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

Hello All:
With the price of fuel going up and the price of AeroTows close behind
it I think the need to follow the lead of our brethren in the UK is
close at hand. I have heard talk of the infamous $100.00 tow and know
that I for one can't afford it, I have to work for a living as do most
of you! I and some of my fellow pilots are wanting to start a new club
and are want to use winch, auto tows and reverse pulley launching
exclusively. Let's discuss the different aspects of ground launching as
the only thing that will save our sport and make it inviting once again
to new students.
Thanks
Rusty

Rusty wrote:
Hello All:
With the price of fuel going up and the price of AeroTows close behind
it I think the need to follow the lead of our brethren in the UK is
close at hand. I have heard talk of the infamous $100.00 tow and know
that I for one can't afford it, I have to work for a living as do most
of you! I and some of my fellow pilots are wanting to start a new club
and are want to use winch, auto tows and reverse pulley launching
exclusively. Let's discuss the different aspects of ground launching as
the only thing that will save our sport and make it inviting once again
to new students.
Thanks
Rusty

http://groups.yahoo.com/group/winchdesign/
Many of the issues are discuseed here and there are some archival
files/images to review. I'm quite happy to carry on here or in the
group.

There are a few stumbling blocks to ground launching, but most can be
overcome. Space is definitely one. If your launch rope can span
4000ft or more, it's very attractive. Others have done with less
distance. Location helps. Thinking outside the box helps also.

So, where are you? Appears you may be in Texas. That could be
fortunate as there are some ground launch activities there, in case
pilot and instructor qualifications are needed. If you are seriously
considering starting a club in the US, have a look here
http://www.soarcsa.org/ssa/clubs/2005_start_here.htm

Frank Whiteley
SSA Clubs & Chapters Committee member
CSA Winchmeister

I did all my training as far as passenger carrying , using a reverse auto
tow system. If there is runway length available, I think nothing will beat
it for speed and low cost.We regularly got 3000 foot launches using 6000
foot of 16 guage piano wire.
Ken Reynolds

On Fri, 2 Sep 2005 07:26:26 UTC, "Ken Reynolds"
wrote:

: I did all my training as far as passenger carrying , using a reverse auto
: tow system. If there is runway length available, I think nothing will beat
: it for speed and low cost.

And there is nothing to encourage take off like two tons of pickup
heading towards you at a closing speed of over 100mph ... I think both
the glider and the pilot are launched by fear.

Ian

PS But seriously, did a reverse pulley autotow at Connel a few years
back, very easy smooth launch.
--

16 gauge piano wire sounds remarkably thin, unless it was a special high
tensile type. Cotsold GC and Essex GC in the UK used 13 gauge (easier
than 11 gauge to handle, join, etc. but prone to breaks) or later 11
gauge (rarely broke, but harder to tie knots, and needed larger pulley
diameter for reverse pulley). The large diameters required led to
Cotswold going for a non-rotating "pulley" made up from lots of small
rollers round its rim (but it had no guillotine). Essex used two large
rollers, lots of inertia, but it enabled a flat anvil to be between them
so that a spring-loaded chisel could be released to cut the cable in
emergency.

Before reverse pulley, Essex used 13 gauge for straight autotow. It
often broke. Theoretically, the weak link should be weaker than the
cable, but we were using uncalibrated polypropylene rope of uncertain
breaking strain.

Starting over, I would be looking at Dyneema stronger than the highest
rated weak link needed, and the main cable should rarely if ever break.
For reverse pulley, I would look at the Cotswold type but incorporate a
flat part of the "pulley" with an anvil in line with the pivot, like the
Essex set up. The spring loaded chisel would go through the hollow pivot
shaft.

For the benefit of those who have not seen a pulley system, it needs to
pivot about a horizontal axle, and to swing to some extent, to equalise
the angles and allow the cable to run true from the glider (which might
be to one side of the runway, e.g. in a cross wind), into the top of the
pulley, and out from the bottom to the tow vehicle.

Chris N.




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Hello Again:
Thank you all for the response, it is all very welcome. I do live in
South Texas and we have access to a basically un-used well kept
200'x6000' hard packed grass field. We have recently picked up an
older winch that needs a litte TCL but with a little work will be very
usable. We are also setting up for straight auto-tow and are in the
process of building pulleys for reverse pulley. One of the many
questions I have is this: is a parachute necessary on straight auto-tow
and if so how far from the glider should the parachute be located?
Many more questions later.
Thanks
Rusty

Chris Nicholas wrote:
16 gauge piano wire sounds remarkably thin, unless it was a special high
tensile type. Cotsold GC and Essex GC in the UK used 13 gauge (easier
than 11 gauge to handle, join, etc. but prone to breaks) or later 11
gauge (rarely broke, but harder to tie knots, and needed larger pulley
diameter for reverse pulley). The large diameters required led to
Cotswold going for a non-rotating "pulley" made up from lots of small
rollers round its rim (but it had no guillotine). Essex used two large
rollers, lots of inertia, but it enabled a flat anvil to be between them
so that a spring-loaded chisel could be released to cut the cable in
emergency.

Before reverse pulley, Essex used 13 gauge for straight autotow. It
often broke. Theoretically, the weak link should be weaker than the
cable, but we were using uncalibrated polypropylene rope of uncertain
breaking strain.

Starting over, I would be looking at Dyneema stronger than the highest
rated weak link needed, and the main cable should rarely if ever break.
For reverse pulley, I would look at the Cotswold type but incorporate a
flat part of the "pulley" with an anvil in line with the pivot, like the
Essex set up. The spring loaded chisel would go through the hollow pivot
shaft.

For the benefit of those who have not seen a pulley system, it needs to
pivot about a horizontal axle, and to swing to some extent, to equalise
the angles and allow the cable to run true from the glider (which might
be to one side of the runway, e.g. in a cross wind), into the top of the
pulley, and out from the bottom to the tow vehicle.

Chris N.




__________________________________________________ _________
How much free photo storage do you get? Store your holiday
snaps for FREE with Yahoo! Photos http://uk.photos.yahoo.com

Frank Whiteley wrote:
Rusty wrote:
Hello All:
With the price of fuel going up and the price of AeroTows close behind
it I think the need to follow the lead of our brethren in the UK is
close at hand. I have heard talk of the infamous $100.00 tow and know
that I for one can't afford it, I have to work for a living as do most
of you! I and some of my fellow pilots are wanting to start a new club
and are want to use winch, auto tows and reverse pulley launching
exclusively. Let's discuss the different aspects of ground launching as
the only thing that will save our sport and make it inviting once again
to new students.
Thanks
Rusty

http://groups.yahoo.com/group/winchdesign/
Many of the issues are discuseed here and there are some archival
files/images to review. I'm quite happy to carry on here or in the
group.

There are a few stumbling blocks to ground launching, but most can be
overcome. Space is definitely one. If your launch rope can span
4000ft or more, it's very attractive. Others have done with less
distance. Location helps. Thinking outside the box helps also.

So, where are you? Appears you may be in Texas. That could be
fortunate as there are some ground launch activities there, in case
pilot and instructor qualifications are needed. If you are seriously
considering starting a club in the US, have a look here
http://www.soarcsa.org/ssa/clubs/2005_start_here.htm

Frank Whiteley
SSA Clubs & Chapters Committee member
CSA Winchmeister


..... Thinking outside the box helps also....

Frank, well said!
Many folks in the club I recently left in NE Ohio where dead set
against any kind of ground launching for they had heard how dangerous
it is and that you can not soar away out of a winch launch. Most of the
nay-sayers had never ground launched nor had they seen a modern winch
in action.
I think the main obstacle for introducing winch- or ground launching in
the US is to change the perception of what a modern winch is capable of
and at what cost at that.

'Folks - It ain't your daddy's Gehrlein winch anymore!!'

Anybody interested feel free to read up on that issue at (or join)
http://groups.yahoo.com/group/winchdesign/ .

I think we have collected the most comprehensive set of information
regarding winch launching in the last year and a half from practical
'how to' knowledge to all sorts of theoretical papers on the physics of
a winch launch.
Lets get to work!

Uli Neumann

GM wrote:

Many folks in the club I recently left in NE Ohio where dead set
against any kind of ground launching for they had heard how dangerous

Frankly, winch launching *is* dangerous if don't have the required
knowledge and aren't dead serious about it. But that's nothing new in
aviation.

it is and that you can not soar away out of a winch launch.

This depends on your location.

If you think of introducing winch operation at your site, then I suggest
you take the following steps.

1. Answer the following questions: How long will the cable be? How much
height can be achieved with this cable lenghth? Is this enough to get
away? (Always, sometimes, rarely).

2. Is a winch operation feasable at your site at all? (It mixes poorely
with scheduled Airliers.)

3. Calculate the cost.

4. Two or three pilots go somewhere where they have a winch operation.
Try it. Talk to them.

5. Best would be if you could hire a winch for a weekend at your place.
Together with the winch operator, of course, and a flight instructor.
Maybe obsolete if step 4 includes enough pilots.

6. Based on that experience, decide.

7. Most important: If you decide pro winch, get proper istruction, or
you *will* have fatalities. (Not panicking, I love winch launches. But
they *are* serious.)

Stefan

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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Chris Nicholas wrote:
16 gauge piano wire sounds remarkably thin, unless it was a special high
tensile type. Cotsold GC and Essex GC in the UK used 13 gauge (easier
than 11 gauge to handle, join, etc. but prone to breaks) or later 11
gauge (rarely broke, but harder to tie knots, and needed larger pulley
diameter for reverse pulley). The large diameters required led to
Cotswold going for a non-rotating "pulley" made up from lots of small
rollers round its rim (but it had no guillotine). Essex used two large
rollers, lots of inertia, but it enabled a flat anvil to be between them
so that a spring-loaded chisel could be released to cut the cable in
emergency.

Before reverse pulley, Essex used 13 gauge for straight autotow. It
often broke. Theoretically, the weak link should be weaker than the
cable, but we were using uncalibrated polypropylene rope of uncertain
breaking strain.

Starting over, I would be looking at Dyneema stronger than the highest
rated weak link needed, and the main cable should rarely if ever break.
For reverse pulley, I would look at the Cotswold type but incorporate a
flat part of the "pulley" with an anvil in line with the pivot, like the
Essex set up. The spring loaded chisel would go through the hollow pivot
shaft.

For the benefit of those who have not seen a pulley system, it needs to
pivot about a horizontal axle, and to swing to some extent, to equalise
the angles and allow the cable to run true from the glider (which might
be to one side of the runway, e.g. in a cross wind), into the top of the
pulley, and out from the bottom to the tow vehicle.

Chris N.

When using steel wire and wheels/pulleys, the diameter of the
wheels/pulleys should be 60 times the diameter of the wire to prevent
work hardening. That's why 7/7 wire rope works with much small
diameter rollers and guides on winches.

See http://tinyurl.com/c3pd5

Frank Whiteley