Methods and apparatuses for indicating and/or adjusting tension in pliant tension members, including aircraft recovery lines

• US 7,578,467 B2
• Filed: 10/30/2006
• Issued: 08/25/2009
• Est. Priority Date: 10/30/2006
• Status: Active Grant

• Current Assignee: Insitu Incorporated (The Boeing Co.)
• Original Assignee: Insitu Incorporated (The Boeing Co.)
• Inventors: Goodrich, Wayne
• Primary Examiner(s): Mansen; Michael R
• Assistant Examiner(s): BROOKMAN, STEPHEN A
• Application Number:
  US11/590,223
• Publication Number:
  US 20080099604A1
• Time in Patent Office: 1,030 Days
• Field of Search: 244/110.C, 244/110.F, 244/110.R, 244/116, 738/623.92, 738/623.93, 738/625.6, 738/625.7, 294/132, 294/82.14, 43/16, 43/17, 248/217.1, 248/648, 24/711, 24/71.R
• US Class Current: 244/110.00C
• CPC Class Codes: B64F 1/029 using a cable or tether
• CPC Class Codes: B64U 70/30 for capturing UAVs in flight by ground or sea-based arresting gear, e.g. by a cable or a net
• CPC Class Codes: B66C 1/10 by mechanical means
• CPC Class Codes: B66C 23/18 specially adapted for use in particular purposes

Abstract

Methods and apparatuses for measuring and adjusting tension in pliant tension members, including aircraft recovery lines. A tool for indicating tension in a pliant tension member in accordance with one embodiment of the invention, for example, can include a first support member releasably coupled to a flexible line suspended from a support structure. The first support member is positioned generally parallel to the flexible line. The tool can also include a second support member coupled to the first support member and positioned at an acute angle relative to the first support member. The second support member has a center of gravity at a selected distance from the flexible line. The second support member is generally horizontal when the tension in the flexible line is at a desired value.

Claims

1. A tool for indicating tension in a flexible line, the tool comprising:

a first support member releasable coupled to the flexible line suspended from a support structure, the first support member being positioned generally parallel to the flexible line, wherein the first support member comprises an elongated bar having a first contact member releasably coupled to a first portion of the flexible line and a second contact member releasably coupled to a second portion of the flexible line below the first portion of the flexible line; and

a second support member integral with the first support member and fixed at an acute angle relative to the first support member, the second support member having a center of gravity at a selected distance from the flexible line, wherein the second support member is generally horizontal when the tension in the flexible line is at a desired value.

2. The tool of claim 1 wherein:

the first contact member includes an open-ended loop positioned to receive the first portion of the flexible line; and

the second contact member includes a line engagement member having a generally U-shaped channel positioned to receive the second portion of the flexible line.

3. The tool of claim 2, further comprising a non-slip material in at least a portion of the channel and positioned to engage the second portion of the flexible line.

4. The tool of claim 1 wherein the center of gravity is a first center of gravity, and the tool further comprises a weight having a known value releasably carried by the second support member, wherein the combination of the weight and the second support member have a second center of gravity at a selected distance from the flexible line.

5. The tool of claim 1 wherein:

the first contact member is spaced apart from the second contact member by a distance L₁;

the second support member has a weight W and the center of gravity of the weight W is spaced apart from the flexible line by a distance L₂ when the second support member is generally horizontal;

the second support member is positioned at an angle θ

from the first support member; and

for a given tension value T₀, the dimensions relate as follows

6. The tool of claim 1 wherein the first and second support members are generally rigid support members composed of metal or composite materials.

7. The tool of claim 1 further comprising a third support member coupled to and extending between the first support member and the second support member.

8. An aircraft handling system, comprising:

a support structure;

a flexible recovery line suspended from the support structure in a generally downward direction and having an intercept portion positioned to intercept an unmanned aircraft in flight; and

a tension indicating apparatus releasably carried by the recovery line and positioned to indicate the tension in the recovery line, the tension indication apparatus including—

a first generally rigid bar releasably coupled to the recovery line and positioned generally parallel to the recovery line, wherein the first bar includes a first attachment device releasable coupled to a first portion of the recovery line and a second attachment device releasable coupled to a second portion of the recovery line below the first portion of the recovery line; and

a second generally rigid bar integral with the first bar and fixed at an acute angle relative to the first bar, the second bar having a center of gravity at a selected distance from the recovery line, wherein the second bar is generally horizontal when the tension in the recovery line is at a desired value.

9. The system of claim 8 wherein the support structure includes a first portion and a second portion, and wherein at least one of the first and second portions is movable relative to the other.

10. The system of claim 8 wherein the support structure is configured to carry both a lateral load and a vertical load via the recovery line.

11. The system of claim 8, further comprising one or more axially extendable members coupled to the recovery line and positioned to extend when tension is applied to the recovery line.

12. The system of claim 8 wherein the center of gravity is a first center of gravity, and wherein the system further comprises a weight having a known value releasably carried by the second bar, wherein the combination of the weight and the second bar have a second center of gravity at a selected distance from the recovery line.

13. The system of claim 8 wherein the tension indicating apparatus further comprises a third bar coupled to and extending between the first bar and the second bar.

14. The system of claim 8, further comprising the aircraft, and wherein the aircraft includes a lifting surface and a capture device mounted to the lifting surface and configured to releasably secure the aircraft to the recovery line when the aircraft intercepts the recovery line.

15. The system of claim 8 wherein:

the first attachment device includes a C-shaped loop positioned to receive the first portion of the recovery line; and

the second attachment device includes a generally U-shaped channel positioned to receive the second portion of the recovery line.

16. A tool for indicating tension in a flexible recovery line suspended in a generally downward direction from an extendable boom, the recovery line having an intercept portion positioned to intercept an unmanned aircraft in flight, the tool comprising:

a first generally rigid portion integral with a second generally rigid portion, wherein the second portion is fixed at an acute angle relative to the first portion, and wherein the first and second portions comprise elongated bars;

a first engagement member and a second engagement member carried by the elongated bar of the first portion, the first engagement member being releasably coupled to a first portion of the recovery line and the second engagement member being releasably coupled to a second portion of the recovery line, wherein the second portion of the recovery line is lower than the first portion of the recovery line, and wherein the first portion is generally parallel with the recovery line after installation; and

a weight having a known value carried by the second portion and spaced apart from the recovery line by a selected distance such that, when the tension in the recovery line is at a desired value, the second portion is generally horizontal.

17. The tool of claim 16, further comprising a third portion coupled to the first portion and the second portion and extending between the first portion and the second portion such that the tool has a generally triangular configuration.

18. A method for indicating tension in a flexible line, the method comprising:

releasably attaching a first support member of a tension indication tool to a flexible line suspended in a generally downward direction from a support structure with the first support member positioned generally parallel to the flexible line, the first support member including an elongated bar having a first contact member releasably coupled to a first portion of the flexible line and a second contact member releasably coupled to a second portion of the flexible line below the first portion of the flexible line, and wherein the tool includes a second support member integral with the first support member and fixed at an acute angle relative to the first support member, the second support member having a center of gravity at a selected distance from the flexible line; and

adjusting the tension in the flexible line until the second support member is generally horizontal.

19. The method of claim 18 wherein the first contact member includes an open-ended loop;

and

the second contact member includes a line engagement member having a generally U-shaped channel positioned to receive the second portion of the flexible line.

20. The method of claim 18 wherein the first support member and the second support member are composed of metal or composite materials.

21. The method of claim 18, further comprising applying tension to the flexible line before releasably attaching the first support member to the flexible line.

22. The method of claim 18 wherein adjusting the tension in the flexible line comprises at least one of (a) increasing the tension in the flexible line if the second support member is tilted generally downward after releasably attaching the tool to the flexible line, and (b) decreasing the tension in the flexible line if the second support member is tilted generally upward after releasably attaching the tool to the flexible line.

23. The method of claim 18 wherein the center of gravity is a first center of gravity, and wherein the method further comprises attaching a weight having a known value to the second support member before adjusting the tension, wherein the combination of the weight and the second support member have a second center of gravity at a selected distance from the flexible line.

24. The method of claim 18 wherein the first attachment device is spaced apart from the second attachment device by a distance L₁, the second support member is positioned at an angle θ

from the first support member, and the center of gravity is a first center of gravity, and wherein the method further comprises;

attaching a weight having a known value W to the second support member, wherein the weight and the second support member have a second center of gravity;

adjusting a lateral position of the weight relative to the flexible line until the second support member is generally horizontal and the second center of gravity is a distance L₂ from the flexible line; and

calculating the tension T₀ in the flexible line using the following equation—

25. A method for handling an unmanned aircraft, comprising:

deploying a flexible recovery line from an extendable boom, the recovery line being suspended from the boom in a generally downward direction and having an intercept portion positioned to intercept an unmanned aircraft in flight;

applying tension to the recovery line;

releasably attaching a first elongated bar of a tension indication tool to the recovery line with the first bar positioned generally parallel to the recovery line, the first bar including a first engagement member releasably coupled to a first portion of the recovery line and a second engagement member releasably coupled to a second portion of the recovery line below the first portion of the recovery line, and wherein the tool includes a second elongated bar integral with the first bar and fixed at an acute angle relative to the first bar, the second bar having a center of gravity at a selected distance from the recovery line; and

adjusting the tension in the recovery line until the second bar is generally horizontal.

26. The method of claim 25, further comprising:

releasably capturing the aircraft in flight with the recovery line after adjusting the tension in the recovery line; and

retrieving the aircraft from the recovery line.

27. The method of claim 25, further comprising moving at least one of a first portion and a second portion of the boom relative to the other to place the boom in an extended position before deploying the flexible recovery line.

28. The method of claim 25 wherein:

the first engagement member includes a C-shaped loop; and

the second engagement member includes a generally U-shaped channel positioned to receive the second portion of the recovery line.

29. The method of claim 25 wherein adjusting the tension in the recovery line comprises:

increasing the tension in the recovery line if the second bar is tilted generally downward after releasably attaching the first bar of the tool to the recovery line, and

decreasing the tension in the recovery line if the second bar is tilted generally upward after releasably attaching the first bar of the tool to the recovery line.

30. The method of claim 25 wherein the center of gravity is a first center of gravity, and wherein the method further comprises:

attaching a weight having a known value to the second bar before adjusting the tension in the recovery line, wherein the combination of the weight and the second bar defines a second center of gravity at a selected distance from the recovery line; and

adjusting a lateral position of the weight relative to the recovery line to one or more predefined positions corresponding to particular tension values before adjusting the tension in the recovery line.