ROTARY WING AIRCRAFT WITH AN INTERFACE FRAME JOINING THE FUSELAGE TAIL BOOM AND THE TAIL CONE

Abstract

A rotary wing aircraft comprising a fuselage tail boom, a tail cone and an interface frame, the interface frame in turn having a connecting structure directly attached to the tail cone by means of a tail cone mechanical connection and a connecting sleeve fitting axially the fuselage tail boom, the connecting sleeve and the fuselage tail boom being directly attached by means of a one boom mechanical connection; the interface frame thereby joining the fuselage tail boom and the tail cone.

Claims

1. A rotary wing aircraft comprising: a fuselage tail boom extending longitudinally along a longitudinal axis, the fuselage tail boom having a tail boom inner surface, which delimits the interior of the fuselage tail boom, and a tail boom outer surface opposite the tail boom inner surface, a tail cone extending longitudinally along the longitudinal axis, an interface frame in turn having: a connecting sleeve extending longitudinally along the longitudinal axis; the connecting sleeve comprising a connecting sleeve inner surface, which delimits the interior of the connecting sleeve, and a connecting sleeve outer surface opposite the connecting sleeve inner surface; the connecting sleeve outer surface overlapping the tail boom inner surface so that the connecting sleeve and the fuselage tail boom fit axially; the connecting sleeve and the fuselage tail boom being directly attached by means of at least one boom mechanical connection, and a connecting structure directly attached to the tail cone by means of at least one tail cone mechanical connection, the interface frame being made of composite material thereby joining the fuselage tail boom and the tail cone; the boom mechanical connection being shear loaded and a circumferential gap is defined along a bushing axis, between fuselage tail boom and the connecting sleeve.

2. The rotary wing aircraft of claim 1, wherein the fuselage tail boom, the tail cone and the interface frame are made of a same composite material.

3. The rotary wing aircraft of claim 2, wherein the composite material is carbon fiber reinforced plastic.

4. The rotary wing aircraft of claim 1, wherein the connecting structure comprises a tubular region extending longitudinally along the longitudinal axis, the tubular region having a tubular region inner surface, which delimits the interior of the tubular region, and a tubular region outer surface opposite the tubular region inner surface; wherein the tail cone comprises a tail cone inner surface, which delimits the interior of the tail cone, and a tail cone outer surface opposite the tail cone inner surface; and wherein the tubular region outer surface overlaps the tail cone inner surface, the tubular region being directly attached to the tail cone by means of the at least one tail cone mechanical connection.

5. The rotary wing aircraft of claim 4, wherein the at least one tail cone mechanical connection is a rivet.

6. The rotary wing aircraft of claim 1, wherein the at least one boom mechanical connection comprises: an anchor nut attached to the connecting sleeve inner surface, and a bolt piercing the connecting sleeve and the fuselage tail boom and locked by the anchor nut, thereby attaching the fuselage tail boom and the connecting sleeve.

7. The rotary wing aircraft of claim 6, wherein the anchor nut is attached to the connecting sleeve inner surface by means of an anchor nut ring.

8. The rotary wing aircraft of claim 6, wherein the at least one boom mechanical connection further comprises: a boom bushing lining a boom through-hole drilled in the fuselage tail boom, and a frame bushing lining a frame through-hole drilled in the connecting sleeve, the frame bushing having a same inner bushing diameter and a same bushing axis as the boom bushing, thereby forming a bolt passageway thorough which the bolt pierces the connecting sleeve and the fuselage tail boom.

9. The rotary wing aircraft of claim 8, wherein the frame bushing is provided with a frame flange extending over the connecting sleeve outer surface and/or wherein the boom bushing is provided with a boom flange extending over the tail boom inner surface, in such a manner that the circumferential gap is defined in between the tail boom inner surface and the connecting sleeve outer surface.

10. The rotary wing aircraft of claim 1, wherein the connecting sleeve comprises two mouse holes symmetric to one another with respect to a longitudinal symmetry plane of the connecting sleeve, each one of the two mouse holes giving rise to a joggle in the connecting sleeve perimeter such that the connecting sleeve inner surface overlaps the tail boom outer surface along a first region of the connecting sleeve perimeter delimited by the two mouse holes (9), and the connecting sleeve outer surface overlaps the tail boom inner surface along a second region of the connecting sleeve perimeter delimited by the two mouse holes and complementary to the first region of the perimeter.

11. The rotary wing aircraft of claim 10, wherein a recess is provided on the tail boom outer surface, the connecting sleeve fitting in the recess along the first region of the connecting sleeve perimeter.

12. A method for assembling a fuselage tail boom and a tail cone of a rotary wing aircraft according to claim 1, the method comprising the steps of: (i) providing an interface frame, the interface frame comprising a connecting structure and a connecting sleeve extending longitudinally along the longitudinal axis; the connecting sleeve comprising a connecting sleeve inner surface, which delimits the interior of the connecting sleeve, and a connecting sleeve outer surface opposite the connecting sleeve inner surface; (ii) providing the connecting sleeve with at least one boom mechanical connection; (iii) directly attaching the connecting structure to the tail cone by means of at least one tail cone mechanical connection; (iv) overlapping the connecting sleeve outer surface with the tail boom inner surface, thus axially fitting the connecting sleeve and the fuselage tail boom; and (v) securing the at least one boom mechanical connection so that the fuselage tail boom and the connecting sleeve are directly attached.

13. The method of claim 12, wherein the at least one boom mechanical connection comprises: an anchor nut attached to the connecting sleeve inner surface, and a bolt piercing the connecting sleeve and the fuselage tail boom and locked by the anchor nut, thereby attaching the fuselage tail boom and the connecting sleeve.

14. The method of claim 13, wherein the at least one boom mechanical connection further comprises: a boom bushing lining a boom through-hole drilled in the fuselage tail boom, a frame bushing lining a frame through-hole drilled in the interface frame, and the frame bushing having a same inner bushing diameter and a same bushing axis as the boom bushing, thereby forming a bolt passageway thorough which the bolt pierces the connecting sleeve and the fuselage tail boom, wherein the frame bushing is provided with a frame flange extending over the connecting sleeve outer surface and/or wherein the boom bushing is provided with a boom flange extending over the tail boom inner surface, in such a manner that the circumferential gap is defined in between the tail boom inner surface and the connecting sleeve outer surface, the circumferential gap allowing for the axial fitting of step (iv).

15. The method of claim 12, wherein the connecting sleeve comprises two mouse holes symmetric to one another with respect to a longitudinal symmetry plane of the connecting sleeve, each one of the two mouse holes giving rise to a joggle in the connecting sleeve perimeter such that, in step (iv), the connecting sleeve inner surface overlaps the tail boom outer surface along a first region of the connecting sleeve perimeter delimited by the two mouse holes, and the connecting sleeve outer surface overlaps the tail boom inner surface along a second region of the connecting sleeve perimeter delimited by the two mouse holes and complementary to the first region of the perimeter.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0065] These and other features and advantages of the invention will become more evident in the light of the following detailed description of preferred embodiments, given only by way of illustrative and non-limiting example, in reference to the attached figures:

[0066] FIG. 1 shows a perspective view of the rear of a rotary wing aircraft in which the tail cone and the fuselage tail boom are joined by an interface frame.

[0067] FIG. 2 represents a perspective view of the tail cone attached to an interface frame comprising mouse holes and of the fuselage tail boom before being axially fitted in the connecting sleeve of the interface frame.

[0068] FIG. 3 illustrates the embodiment of FIG. 2 after the axial fitting of the fuselage tail boom and the connecting sleeve.

[0069] FIG. 4 shows in detail the joggle in the connecting sleeve perimeter, defined by a mouse hole.

[0070] FIG. 5 depicts a longitudinal section of the rear of the rotary wing aircraft, wherein the connecting sleeve of the interface frame is directly attached to the fuselage tail boom and the tubular region of the connecting sleeve is directly attached to the tail cone.

[0071] FIG. 6 illustrates in detail the boom mechanical connection used in the embodiment of FIG. 5.

DETAILED DESCRIPTION OF THE INVENTION

[0072] FIG. 1 shows the rear of a rotary wing aircraft A in which the fuselage tail boom 2 is joined to the tail cone 1 by means of an interface frame 3 directly attached to both the fuselage tail boom 2 and the tail cone 1. The tail cone 1, the connecting sleeve 3.1 of the interface frame 3 and the fuselage tail boom 2 extend longitudinally along the longitudinal axis X. In the embodiment of FIG. 1, part of the interface frame 3 is visible from the exterior of the rotary wing aircraft A—the provision of two mouse holes 9, one of which is hidden in the figure, enables a change of the surfaces of the fuselage tail boom 2 and the connecting sleeve 3.1 that overlap, that is, that face one another.

[0073] Along the first region 3.1.1 of the connecting sleeve perimeter, delimited by the mouse holes 9, the connecting sleeve inner surface 3.1.3 overlaps the tail boom outer surface 2.2. The connecting sleeve outer surface 3.1.4 is therefore visible from the outside of the rotary wing aircraft.

[0074] Along the second region 3.1.2 of the connecting sleeve perimeter, complementary to the first region 3.1.1, the connecting sleeve outer surface 3.1.4 overlaps the tail boom inner surface 2.1. Hence, the tail boom outer surface 2.2 is visible from the outside of the rotary wing aircraft A, as depicted at the bottom part of the rotary wing aircraft A of the figure.

[0075] The connecting structure 3.2, directly attached to the tail cone 1, is hidden in FIG. 1 by the tail cone 1 itself.

[0076] The embodiment comprising two mouse holes 9 is depicted in greater detail in FIG. 2, wherein the fuselage tail boom 2 is not attached to the connecting sleeve 3.1 yet.

[0077] For the sake of illustration, the tail cone 1 is only partially shown. In consequence, the connecting structure 3.2, despite being covered by—and attached to—the tail cone 1, can be seen in FIG. 2, separated from the connecting sleeve 3.1 by a dotted line. The features of the connecting structure 3.2 represented in in FIG. 5 are of course applicable to the present embodiment—as an example, the tubular region outer surface 3.2.1.2 of FIG. 5 is also shown in FIG. 2.

[0078] The mouse holes 9 define two complementary regions along the connecting sleeve perimeter—the first region 3.1.1, located below the mouse holes 9 according to the reference of FIG. 2, and the second region 3.1.2, located above the mouse holes 9.

[0079] A recess 12 is defined in the area of the tail boom outer surface 2.2 that receives the connecting sleeve inner surface 3.1.3, as is illustrated in FIG. 3.

[0080] In this figure, the fuselage tail boom 2 and the connecting sleeve fit axially—they are secured by means of a boom mechanical connection 6, not shown in the figure. Boom mechanical connections 6 as those shown in FIGS. 4 and 5, but without the frame flange 4.1 and the boom flange 5.1, are examples applicable to the present embodiment.

[0081] The references of FIG. 3 correspond to those of FIGS. 1 and 2. In particular, along the second region 3.1.2 of the connecting sleeve perimeter, the connecting sleeve inner surface 3.1.3 can be seen at the interior of the interface frame 3. The connecting sleeve outer surface 3.1.4 corresponding to this second region 3.1.2 is hidden by the fuselage tail boom 2 and overlaps the tail boom inner surface 2.1, as can be better appreciated in FIG. 2.

[0082] In turn, along the first region 3.1.1 of the connecting sleeve perimeter, the connecting sleeve outer surface 3.1.4 can be seen from the exterior of the rotary wing aircraft A. The connecting sleeve inner surface 3.1.3 overlaps the tail boom outer surface 2.2, in particular the recess 12, as can be better appreciated in FIG. 2.

[0083] FIG. 4 shows in greater detail the mouse holes 9 of the embodiment of FIGS. 1, 2 and 3. It can be seen that a joggle 14 is provided between the first region 3.1.1 and the second region 3.1.2 of the connecting sleeve perimeter to allow for the above explained change of overlapping surfaces.

[0084] In the embodiment of FIG. 5, a longitudinal section of the interface frame 3 and of part of the tail cone 1 and of the fuselage tail boom 2 is shown. The interface frame 3 comprises a connecting sleeve 3.1 and a connecting structure 3.2, which in turn comprises a tubular region 3.2.1. The tubular region 3.2.1 and the connecting sleeve 3.1 extend longitudinally along the longitudinal axis X.

[0085] The tubular region 3.2.1 comprises a tubular region inner surface 3.2.1.1, which delimits the interior of the tubular region 3.2.1, and a tubular region outer surface 3.2.1.2 opposite the tubular region inner surface 3.2.1.1. Likewise, the tail cone 1 comprises a tail cone inner surface 1.1, which delimits the interior of the tail cone 1, and a tail cone outer surface 1.2 opposite the tail cone inner surface 1.1. The tail cone inner surface 1.1 overlaps the tubular region outer surface 3.2.1.2, that is, both surfaces partially face, extend over and cover one another. The tubular region 3.2.1, and therefore the interface frame 3, is directly attached to the tail cone 1 by means of a rivet 13.

[0086] As has been described for the previous embodiments, the connecting sleeve 3.1 defines a connecting sleeve inner surface 3.1.3, which delimits the interior of the connecting sleeve 3.1, and a connecting sleeve outer surface 3.1.4 opposite the connecting sleeve inner surface 3.1.3. In this embodiment, the overlapping between the connecting sleeve 3.1 and the fuselage tail boom 2 takes place exclusively between the connecting sleeve outer surface 3.1.4 and the tail boom inner surface 2.1. Thus, no substantial part of the connecting sleeve inner surface 3.1.3 can be seen from the exterior of the rotary wing aircraft in the present embodiment.

[0087] The boom mechanical connection 6 of this embodiment is thoroughly depicted in FIG. 6. An anchor nut 10 is attached to the connecting sleeve inner surface 3.1.3. This can be done before the axial fitting of the connecting sleeve 3.1 and the fuselage tail boom 2, thus allowing for easily securing the fuselage tail boom 2 and the connecting sleeve 3.1 with a bolt 8 without accessing the interior of the fuselage tail boom 3, that is, from the outside of the rotary wing aircraft A. An anchor nut ring 15 is provided in between the anchor nut 10 and the connecting sleeve inner surface 3.1.3.

[0088] The bolt 8 pierces (i.e. runs across/goes through) the connecting sleeve 3.1 and the fuselage tail boom 2 and is locked by the anchor nut 10, thereby attaching the fuselage tail boom 2 and the connecting sleeve 3.1.

[0089] The boom mechanical connection 6 of this embodiment additionally comprises a boom bushing 5 lining a boom through-hole drilled in the fuselage tail boom 2 and a frame bushing 4 lining a frame through-hole drilled in the interface frame 3. The frame bushing 4 has a same inner bushing diameter d and a same bushing axis Y as the boom bushing 5, thereby forming a bolt passageway thorough which the bolt 8 pierces the connecting sleeve 3.1 and the fuselage tail boom 2.

[0090] Likewise, the frame bushing 4 is provided with a frame flange 4.1 extending over the connecting sleeve outer surface 3.1.4, and the tail boom bushing 5 is provided with a boom flange 5.1 extending over the tail boom inner surface 2.1. The frame flange 4.1 and the boom flange 5.1 play the role of a stop for one another, as a result of which the connecting sleeve outer surface 3.1.4 is separated from the tail boom inner surface 2.1 by a circumferential gap 11, as depicted in FIGS. 5 and 6. The same effect could be achieved with just one of the frame flange 4.1 and the boom flange 5.1, in which case the frame flange 4.1 would act as a stop of the tail boom inner surface 2.1 or the boom flange 5.1 would act as a stop for the connecting sleeve outer surface 3.1.4.

[0091] A washer 16 is positioned between the head of the bolt 8 and the tail boom outer surface 2.2 to prevent them from directly contacting one another.

[0092] The boom bushing 5, including the boom flange 5.1, and the frame bushing 4, including the frame flange 4.1, are respectively bonded to the fuselage tail boom 2 and to the connecting sleeve 3.1 by means of an adhesive 17.

REFERENCES

[0093]

TABLE-US-00001 A.—Rotary wing aircraft 1.—Tail cone 1.1.—Tail cone inner surface 1.2.—Tail cone outer surface 2.—Fuselage tail boom 2.1—Fuselage tail boom inner surface 2.2.—Fuselage tail boom outer surface 3.—Interface frame 3.1.—Connecting sleeve 3.1.1.—First region 3.1.2—Second region 3.1.3.—Connecting sleeve inner surface 3.1.4.—Connecting sleeve outer surface 3.2.—Connecting structure 3.2.1.—Tubular region 3.2.1.1.—Tubular region inner surface 3.2.1.2.—Tubular region outer surface 4.—Frame bushing 4.1.—Frame flange 5.—Boom bushing 5.1.—Boom flange 6.—Boom mechanical connexion 8.—Bolt 10.—Anchor nut 11.—Circumferential gap 12.—Recess 13.—Rivet 14.—Joggle 15.—Anchor nut ring 16.—Washer 17.—Adhesive X.—Longitudinal axis Y.—Bushing axis d.—Bushing diameter