator and towards its other end the spring is supported in a journal bearing carried by the elevator, the other end of the spring being provided with a lever projecting towards the hinge axis, the free end of the lever being connected by a link to a pivot carried by the tail plane so that rotation of the elevator about its hinge causes the spring to be twisted.

[0014] Accordingly, there is a need to obtain control surfaces with an anti-flutter balance weight that reduces the aerodynamic drag.

Summary of the invention



[0015] The object of the present invention is to provide a control surface that overcomes the drawbacks existing in the prior art systems with respect to the aerodynamic drag caused by the anti-flutter balance weight installation.

[0016] The invention provides a control surface for an aircraft, comprising a leading edge and a trailing edge and able to rotate around a spanwise hinge line when assembled to at least one another portion of the aircraft, that additionally comprises a balance weight completely installed ahead of and adjacent to the most frontal portion of the leading edge, such that the balance weight comprises an external surface with a portion in contact with the leading edge and a portion not in contact with the leading edge.

[0017] The position and configuration of the balance weight of the invention prevents flutter and at the same time limits the aerodynamic drag. In some embodiments, the invention allows to prevent flutter with no impact on the aerodynamic drag of the control surface.

[0018] The invention also provides a control structure for an aircraft, comprising a control surface for an aircraft of the invention and a stabilizer that supports the control surface, the control surface being able to rotate with respect to the stabilizer around a hinge line, the stabilizer comprising a leading edge, a trailing edge and a torsion box, such that at least part of the leading edge of the control surface and the balance weight completely installed ahead of and adjacent to the most frontal portion of the leading edge of the control surface are placed inside the trailing edge of the stabilizer. At least part of the leading edge and the balance weight are placed inside the trailing edge of the stabilizer in the whole movement range, in particular in the authorized hinging angles range, of the control surface. In particular, the entire leading edge of the control surface may be placed inside the trailing edge of the stabilizer, at any hinging angle of the control surface in the stabilizer, such that it does not form a horn above the extrados or below the intrados of the stabilizer. The anti-flutter balance weight thus has no impact on the aerodynamic drag of the control surface.

[0019] The invention also provides an aircraft with the above control structures and control surfaces.

[0020] The following are some of the advantages of the invention:
  • It reduces weight in comparison with balance weight installed in the tip of the torsion box.
  • It reduces aerodynamic drag in comparison with anti-flutter medium such as an aerodynamic horn.
  • It does not require special (very high density) materials.
  • It allows to have an easy replaceable part to allow full interchangeability of control surfaces (elevators or rudders) between different types of plane.
  • It can be installed on new aircraft or as retrofit to existing aircraft.


[0021] Other characteristics and advantages of the present invention will be clear from the following detailed description of several embodiments illustrative of its object in relation to the attached figures.

Brief description of drawings



[0022] 

Figure 1 shows a prior art solution that uses anti-flutter balance weights in aircraft.

Figure 2 shows a control surface of an aircraft with a balance weight according to the invention.

Figure 3 shows a cross section A-A of Figure 2.

Figure 4 shows a cross section of a control structure for an aircraft, comprising a control surface and a stabilizer, before installing the balance weight.

Figures 5 and 6 show a cross section of several positions of a control structure for an aircraft, comprising a control surface and a stabilizer, with the balance weight.

Figures 7, 8 and 9 show cross sections of different designs of the balance weight.

Figure 10 shows the tail of a conventional aircraft.


Detailed description of the invention



[0023] Figure 2 shows an example of a control surface 1 of an aircraft with a balance weight 6 of the invention. In this case, an elevator is shown.

[0024] The control surface 1 of Figure 2 comprises a leading edge 3 and a trailing edge 4, and is able to rotate around a hinge line 5 when assembled in the aircraft (the hinge line 5 can be seen in Figure 4). It also comprises a balance weight 6 completely installed ahead of and adjacent to the most frontal portion 7 of the leading edge 3, taking advantage of the geometry of the control surface 1.

[0025] In Figure 2 it can also be seen that the balance weight 6 can be a profile and it can be made of metal.

[0026] Figure 3 shows a cross section A-A of Figure 2. It can be seen that the balance weight 6 is fastened to the most frontal portion 7 of the leading edge 3 of the control surface, such that the balance weight 6 is completely installed ahead of said most frontal portion 7. It can be fastened by means of fasteners 10 (for example, bolts and anchor nuts). It can also be seen that the cross-section of the profile has a drop-like shape in this embodiment.

[0027] Flight direction, which serves as a reference for establishing relative positions, is shown in Figures 1, 2 and 3.

[0028] The installation of the balance weight 6 with fasteners 10 and the easy access to the balance weight 6 allows an easy and adequate replacement when necessary. In this way it is possible to adjust the balance weight 6 even during the exploitation of the control surface 1. It allows full interchangeability of the control surfaces between different types of plane which need different balance weight 6 because of their own configuration.

[0029] Figure 4 shows a control structure 11 for an aircraft, with a control surface 1 for an aircraft (as the one represented in Figure 2) and a stabilizer 2 that supports the control surface 1. In these figures the control surface 1 is an elevator, and the stabilizer 2 is a horizontal stabilizer (HTP). The elevator is able to rotate with respect to the horizontal stabilizer around a hinge line 5. Figures 5 and 6 show different rotation positions of the elevator (Figure 9 at 30º and Figure 10 at - 15º). As it can be seen in Figures 5 and 6, the balance weight 6 is always inside the control structure 11 and allows full up and down elevator positions.

[0030] Also, the horizontal stabilizer has the usual configuration, comprising a leading edge, a trailing edge and a torsion box. At least part of the leading edge 3 of the elevator and the balance weight 6 completely installed ahead of and adjacent to the most frontal portion 7 of the leading edge 3 of the elevator are placed inside the trailing edge of the horizontal stabilizer to avoid any aerodynamic drag augmentation.

[0031] An equivalent arrangement can be obtained for a control structure 11 for an aircraft with a rudder and a vertical stabilizer (VTP).

[0032] In an embodiment, the entire leading edge 3 of the control surface may be placed inside the trailing edge of the corresponding stabilizer at any hinging angle of the control surface in the stabilizer.

[0033] For instance, the height of the profile (balance weight 6) can be 40 mm. If a profile of steel of 40 mm high, 1,5 m long and approximately 4 cm2 of cross-section is installed, a saving of 6,6 kg can be achieved.

[0034] Another way to save weight is to use different materials. For example, the above geometry made of aluminium would weight 2,2 kg.

[0035] In an embodiment of the invention the density of the material of the balance weight 6 is higher than the density of the material of rest of the control surface 1.

[0036] Another possibility is to design smaller or shorter profiles in order to achieve a better integration in the existing structure, as shown in Figure 7. In this example the portion of the external surface of the profile not in contact with the leading edge 3 of the control surface 1 is rounded.

[0037] Another option is to use other cross sections to avoid problems with sealing profile functionality, as shown in Figure 8.

[0038] Another option is to optimize the position of the concentration of the balance weight 6 according to a specific structure configuration, as shown in Figure 9. In this figure the balance weight 6 comprises a first portion 8 fastened to the leading edge 3 of the control surface 1 and a second portion 9 away from the first portion 8. This option increases the distance between the second portion 9 and hinge line 5 reducing the balance weight necessary to avoid flutter.

[0039] Figure 10 shows the tail of a conventional aircraft 12, where the relative positions of the elevator, the horizontal stabilizer, the rudder and the vertical stabilizer can be seen.

[0040] Although the present invention has been fully described in connection with preferred embodiments, it is evident that modifications may be introduced within the scope thereof, not considering this as limited by these embodiments, but by the contents of the following claims.


Claims

1. Control surface (1) for an aircraft, comprising a leading edge (3) and a trailing edge (4) and able to rotate around a spanwise hinge line (5) when assembled to at least one another portion of the aircraft, characterized in that it additionally comprises a balance weight (6) completely installed ahead of and adjacent to the most frontal portion (7) of the leading edge (3), such that the balance weight (6) comprises an external surface with a portion in contact with the leading edge (3) and a portion not in contact with the leading edge (3).
 
2. Control surface (1) for an aircraft, according to claim 1, wherein the balance weight (6) is a profile.
 
3. Control surface (1) for an aircraft, according to claim 2, wherein the profile has a drop-like shape cross-section.
 
4. Control surface (1) for an aircraft, according to claim 2 or 3, wherein the portion of the external surface of the profile not in contact with the leading edge (3) is rounded.
 
5. Control surface (1) for an aircraft, according to claim 2, wherein the profile comprises a first portion (8) fastened to the leading edge (3) of the control surface (1) and a second portion (9) away from the first portion (8) of the profile.
 
6. Control surface (1) for an aircraft, according to any of the previous claims, wherein the balance weight (6) is fastened to the most frontal portion (7) of the leading edge (3) by means of fasteners (10).
 
7. Control surface (1) for an aircraft, according to claim 6, wherein the fasteners (10) are bolts and anchor nuts.
 
8. Control surface (1) for an aircraft according to any of the previous claims, wherein the density of the material of the balance weight (6) is higher than the density of the material of the control surface (1).
 
9. Control surface (1) for an aircraft according to any of the previous claims, wherein the balance weight (6) is made of metal.
 
10. Control structure (11) for an aircraft, comprising a control surface (1) for an aircraft of any of claims 1 to 8 and a stabilizer (2) that supports the control surface (1), the control surface (1) being able to rotate with respect to the stabilizer (2) around a hinge line (5), the stabilizer (2) comprising a leading edge, a trailing edge and a torsion box, such that at least part of the leading edge (3) of the control surface (1) and the balance weight (6) completely installed ahead of and adjacent to the most frontal portion (7) of the leading edge (3) of the control surface (1) are inside the trailing edge of the stabilizer (2).
 
11. Control structure (11) for an aircraft, according to claim 10, wherein the control surface (1) is an elevator and the stabilizer (2) is a horizontal stabilizer.
 
12. Control structure (11) for an aircraft, according to claim 10, wherein the control surface (1) is a rudder and the stabilizer (2) is a vertical stabilizer.
 
13. Aircraft (12) comprising control structures (11) of claim 10.
 




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Cited references

REFERENCES CITED IN THE DESCRIPTION



This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

Patent documents cited in the description