Suspension For Aircraft Tail Wheel

Abstract

A reciprocating shock absorber combined with a coil spring are interposed between the fuselage of an aircraft and the tail wheel. When the tail wheel engages the runway, its attachment pivots, thereby compressing the shock absorber and the coil spring. This results in smooth transfer of forces from the tail wheel to the fuselage and to the pilot and passengers. If desired, one or more tension springs may counteract the forces imposed by the coil spring to restore the extended configuration of the coil spring and shock absorber.

Claims

1. An improved suspension for an aircraft tail wheel, comprising: a) a first bracket fixedly connectable to an aircraft fuselage; b) an elongated arm having a first end pivotably connected to said first bracket; c) a reciprocating shock absorber having a first end pivotably mounted to said first bracket and a second end pivotably mounted to a second bracket, said elongated arm having a second end fixedly mounted to said second bracket; d) a tire attached to said second bracket via an axle coupled to a fork mounted on said second bracket; e) whereby when said tire engages a ground surface when said aircraft is landing, said elongated arm pivots about said first bracket and said shock absorber pivots about said first bracket and compresses, thereby dampening forces created by said tire engaging said ground surface.

2. The improved suspension of claim 1, wherein a compression spring surrounds said shock absorber and compresses when said shock absorber compresses.

3. The improved suspension of claim 1, wherein said first end of said shock absorber is at an end of a piston rod and said second end of said shock absorber is at an end of a cylinder.

4. The improved suspension of claim 3, wherein said coil spring is mounted between a disk on said piston rod and said cylinder.

5. The improved suspension of claim 4, wherein said disk is a first disk and said coil spring engages a second disk on said cylinder.

6. The improved suspension of claim 1, wherein said first bracket is L-shaped.

7. The improved suspension of claim 2, wherein a tension spring is connected between said first and second brackets to exert a restoring force in opposition to compression of said compression spring.

8. The improved suspension of claim 1, wherein said shock absorber comprises two side-by-side shock absorbers mounted between said first and second brackets.

9. The improved suspension of claim 7, wherein a chain is interposed between said tension spring and said second bracket.

10. The improved suspension of claim 9, wherein said first bracket is L-shaped.

11. The improved suspension of claim 10, wherein a first leg of said first bracket is connected to said fuselage and a second leg of said first bracket is connected to said first end of said shock absorber.

12. The improved suspension of claim 6, wherein said first bracket comprises two parallel L-shaped brackets mounted to either side of said elongated arm.

13. The improved suspension of claim 12, wherein said coil spring is mounted between a disk on said piston rod and said cylinder.

14. The improved suspension of claim 13, wherein said disk is a first disk and said coil spring engages a second disk on said cylinder.

15. The improved suspension of claim 14, wherein a tension spring is connected between said first and second brackets to exert a restoring force in opposition to compression of said compression spring.

16. An improved suspension for an aircraft tail wheel, comprising: a) a first L-shaped bracket fixedly connectable to an aircraft fuselage; b) an elongated arm having a first end pivotably connected to said first bracket; c) a reciprocating shock absorber having a first end pivotably mounted to said first bracket and a second end pivotably mounted to a second bracket, said elongated arm having a second end fixedly mounted to said second bracket and a compression spring surrounding said shock absorber and which compresses when said shock absorber compresses; d) a tire attached to said second bracket via an axle coupled to a fork mounted on said second bracket; e) whereby when said tire engages a ground surface when said aircraft is landing, said elongated arm pivots about said first bracket and said shock absorber pivots about said first bracket and compresses, thereby dampening forces created by said tire engaging said ground surface.

17. The improved suspension of claim 16, wherein said first end of said shock absorber is at an end of a piston rod and said second end of said shock absorber is at an end of a cylinder, said coil spring being mounted between a first disk on said piston rod and a second disk on said cylinder.

18. The improved suspension of claim 16, wherein a tension spring is connected between said first and second brackets to exert a restoring force in opposition to compression of said compression spring.

19. The improved suspension of claim 16, wherein a first leg of said first bracket is connected to said fuselage and a second leg of said first bracket is connected to said first end of said shock absorber.

20. The improved suspension of claim 16, wherein said first bracket comprises two parallel L-shaped brackets mounted to either side of said elongated arm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG. 1 shows a side view of a prior art leaf spring suspension system for an aircraft tail wheel.

[0020] FIG. 2 shows a further perspective view of a leaf spring type prior art suspension system for a tail wheel as assembled to the fuselage of an aircraft.

[0021] FIG. 3a shows a side perspective view of a first embodiment of the present invention.

[0022] FIG. 3b shows an exploded perspective view of the embodiment of FIG. 3a.

[0023] FIG. 4 shows a view similar to that of FIG. 3a but showing the embodiment affixed to the fuselage of an aircraft.

[0024] FIG. 5 shows a side perspective view from the other side of the first embodiment.

[0025] FIG. 6 shows a view looking rearward of the first embodiment of the present invention with the further proviso of tension springs.

[0026] FIG. 7 shows a side perspective view of a second embodiment of the present invention as attached to the fuselage of a small aircraft.

[0027] FIG. 8 shows a further perspective view from another angle of the second embodiment of the present invention.

SPECIFIC DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Reference is first made to FIGS. 3a-6 which depict a first embodiment of the present invention in which a single shock absorber is included. The first embodiment is generally designated by the reference numeral 20 and is seen to include parallel L-shaped brackets 21 and 23 having holes 25, 27, 29, 31 and holes 30 and 33 (FIG. 3b) opposed to the holes 29 and 31, respectively. The holes 25 and 27 facilitate mounting the device 20 on the fuselage of an aircraft. The holes 31 and 33 (FIG. 3b) mount a shaft 37 (FIG. 3b) allowing pivoting of the attachment end 35 of a shock absorber 40 having a cylinder 41 and a piston 54 (shown in phantom in FIG. 3) attached to a piston rod 43. The piston rod 43 is attached to the attachment end 35 and is constrained to move therewith. A compression coil spring 47 extends between a disk 49 permanently affixed to the outer walls of the cylinder 41 and a further disk 51 attached to the attachment end 35. The cylinder 41 has a U-shaped bracket 53 that attaches about a pivot bolt 38 (FIG. 3b) extending through holes 55 and 56 (FIG. 3b). A further bracket 57 is designed to allow attachment of a tire 60 as seen, for example, in FIGS. 4, 5 and 6.

[0029] With further reference, in particular, to FIGS. 3a and 3b, a plate 63 is attached between further plate 65 carrying the pivot at hole 55 and in which the cylinder 41 pivots and at its other end to a bracket 67 pivotably attached at the hole 69 by bolt 66. These features are also seen, in particular, in FIGS. 4-6.

[0030] FIG. 4 shows the brackets 21, 23 mounted on the fuselage 32 of the aircraft. As seen, a bracket 34 depends downwardly from the fuselage 32 and attaches to a bracket 36 affixed via the hole 29 and a bolt 28 and nut 26. Similarly, the hole 25 allows attachment to the fuselage 32 using a bolt 42 and nut 44 to a bracket 58 attached to the fuselage 32. Wheel or tire 60 is attached to the bracket 57 by virtue of a fork 62 affixed to the bracket 57 and able to rotate with respect to the bracket 57 by virtue of a bearing 68.

[0031] As should be understood with particular reference, for example, to FIG. 4, when the airplane is landing in the left hand direction in the view of FIG. 4, when the tire 60 touches the ground this causes pivoting of the bracket 63 in the direction of the arrow 70 as well as pivoting of the spring 47 and shock absorber 40 about the pivot bolt 72. While the shock absorber 40 and spring 47 are pivoting about the bolt 72, that action also causes compression of the shock absorber 40 and compression of the spring 47 to dampen the forces imposed upon the fuselage 32 by engagement of the tire 60 with the runway. Thus, during this action, the tire 60 pivots closer to the fuselage 32. At some point, the restoring force of the spring 47 causes the tire 60 to pivot in the opposite direction as the forces are dampened.

[0032] With reference to FIG. 6, if desired, tension springs 80 may be interconnected with a chain 81 and an attachment 83 to the bracket 57 on the one hand, and a ring 85 attached to the bracket 21. A similar tension spring assembly not clearly shown in FIG. 6 but with its chain 81 visible is attached on the other side of the tire. The tension springs 80 provide a restoring force assisting the compression spring 47 in expanding the shock absorber 40 by moving the piston 54 upward within the cylinder 41. In this way, the forces imposed upon the fuselage 32 by the tire 60 engaging the runway are dampened in a much superior manner than is the case with the leaf springs 8 shown in FIGS. 1 and 2.

[0033] With reference now to FIGS. 7 and 8, a further embodiment is shown in which corresponding elements are described using like primed reference numerals.

[0034] Thus, the embodiment of FIGS. 7-8 is generally designated by the reference numeral 100 and includes a tire 60′ attached to a bracket 57′ by a set of forks 62′ pivotably mounted to the bracket 57′ via a bearing 68′ that allows rotation of the tire 60′ with respect to the bracket 57′. The brackets 21′ and 23′ affix the device 100 to the fuselage 32′ of the associated airplane. This is done through the provision of brackets 34′ and 58′.

[0035] In this embodiment, plural shock absorbers 40′ are attached to the device and coil springs may be omitted or included as desired. Additionally, tension springs may be included or omitted as desired. The main difference between the embodiment of FIGS. 3a-6 on the one hand, and the embodiment of FIGS. 7-8 on the other hand is the proviso of plural shock absorbers 40′.

[0036] Either embodiment of the present invention operates in a vastly superior manner than is the case with prior art leaf spring suspension systems. The dampening of forces exerted on the fuselage when the tire engages the runway upon landing is highly superior to the dampening created by stiff leaf springs which have barely any give to them, and can result in severe damage to the fuselage including cracking it and causing the aircraft to become non-air worthy. The present invention eliminates the bouncing effect of the prior art leaf springs, resulting in a smooth engagement of the tail wheel 60, 60′ onto the runway and little or no bouncing thereafter. Through the use of the present invention, such issues are eliminated and the aircraft is not only rendered safer, additionally, the ride during landing is rendered highly more comfortable. Additionally, the brackets and other structural components are designed to eliminate the shimmy of the tail wheel that results from use of narrow leaf springs 8.

[0037] Accordingly, an invention has been disclosed in terms of preferred embodiments thereof, which fulfill each and every one of the objects of the invention as set forth hereinabove and provide a new and useful improved suspension for aircraft tail wheel of great novelty and utility.

[0038] Of course, various changes, modifications and alterations in the teachings of the present invention may be contemplated by those skilled in the art without departing from the intended spirit and scope thereof.

[0039] As such, it is intended that the present invention only be limited by the terms of the appended claims.