Leading edge nose structure on the vertical stabilizer of an aircraft

Abstract

An aircraft with a fuselage, wings, horizontal stabilizers and a vertical stabilizer, wherein on a front portion of the vertical stabilizer an elongated one-piece nose element is mounted which forms lateral air guide surfaces. To the front end of the nose element a perforated metal plate nose member is attached. The front end of the nose element being closed and between this closed front end and the nose member an elongated air channel is formed.

Claims

1. An aircraft comprising: a fuselage, wings, horizontal stabilizers, a vertical stabilizer, an elongated one-piece closed nose element mounted on a front portion of said vertical stabilizer forming lateral air guide surfaces, the lateral air guide surfaces corresponding to exterior surfaces of the elongated one-piece closed nose element in contact with an ambient air flow and located downstream from a front end of the elongated one-piece closed nose element nose element, and a perforated metal plate nose member attached to a front end of the elongated one-piece closed nose element wherein the front end of the nose element corresponds to a leading edge of the elongated one-piece closed nose element, the front end of said elongated one-piece closed nose element being closed and between the closed front end and the nose member, an elongated air channel is formed, wherein the elongated one-piece closed nose element is formed as a separate part that is mounted to a front spar of the vertical stabilizer and extends exclusively in front of the front spar.

2. The aircraft according to claim 1, wherein said air channel extends to the upper end of the vertical stabilizer and is open at the upper end of the air channel.

3. The aircraft according to claim 2, wherein the cross-section of said air channel decreases from the lower end of the air channel to the upper end of the air channel.

4. The aircraft according to claim 1, wherein said air channel is connected to a suction pump.

5. The aircraft according to claim 1, wherein at the front end of the nose member an elongated enforcement element is attached to an inner surface of the nose member, the enforcement element comprising a plurality of openings.

6. The aircraft according to claim 5, wherein said enforcement element is arranged symmetrically with respect to a vertical plane through the longitudinal axis of the fuselage and is formed in cross-section so that at least one vertical channel is formed between said enforcement element and the inner surface of said nose member.

7. The aircraft according to claim 1, wherein said nose member comprises titanium or a titanium alloy.

8. An aircraft comprising: a fuselage, wings, horizontal stabilizers, a vertical stabilizer, an elongated one-piece closed nose element mounted on a front portion of the vertical stabilizer having an exterior surface in contact with an ambient air flow, and a perforated metal plate attached to a leading edge of the elongated one-piece closed nose element, an elongated air channel located at the leading edge of the elongated one-piece closed nose element and formed between the exterior surface of the elongated one-piece closed nose element and the perforated metal plate attached to the leading edge of the elongated one-piece closed nose element, wherein the elongated one-piece closed nose element is formed as a separate part that is mounted to a front spar of the vertical stabilizer and extends in exclusively front of the front spar.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following the invention will be described with reference to the drawings showing preferred embodiments.

(2) FIG. 1 is a schematic illustration of an aircraft in which a design according to the invention is provided.

(3) FIG. 2 shows a view of the vertical stabilizer incorporating an embodiment of the invention.

(4) FIG. 3 shows a partially schematic cross-sectional illustration of a portion of the vertical stabilizer along lines A-A in FIG. 2.

(5) FIG. 4 shows the elements of FIG. 3 before assembling.

(6) FIG. 5 shows a partial view in the direction of Arrow B in FIG. 4.

(7) FIG. 6 shows in a view corresponding to FIG. 4 another embodiment of the invention.

(8) FIG. 7 shows the elements of FIG. 7 before assembling.

(9) FIG. 8 shows graphs of the pressure distribution along the outer surface of the nose member and inside the channels of the embodiment of FIGS. 3 and 4 for different flight conditions.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(10) The aircraft 1 shown in FIG. 1 comprises a fuselage 2, wings 3 and 4, horizontal stabilizers 5 and 6 and a vertical stabilizer 7 to the rear end of which the rudder 8 is connected. At the front end of the vertical stabilizer 7, an air suction region 9 designed according to the invention is provided.

(11) As shown in more detail in FIG. 2, at the front end of the vertical stabilizer 7 an elongated one-piece nose element is mounted which together with a perforate metal plate nose member forms an elongated air channel 9 which structure will be described in detail in the following with respect to FIGS. 3 to 5. As also indicated in FIG. 2, the schematically shown HF-antenna 15 is located within the one-piece nose element.

(12) As shown in FIG. 3, the free rear ends 21, 22 of the outer layer of the nose element 20 are mounted by means of screws 13 to T-shaped elements 11, 12 secured to a front spar 10 of the vertical stabilizer 7, as well known. The nose element 20 is closed at its front end which forms a curved front portion. The nose element 20 may comprise a GFRP sandwich forming a glass fiber enforced foam core with outer layers of glass fiber meshes impregnated with the polymer that forms the core. To the front end of the nose element 20, an elongated curved perforated metal plate nose member 25 is attached by means of an adhesive, as indicated in the blown-up partial sketch C in FIG. 3. To obtain smooth flow surfaces on the outside of the nose structure, the ends 26 of the nose member 25 are reduced in thickness by rolling, as indicated in FIG. 4 at D. The nose member 25 preferably comprises titanium or stainless steel plate material and the perforations or holes 40 can be generated by laser drilling wherein e.g., 4 million holes per m2 may be provided and the holes may be circularly or triangularly shaped. The front end of the nose element 20 and the nose member 25 form the elongated air channel 9.

(13) In the front end of the nose member 25 elongated enforcement elements 30 are attached to its inner surface. In this particular embodiment, three enforcement elements 30 are employed and one enforcement element 30 is centered with respect to the tip end of nose member 25, whereas the other enforcement elements 30 are located laterally with respect to the centered element. These enforcement elements may comprise the same material as the nose member 25 and may have outwardly bent ends for surface engagement with the nose member 25. Attachment thereto may be effected by brazing. As indicated, the enforcement elements 30 are arranged symmetrically with respect to a vertical plane through the longitudinal axis of the fuselage which plane is shown in FIG. 3 in dotted line. The enforcement elements 30 have a cross-section so that one or more vertical channels 32 are formed between the enforcement elements and the inner surface of the nose member 25. Thus, in this embodiment three channels 32 are formed.

(14) As indicated in FIG. 2, the air channel 9 is open at its upper end so that in operation air is sucked out of the air channel due to the air flowing across the upper end of the vertical stabilizer 7.

(15) To adjust the pressure in the air channel 9, the enforcement elements 30 comprises orifices 31 (FIG. 5). Therefore, the pressure drop from the perforated nose member 25 provides for the needed suction distribution along the nose member 25. In particular, FIG. 8 shows graphs of the resulting pressure distribution along the outer surface of the nose member 25 (Curves I) and inside the different channels 32 (Curves II) for different flight conditions wherein the abscissa of the graphs indicates the distance from the tip end of the nose member 25 in a plane perpendicular to the longitudinal direction of the nose member 25. In Graph a) the distribution for a flight in line is shown whereas Graph b) shows the distribution for a jaw flight.

(16) As can be seen, the pressure distribution I on the outer surface of the nose member 25 has a peak at the tip end and strongly decreases with increasing distance from the tip end. Further, as indicated by curves II in the centered channel 32 the highest pressure occurs whereas the laterally arranged channels 32 show a significantly lower pressure.

(17) Theses distributions and especially the pressure drop along the outer surface of the nose member 25 can be adjusted for a given nose member 25 by properly choosing the number and the dimensions of the orifices 31.

(18) In the embodiment of FIGS. 6 and 7 the elements corresponding to those of FIGS. 3 to 5 are designated with the same reference numerals plus a single quote mark (). Elements identical with those of FIGS. 3 to 5 will not be described again.

(19) The shape of the one-piece nose element 20 is slightly different in that its closed front end is formed by a relatively thin wall which is not curved but straight. It is formed by a GFRP sandwich with a honeycomb core.

(20) The nose member 25 is to be fixed by means of an adhesive bonding on the outer surfaces of the nose element 20 as indicated in FIG. 7. Further, the nose member 25 is provided with a sole enforcement element 30 only so that it comprises a single vertical channel 32.

(21) While at least one exemplary embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the exemplary embodiment(s). In addition, in this disclosure, the terms comprise or comprising do not exclude other elements or steps, the terms a or one do not exclude a plural number, and the term or means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.