Anti-Flip Approach for Amphibious Aircraft

Abstract

Disclosed are various embodiments for reducing or eliminating the nose-down pitching moment during water landings of amphibious aircraft when the landing gear is in the down position. Shielding struts forward of the wheels generate hydrodynamic lift and reduce hydrodynamic drag in order to alter the pitching moment about the aircraft center of mass.

Claims

1. A deflector strut system configured in front of each nose wheel of an amphibious aircraft to reduce or to eliminate the nose-down pitching moment during wheels-down water landings, the system comprising a shield or deflector strut positioned forward of each nose wheel when the nose gear is in the down position.

2. The system of claim 1 wherein the deflector strut is narrower in the spanwise direction than the nose wheel and tire.

3. The system of claim 1 wherein the deflector strut has a non-constant spanwise width.

4. The system of claim 1 wherein the deflector strut has a concave upstream surface.

5. The system of claim 1 wherein the deflector strut has a convex upstream surface.

5. The system of claim 1 wherein the perpendicular bisector to the deflector strut from its centroid is a line that extends substantially through the center of mass of the aircraft.

6. The system of claim 1 wherein the perpendicular bisector of the deflector strut from its centroid is a line that extends in front of the center of mass of the aircraft.

7. The system of claim 1 wherein the deflector strut is curved.

8. The system of claim 1 wherein the lower extremity of the deflector strut consists of a replaceable segment.

9. The system of claim 1 wherein the deflector strut is incorporated into the nose wheel support structure.

10. The system of claim 1 wherein the deflector strut is a spring for the nose wheel.

11. The system of claim 1 wherein the top of the deployed deflector strut is forward of the bottom of the deployed deflector strut.

12. The system of claim 1 wherein the deflector strut is deployed in the down position by means of mechanical connection to the nose gear.

13. A deflector strut system configured in front of each main gear wheel of an amphibious aircraft to reduce the hydrodynamic drag during water landings, the system comprising: a deflector strut; and structure to support the strut.

14. The system of claim 13 wherein the spanwise width of the deflector strut is less than the width of the main gear wheel and tire assembly.

15. The system of claim 13 wherein the top of the deflector strut is forward of the bottom of the strut.

16. The system of claim 13 wherein the deflector strut is mechanically connected to the main gear.

Description

DESCRIPTION OF THE DRAWINGS

[0025] In FIG. 1, a conventional amphibious aircraft 1 with floats 2 lands on the water surface 3 with the nose wheels 4 and main wheels 5 mistakenly in the down position. Force vector 6 is generated on the nose wheel support structure 7, and force vector 8 is generated on the main wheels, resulting in a large nose-down pitching moment 9 about the aircraft center of mass 10.

[0026] In FIG. 2, deflector struts 11 have been incorporated into the support structure forward of nose wheels 4 and support structure 7 to generate force vector 12, along a line 13 that is oriented forward of the aircraft center of mass 10, resulting in a nose-up pitching moment 14. Deflector struts 15 have been incorporated forward of the main wheels 5 to generate force vector 16, along a line 17.

[0027] In FIG. 3, deflector strut 11 is mounted forward of nose wheel 4 and its support structure 7.

[0028] In FIG. 4, illustrates a concave geometry of the upstream surface 19 of a deflector strut 20, positioned upstream of nose wheel 4 in a horizontal cross section below the wheel axle.

[0029] In FIG. 5, a horizontal cross section below the wheel axle illustrates a wedge geometry of the upstream side 21 of a deflector strut 22, with half angle 23, positioned upstream a distance 24 forward of nosewheel 4 of width 25.

REFERENCES

[0030] Chapman, R. B. 1971 Spray Drag of Surface-Piercing Struts, TP251, Naval Undersea Research and Development Center, September.

[0031] Hoerner, S. F. 1965 Fluid-Dynamic Drag, self-published.

[0032] Kiceniuk, T. 1954 A Preliminary Experimental Study of Vertical Hydrofoils of Low Aspect Ratio Piercing a Water Surface, Report No. E-55.2, Hydrodynamics Laboratory California Institute of Technology, Pasadena, Calif.

[0033] Tulin, M. P. 1957 David W. Taylor Model Basin, Washington, D.C., USA, Department of the Navy, Published in: Schiffstechnik, Band 4, Heft 21.

[0034] von Karman, T. 1929 The Impact on Seaplane Floats during Landing, National Advisory Committee for Aeronautics, 321 309-313.

[0035] Wagner, H. 1933 Über das Gleiten von Wasserfahrzeugen, Jahrbuch der Schiffbautechnik,” 34. Also published in English as NACA TM 1139. Washington, April 1948.

[0036] Wu, T. Y-T. 1972 Cavity and wake flows, Annual Reviews of Fluid Mechanics, 4, 243-284.

[0037] The particulars shown herein are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of various embodiments of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for the fundamental understanding of then invention, the description taken with the drawings and/or examples making apparent to those skilled in the art how the several forms of the invention may be embodied in practice.

[0038] As used herein and unless otherwise indicated, the terms “a” and “an” are taken to mean “one”, “at least one” or “one or more”. Unless otherwise required by context, singular terms used herein shall include pluralities and plural terms shall include the singular.

[0039] Unless the context clearly requires otherwise, throughout the description and the claims, the words ‘comprise’, ‘comprising’, and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”. Words using the singular or plural number also include the plural and singular number, respectively. Additionally, the words “herein,” “above,” and “below” and words of similar import, when used in this application, shall refer to this application as a whole and not to any particular portions of the application.

[0040] The description of embodiments of the disclosure is not intended to be exhaustive or to limit the disclosure to the precise form disclosed. While the specific embodiments of, and examples for, the disclosure are described herein for illustrative purposes, various equivalent modifications are possible within the scope of the disclosure, as those skilled in the relevant art will recognize.

[0041] All of the references cited herein are incorporated by reference. Aspects of the disclosure can be modified, if necessary, to employ the systems, functions, and concepts of the above references and application to provide yet further embodiments of the disclosure. These and other changes can be made to the disclosure in light of the detailed description.

[0042] Specific elements of any foregoing embodiments can be combined or substituted for elements in other embodiments. Moreover, the inclusion of specific elements in at least some of these embodiments may be optional, wherein further embodiments may include one or more embodiments that specifically exclude one or more of these specific elements. Furthermore, while advantages associated with certain embodiments of the disclosure have been described in the context of these embodiments, other embodiments may also exhibit such advantages, and not all embodiments need necessarily exhibit such advantages to fall within the scope of the disclosure.