SAFE Winch Launching

Frank,

I believe that John Kangas is also mowing the King Mountain Glider Park
"Frank Whiteley" wrote in message ...
On Jul 13, 10:42 am, "Wayne Paul" wrote:

I concur that the US needs an economical way to launch sailplanes. As elsewhere in the world, a good winch seems to be the answer.

I don't have a ground-launch endorsement in my log book; however, I hope to get the training in the near future.

In order for the endorsement to have any value, I will need to install a CG hook on my HP-14 and travel to a facility with a winch. There are a couple of auto/truck ground launching operation less then 300 mile; however, I will have the travel about 700 mile to use a winch. This should give you some sense of the US lack of winch launch accessibility.


Wayne,

I was talking with Bill Corbin today about the prospect of finding a
winch for King Mountain. Any old Gehrlein model 62's languishing
about out there readers? We may be launching with one starting
Tuesday. I spent 8 hours on the tractor mowing the launch and
recovery area and runways today, such is the rain we've had in
Colorado this year.

Frank Whiteley

Frank,

John Kangas mowed the King Mountain Glider Park (http://www.kingmountaingliderpark.com/) last week end. He also installed tie-downs getting ready for the Aug 17 "grand opening" . (Are you planning to attend?)

As you know, one of John's goals is the installation of a winch. He feels the field's proximity to the mountain and associate know areas which generate thermals will make flying cross-country from a winch a "piece of cake." I am sure he would be interested in knowing about an old Gehrlein that is languishing somewhere here in the US. (There is also a glider operation "start up" in Baker City, OR that is looking for an old winch.)

I flew my Gold 300km triangle out of Mackay, Idaho and one of the turnpoints was the King Mountain Glider Park coordinates. (http://www.soaridaho.com/Flights/6F_Gold_Distance.html)

With the proximity of both the King Mountain Glider Park and Baker City, a CG hook for my HP-14 is on my winter project list.

Wayne
http://www.soaridaho.com/

"Frank Whiteley" wrote in message ...
On Jul 13, 10:42 am, "Wayne Paul" wrote:
"Del C" wrote in ...
At 15:01 13 July 2009, Wayne Paul wrote:

I concur that the US needs an economical way to launch sailplanes. As elsewhere in the world, a good winch seems to be the answer.

I don't have a ground-launch endorsement in my log book; however, I hope to get the training in the near future.

In order for the endorsement to have any value, I will need to install a CG hook on my HP-14 and travel to a facility with a winch. There are a couple of auto/truck ground launching operation less then 300 mile; however, I will have the travel about 700 mile to use a winch. This should give you some sense of the US lack of winch launch accessibility.


Wayne,

I was talking with Bill Corbin today about the prospect of finding a
winch for King Mountain. Any old Gehrlein model 62's languishing
about out there readers? We may be launching with one starting
Tuesday. I spent 8 hours on the tractor mowing the launch and
recovery area and runways today, such is the rain we've had in
Colorado this year.

Frank Whiteley

Unfortunately, I have a wedding here in Colorado to attend, so I won't
be able to come to Idaho.

Frank

On Jul 14, 6:12*am, "Wayne Paul" wrote:
Frank,

I believe that John Kangas is also mowing the King Mountain Glider Park"Frank Whiteley" wrote in ...

On Jul 13, 10:42 am, "Wayne Paul" wrote:



I concur that the US needs an economical way to launch sailplanes. As elsewhere in the world, a good winch seems to be the answer.

I don't have a ground-launch endorsement in my log book; however, I hope to get the training in the near future.

In order for the endorsement to have any value, I will need to install a CG hook on my HP-14 and travel to a facility with a winch. There are a couple of auto/truck ground launching operation less then 300 mile; however, I will have the travel about 700 mile to use a winch. This should give you some sense of the US lack of winch launch accessibility.

Wayne,

I was talking with Bill Corbin today about the prospect of finding a
winch for King Mountain. *Any old Gehrlein model 62's languishing
about out there readers? *We may be launching with one starting
Tuesday. *I spent 8 hours on the tractor mowing the launch and
recovery area and runways today, such is the rain we've had in
Colorado this year.

Frank Whiteley

Bob wrote:
Snip...
Maybe the “new”
technology is better, but keeping it in context – it is a potential
alternative to the proven traditional technology, not *THE* definitive
answer. This is what is being lost in this ongoing point and counter-
point dialog.
Indeed...
- - - - - -

There are many of us who believe in the merits of winch launching; and
that U.S. glider pilots would benefit from the widespread adoption of
the technique.
And I'm one of 'em. Soaring as an activity is sufficiently arcane and
the group (worldwide) that practices it sufficiently thinly spread that
internecine warfare fits the "foot shot" definition, in my book.
- - - - - -

It would benefit the soaring community if the polarized principals in
this personal disagreement would spend their time advocating winch
launching as a method, rather than publicly arguing over technical
details that may or may not be relevant.
"Roger that!" (What a concept!!!)
- - - - - -

Snip... If we could re-focus this obsessive, bias,
and argumentative dialog into promoting the use of ground launching it
would be of greater benefit to the soaring community at large.

Anyone agree?
"Ayup..."
- - - - - -

Bob Lacovara
(Winch pilot, winch driver, winch advocate)
Ditto your sig-line and tack-on 'engineer/*soaring* advocate.' (Sadly,
sometimes that last does NOT go without saying!) :-)

Bob - all soaring is good - W.

Just exacly where are you making these tensions measurements????

Are you making them at the weak link??

Are you making these measurements at the winch end of things?

I'd really like to know...

At 22:34 14 July 2009, Gary Emerson wrote:
Just exacly where are you making these tensions measurements????

Are you making them at the weak link??

Are you making these measurements at the winch end of things?

I'd really like to know...


That is the question that is puzzling me too. The tension sensed by the
winch will, and should be constantly changing during the launch, measuring
that would be, how can I put it, useless.
The tension at the glider release hook will be relatively constant but
measuring that introduces the problem of the addional weight of the device
that does it and a reliable transmission of data to the ground.

At 22:34 14 July 2009, Gary Emerson wrote:
Just exacly where are you making these tensions measurements????

Are you making them at the weak link??

Are you making these measurements at the winch end of things?

I'd really like to know...


I'm going to throw in my two cents here. I've been trying to get hard
data and information from first hand experiences for several years, now,
there just isn't much real stuff publicly available. There is, however,
a growing body of theory (which is good), speculation (not so good), and a
lot of bold statements that I have been, so far, unable to verify.

First, as far as I find out, the only tension/torque controlled winches
currently in day to day use use either electric or hydraulic drive
systems. For an electric winch, the torque applied to the drum can be
controlled based on drive current and drum speed. In the hydraulic case,
torque control is achieved by adjusting hydraulic pressure. In both
cases, this allows applying a specific amount of torque to the drum, which
approximates the desired amount of tension on the rope. In neither case is
the actual rope tension being measured. Drum inertia, rope oscillations,
etc., will also affect the rope tension. Apparently, though, at least
some of these winches provide tension controlled launches on a practical
basis.

There is one winch with an automated controls system under development in
the US, which uses a diesel engine and automatic transmission, with a
running line tensiometer (RLT) at the winch end. I have not been able to
obtain any information on whether the tension control program is actually
in use, and whether it is resulting in any real improvement over more
conventional winch launches.

One group in the UK has flown with a recording load cell to collect data
during a dispute with the manufacturer of their (conventional) winch. The
load cell was apparently placed at the weak link end of the rope. I've
seen about 10 distinct graphs produced by this device, and they look
terrible (large excursions in tension). However, despite loud
proclamations that "hundreds" of similar flights have been recorded on
several winches, I've never been able to get hold of any further data. I
also have been unable to obtain information on the device itself, how it
was calibrated, the circumstances under which the data was recorded, and
whether there were electrical, mechanical, driver, and/or pilot related
issues that could affect the data.

It does look rather straightforward to put a recording or wireless load
cell at the glider end of the rope, or use an RLT or even measure the load
directly from the winch axle (which I'll have provision for in the winch
I'm designing). So, I expect we'll be seeing more data in the future.

That's all I know at the moment, if there is anyone lurking out there
with solid data, I'd love to hear about it...

Marc

At 00:30 15 July 2009, Don Johnstone wrote:
At 22:34 14 July 2009, Gary Emerson wrote:
Just exacly where are you making these tensions measurements????

Are you making them at the weak link??

Are you making these measurements at the winch end of things?

I'd really like to know...


That is the question that is puzzling me too. The tension sensed by the
winch will, and should be constantly changing during the launch,
measuring
that would be, how can I put it, useless.
The tension at the glider release hook will be relatively constant but
measuring that introduces the problem of the addional weight of the
device
that does it and a reliable transmission of data to the ground.

That is the bit that the proponents of constant tension winch launching
seem to gloss over. How do you measure tension in a long and thrashing
cable that is being wound into a winch at up to 70 knots as the glider
lifts off? There are gadgets called running line tensiometers that are
used in underground cable laying, but they don't work at the sort of
speeds required.

The other approach is to mount a load cell at the glider end and transmit
the data back to the winch in some way, such as a radio link.

Even if you can directly measure tension in the cable, you have to bear in
mind that the glider has to pull against that tension and that changes in
its pitch angle due to pilot inputs or gusts will temporarily increase or
reduce the tension. You would therefore have to damp the system or it
would tend to hunt. I know as a glider pilot and winch driver myself, that
the less you can change the pitch angle of the glider and the throttle
setting of the winch, the steadier the launch becomes. If the pilot is
trying to control the airspeed with the stick at the same time that the
winch is trying to sense and maintain a constant tension, there is a risk
that they will end up chasing each other, especially when separated by a
long, sagging (even Dyneema sags slightly) and slightly elastic cable.

In practice the Skylaunch approach of limiting the power setting as
appropriate to the glider type, headwind component and weak link strength
seems to work well. If the pilot pulls back harder, or the glider runs
into a thermal, it slows the winch engine down by just the right amount.
Easing forward or hitting sink allows the engine to speed up. Since we
replaced Tost winches with Skylaunches, broken weak links have almost
become a thing of the past and the vast majority of the launches are
correctly speeded given correct pilot inputs. The pilot can control the
airspeed by changing the pitch angle.

Derek Copeland

People trying to design tension controlled winches are re-inventing
the wheel. Conventional winches already do that. IF the power setting
is retained constant in conventional winches with a torque converter,
the tension will be constant excluding the inertia factor. Every winch
will have inertia and delay and none will be able to respond
instantaneously to changes in wire load.

A tension meter can be installed in any type of winch, electric,
hydraulic or conventional. There is no difference between the
different types there and power can be controlled by one if desired.
The issue is, does it make sense? Is the approximation calculated by
the British design good enough? Or do we need a real time tension
control winch? Would the inertia i the system even make this possible
or desirable?

I would say that setting the desired tension according to type and
conditions by approximation, ala Skylaunch, and not worrying about the
fluctuations is plenty good enough. The main reason is because
designing a winch to be truly controlled in real time by the actual
and current tension, micro second by microsecond, is probably very
expensive, unproven and would not solve the inertia delay issue of the
winch. Trying to chase the gusts so to speak - how would that work? A
conventional winch type already lets the drum slow down and/or pulls
the engine revs down if the cable tension increases due to a gust or
thermal - thus reducing the tension - this is already a mechanically
built in constant torque effect.

This is by no means perfect, but certainly good enough to give mostly
smooth launches. In gusty conditions, there is no winch in the world,
not even on paper, that can react fast enough to dampen away the
oscillations in cable tension and airspeed, due to the time delay in
reacting to the changes in cable tension.

We just need to figure out how to make a cheap reliable winch and find
places to use them at. At $10-$15 a launch, a glider club or operator
would quickly make a nice income, like European clubs do. The real
cost of a winch launch is something like $3-5 per launch including
maintenance, reserves and replacements. 30 launches a week x $10
profit = $1,200 extra a month. That's one very nice glider upgrade
every 5 years. This is one of the main reasons why European clubs have
such nice equipment.
Tom

At 04:19 15 July 2009, tommytoyz wrote:
We just need to figure out how to make a cheap reliable winch and find
places to use them at. At $10-$15 a launch, a glider club or operator
would quickly make a nice income, like European clubs do. The real
cost of a winch launch is something like $3-5 per launch including
maintenance, reserves and replacements. 30 launches a week x $10
profit = $1,200 extra a month. That's one very nice glider upgrade
every 5 years. This is one of the main reasons why European clubs have
such nice equipment.

There are winches already in operation in the US, there are groups who
want to operate them, and there are groups trying to design and
manufacture them. I think we need all of the above.

I'm part of a wanna-be operating group, with limited funds. That pretty
much means either finding a rebuildable Gehrlein, importing an inexpensive
used winch from Europe, or homebrewing a new winch (based on the UK spec).
I prefer the latter, as I think there is still plenty of room for
optimization, both in fabrication and operation. While I respect those
who are trying to push the envelope with advance power systems and launch
automation, a simple single drum winch based on automotive components will
be good enough for our local group get started.

If you aren't a member of the Yahoo Winch Design group, please consider
joining. While we have our share of spats, there is progress being made
towards coming up with component designs for a cheap reliable
non-automated winch...

Marc