Let's talk ground launching........

Yes, you need a drogue, at least for piano wire cable. If not, it drops
into a terrible snarl-up. Dyneema/Spectra, I don't know - ask people who
have tried it.

For lengths and hardware on the cable, I have seen many different
variations. The most complex was at Dunstable, UK some years ago, which
included many features for which I could understand the reason,
including a long shock rope between drogue and rings. I believe that the
safest arrangement is short (2-6 feet), plastic-tube-covered strop from
Tost rings to Tost weak link; weak link with easy-change connections;
long strop (30-80 feet) from weak link to drogue (to keep billowing
drogue well in front of glider in a power failure situation); swivel;
and then main cable.

It is an official BGA "Recommended Practice" that the shock rope should
be stiffened with plastic hose or similar, to prevent it wrapping round
the wheel axle and being unable to release. There are, however, many
more aspects of the hardware that could usefully be standardised, or at
least listed for guidance so that if people do something different it
should be a conscious decision with good reason, not just ignorance or
lack of experience.

No doubt someone from Dunstable will correct the following if I got it
wrong or it has changed, but my notes of their assembly were as follows,
starting at the glider end:

1. Tost rings

2. wire rope a few feet long.

3. ferrule to secure end of 2 into a loop.

4. plastic hose over 2.

5. ferrule to secure other end of 2 into a loop.

6. oval link with flat section on one side.

7. quick-release hook mating with 6.

8. shackle.

9. weak link assembly.

10. shackle.

11. shock rope about 80 feet long.

12. shackle.

13. triangular ring on end of drogue.

14. drogue.

15. metal end fitting on drogue.

16. shackle.

17. plate on shackle to take the wear.

18. swivel.

19. shackle.

20. oval link with flat section on one side.

21. quick-release hook mating with 20.

22. loop of main winch cable.

23. first ferrule securing 22.

24. plate on loop to take the wear.

25. second ferrule securing 22 and 24.

Most of the hardware is standard off-the shelf stuff. The "plate . . .
to take the wear" looked like a special, and it was oval, about 2x3
inches and 1/4 inch thick (50x75 mm, 6 mm thick) and had two holes
through which the legs of the shackle projected. It had the effect of
being the largest diameter thing on the assembly, so would be the one to
take the wear from running over the ground, hence protecting swivel
etc..

I hope this helps.

Chris N.








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On Fri, 02 Sep 2005 13:35:49 +0000, Chris Nicholas wrote:

I'm not from Dunstable but.....

I think items 7 and 10 should be swapped so the weak link is part of the
wire strop assembly and item 4 should be selected so its colour matches
the colour of the weak link.

No doubt someone from Dunstable will correct the following if I got it
wrong or it has changed, but my notes of their assembly were as follows,
starting at the glider end:

1. Tost rings

2. wire rope a few feet long.

3. ferrule to secure end of 2 into a loop.

4. plastic hose over 2.

5. ferrule to secure other end of 2 into a loop.

6. oval link with flat section on one side.

7. quick-release hook mating with 6.

8. shackle.

9. weak link assembly.

10. shackle.

11. shock rope about 80 feet long.

12. shackle.

13. triangular ring on end of drogue.

14. drogue.

15. metal end fitting on drogue.

16. shackle.

17. plate on shackle to take the wear.

18. swivel.

19. shackle.

20. oval link with flat section on one side.

21. quick-release hook mating with 20.

22. loop of main winch cable.

23. first ferrule securing 22.

24. plate on loop to take the wear.

25. second ferrule securing 22 and 24.

--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |