ROTARY WING AIRCRAFT WITH AN AT LEAST PARTIALLY NON-RETRACTABLE LANDING GEAR

Abstract

The disclosure is related to a rotary wing aircraft with a fuselage and an at least partially non-retractable landing gear, wherein the at least partially non-retractable landing gear comprises at least three individual support legs, wherein at least one individual support leg of the at least three individual support legs is mounted pivotally to the fuselage by means of an associated pivot bearing arrangement, wherein the at least one individual support leg is further connected to the fuselage via at least one torsion element with a predetermined elastic range, and wherein the at least one torsion element is adapted to act, in the predetermined elastic range, as a torsional spring, and, outside of the predetermined elastic range, as an energy absorber.

Claims

1. A rotary wing aircraft with a fuselage and an at least partially non-retractable landing gear, wherein the at least partially non-retractable landing gear comprises at least three individual support legs, wherein at least one individual support leg of the at least three individual support legs is mounted pivotally to the fuselage by means of an associated pivot bearing arrangement, wherein the at least one individual support leg is further connected to the fuselage via at least one torsion element with a predetermined elastic range, and wherein the at least one torsion element is adapted to act, in the predetermined elastic range, as a torsional spring, and, outside of the predetermined elastic range, as an energy absorber.

2. The rotary wing aircraft of claim 1, wherein the associated pivot bearing arrangement is provided to enable rotation of the at least one individual support leg about an associated rotation axis defined by the associated pivot bearing arrangement and to transfer shear forces from the at least one individual support leg to the fuselage, and wherein the at least one torsion element is embodied with an inherent nonlinear force characteristic.

3. The rotary wing aircraft of claim 1, wherein the associated pivot bearing arrangement comprises at least one shear pin which is provided to transfer shear forces from the at least one individual support leg to the fuselage, and wherein the at least one torsion element rigidly attaches the at least one individual support leg to the fuselage to limit at least in the predetermined elastic range of the at least one torsion element rotation of the at least one individual support leg about the rotation axis defined by the at least one shear pin.

4. The rotary wing aircraft of claim 3, wherein the at least one torsion element comprises at least one torque tube that rigidly attaches the at least one individual support leg to the fuselage to limit at least in the predetermined elastic range of the at least one torsion element rotation of the at least one individual support leg about the associated pivot bearing arrangement, and wherein the at least one torque tube comprises in its length direction at least one of a circular cross section, an elliptic cross section, a polygonal cross section, a constant outer diameter, a varying outer diameter, a constant wall thickness, a varying wall thickness, one or more holes, one or more slots, one or more grooves, one or more rims, one or more weak points, or one or more steps.

5. The rotary wing aircraft of claim 4, wherein the at least one torque tube is provided in its length direction with end flanges, wherein each end flange comprises in the length direction of the at least one torque tube at least one of a circular cross section, an elliptic cross section, a polygonal cross section, a plurality of circular holes, a plurality of polygonal holes, or a plurality of slots.

6. The rotary wing aircraft of claim 3, wherein the at least one individual support leg comprises at least a first mounting flange and a second mounting flange, and wherein the first mounting flange and the second mounting flange are pivotally mounted to the fuselage by means of the at least one shear pin.

7. The rotary wing aircraft of claim 3, wherein the at least one shear pin comprises a first shear pin for pivotally mounting the first mounting flange to the fuselage, and a second shear pin for pivotally mounting the second mounting flange to the fuselage.

8. The rotary wing aircraft of claim 7, wherein the first shear pin and the second shear pin are rigidly mounted to the fuselage.

9. The rotary wing aircraft of claim 3, wherein the at least one torque tube is rigidly mounted to the first mounting flange and to the fuselage.

10. The rotary wing aircraft of claim 9, wherein the at least one torsion element comprises an additional torque tube that rigidly attaches the at least one individual support leg to the fuselage to limit at least in the predetermined elastic range of the at least one torsion element rotation of the at least one individual support leg about the associated rotation axis defined by the at least one shear pin, wherein the additional torque tube is rigidly mounted to the second mounting flange and to the fuselage.

11. The rotary wing aircraft of claim 3, wherein the at least one individual support leg comprises a third mounting flange that is arranged along the associated rotation axis of the at least one individual support leg between the first mounting flange and the second mounting flange, and wherein the at least one torque tube is rigidly mounted to the third mounting flange and to the fuselage close to the first mounting flange.

12. The rotary wing aircraft of claim 11, wherein the at least one torsion element comprises an additional torque tube that rigidly attaches the at least one individual support leg to the fuselage to limit at least in the predetermined elastic range of the at least one torsion element rotation of the at least one individual support leg about the associated rotation axis defined by the at least one shear pin, wherein the additional torque tube is rigidly mounted to the third mounting flange and to the fuselage close to the second mounting flange.

13. The rotary wing aircraft of claim 11, wherein the at least one shear pin connects the first mounting flange to the second mounting flange.

14. The rotary wing aircraft of claim 10, wherein the additional torque tube comprises in its length direction at least one of a circular cross section, an elliptic cross section, a polygonal cross section, a constant outer diameter, a varying outer diameter, a constant wall thickness, a varying wall thickness, one or more holes, one or more grooves, one or more rims, one or more weak points, or one or more steps.

15. The rotary wing aircraft of claim 14, wherein the additional torque tube is provided in its length direction with end flanges, wherein each end flange comprises in the length direction of the additional torque tube at least one of a circular cross section, an elliptic cross section, a polygonal cross section, a plurality of circular holes, a plurality of polygonal holes, or a plurality of slots.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Illustrative embodiments of the disclosure are outlined by way of example in the following description with reference to the attached drawings. In these attached drawings, identical or identically functioning components and elements are labelled with identical reference numbers and characters and are, consequently, only described once in the following description.

[0042] FIG. 1 shows a perspective view of a rotary wing aircraft with a fuselage and an at least partially non-retractable landing gear according to the present disclosure;

[0043] FIG. 2A to FIG. 2C show perspective views of the rotary wing aircraft with the fuselage and the at least partially non-retractable landing gear of FIG. 1, with different ground contact devices;

[0044] FIG. 3 shows a perspective view of an individual support leg of the at least partially non-retractable landing gear of FIG. 1 to FIG. 2C according to a first embodiment;

[0045] FIG. 4 shows a cut view of the rotary wing aircraft of FIG. 1 to FIG. 2C with the individual support leg of FIG. 3;

[0046] FIG. 5 shows a cut view of the fuselage of the rotary wing aircraft of FIG. 1 to FIG. 2C with the individual support leg of FIG. 3, with two torque tubes, seen along a cut line V-V in FIG. 3 and FIG. 4;

[0047] FIG. 6A to FIG. 6G show perspective views of illustrative variants of the torque tube(s) of FIG. 5;

[0048] FIG. 7 shows a perspective view of an individual support leg of the at least partially non-retractable landing gear of FIG. 1 to FIG. 2C according to a second embodiment;

[0049] FIG. 8 shows a cut view of the rotary wing aircraft of FIG. 1 to FIG. 2C with the individual support leg of FIG. 7;

[0050] FIG. 9 shows a cut view of the fuselage of the rotary wing aircraft of FIG. 1 to FIG. 2C with the individual support leg of FIG. 7, seen along a cut line IX-IX in FIG. 7 and FIG. 8;

[0051] FIG. 10 shows a perspective view of an individual support leg of the at least partially non-retractable landing gear of FIG. 1 to FIG. 2C according to a third embodiment;

[0052] FIG. 11 shows a cut view of the rotary wing aircraft of FIG. 1 to FIG. 2C with the individual support leg of FIG. 10;

[0053] FIG. 12 shows a cut view of the fuselage of the rotary wing aircraft of FIG. 1 to FIG. 2C with the individual support leg of FIG. 10, seen along a cut line XII-XII in FIG. 10 and FIG. 11;

[0054] FIG. 13 shows a force deflection diagram with force deflection curves; and

[0055] FIG. 14 shows a deformation mechanics diagram.

DETAILED DESCRIPTION

[0056] FIG. 1 shows an aircraft 1 that is by way of example illustrated as a rotary wing aircraft, in particular as a Vertical Take-Off and Landing aircraft, and, more particularly, as a helicopter. Thus, for purposes of simplicity and clarity, the aircraft 1 is hereinafter referred to as the “helicopter 1”.

[0057] Illustratively, the helicopter 1 comprises a fuselage 2 that forms, by way of example, a cabin 2a and a cockpit 2b. The fuselage 2 is connected to a tail boom 3 and comprises a lower fuselage region 2c, as well as an upper fuselage region 2d. Furthermore, the fuselage 2 is provided with an underside shell 2e, a portside shell 2f, and a starboard side shell 2g. Moreover, lateral quarter shells 4 are preferably provided in an area of the portside shell 2f and the starboard side shell 2g which is close to the underside shell 2e.

[0058] According to one aspect, the helicopter 1 comprises a landing gear 10. At this point it should be noted that only a part of the helicopter 1 with the fuselage 2 and the landing gear 10 is shown to illustrate the landing gear 10 and connection of the landing gear 10 to the fuselage 2 in more detail, while illustration of other well-known components is omitted, for simplicity and clarity of the drawing. For instance, neither the tail boom 3 is illustrated in greater detail for showing e.g., a suitable counter-torque device, nor a main rotor is shown, and so on.

[0059] Preferably, the landing gear 10 is at least partially non-retractable and, by way of example, the landing gear 10 is non-retractable. According to the present disclosure, the landing gear 10 comprises at least three individual support legs, wherein at least one individual support leg of the at least three individual support legs is mounted pivotally to the fuselage 2, as described in more detail below.

[0060] By way of example, and not for restricting the present disclosure accordingly, the landing gear 10 comprises four individual support legs, from which only two individual support legs are visible in FIG. 1 and labelled with the reference signs 10a, 10b. The individual support legs 10a, 10b are preferably separately mounted pivotally to the fuselage 2 at the lateral quarter shells 4.

[0061] Illustratively, the individual support leg 10a comprises a leg box 11a that may be aerodynamically shaped. The leg box 11a may be connected via a support rod 12a to a solid base 13a that forms a ground contact device. By way of example, the solid base 13a is formed as a base plate or pad. Similarly, the individual support leg 10b comprises a leg box 11b that may also be aerodynamically shaped and that may be connected via a support rod 12b to a solid base 13b that forms a ground contact device. By way of example, the solid base 13b is also formed as a base plate or pad.

[0062] It should be noted that the individual support legs 10a, 10b are illustratively configured identically, at least within predetermined manufacturing tolerances. However, they may also distinguish from each other and be arranged differently on the fuselage 2. For instance, instead of providing the helicopter 1 with four individual support legs as illustrated, only three individual support legs may be provided. In this case, two of the three individual support legs may be mounted similar to what is shown in FIG. 1 either in a front or in an aft region of the helicopter 1, while the third individual support leg is respectively mounted in the aft or the front region and oriented perpendicular to the two other individual support legs, and so on.

[0063] FIG. 2A shows a cut-out of the helicopter 1 with the fuselage 2 and the landing gear 10 of FIG. 1. The fuselage 2 has the lower fuselage region 2c with the underside shell 2e and the lateral quarter shell 4, to which the individual support leg 10a with the leg box 11a of the landing gear 10 is mounted pivotally. However, by way of example the leg box 11a is now connected to a snow shoe 14a.

[0064] FIG. 2B shows a cut-out of the helicopter 1 with the fuselage 2 and the landing gear 10 of FIG. 1. The fuselage 2 has the lower fuselage region 2c with the underside shell 2e and the lateral quarter shell 4, to which the individual support leg 10a with the leg box 11a of the landing gear 10 is mounted pivotally. However, by way of example the leg box 11a now rotatably supports a wheel 15a.

[0065] FIG. 2C shows a cut-out of the helicopter 1 with the fuselage 2 and the landing gear 10 of FIG. 1. The fuselage 2 has the lower fuselage region 2c with the underside shell 2e and the lateral quarter shell 4, to which the individual support legs 10a, 10b with the leg boxes 11a, 11b of the landing gear 10 are respectively mounted pivotally. However, by way of example the leg boxes 11a, 11b are now illustratively connected to a common skid 16a.

[0066] FIG. 3 shows an illustrative support leg 30 that may be mounted pivotally to associated fuselage frames 40. For instance, the support leg 30 may be used to realize one or more of the individual support legs 10a, 10b of FIG. 1. In this case, the fuselage frames 40 are preferably an integral part of the fuselage 2 of FIG. 1.

[0067] Illustratively, the fuselage frames 40 include two separate individual webs 41, 42 which are respectively provided with an associated mounting plate 41a, 42a. The mounting plates 41a, 42a are preferably adapted to support the support leg 30, as described hereinafter.

[0068] The support leg 30 is preferably adapted for being mounted pivotally to the fuselage, i.e., the fuselage frames 40, by means of an associated pivot bearing arrangement 35. The pivot bearing arrangement 35 is illustratively provided to enable rotation of the support leg 30 about an associated rotation axis (44 in FIG. 5) defined by the pivot bearing arrangement 35 and to transfer shear forces from the support leg 30 to the fuselage, i.e., the fuselage frames 40. By way of example, the pivot bearing arrangement 35 comprises at least one shear pin 35a which is provided to transfer shear forces from the support leg 30 to the fuselage, i.e., the fuselage frames 40.

[0069] The individual support leg 30 is preferably further adapted for being connected to the fuselage, i.e., the fuselage frames 40, via at least one torsion element 36 with a predetermined elastic range, wherein the at least one torsion element 36 is adapted to act, in the predetermined elastic range, as a torsional spring, and, outside of the predetermined elastic range, as an energy absorber. The at least one torsion element 36 is preferentially embodied with an inherent nonlinear force characteristic. Preferably, the at least one torsion element 36 rigidly attaches the support leg 30 to the fuselage, i.e., the fuselage frames 40, to limit at least in the predetermined elastic range of the at least one torsion element 36 rotation of the support leg 30 about the rotation axis (44 in FIG. 5) defined by the pivot bearing arrangement 35. More specifically, the at least one torsion element 36 may comprise at least one torque tube 37 that rigidly attaches the support leg 30 to the fuselage, i.e., the fuselage frames 40, to limit at least in the predetermined elastic range of the at least one torsion element 36 rotation of the support leg 30 about the pivot bearing arrangement 35.

[0070] By way of example, the pivot bearing arrangement 35 comprises a single shear pin 35a and the at least one torsion element 36 is formed by two torque tubes 37, 38, which may be made of different materials. Each one of the torque tubes 37, 38 is preferably provided in its length direction, which is illustrated for both torque tubes 37, 38 with a dashed line 39, with associated end flanges 37a, 37b, 38a, 38b. Each end flange 37a, 37b, 38a, 38b may comprise in the length direction 39 at least one of a circular cross section, an elliptic cross section, a polygonal cross section, a plurality of circular holes, a plurality of polygonal holes, or a plurality of slots, etc. Furthermore, each one of the torque tubes 37, 38 may be formed in its length direction 39 with at least one of a circular cross section, an elliptic cross section, a polygonal cross section, a constant outer diameter, a varying outer diameter, a constant wall thickness, a varying wall thickness, one or more holes, one or more slots, one or more grooves, one or more rims, one or more weak points, or one or more steps.

[0071] Preferably, the shear pin 35a is adapted for pivotally mounting a first mounting flange or lug 34a that is rigidly mounted to the torque tube 37, and a second mounting flange or lug 34c that is rigidly mounted to the torque tube 38, to the fuselage, i.e., the fuselage frames 40. The mounting lugs 34a, 34c are preferably integrated into a leg box 31 of the support leg 30, which e.g., implements one of the leg boxes 11a, 11b of FIG. 1.

[0072] More specifically, the mounting lugs 34a, 34c are preferably formed as longitudinal end flanges of associated longitudinal frames or spars 31b, 31a of the leg box 31. Illustratively, the longitudinal frames 31a, 31b delimit the leg box 31 laterally and form together with upper and lower skins 32a, 32b which extend between the longitudinal frames 31a, 31b a box-shaped structure 32. Close to the longitudinal frame 31a a leading-edge fairing 33a may be mounted to the leg box 31 and close to the longitudinal frame 31b a trailing-edge fairing 33b may be mounted to the leg box 31 such that the latter is preferably aerodynamically shaped. However, instead of providing the leg box 31 with the fairings 33a, 33b, the leg box 31 as such may be formed with an aerodynamic shape.

[0073] Illustratively, the leg box 31 further comprises a transversal frame 31d that interconnects the longitudinal frames 31a, 31b close to the mounting lugs 34c, 34a. The transversal frame 31d is preferably interrupted by another longitudinal frame 31c that forms an associated mounting flange or lug 34b and that is arranged between the longitudinal frames 31a, 31b. Alternatively, the mounting lug 34b may be an integral part of the transversal frame 31d.

[0074] In an illustrative mounting procedure for mounting the support leg 30 and, more particularly, the leg box 31 to the fuselage, i.e., the fuselage frames 40, initially the end flange 37a of the torque tube 37 is rigidly mounted in a torque proof manner to the mounting plate 41a of the web 41, e.g., by means of a plurality of fasteners (51 in FIG. 5) and the end flange 38b of the torque tube 38 is rigidly mounted in a torque proof manner to the mounting plate 42a of the web 42, e.g., by means of a plurality of fasteners (53 in FIG. 5). Then, the leg box 31 is positioned such that the mounting lug 34b is arranged between the end flange 37b of the torque tube 37 and the end flange 38a of the torque tube 38, the mounting lug 34a is arranged adjacent the mounting plate 41a, and the mounting lug 34c is arranged adjacent the mounting plate 42a. Thus, the shear pin 35a may be inserted through the mounting lug 34c, the mounting plate 42a, the torque tube 38, the mounting lug 34b, the torque tube 37, the mounting plate 41a, and the mounting lug 34a. Finally, the shear pin 35a may be fixed in this position by means of associated fasteners, e.g., suitable washer/nut combinations 43a, 43b, and the end flange 37b of the torque tube 37 as well as the end flange 38a of the torque tube 38 are rigidly mounted in a torque proof manner to the mounting lug 34b of the leg box 31, e.g., by means of a plurality of fasteners (52 in FIG. 5).

[0075] FIG. 4 shows the support leg 30 of FIG. 3 that illustratively realizes the support leg 10a of the landing gear 10 of FIG. 1 with the support rod 12a and the solid base 13a, and that is mounted pivotally to the fuselage 2 of FIG. 1 in the lower fuselage region 2c at the portside shell 2f. More specifically, the support leg 30 comprises the leg box 31 of FIG. 3, from which only the mounting lug 34c is visible, which is pivotally supported at the mounting plate 42a of the web 42 of the fuselage 2 by means of the pivot bearing arrangement 35.

[0076] FIG. 5 shows the support leg 30 of FIG. 3 that illustratively realizes the support leg 10a of FIG. 1, and that is mounted pivotally to the fuselage 2 of FIG. 1 and, more particularly, to the mounting plates 41a, 42a of the webs 41, 42 of FIG. 3. As described above at FIG. 3, the end flange 37a of the torque tube 37 is rigidly mounted in a torque proof manner to the mounting plate 41a of the web 41 by means of a plurality of fasteners 51, the end flange 38b of the torque tube 38 is rigidly mounted in a torque proof manner to the mounting plate 42a of the web 42 by means of a plurality of fasteners 53, and the end flange 37b of the torque tube 37 as well as the end flange 38a of the torque tube 38 are rigidly mounted in a torque proof manner to the mounting lug 34b of the leg box 31 by means of a plurality of fasteners 52. Furthermore, the shear pin 35a is inserted through the mounting lug 34c, the mounting plate 42a, the torque tube 38, the mounting lug 34b, the torque tube 37, the mounting plate 41a, as well as the mounting lug 34a, and hold in position by means of the washer/nut combinations 43a, 43b.

[0077] Preferably, the shear pin 35a enables rotation of the support leg 30 about the shear pin 35a, i.e., about a respective rotation axis 44 that corresponds illustratively to the length direction 39 of the torque tubes 37, 38. However, the support leg 30 is connected via the torque tubes 37, 38 to the fuselage 2 such that the torque tubes 37, 38 allow rotation of the support leg 30 about the rotation axis 44, as illustrated with an arrow 45, in their associated predetermined elastic range by acting as torsional springs, i.e., by means of elastic deformation. Nevertheless, outside of the predetermined elastic range the torque tubes 37, 38 act as energy absorbers, i.e., by means of plastic deformation.

[0078] FIG. 6A shows the torque tubes 37, 38 with the end flanges 37a, 37b, 38a, 38b of FIG. 3 and FIG. 5. By way of example, the torque tubes 37, 38 have identical tube walls 60a, 60b and respectively comprise a plurality of circular holes 61 provided in each one of the end flanges 37a, 37b, 38a, 38b to enable mounting of the torque tubes 37, 38 as described above.

[0079] By way of example, the torque tubes 37, 38 are formed identically, at least within predetermined manufacturing tolerances. However, the torque tubes 37, 38 may also be provided with differing shapes, as described hereinafter.

[0080] FIG. 6B shows the torque tubes 37, 38 with the end flanges 37a, 37b, 38a, 38b and the tube walls 60a, 60b of FIG. 6A according to a first variant. Furthermore, the mounting plates 41a, 42a, and the mounting lug 34b of FIG. 3 and FIG. 5 are shown.

[0081] According to the first variant, the torque tubes 37, 38 may have different tube lengths 61a, 61b. Alternatively, or in addition, they may have different tube diameters 62a, 62b.

[0082] FIG. 6C shows the torque tubes 37, 38 with the end flanges 37a, 37b, 38a, 38b and the tube walls 60a, 60b of FIG. 6A according to a second variant. Furthermore, the mounting plates 41a, 42a, and the mounting lug 34b of FIG. 3 and FIG. 5 are shown.

[0083] According to the second variant, the torque tubes 37, 38 may still have different tube lengths 61a, 61b and/or different tube diameters 62a, 62b. However, alternatively, or in addition, they may have different tube wall thicknesses 63a, 63b.

[0084] FIG. 6D shows a third variant of the torque tube 37 with the end flanges 37a, 37b, the tube wall 60a with the wall thickness 63a, and the plurality of circular holes 61 provided in each one of the end flanges 37a, 37b according to FIG. 6A. According to this third variant, the wall thickness 63a may vary in the length direction 39 of the torque tube 37.

[0085] It should be noted that the torque tube 38 of FIG. 6A may be embodied similar to the torque tube 37. Therefore, the torque tube 37 is described in FIG. 6D, as well as in FIG. 6E to FIG. 6G, representative for both torque tubes 37, 38, for simplicity and brevity.

[0086] FIG. 6E shows a fourth variant of the torque tube 37 with the end flanges 37a, 37b, the tube wall 60a, and the plurality of circular holes 61 provided in each one of the end flanges 37a, 37b according to FIG. 6A. According to this fourth variant, the tube wall 60a is provided with a plurality of slots 64 in the length direction 39 of the torque tube 37.

[0087] FIG. 6F shows a fifth variant of the torque tube 37 with the end flanges 37a, 37b, the tube wall 60a, and the plurality of circular holes 61 provided in the end flange 37a according to FIG. 6A. According to this fifth variant, the end flange 37b is provided with a plurality of elongated holes 65 in peripheral direction.

[0088] FIG. 6G shows a sixth variant of the torque tube 37 with the end flanges 37a, 37b, the tube wall 60a, and the plurality of circular holes 61 provided in each one of the end flanges 37a, 37b according to FIG. 6A. According to this sixth variant, the tube diameter 62a according to FIG. 6B of the torque tube 37 varies.

[0089] FIG. 7 shows an illustrative support leg 70 according to a first variant, which may be mounted pivotally to the fuselage frames 40 of FIG. 3 with the webs 41, 42, which now illustratively comprise an additional web 73 with an associated mounting plate 73a. Similar to the support leg 30 of FIG. 3, the support leg 70 may be used to realize one or more of the individual support legs 10a, 10b of FIG. 1.

[0090] The support leg 70 is embodied similar to the support leg 30 of FIG. 3. Therefore, only distinguishing components of the support leg 70 with respect to the support leg 30 of FIG. 3 are described in more detail hereinafter, for brevity and conciseness.

[0091] The support leg 70 is preferably adapted for being mounted pivotally to the fuselage, i.e., the fuselage frames 40, by means of two individual pivot bearing units 74a, 74b. The pivot bearing units 74a, 74b are illustratively provided to enable rotation of the support leg 70 about an associated rotation axis (44 in FIG. 9) defined by the pivot bearing units 74a, 74b and to transfer shear forces from the support leg 70 to the fuselage, i.e., the fuselage frames 40.

[0092] By way of example, each one of the pivot bearing units 74a, 74b comprises a shear pin 75a, 75b that is illustratively integrated into an associated shear pin attachment 76a, 76b and provided to transfer shear forces from the support leg 70 to the fuselage, i.e., the fuselage frames 40. Preferably, the shear pin 75b is adapted for pivotally mounting the mounting flange or lug 34a that is rigidly mounted to the torque tube 37 to the fuselage, i.e., the fuselage frames 40, and the shear pin 75a is adapted for pivotally mounting the mounting flange or lug 34c that is rigidly mounted to the torque tube 38, to the fuselage, i.e., the fuselage frames 40.

[0093] In contrast to FIG. 3, only the mounting lugs 34a, 34c are integrated into a leg box 71 of the support leg 70 and illustratively formed as longitudinal end flanges of the longitudinal frames or spars 31b, 31a of the leg box 71, while the mounting flange or lug 34b is omitted. Illustratively, the longitudinal frames 31a, 31b delimit the leg box 71 laterally and form together with upper and lower skins 72a, 72b which extend between the longitudinal frames 31a, 31b the box-shaped structure 32.

[0094] In an illustrative mounting procedure for mounting the support leg 70 and, more particularly, the leg box 71 to the fuselage, i.e., the fuselage frames 40, initially the end flange 37a of the torque tube 37 is rigidly mounted in a torque proof manner to the mounting lug 34a of the leg box 71, e.g., by means of a plurality of fasteners (51 in FIG. 9) and the end flange 38b of the torque tube 38 is rigidly mounted in a torque proof manner to the mounting lug 34c of the leg box 71, e.g., by means of a plurality of fasteners (53 in FIG. 9). Then, the leg box 71 is positioned such that the mounting plate 73a of the web 73 is arranged between the end flange 37b of the torque tube 37 and the end flange 38a of the torque tube 38, the mounting lug 34a is arranged adjacent the mounting plate 41a, and the mounting lug 34c is arranged adjacent the mounting plate 42a. Thus, the shear pin 75a of the pivot bearing unit 74a may be inserted through the mounting plate 42a into the mounting lug 34c, and the shear pin 75b of the pivot bearing unit 74b may be inserted through the mounting plate 41a into the mounting lug 34a. Then, the shear pin attachments 76a, 76b of the pivot bearing units 74a, 74b are fixed in their respective positions by means of associated fasteners (91, 92 in FIG. 9), e.g., suitable bolts or screws, and the end flange 37b of the torque tube 37 as well as the end flange 38a of the torque tube 38 are rigidly mounted in a torque proof manner to the mounting plate 73a of the web 73, e.g., by means of a plurality of fasteners (52 in FIG. 9).

[0095] FIG. 8 shows the support leg 70 of FIG. 7 that illustratively realizes the support leg 10a of the landing gear 10 of FIG. 1 with the support rod 12a and the solid base 13a, and that is mounted pivotally to the fuselage 2 of FIG. 1 in the lower fuselage region 2c at the portside shell 2f. More specifically, the support leg 70 comprises the leg box 71 of FIG. 7, which is pivotally supported at the mounting plate 42a of the web 42 of the fuselage 2 by means of the pivot bearing unit 74a.

[0096] FIG. 9 shows the support leg 70 of FIG. 7 that illustratively realizes the support leg 10a of FIG. 1, and that is mounted pivotally to the fuselage 2 of FIG. 1 and, more particularly, to the mounting plates 41a, 42a, 73a of the webs 41, 42, 73 of FIG. 7. As described above at FIG. 7, the end flange 37a of the torque tube 37 is rigidly mounted in a torque proof manner to the mounting lug 34a of the leg box 71 by means of the plurality of fasteners 51, the end flange 38b of the torque tube 38 is rigidly mounted in a torque proof manner to the mounting lug 34c of the leg box 71 by means of the plurality of fasteners 53, and the end flange 37b of the torque tube 37 as well as the end flange 38a of the torque tube 38 are rigidly mounted in a torque proof manner to the mounting plate 73a of the leg box 71 by means of the plurality of fasteners 52. Furthermore, the shear pin 75a is inserted through the mounting plate 42a into the mounting lug 34c, and the shear pin 75b is inserted through the mounting plate 41a into the mounting lug 34a. Moreover, the shear pin attachments 76a, 76b of the pivot bearing units 74a, 74b are fixed in their respective positions at the mounting plates 42a, 41a by means of the fasteners 91, 92.

[0097] Preferably, the shear pins 75a, 75b enable rotation of the support leg 70 about the shear pins 75a, 75b, i.e., about the rotation axis 44. However, the support leg 70 is connected via the torque tubes 37, 38 to the fuselage 2 such that the torque tubes 37, 38 allow rotation of the support leg 70 about the rotation axis 44, as illustrated with the arrow 45, in their associated predetermined elastic range by acting as torsional springs, i.e., by means of elastic deformation. Nevertheless, outside of the predetermined elastic range the torque tubes 37, 38 act as energy absorbers, i.e., by means of plastic deformation.

[0098] FIG. 10 shows an illustrative support leg 100 according to a second variant, which may be mounted pivotally to the fuselage frames 40 of FIG. 7 with the webs 41, 42, 73. Similar to the support leg 70 of FIG. 7, the support leg 100 may be used to realize one or more of the individual support legs 10a, 10b of FIG. 1.

[0099] The support leg 100 is embodied similar to the support leg 70 of FIG. 7 with the leg box 71. However, in contrast to FIG. 7 only the torque tube 37 is used with the support leg 100 and the torque tube 38 of FIG. 7 is omitted.

[0100] In an illustrative mounting procedure for mounting the support leg 100 and, more particularly, the leg box 71 to the fuselage, i.e., the fuselage frames 40, initially the end flange 37a of the torque tube 37 is rigidly mounted in a torque proof manner to the mounting lug 34a of the leg box 71, e.g., by means of a plurality of fasteners (51 in FIG. 12). Then, the leg box 71 is positioned such that the mounting plate 73a of the web 73 is arranged adjacent the end flange 37b of the torque tube 37, the mounting lug 34a is arranged adjacent the mounting plate 41a, and the mounting lug 34c is arranged adjacent the mounting plate 42a. Thus, the shear pin 75a of the pivot bearing unit 74a may be inserted through the mounting plate 42a into the mounting lug 34c, and the shear pin 75b of the pivot bearing unit 74b may be inserted through the mounting plate 41a into the mounting lug 34a. Then, the shear pin attachments 76a, 76b of the pivot bearing units 74a, 74b are fixed in their respective positions by means of associated fasteners (91, 92 in FIG. 12), e.g., suitable bolts or screws, and the end flange 37b of the torque tube 37 is rigidly mounted in a torque proof manner to the mounting plate 73a of the web 73, e.g., by means of a plurality of fasteners (52 in FIG. 12).

[0101] FIG. 11 shows the support leg 100 of FIG. 10 that illustratively realizes the support leg 10a of the landing gear 10 of FIG. 1 with the support rod 12a and the solid base 13a, and that is mounted pivotally to the fuselage 2 of FIG. 1 in the lower fuselage region 2c at the portside shell 2f. More specifically, the support leg 100 comprises the leg box 71 of FIG. 10, which is pivotally supported at the mounting plate 42a of the web 42 of the fuselage 2 by means of the pivot bearing unit 74a.

[0102] FIG. 12 shows the support leg 100 of FIG. 10 that illustratively realizes the support leg 10a of FIG. 1, and that is mounted pivotally to the fuselage 2 of FIG. 1 and, more particularly, to the mounting plates 41a, 42a, 73a of the webs 41, 42, 73 of FIG. 10. As described above at FIG. 10, the end flange 37a of the torque tube 37 is rigidly mounted in a torque proof manner to the mounting lug 34a of the leg box 71 by means of the plurality of fasteners 51, and the end flange 37b of the torque tube 37 is rigidly mounted in a torque proof manner to the mounting plate 73a of the leg box 71 by means of the plurality of fasteners 52. Furthermore, the shear pin 75a is inserted through the mounting plate 42a into the mounting lug 34c, and the shear pin 75b is inserted through the mounting plate 41a into the mounting lug 34a. Moreover, the shear pin attachments 76a, 76b of the pivot bearing units 74a, 74b are fixed in their respective positions at the mounting plates 42a, 41a by means of the fasteners 91, 92.

[0103] Preferably, the shear pins 75a, 75b enable rotation of the support leg 100 about the shear pins 75a, 75b, i.e., about the rotation axis 44. However, the support leg 100 is connected via the torque tube 37 to the fuselage 2 such that the torque tube 37 allows rotation of the support leg 100 about the rotation axis 44, as illustrated with the arrow 45, in its associated predetermined elastic range by acting as a torsional spring, i.e., by means of elastic deformation. Nevertheless, outside of the predetermined elastic range the torque tube 37 acts as an energy absorber, i.e., by means of plastic deformation.

[0104] FIG. 13 shows a force deflection diagram 130 with a stroke axis 135 and a force axis 137, as well as two illustrative force deflection curves 132, 134. More specifically, the force deflection curves 132, 134 indicate, for two different landing gears, forces acting on the landing gears in response to strokes on the landing gears. By way of example, the force deflection curve 132 is associated with a conventional skid-type landing gear and the force deflection curve 134 is associated with the at least partially non-retractable landing gear 10 of the rotary wing aircraft 1 of FIG. 1.

[0105] More generally, the main task of a landing gear of a rotary wing aircraft is to take, store, and/or dissipate respective kinetic energy of the rotary wing aircraft during landing. In general, the best practice to do so is a non-linear working curve, i.e., force deflection curve of a given landing gear assembly. This force deflection curve is usually created by various means, e.g., with a hydro/pneumatic strut (Oleo Damper) or due to plasticization of materials (for conventional skid-type landing gears).

[0106] Preferably, the force deflection curve is at least approximately bi-linear. Such a bi-linear behavior limits occurring forces and loads to an acceptable level, which is beneficial for a respective static sizing of the rotary wing aircraft's fuselage, and makes use of the stroke below the fuselage which is usually sufficiently available due to a comparatively big ground clearance below the fuselage. According to the present disclosure, this is achieved by using a material with high plasticization capabilities, such as e.g., aluminum, for realization of the at least one torsion element, i.e., the torque tube(s). After reaching yield strength in a hard or downward crash landing, the material is locally in the state of plastic deformation. As described above with reference to FIG. 3 to FIG. 12, this may be achieved by using a simple metallic torque tube, which may be split into two torque tubes, e.g., for manufacturing reasons. As a result, this will lead to the desired flattened resp. locally more linearized force deflection curve 134.

[0107] More particularly, the force deflection curve 134 is illustratively composed of two essentially linear parts, i.e., linear approximations 138, 139. The linear approximation 138 illustrates an elastic domain 131 of the at least one torsion element of the at least partially non-retractable landing gear 10 of the rotary wing aircraft 1 of FIG. 1, and the linear approximation 139 illustrates a plastic domain of the at least one torsion element of the at least partially non-retractable landing gear 10 of the rotary wing aircraft 1 of FIG. 1. The exact shape of the force deflection curve 134 in the elastic/plastic domains 131, 133 is characterized by the choice of the alloy and by its geometrical shape. Illustrative suitable geometrical shapes are shown, by way of example, in FIG. 6A to FIG. 6G.

[0108] FIG. 14 shows an illustrative deformation mechanics diagram 140. By way of example, the deformation mechanics diagram 140 is illustrated for the torque tube 37 of FIG. 3 to FIG. 12, which is shown without the end flanges 37a, 37b, for simplicity. More specifically, the torque tube 37 is shown with gridlines 141 to illustrate deformation of the torque tube 37 upon twisting of the torque tube 37 by means of oppositely applied torques 142, 143.

[0109] It should be noted that modifications to the above described embodiments are within the common knowledge of the person skilled in the art and, thus, also considered as being part of the present disclosure. More particularly, the at least partially non-retractable landing gear 10 of the rotary wing aircraft 1 of FIG. 1 described above is mainly characterized in that the load reaction respectively load path for normal loads and for bending loads is separated such that an underlying design may be adapted easily to individual loading conditions. These loading conditions may, in turn, be influenced by the design itself as respective individual components of the load with their corresponding equilibration of forces and moments are acting in perpendicular planes which have a minor interaction to each other. In consequence, the respective individual load components may easily be separated for sizing and material selection and, thus, for optimization.

[0110] Moreover, a dedicated “weak point” may be predefined in the overall structure of the landing gear at the location of the torque tube(s). This location triggers the global behavior of the landing gear and may be taken as reference point for the design of the landing gear: all loads exceeding a certain level may be cut-off if exceeding a predetermined threshold value.

[0111] During normal operation, preferably the entire, at least partially non-retractable landing gear according to the present disclosure acts in its elastic regime, but as during operation local short-time overload may take place, the torque tube(s) takes these overload forces and dissipates small fractions of energy by plasticization. Accordingly, during normal operation the plasticization of the torque tube(s) may be used as an indicator and measurement device for the loads which occurred during operation. As all other parts are preferably still operating in their elastic range when the torque tube(s) already operates in its plastic range, only the torque tube(s) has to be exchanged from time to time.

[0112] The shown innovative arrangement is further beneficial, in that, should a hard or downward crash landing within the design envelope occur, the deformed element, i.e., the torque tube(s) is of simple and easily exchangeable nature and, thus, may be exchanged quickly. Further benefit is achieved as the torque tube(s), by magnitude of its deformation, provides a clear indication of forces having acted on the inventive landing gear and, thus, allows simple classification of incident severity and associated required return-to-service actions.

[0113] In addition, the inventive landing gear provides a solution to provide multiple landing gear configurations (wheeled, skid, etc.) on a common airframe structure without requiring significant structural changes in manufacturing (cost) or inclusions of structural provisions (weight) for multiple configurations.

REFERENCE LIST

[0114] 1 rotary wing aircraft [0115] 2 fuselage [0116] 2a cabin [0117] 2b cockpit [0118] 2c lower fuselage region [0119] 2d upper fuselage region [0120] 2e underside shell [0121] 2f portside shell [0122] 2g starboard side shell [0123] 3 tail boom [0124] 4 lateral quarter shells [0125] 10 non-retractable landing gear [0126] 10a, 10b individual support legs [0127] 11a, 11b aerodynamically shaped leg boxes [0128] 12a, 12b support rods [0129] 13a, 13b solid bases [0130] 14a snow shoe [0131] 15a wheel [0132] 16a skid [0133] 30 support leg [0134] 31 aerodynamically shaped leg box [0135] 31a, 31b, 31c longitudinal frames [0136] 31d transversal frame [0137] 32 box-shaped structure [0138] 32a, 32b upper and lower skins [0139] 33a leading-edge fairing [0140] 33b trailing-edge fairing [0141] 34a, 34b, 34c mounting lugs [0142] 35 pivot bearing arrangement [0143] 35a shear pin [0144] 36 torsion element [0145] 37 torque tube [0146] 37a, 37b end flanges [0147] 38 torque tube [0148] 38a, 38b end flanges [0149] 39 torque tube length direction [0150] 40 fuselage frames [0151] 41, 42 individual webs [0152] 41a, 42a frame mounting plates [0153] 43a, 43b washer/nut combinations [0154] 44 rotation axis [0155] 45 support leg rotation [0156] 51, 52, 53 pluralities of fasteners [0157] 60a, 60b tube walls [0158] 61 plurality of circular holes [0159] 61a, 61b tube lengths [0160] 62a, 62b tube diameters [0161] 63a, 63b tube wall thicknesses [0162] 64 plurality of slots [0163] 65 plurality of elongated holes [0164] 70 support leg [0165] 71 aerodynamically shaped leg box [0166] 72a, 72b upper and lower skins [0167] 73 individual web [0168] 73a frame mounting plate [0169] 74a, 74b pivot bearing units [0170] 75a, 75b shear pins [0171] 76a, 76b shear pin attachments [0172] 91, 92 pluralities of screws [0173] 100 support leg [0174] 130 force deflection diagram [0175] 131 elastic domain [0176] 132, 134 force deflection curves [0177] 133 plastic domain [0178] 135 stroke axis [0179] 137 force axis [0180] 138, 139 linear approximations [0181] 140 deformation mechanics diagram [0182] 141 gridlines [0183] 142, 143 applied torque