New winch height record [Archive]

Bill Daniels

November 26th 07, 02:38 AM

George Moore of Spokane, WA has developed some very convincing math that
says 50% of the initial rope length should be possible as release height
under no wind conditions.

As you go to longer ropes, the percentage used for ground roll and rotation
into the climb becomes less and as you get higher, you may encounter higher
headwinds which also adds to release height. I would expect higher
percentages simply due to longer ropes.

All this depends on several things. Using Spectra or Dyneema rope which is
10 - 12% the weight of steel cable for a given strength, using adequate
power to maintain a rope tension of 1 to 1.5 x glider weight and managing
that tension precisely with a computer.

In this case, they used an ASK-21 which specifies a black 2200 pounds-force
weak link. This allows a lot of power to be transfered to the glider.
Apparently it was flown solo which means a tension factor of ~1.5 x weight
was possible.

All very technical, of course. Where it's a game changer is training,
particularly glider aerobatic training. An aero tow to 1700 meters is way
over 100 Euro. The winch launch was probably less than 10 Euro.

I like to think of quietly lobbing an instructor with a pre-solo student up
over a vertical mile at 6AM for 40 minutes of instruction in glassy smooth
air.

Bill Daniels

"bagmaker" > wrote in message
...
>
> A typical winch launch yeilds about 1/3 of the runway/field available,
> this is a fantastic result, Bill!
> Perhaps we should be measuring the launch as a percentage of field
> length, then there would actually be a record available for everyone to
> shoot for, regardless of locality.
> So...
> With a runway of 3100m and a launch of 1718, the current known record
> is 55.42%
>
>
> Get out there and break it!!
>
>
> bagger
>
>
>
>
> --
> bagmaker

Todd

November 26th 07, 02:51 AM

In my corner of the soaring world, we have lots of 1 mile by 1 mile
fields (section lines) so the diagonals area bit under 7500 ft. Still
might be good for an almost 4000 ft launch. Any friendly farmers out
there?

[email protected]

November 26th 07, 03:30 AM

What is a Mel winch?

What does UHMWPE mean?

Thanks,

Michael

Bill Daniels wrote:
> From Europe:
>
> ________________________________________________
> "On Sun, November 25, 2007 9:31 am, peternarinx wrote:
> Yesterday, on the airfield of Weelde ( EBWE) in Belgium, Peter
> Mink reached 1718m AGL with an ASK21 and a Mel winch."
>
> "The length of the runway is 3100m including the grass at both ends
> and the winch is on the ground. You can see the airfield on google
> earth 51 23 48 N , 04 37 77 E. They said that the conditions were
> not optimal yesterday......."
> _________________________________________________
>
> 1718 meters is 5,636 feet AGL. The runway length is 3100 meters or 10,170
> feet.
>
> With the new light weight UHMWPE winch rope and a modern high performance
> winch, great heights can be achieved.
>
> Bill Daniels

[email protected]

November 26th 07, 03:35 AM

Marc Ramsey[_2_]

November 26th 07, 03:41 AM

wrote:
> What is a Mel winch?

Picture here:

http://www.machinefabriek-el.nl/content_6.asp

> What does UHMWPE mean?

Ultra High Molecular Weight PolyEthylene

Marc

Wayne Paul

November 26th 07, 03:52 AM

Here is a YouTube video of a MEL winch:
http://www.youtube.com/watch?v=3quhC6cD6rU

Wayne
http://www.soaridaho.com/

" > wrote in message
...
> What is a Mel winch?
>
> What does UHMWPE mean?
>
> Thanks,
>
> Michael
>
> Bill Daniels wrote:
>> From Europe:
>>
>> ________________________________________________
>> "On Sun, November 25, 2007 9:31 am, peternarinx wrote:
>> Yesterday, on the airfield of Weelde ( EBWE) in Belgium, Peter
>> Mink reached 1718m AGL with an ASK21 and a Mel winch."
>>
>> "The length of the runway is 3100m including the grass at both ends
>> and the winch is on the ground. You can see the airfield on google
>> earth 51 23 48 N , 04 37 77 E. They said that the conditions were
>> not optimal yesterday......."
>> _________________________________________________
>>
>> 1718 meters is 5,636 feet AGL. The runway length is 3100 meters or
>> 10,170
>> feet.
>>
>> With the new light weight UHMWPE winch rope and a modern high performance
>> winch, great heights can be achieved.
>>
>> Bill Daniels

2cernauta2

November 26th 07, 12:49 PM

On Sun, 25 Nov 2007 15:53:27 -0800, "BT" > wrote:

>how many glider club or commercial operations have 10,000ft of "runway"
>available.
>granted.. for most 4000ft runways.. it could prove very beneficial
>
>BT

Wouldn't it be possible to locate the winch outside the airfield's
boundary, and launch with a longer rope on a 600m runway?
Is this common practice at some glider sites?

Aldo Cernezzi

Andreas Maurer[_1_]

November 26th 07, 02:32 PM

On Sun, 25 Nov 2007 21:27:23 +0000, bagmaker
> wrote:

>With a runway of 3100m and a launch of 1718, the current known record
>is 55.42%

I can offer 63.8% (Ka-8b, 670 m height on a 1050 m standard steel
cable).

Bye
Andreas

John Smith

November 26th 07, 03:03 PM

2cernauta2 wrote:

> Wouldn't it be possible to locate the winch outside the airfield's
> boundary, and launch with a longer rope on a 600m runway?
> Is this common practice at some glider sites?

If geography allows you to retrieve the cable (no bushes, roads, walls,
rivers, whatever between start place and winch), if the safety of
uninvolved persons is not compromised, if there's no road, house,
whatever the cable can fall onto, if you can find an agreement with the
farmers whose fields you will cross while retrieveing the cable... and
be sure there's no regulation which prohibits cables above a certain
height. If you can fulfill all these requirements, then it would
certainly be worth to give it a try.

Bill Daniels

November 26th 07, 03:28 PM

"John Smith" > wrote in message
...
> 2cernauta2 wrote:
>
>> Wouldn't it be possible to locate the winch outside the airfield's
>> boundary, and launch with a longer rope on a 600m runway?
>> Is this common practice at some glider sites?
>
> If geography allows you to retrieve the cable (no bushes, roads, walls,
> rivers, whatever between start place and winch), if the safety of
> uninvolved persons is not compromised, if there's no road, house, whatever
> the cable can fall onto, if you can find an agreement with the farmers
> whose fields you will cross while retrieveing the cable... and be sure
> there's no regulation which prohibits cables above a certain height. If
> you can fulfill all these requirements, then it would certainly be worth
> to give it a try.

I would speculate that Spectra or Dyneema is a lot more forgiving in this
regard. It's possible that sites unsuitable for steel cable would be
workable if Spectra or Dyneema is used.

Steel cable is heavy and can damage anything it falls on. Because it forms
kinks and weak points, is easier to break. It's electrically conductive so
power lines are an extreme hazard.

Spectra or Dyneema is so light that it 'floats down' more than falls so is
unlikely to damage anything unless it is pulled across something under
tension or the connecting hardware does the damage. It's also a very poor
conductor.

Bill Daniels

Cats

November 26th 07, 05:42 PM

On Nov 26, 3:03 pm, John Smith > wrote:
> 2cernauta2 wrote:
> > Wouldn't it be possible to locate the winch outside the airfield's
> > boundary, and launch with a longer rope on a 600m runway?
> > Is this common practice at some glider sites?
>
> If geography allows you to retrieve the cable (no bushes, roads, walls,
> rivers, whatever between start place and winch), if the safety of
> uninvolved persons is not compromised, if there's no road, house,
> whatever the cable can fall onto, if you can find an agreement with the
> farmers whose fields you will cross while retrieveing the cable... and
> be sure there's no regulation which prohibits cables above a certain
> height. If you can fulfill all these requirements, then it would
> certainly be worth to give it a try.

And if cable breaks at *all* heights can be safely dealt with...

brtlmj

November 26th 07, 06:14 PM

> I like to think of quietly lobbing an instructor with a pre-solo student up
> over a vertical mile at 6AM for 40 minutes of instruction in glassy smooth
> air.

This is slightly OT, but... is there an optimal launch height at each
stage of training? For example, a few really high launches at the very
beginning (so that the student has time to practice things like speed
control and turns), and then a lot of standard (~1500ft) launches
(circuit planning and landing)?

Bartek

Bill Daniels

November 26th 07, 06:37 PM

"brtlmj" > wrote in message
...
>> I like to think of quietly lobbing an instructor with a pre-solo student
>> up
>> over a vertical mile at 6AM for 40 minutes of instruction in glassy
>> smooth
>> air.
>
> This is slightly OT, but... is there an optimal launch height at each
> stage of training? For example, a few really high launches at the very
> beginning (so that the student has time to practice things like speed
> control and turns), and then a lot of standard (~1500ft) launches
> (circuit planning and landing)?
>
> Bartek

Of course. Early trainees gets high launches until they can fly the glider
reasonably well and then a lot of low launches for landings and launch
failure training.

For low launches, 1500 feet or less, a retrieve winch can be used to get the
rope back for another launch achiving a launch every 2 minutes or so.

It would be great to have both capabilities.

Bill D

Mike Schumann

November 26th 07, 06:39 PM

You would also need to make an adjustment for headwinds to make it really
fair.

Mike Schumann

"bagmaker" > wrote in message
...
>
> A typical winch launch yeilds about 1/3 of the runway/field available,
> this is a fantastic result, Bill!
> Perhaps we should be measuring the launch as a percentage of field
> length, then there would actually be a record available for everyone to
> shoot for, regardless of locality.
> So...
> With a runway of 3100m and a launch of 1718, the current known record
> is 55.42%
>
>
> Get out there and break it!!
>
>
> bagger
>
>
>
>
> --
> bagmaker

--
Posted via a free Usenet account from http://www.teranews.com

Mike Schumann

November 26th 07, 06:41 PM

Rent a 100' wide swath in the middle of a field.

Mike Schumann

"Todd" > wrote in message
...
> In my corner of the soaring world, we have lots of 1 mile by 1 mile
> fields (section lines) so the diagonals area bit under 7500 ft. Still
> might be good for an almost 4000 ft launch. Any friendly farmers out
> there?

--
Posted via a free Usenet account from http://www.teranews.com

Mike Schumann

November 26th 07, 06:42 PM

You would need to be able to get the gliders from the landing runway to the
launch point.

Mike Schumann

"2cernauta2" > wrote in message
...
> On Sun, 25 Nov 2007 15:53:27 -0800, "BT" > wrote:
>
>>how many glider club or commercial operations have 10,000ft of "runway"
>>available.
>>granted.. for most 4000ft runways.. it could prove very beneficial
>>
>>BT
>
> Wouldn't it be possible to locate the winch outside the airfield's
> boundary, and launch with a longer rope on a 600m runway?
> Is this common practice at some glider sites?
>
>
> Aldo Cernezzi

--
Posted via a free Usenet account from http://www.teranews.com

mart

November 26th 07, 08:48 PM

Wouldn't it be possible to locate the winch outside the airfield's
boundary, and launch with a longer rope on a 600m runway?
Is this common practice at some glider sites?

We do. Mount Beauty Gliding Club.
You will not believe the hassle it gives though. Everytime closing the gate to prevent cows entering the runway, chasing cattle of the cable before launching and cow**** around the winch. No joke.

Very happy with the extra 1000 ft.

Martin Gregorie[_1_]

November 26th 07, 11:38 PM

Mike Schumann wrote:
> Rent a 100' wide swath in the middle of a field.
>
That might work OK when the wind is directly down the strip, but what
about cross winds, especially with a new-chum driver or a cable break?

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

November 27th 07, 12:32 AM

it could work to the south.. to launch to the south.. about 1/3 mile to the
power line..
to the north.. can't run the cable across the road
great idea though
BT

"2cernauta2" > wrote in message
...
> On Sun, 25 Nov 2007 15:53:27 -0800, "BT" > wrote:
>
>>how many glider club or commercial operations have 10,000ft of "runway"
>>available.
>>granted.. for most 4000ft runways.. it could prove very beneficial
>>
>>BT
>
> Wouldn't it be possible to locate the winch outside the airfield's
> boundary, and launch with a longer rope on a 600m runway?
> Is this common practice at some glider sites?
>
>
> Aldo Cernezzi

Mike Schumann

November 27th 07, 03:36 AM

OK, Rent a 200' wide strip and ask the farmer to plant soybeans or alfalfa.

Mike Schumann

"Martin Gregorie" > wrote in message
...
> Mike Schumann wrote:
>> Rent a 100' wide swath in the middle of a field.
>>
> That might work OK when the wind is directly down the strip, but what
> about cross winds, especially with a new-chum driver or a cable break?
>
>
> --
> martin@ | Martin Gregorie
> gregorie. | Essex, UK
> org |

--
Posted via a free Usenet account from http://www.teranews.com

bumper

November 27th 07, 05:53 AM

Ultra High Molecular Weight Polyethylene

UHMW is tougher than Teflon and almost as slick. Handy to have around as it
makes a good anti-chafe tape. The tape, not the rope, like most good things
in life, is available from McMaster-Carr on-line (g).

bumper

" > wrote in message
...
> What is a Mel winch?
>
> What does UHMWPE mean?
>
> Thanks,
>
> Michael
>
> Bill Daniels wrote:
>> From Europe:
>>
>> ________________________________________________
>> "On Sun, November 25, 2007 9:31 am, peternarinx wrote:
>> Yesterday, on the airfield of Weelde ( EBWE) in Belgium, Peter
>> Mink reached 1718m AGL with an ASK21 and a Mel winch."
>>
>> "The length of the runway is 3100m including the grass at both ends
>> and the winch is on the ground. You can see the airfield on google
>> earth 51 23 48 N , 04 37 77 E. They said that the conditions were
>> not optimal yesterday......."
>> _________________________________________________
>>
>> 1718 meters is 5,636 feet AGL. The runway length is 3100 meters or
>> 10,170
>> feet.
>>
>> With the new light weight UHMWPE winch rope and a modern high performance
>> winch, great heights can be achieved.
>>
>> Bill Daniels

Del C

November 27th 07, 01:39 PM

Our experience of UHMWPE cable was that it 'floats'
much further downwind after a cable break, so is more
likely to go across something!

Del Copeland
Lasham Gliding Society, UK
At 15:30 26 November 2007, Bill Daniels wrote:
>
>
>I would speculate that Spectra or Dyneema is a lot
>more forgiving in this
>regard. It's possible that sites unsuitable for steel
>cable would be
>workable if Spectra or Dyneema is used.
>
>Steel cable is heavy and can damage anything it falls
>on. Because it forms
>kinks and weak points, is easier to break. It's electrically
>conductive so
>power lines are an extreme hazard.
>
>Spectra or Dyneema is so light that it 'floats down'
>more than falls so is
>unlikely to damage anything unless it is pulled across
>something under
>tension or the connecting hardware does the damage.
> It's also a very poor
>conductor.
>
>Bill Daniels

brtlmj

November 27th 07, 09:29 PM

On Nov 26, 10:37 am, "Bill Daniels" <bildan@comcast-dot-net> wrote:

> It would be great to have both capabilities.

....and that would probably require two winches. Even though one could
release at 1500ft when being launched by a 4000ft-capable winch, it
would probably be pointless. But then, would it be possible to operate
two winches safely?

Bartek

tommytoyz

November 27th 07, 10:40 PM

Bartek,
Most winches have more than one drum. In Europe, one winch can have up
to 8 separate drums and lines. This enables a launch every 3 minutes
or less.
http://www.hydrostart.nl/EN/
Tom

brtlmj

November 27th 07, 11:07 PM

> Most winches have more than one drum. In Europe, one winch can have up
> to 8 separate drums and lines. This enables a launch every 3 minutes
> or less.http://www.hydrostart.nl/EN/

Oh, sure. But what if a club wanted to have one winch for high
launches, located at the far end of a runway, and another one for
circuit practice, located in the middle of the runway?

Bartek

Marc Ramsey

November 27th 07, 11:13 PM

tommytoyz wrote:
> Bartek,
> Most winches have more than one drum. In Europe, one winch can have up
> to 8 separate drums and lines. This enables a launch every 3 minutes
> or less.
> http://www.hydrostart.nl/EN/

I've watched them launch gliders at Lasham at that rate using a single
drum of a Tost winch and a retrieve winch. There is a price to be paid,
of course, maybe 200 feet less altitude (if that much), but a retrieve
winch is somewhat less expensive than upgrading to an 8 drum Hydrostart...

Marc

John Smith

November 27th 07, 11:36 PM

brtlmj wrote:

> Oh, sure. But what if a club wanted to have one winch for high
> launches, located at the far end of a runway, and another one for
> circuit practice, located in the middle of the runway?

I don't see the point. I've never felt that a winch launch was too high,
even for primary circuit training. There are always some exercises which
you can do with students. I know a couple of maneuvres which destroy
altitude pretty efficiently... And if everything else fails, you can
always practise a rope break.

Bill Daniels

November 27th 07, 11:45 PM

"brtlmj" > wrote in message
...
>> Most winches have more than one drum. In Europe, one winch can have up
>> to 8 separate drums and lines. This enables a launch every 3 minutes
>> or less.http://www.hydrostart.nl/EN/
>
> Oh, sure. But what if a club wanted to have one winch for high
> launches, located at the far end of a runway, and another one for
> circuit practice, located in the middle of the runway?
>
> Bartek

I think one winch would be enough. You don't need to do high launches and
low launches at the same time. It's just ascheduling. Plan some high
launches early and some landing practice late. Give the guys who want to
soar the mid-day slot. A winch can be moved around easily.

That said, many European and British clubs do use several winches at the
same time. Again, it's just a scheduling and organizational problem.

One thing a lot of US pilots seem to miss is that a winch can, and probably
will, operate from sun up to sun down. There's no noise problem. Cost is
not an issue. If you find lift, great. If not, the cost of a winch launch
is so low and it's so much fun, just glide down for a landing and do it
again.

Spending a day trying to get that glass racer down in the smallest patch
possible is huge fun. Since you have to push it back to the start line, you
have a big incentive to land short. Knowing you can land very short if need
be is a big relief on a XC. 20 or so consecutive landings will do that.

Another fun thing is to watch is the private owners who arrive at 11:00
expecting lift to start at 12:30 when the find out a solo student has been
soaring for two hours off a winch launch.

Bill Daniels

Martin Gregorie[_1_]

November 28th 07, 12:00 AM

tommytoyz wrote:
> Bartek,
> Most winches have more than one drum. In Europe, one winch can have up
> to 8 separate drums and lines. This enables a launch every 3 minutes
> or less.
> http://www.hydrostart.nl/EN/
> Tom
>
A properly motivated crew and non-chatty instructors can manage 20 launches
an hour off a dual drum winch. Its probably hard to beat that no matter how
many drums you have because you start to be held up by pilots getting ready
or, depending on your field layout, landing gliders interfering with
launches.

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

brtlmj

November 28th 07, 12:16 AM

On Nov 27, 3:36 pm, John Smith > wrote:
> I don't see the point. I've never felt that a winch launch was too high,
> even for primary circuit training. There are always some exercises which
> you can do with students. I know a couple of maneuvres which destroy
> altitude pretty efficiently... And if everything else fails, you can
> always practise a rope break.

Yeah, I am probably looking for nonexistent problems ;-)

Bartek

Bill Daniels

November 28th 07, 12:56 AM

"Martin Gregorie" > wrote in message
...
> tommytoyz wrote:
>> Bartek,
>> Most winches have more than one drum. In Europe, one winch can have up
>> to 8 separate drums and lines. This enables a launch every 3 minutes
>> or less.
>> http://www.hydrostart.nl/EN/
>> Tom
>>
> A properly motivated crew and non-chatty instructors can manage 20
> launches
> an hour off a dual drum winch. Its probably hard to beat that no matter
> how
> many drums you have because you start to be held up by pilots getting
> ready
> or, depending on your field layout, landing gliders interfering with
> launches.
>
>
> --
> martin@ | Martin Gregorie
> gregorie. | Essex, UK
> org |

The payoff for multiple durms is when you use very long cables (ropes?)
When retrieve time becomes a large part of the time budget, it's better to
be pulling a lot of ropes back at one time. If you are using a 3000 meter
runway, 4, 6 or even 8 drums really do make sense.

With heavy steel cable, it wasn't really possible to pull more than 6 cables
at once - the tractors just didn't have enough traction. With the
widespread use of super lightweight UHMWPE, 8 drums is easily possible.

For short runways, a single drum and a retrieve winch is probably
unbeatable.

Bill Daniels

MaD

November 28th 07, 12:16 PM

On 28 Nov., 01:00, Martin Gregorie > wrote:
> tommytoyz wrote:
> > Bartek,
> > Most winches have more than one drum. In Europe, one winch can have up
> > to 8 separate drums and lines. This enables a launch every 3 minutes
> > or less.
> >http://www.hydrostart.nl/EN/
> > Tom
>
> A properly motivated crew and non-chatty instructors can manage 20 launches
> an hour off a dual drum winch. Its probably hard to beat that no matter how
> many drums you have because you start to be held up by pilots getting ready
> or, depending on your field layout, landing gliders interfering with
> launches.
>
> --
> martin@ | Martin Gregorie
> gregorie. | Essex, UK
> org |

We use a 6-drum winch and about 1km (3300ft) steel rope. We actually
achieved 34 launches one time during regional championships. Of course
everybody was ready and plenty of ground crew available.
Amazingly, the theoretically possible maximum is over 40 launches per
hour (10-15s hookup and pull up slack, 30-35s launch, 15-20s pull in
rope, 120-150s retrieve @ 30km/h = 8-10min/6launches).

regards
Marcel

Martin Gregorie[_1_]

November 28th 07, 01:25 PM

Bill Daniels wrote:
>
> The payoff for multiple durms is when you use very long cables (ropes?)
> When retrieve time becomes a large part of the time budget, it's better to
> be pulling a lot of ropes back at one time. If you are using a 3000 meter
> runway, 4, 6 or even 8 drums really do make sense.
>
Yes, I can see that - I'm used to 1000 m and was talking from experience
at that length.

However, I suspect my other point still holds with a lot of drums, that
once you get up towards 20 launches an hour the readiness of staged
gliders to accept a launch starts to become the critical factor.

>
> For short runways, a single drum and a retrieve winch is probably
> unbeatable.
>
I know about them but have never seen one in action. How long can the
run be before this becomes impractical?

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

Del C

November 28th 07, 01:57 PM

To see Lasham's retrieve winch set in action see URL:

http://uk.youtube.com/watch?v=1Slucbodmzo

In normal club use we get about 25 launches per hour
from this set up. The biggest problem is getting pilots
in their gliders and ready to launch. That is why we
line gliders up 3 at a time, so at least the second
two are ready! If all pilots were ready to launch and
we had a good team of helpers, we could easily achieve
30 launches an hour or more. We use just one drum and
4.7 mm steel cable on a normal two-drum Tost winch.
The retrieve winch is a Skylaunch product fitted with
2.5 mm steel cable: see www.skylaunchuk.com

Derek Copeland

At 23:24 27 November 2007, Marc Ramsey wrote:
>tommytoyz wrote:
>> Bartek,
>> Most winches have more than one drum. In Europe, one
>>winch can have up
>> to 8 separate drums and lines. This enables a launch
>>every 3 minutes
>> or less.
>> http://www.hydrostart.nl/EN/
>
>I've watched them launch gliders at Lasham at that
>rate using a single
>drum of a Tost winch and a retrieve winch. There is
>a price to be paid,
>of course, maybe 200 feet less altitude (if that much),
>but a retrieve
>winch is somewhat less expensive than upgrading to
>an 8 drum Hydrostart...
>
>Marc
>

Bill Daniels

November 28th 07, 02:32 PM

"Martin Gregorie" > wrote in message
...

>> For short runways, a single drum and a retrieve winch is probably
>> unbeatable.
>>
> I know about them but have never seen one in action. How long can the run
> be before this becomes impractical?
>

Not sure - somebody needs to do some believable side by side tests. The UK
retrieve winch operations are still using steel cables on fairly short runs.
Those don't seem to suffer much from lifting two cables. Obviously, Dyneema
cables will have a large effect on retrieve winch operations by reducing the
losses associated with lifting a second cable.

It depends on what you are trying to do. Landing practice or launching into
local ridge lift makes launch frequency the most important thing so retrieve
winches are attractive there. Getting high enough to cruise around for a
while looking for thermals probably means long runs and multiple drums are a
better approach.

Very high launches for training probably eliminates retrieve winches from
consideration.

Bill Daniels

Phil Collin

November 28th 07, 02:57 PM

As an aside,
back in 88 we at 611 VGS at RAF Swanton Morley flew from legal sun up to
legal sun down on the longest day.
Utilising our Van Gelder 6 drum winch and 6 GROB 103's achieved in
excess of our 611 launches in a single day target.
Logistics were fun but just demonstrated what is possible.

Phil

Bill Daniels wrote:
> "Martin Gregorie" > wrote in message
> ...
>
>>> For short runways, a single drum and a retrieve winch is probably
>>> unbeatable.
>>>
>> I know about them but have never seen one in action. How long can the run
>> be before this becomes impractical?
>>
>
> Not sure - somebody needs to do some believable side by side tests. The UK
> retrieve winch operations are still using steel cables on fairly short runs.
> Those don't seem to suffer much from lifting two cables. Obviously, Dyneema
> cables will have a large effect on retrieve winch operations by reducing the
> losses associated with lifting a second cable.
>
> It depends on what you are trying to do. Landing practice or launching into
> local ridge lift makes launch frequency the most important thing so retrieve
> winches are attractive there. Getting high enough to cruise around for a
> while looking for thermals probably means long runs and multiple drums are a
> better approach.
>
> Very high launches for training probably eliminates retrieve winches from
> consideration.
>
> Bill Daniels
>
>

Bill Daniels

November 28th 07, 04:01 PM

611 launches in one day with one winch! Wow! I think that's a world
recond.

Bill Daniels

"Phil Collin" > wrote in message
...
> As an aside,
> back in 88 we at 611 VGS at RAF Swanton Morley flew from legal sun up to
> legal sun down on the longest day.
> Utilising our Van Gelder 6 drum winch and 6 GROB 103's achieved in excess
> of our 611 launches in a single day target.
> Logistics were fun but just demonstrated what is possible.
>
> Phil
>
>
> Bill Daniels wrote:
>> "Martin Gregorie" > wrote in message
>> ...
>>
>>>> For short runways, a single drum and a retrieve winch is probably
>>>> unbeatable.
>>>>
>>> I know about them but have never seen one in action. How long can the
>>> run be before this becomes impractical?
>>>
>>
>> Not sure - somebody needs to do some believable side by side tests. The
>> UK retrieve winch operations are still using steel cables on fairly short
>> runs. Those don't seem to suffer much from lifting two cables.
>> Obviously, Dyneema cables will have a large effect on retrieve winch
>> operations by reducing the losses associated with lifting a second cable.
>>
>> It depends on what you are trying to do. Landing practice or launching
>> into local ridge lift makes launch frequency the most important thing so
>> retrieve winches are attractive there. Getting high enough to cruise
>> around for a while looking for thermals probably means long runs and
>> multiple drums are a better approach.
>>
>> Very high launches for training probably eliminates retrieve winches from
>> consideration.
>>
>> Bill Daniels

Sönke Gutzlaff

November 28th 07, 06:22 PM

"bagmaker" > schrieb im Newsbeitrag
...
>
> A typical winch launch yeilds about 1/3 of the runway/field available,
> this is a fantastic result, Bill!
> Perhaps we should be measuring the launch as a percentage of field
> length, then there would actually be a record available for everyone to
> shoot for, regardless of locality.
> So...
> With a runway of 3100m and a launch of 1718, the current known record
> is 55.42%
>
>
> Get out there and break it!!

950m steel cable + 350hp winch + 20km/h wind + ASK21 = 750m or 78%.
More high was possible, but airspace class C begins at 750m above our
airfield so I had to release the cable.

I think the ASK21 gets the best high on winchlaunch. Our DG1000 always gets
25% less high.

Greetings,
Sönke

Dan G

November 28th 07, 09:15 PM

On Nov 28, 6:22 pm, "Sönke Gutzlaff" > wrote:
> 950m steel cable + 350hp winch + 20km/h wind + ASK21 = 750m or 78%.
> More high was possible, but airspace class C begins at 750m above our
> airfield so I had to release the cable.
>
> I think the ASK21 gets the best high on winchlaunch. Our DG1000 always gets
> 25% less high.
>
> Greetings,
> Sönke

Sönke, what speed do you fly at on the winch, and how much back
pressure do you apply to the stick?

Dan

tommytoyz

November 28th 07, 10:41 PM

Back in Germany we used two twin drum Tost winches on our field and
launched all day long back to back, as long as there were planes
needing to be launched. Wires were retrieved with a retrieve vehicle,
two at a time.

I think the British method of using a single drum winch in combination
with a retrieve winch to be a very sensible idea - even for long
fields and high launches.

The cable is being retrieved before it even hits the ground. So the
retrieve process is shorter and faster than using a retrieve vehicle
by dragging the entire cable length along the ground. The winch
retrieve should there for also save on wear and tear on the cable as
most of th retrieve occurs in the air after the glider releases.

On very high tows, a long portion of the cable is never wound up into
the tow drum and there for a high altitude launch should actually
reduce the cable retrieve process using a cable retrieve winch. The
light weight of the newer cables makes a launch penalty negligible.
The retrieve cable need not be very strong or even in good shape
anyway, as it's only function is to retrieve the cable.

I like this approach and seems the cheapest way to introduce high
frequency winch operations in the USA. I wish Commercial Glider
Operators would buy a single drum winch and a retrieve winch and offer
this launch method. Even at 10-15 a launch - it's still heaps cheaper
and the operator would probably make more money at the end of the day.

Not to speak about the fact that winch launches a far and away more
fun and exiting than aero tows.

Bill Daniels

November 28th 07, 11:13 PM

It could be you're right but I'd still like to see an actual comparison with
and without the retrieve winch at longer and longer distances. Some
validated metrics would help sell the idea. It has yet to be determined
just how long ropes can be with a retrieve winch.

What I'm worried about isn't the weight of Dyneema/Spectra ropes it's the
pull angle at the hook. If the retrieve rope drags back enough to change
that angle it will adversely affect the height achieved.

I know an engineer who was working on a simple "spinner reel" type design
for a retrieve winch that would use 1 or 1.5mm Dyneema. Calculations showed
that the power required is minimal - you could power it with a small car
starter motor and a battery. 2000 meters of thin Dyneema would fit on a
drum not much bigger than a coffee can. With the "spinner reel" concept
Dyneema would pay off the retrieve winch with no rotation of the tiny drum.

On the bright side, using a retrieve winch would cut the fuel use by half.

Bill Daniels

"tommytoyz" > wrote in message
...
> Back in Germany we used two twin drum Tost winches on our field and
> launched all day long back to back, as long as there were planes
> needing to be launched. Wires were retrieved with a retrieve vehicle,
> two at a time.
>
> I think the British method of using a single drum winch in combination
> with a retrieve winch to be a very sensible idea - even for long
> fields and high launches.
>
> The cable is being retrieved before it even hits the ground. So the
> retrieve process is shorter and faster than using a retrieve vehicle
> by dragging the entire cable length along the ground. The winch
> retrieve should there for also save on wear and tear on the cable as
> most of th retrieve occurs in the air after the glider releases.
>
> On very high tows, a long portion of the cable is never wound up into
> the tow drum and there for a high altitude launch should actually
> reduce the cable retrieve process using a cable retrieve winch. The
> light weight of the newer cables makes a launch penalty negligible.
> The retrieve cable need not be very strong or even in good shape
> anyway, as it's only function is to retrieve the cable.
>
> I like this approach and seems the cheapest way to introduce high
> frequency winch operations in the USA. I wish Commercial Glider
> Operators would buy a single drum winch and a retrieve winch and offer
> this launch method. Even at 10-15 a launch - it's still heaps cheaper
> and the operator would probably make more money at the end of the day.
>
> Not to speak about the fact that winch launches a far and away more
> fun and exiting than aero tows.

Del C

November 29th 07, 04:23 AM

Bill,

At Lasham we still use vehicle retrieves and a 2 drum
main winch set up on days or evenings when demand for
winch launches is low, say when we are operating 5
gliders or less. Also the last launch of the day is
always done without the retrieve winch connected so
that we can wind the cable fully into the main winch.
Although I don't have a large data set, comparisions
between the last two launches of the day suggest that
we lose about 80 feet off a typical 1600 ft launch
due to the retrieve winch, which is 5%. This is using
steel cables on both winches. We have used an all synthetic
cable set up in the past when the losses were almost
negligible. Only problem was that the small diameter
synthetic cable on the retrieve winch wore out within
6 weeks due to ground abrasion!

I can't see that there should be any realistic limits
on the length of retrieve cable, as long as you can
keep it light - see UHMWPE cable below. However sideways
drift in a crosswind needs to be a consideration. You
may need a very wide as well as a very long airfield.
The retrieve cables we use are about half the diameter
of the main cables, so only weigh a quarter of the
amount for a given length. The back pull may initiate
a slightly earlier back release,

Our retrieve winch is fitted with a 1.9 litre industrial
VW engine developing about 90 hp, and even that labours
a bit during the retrieve (even with synthetic cables)
so the starter motor idea, if you will excuse the pun,
is a non-starter!

UHMWPE cable, such as Spectra, Plasma or Dyneema (trade
names) is pretty amazing stuff. It looks like washing
line, but is stronger than steel whilst being 10 times
lighter. Unfortunately it is also about five times
more expensive than the equivalent steel cable and
requires modifications to the winch. For the lengths
of winch run we use, normally about 4200ft, it wasn't
found to give that much improvement in height, less
than 100ft, and was deemed by our Committee not to
be cost effective. It would certainly come into its
own on 5000 feet or longer runs, when steel cable starts
to become significantly heavy.

Del Copeland

At 23:12 28 November 2007, Bill Daniels wrote:
>It could be you're right but I'd still like to see
>an actual comparison with
>and without the retrieve winch at longer and longer
>distances. Some
>validated metrics would help sell the idea. It has
>yet to be determined
>just how long ropes can be with a retrieve winch.
>
>What I'm worried about isn't the weight of Dyneema/Spectra
>ropes it's the
>pull angle at the hook. If the retrieve rope drags
>back enough to change
>that angle it will adversely affect the height achieved.
>
>I know an engineer who was working on a simple 'spinner
>reel' type design
>for a retrieve winch that would use 1 or 1.5mm Dyneema.
> Calculations showed
>that the power required is minimal - you could power
>it with a small car
>starter motor and a battery. 2000 meters of thin Dyneema
>would fit on a
>drum not much bigger than a coffee can. With the 'spinner
>reel' concept
>Dyneema would pay off the retrieve winch with no rotation
>of the tiny drum.
>
>On the bright side, using a retrieve winch would cut
>the fuel use by half.
>
>Bill Daniels
>
>
>'tommytoyz' wrote in message
.
>>com...
>> Back in Germany we used two twin drum Tost winches
>>on our field and
>> launched all day long back to back, as long as there
>>were planes
>> needing to be launched. Wires were retrieved with
>>a retrieve vehicle,
>> two at a time.
>>
>> I think the British method of using a single drum
>>winch in combination
>> with a retrieve winch to be a very sensible idea -
>>even for long
>> fields and high launches.
>>
>> The cable is being retrieved before it even hits the
>>ground. So the
>> retrieve process is shorter and faster than using
>>a retrieve vehicle
>> by dragging the entire cable length along the ground.
>>The winch
>> retrieve should there for also save on wear and tear
>>on the cable as
>> most of th retrieve occurs in the air after the glider
>>releases.
>>
>> On very high tows, a long portion of the cable is
>>never wound up into
>> the tow drum and there for a high altitude launch
>>should actually
>> reduce the cable retrieve process using a cable retrieve
>>winch. The
>> light weight of the newer cables makes a launch penalty
>>negligible.
>> The retrieve cable need not be very strong or even
>>in good shape
>> anyway, as it's only function is to retrieve the cable.
>>
>> I like this approach and seems the cheapest way to
>>introduce high
>> frequency winch operations in the USA. I wish Commercial
>>Glider
>> Operators would buy a single drum winch and a retrieve
>>winch and offer
>> this launch method. Even at 10-15 a launch - it's
>>still heaps cheaper
>> and the operator would probably make more money at
>>the end of the day.
>>
>> Not to speak about the fact that winch launches a
>>far and away more
>> fun and exiting than aero tows.
>
>
>

Dan G

November 29th 07, 09:29 AM

On Nov 29, 4:23 am, Del C >
wrote:
> UHMWPE cable, such as Spectra, Plasma or Dyneema (trade
> names) is pretty amazing stuff. It looks like washing
> line, but is stronger than steel whilst being 10 times
> lighter. Unfortunately it is also about five times
> more expensive than the equivalent steel cable and
> requires modifications to the winch. For the lengths
> of winch run we use, normally about 4200ft, it wasn't
> found to give that much improvement in height, less
> than 100ft, and was deemed by our Committee not to
> be cost effective. It would certainly come into its
> own on 5000 feet or longer runs, when steel cable starts
> to become significantly heavy.

From a winch driver's point of view, I've always thought that the most
appealing aspect of UHMWPE is it's pleasant handling - it's light,
doesn't "ping back" if released under tension (which can be disastrous
with steel), and doesn't cut your hands, and you can use much smaller,
cheaper and more fuel-efficient retrieve vehicles. On the other hand,
from the reports I've heard, the winch needs to be set up *perfectly*
or the expensive cable can be ruined in one launch. It's also a
_little_ trickier to repair when it does break, though nothing that
proper training can't handle.

The main issues with UHMWPE seem to be two-fold: the initial cost of
modifying a winch to use the cable, and the lifetime vs. cost ratio.
Right now, UHMWPE doesn't seem to last as many times longer than
steel, as as many times it costs to buy versus steel.

Dan

[email protected]

November 29th 07, 02:53 PM

On 28 Nov., 22:15, Dan G > wrote:
> On Nov 28, 6:22 pm, "Sönke Gutzlaff" > wrote:
>
> > 950m steel cable + 350hp winch + 20km/h wind + ASK21 = 750m or 78%.
> > More high was possible, but airspace class C begins at 750m above our
> > airfield so I had to release the cable.
>
> > I think the ASK21 gets the best high on winchlaunch. Our DG1000 always gets
> > 25% less high.
>
> > Greetings,
> > Sönke
>
> Sönke, what speed do you fly at on the winch, and how much back
> pressure do you apply to the stick?
>
> Dan

We broke this record with 1718 Meter and a 3030 Meter runway (winch
length)
With NO wind condition. (sometimes even tailwind)
In the spring we do some more attempts for a higher record.
Then we wait for better wind/weather conditions.
We had a Notam and a privat airspace till FL70 for the lost month. on
our next attempts we hope to disconnect the cable at FL70

A winch start to 1718 Meter or a higher has some problems to overcome.
Think about wind directions at higher altitudes sometimes 180 degrees
different from ground wind.
Think about the cloud base. in most of the attempts we had to abort
the winchstart halfway due the lower cloudbase.
What happens if the cable brakes at high altitudes?

The winchstart itself takes about 2 min 20 sec. then you still have
about one minute to winch up the rest off the cable.
driving the cable back to the start position, takes about ten minutes,
so a high production would be difficult.

We had a Notam and a privat airspace till FL70 for the lost month. on
the next attempt

Bill Daniels

November 29th 07, 02:57 PM

"Del C" > wrote in message
...
> Bill,
>
> At Lasham we still use vehicle retrieves and a 2 drum
> main winch set up on days or evenings when demand for
> winch launches is low, say when we are operating 5
> gliders or less. Also the last launch of the day is
> always done without the retrieve winch connected so
> that we can wind the cable fully into the main winch.
> Although I don't have a large data set, comparisions
> between the last two launches of the day suggest that
> we lose about 80 feet off a typical 1600 ft launch
> due to the retrieve winch, which is 5%. This is using
> steel cables on both winches. We have used an all synthetic
> cable set up in the past when the losses were almost
> negligible. Only problem was that the small diameter
> synthetic cable on the retrieve winch wore out within
> 6 weeks due to ground abrasion!
>
> I can't see that there should be any realistic limits
> on the length of retrieve cable, as long as you can
> keep it light - see UHMWPE cable below. However sideways
> drift in a crosswind needs to be a consideration. You
> may need a very wide as well as a very long airfield.
> The retrieve cables we use are about half the diameter
> of the main cables, so only weigh a quarter of the
> amount for a given length. The back pull may initiate
> a slightly earlier back release,
>
> Our retrieve winch is fitted with a 1.9 litre industrial
> VW engine developing about 90 hp, and even that labours
> a bit during the retrieve (even with synthetic cables)
> so the starter motor idea, if you will excuse the pun,
> is a non-starter!
>
> UHMWPE cable, such as Spectra, Plasma or Dyneema (trade
> names) is pretty amazing stuff. It looks like washing
> line, but is stronger than steel whilst being 10 times
> lighter. Unfortunately it is also about five times
> more expensive than the equivalent steel cable and
> requires modifications to the winch. For the lengths
> of winch run we use, normally about 4200ft, it wasn't
> found to give that much improvement in height, less
> than 100ft, and was deemed by our Committee not to
> be cost effective. It would certainly come into its
> own on 5000 feet or longer runs, when steel cable starts
> to become significantly heavy.
>
> Del Copeland

We actually tested the power required to retrieve Spectra and the starter
motor is way more powerful than needed. Not sure what your problem is at
Lasham.

The cost of Spectra is more like three times the cost of steel not 5 times -
I checked the prices this morning. It takes a LOT of power to pull steel
cable across an airfield - I can pull a mile of Spectra with one finger.

We need verifiable data from retrieve winches. Your tests at Lasham are not
verifiable since you did no controlled experiments.

Bill Daniels

Dan G

November 29th 07, 04:30 PM

On Nov 29, 2:57 pm, "Bill Daniels" <bildan@comcast-dot-net> wrote:
> We actually tested the power required to retrieve Spectra and the starter
> motor is way more powerful than needed. Not sure what your problem is at
> Lasham.

Derek will answer for himself, but I expect they retrieve against the
pay-out brake on the winch, as per normal operation. If you don't, the
drum will keep turning under its own momentum when the retrieve stops
and you'll get cable everywhere. Not good.

>
> The cost of Spectra is more like three times the cost of steel not 5 times -
> I checked the prices this morning. It takes a LOT of power to pull steel
> cable across an airfield - I can pull a mile of Spectra with one finger.
>
> We need verifiable data from retrieve winches. Your tests at Lasham are not
> verifiable since you did no controlled experiments.

Having been to Lasham myself and talked to people there (though not
yet witnessed the retrieve winch itself operating), I'm perfectly
satisfied that what Derek says about the performance of both UHMWPE
and retrieve winches is correct.

Dan

Bill Daniels

November 29th 07, 05:38 PM

"Dan G" > wrote in message
...
> On Nov 29, 2:57 pm, "Bill Daniels" <bildan@comcast-dot-net> wrote:
>> We actually tested the power required to retrieve Spectra and the starter
>> motor is way more powerful than needed. Not sure what your problem is at
>> Lasham.
>
> Derek will answer for himself, but I expect they retrieve against the
> pay-out brake on the winch, as per normal operation. If you don't, the
> drum will keep turning under its own momentum when the retrieve stops
> and you'll get cable everywhere. Not good.

Yes, they certainly pull against the heavy payout brake - they have to,
they're using steel cable. You have to keep steel under tension to prevent
tangles. Spectra/Dyneema doesn't need that tension.

Spectra/Dyneema doesn't ball up and tangle like steel so you use much
lighter braking force. In fact, with tension control used for braking, very
light reverse torque is more than enough to prevent problems so very, very
little force is needed to pull out a Spectra cable from a winch designed to
take advantage of Spectra/Dyneema.

To get all the benefits of Spectra/Dyneema, you have to not only modify the
winch, you have to change operational techniques. Just throwing it on an
old steel cable winch and using steel cable operating techniques is
guaranteed to fail - as it did at Lasham.
>
>>
>> The cost of Spectra is more like three times the cost of steel not 5
>> times -
>> I checked the prices this morning. It takes a LOT of power to pull steel
>> cable across an airfield - I can pull a mile of Spectra with one finger.
>>
>> We need verifiable data from retrieve winches. Your tests at Lasham are
>> not
>> verifiable since you did no controlled experiments.
>
> Having been to Lasham myself and talked to people there (though not
> yet witnessed the retrieve winch itself operating), I'm perfectly
> satisfied that what Derek says about the performance of both UHMWPE
> and retrieve winches is correct.
>

Derek says Dyneema doesn't work because it's too expensive, wears out faster
than steel and doesn't provide any aditional height. Evedence from many
other sites successfuly using Dyneema is to the contrary on all points. The
difference is that successful sites did their homework and made all the
neccessary changes.

Bill Daniels

Sönke Gutzlaff

November 29th 07, 08:13 PM

"Dan G" > schrieb im Newsbeitrag
...
>On Nov 28, 6:22 pm, "Sönke Gutzlaff" > wrote:
>> 950m steel cable + 350hp winch + 20km/h wind + ASK21 = 750m or 78%.
>> More high was possible, but airspace class C begins at 750m above our
>> airfield so I had to release the cable.
>>
>> I think the ASK21 gets the best high on winchlaunch. Our DG1000 always
>> gets
>> 25% less high.
>>
>> Greetings,
>> Sönke

>Sönke, what speed do you fly at on the winch, and how much back
>pressure do you apply to the stick?

Around 100km/h and the stick full pulled back (I know that's not the optimal
position).
Another helpfull fact is, that the wind is getting stronger when you get
higher so the plane is flying like a kite.
But there are only 1 or 2 days during the year when we have such perfect
wind. Normaly we are reaching around 500m with the 21.

Sönke

Dan G

November 29th 07, 08:35 PM

On Nov 29, 5:38 pm, "Bill Daniels" <bildan@comcast-dot-net> wrote:
> Yes, they certainly pull against the heavy payout brake - they have to,
> they're using steel cable. You have to keep steel under tension to prevent
> tangles. Spectra/Dyneema doesn't need that tension.

The pay-out brake is not to keep the line under tension, it's to stop
the drum when the retrieve stops, or the drum keeps turning and paying
out cable which forms great big loops hanging down from the drum. A
drum of UHMWPE will of course be much lighter than a steel one, but
the drum itself is heavy enough. If the brake is weak you have to tow
very slowly, which is frustrating.

> Derek says Dyneema doesn't work because it's too expensive, wears out faster
> than steel and doesn't provide any aditional height. Evedence from many
> other sites successfuly using Dyneema is to the contrary on all points. The
> difference is that successful sites did their homework and made all the
> neccessary changes.

Lasham isn't the only club that tried UHMWPE and abadonded it.
Pocklington tried it too - with a brand new Skylaunch winch - and also
abandoned it. Another club I know well is only using up their current
stock of it before reverting to steel. A number of sites had initially
very favourable results with UHMWPE but I've never seen any follow-up
results, which were promised by the BGA but have never materialised
(afaik).

Dan

Dan G

November 29th 07, 08:39 PM

On Nov 29, 8:13 pm, "Sönke Gutzlaff" > wrote:
> Around 100km/h and the stick full pulled back (I know that's not the optimal
> position)

Judging by your results that's optimal ;-). However at 54 knots and
full back stick you must have been fairly close to the stall. With the
K21's hook being pretty much on the CG point (unlike, say, a K13's
quite forwards hook) I'd worry about what happens on a cable break. If
you were really switched on I expect it would be fine but with a
moment's hesitation you could end up very nose-high without much
speed...

Dan

Sönke Gutzlaff

November 29th 07, 10:24 PM

>"Dan G" > schrieb im Newsbeitrag
...
>On Nov 29, 8:13 pm, "Sönke Gutzlaff" > wrote:
>> Around 100km/h and the stick full pulled back (I know that's not the
>> optimal
>> position)
>
>Judging by your results that's optimal ;-). However at 54 knots and
>full back stick you must have been fairly close to the stall. With the
>K21's hook being pretty much on the CG point (unlike, say, a K13's
>quite forwards hook) I'd worry about what happens on a cable break. If
>you were really switched on I expect it would be fine but with a
>moment's hesitation you could end up very nose-high without much
>speed...

I've learned that 100km/h is fast enough, our instructors even say 90km/h
ist the perfect speed for the 21 to gain maximun high.
I had lot of cable breaks this year and no problems with the speed. You've
only to react fast enough. And the 21 is a very friendly flying plane (with
our other planes, especially the ASW19 I prefer higher speeds on winch
launch) and you normaly are not pulling the stick full back before you reach
the safety high.

Del C

November 29th 07, 11:22 PM

Er, did you actually read what I wrote Bill? I said
that UHMWPE cable is good stuff, and becomes doubly
advantageous for retrieve winching, where you are pulling
two cables into the air, and for longer runs. It also
doesn't try to untwist when new, unlike stranded steel
cable, or kink like piano wire. As Dan G has pointed
out it is also safer to handle.

The main downside is cost, plus the fact that on short
runs cable weight is not much of an issue and you don't
get that much of a height advantage by using synthetic
cable. We had a period at Lasham when one of our winches
had synthetic cable on one drum and steel cable on
the other, so we were able to do direct comparisons
on alternate launches in the same conditions. As a
percentage of the cable run in still evening air, we
averaged about 38% for steel cable and 41% for synthetic.
For a 4000ft run this works out at 1520 ft for steel
and 1640ft for synthetic, so there was an advantage
of just over 100ft in using synthetic. Off course the
longer the run the greater the advantage would become,
but then how many clubs have a winch run of more than
5000 feet?

Lasham didn't just throw UHMWPE cable onto an existing
winch! We had a number of modifications done in preparation,
to prevent drum crushing and to smooth the rollers,
as recommended by Skylaunch. Our Retrieve winch came
fitted with some very light, orange coloured, synthetic
string, but as I have already said that lasted no time
at all. The one synthetic main cable we tried actually
lasted longer than a steel cable, giving 2500 launches
as compared with about 1900 launches, but this was
not enough to offset the extra cost. I should point
out that we normally launch across two 50 metre wide,
extremely abrasive and rough WW2 concrete runways,
so we suffer high cable wear rates at the best of times.
There is a plan to dig these runways up (when there
is a local building project going on and we can get
a good price for the hard core) and replace them with
smooth narrow tarmac strips for winter operations.
We may then reconsider synthetic winch cables.

The retrieve winch pulls the cable back at about 50mph.
If you don't provide some pay-out braking, not only
will the main winch drum probably over-run when you
stop pulling, but the cable has enough momentum that
it won't stop when you cut the throttle on the retrieve
winch and you pull the rings into the rollers. This
has happened to me on one occasion as a retrieve winch
driver when the main winch driver didn't apply enough
braking. The Skylaunch retrieve winch is powerful enough
to pull back any sort of cable over any reasonable
distance.

I have carried a number of comparison tests in the
last year which I have reported on the Yahoo Winch
Launching Group website. OK I couldn't measure as many
parameters as I would have liked, but they were generally
carried out on relatively still evenings (I instruct
on an evening group) with the same winch and winch
drivers and a small group of pilots, so they should
be fairly indicative. Sometimes I just asked other
pilots and instructors how high they getting under
various circumstances. When we were using the retrieve
winch (we still often vehicle retrieve in the evening)
the most interesting comparison was between the last
few launches and the very final one when we disconnect
the retrieve cable and launch normally, so the cable
can be drawn fully into the winch so we can put it
away. That is how I derived the approximate height
loss attributable to the retrieve winch. At least I'm
not just drawing computer generated curves on a graph,
derived from questionable mathematical models, unlike
certain contributors to the group who have little or
no practical experience of winch launching!

Del Copeland

At 17:42 29 November 2007, Bill Daniels wrote:
>
>'Dan G' wrote in message

>>.com...
>> On Nov 29, 2:57 pm, 'Bill Daniels' wrote:
>>> We actually tested the power required to retrieve
>>>Spectra and the starter
>>> motor is way more powerful than needed. Not sure
>>>what your problem is at
>>> Lasham.
>>
>> Derek will answer for himself, but I expect they retrieve
>>against the
>> pay-out brake on the winch, as per normal operation.
>>If you don't, the
>> drum will keep turning under its own momentum when
>>the retrieve stops
>> and you'll get cable everywhere. Not good.
>
>Yes, they certainly pull against the heavy payout brake
>- they have to,
>they're using steel cable. You have to keep steel
>under tension to prevent
>tangles. Spectra/Dyneema doesn't need that tension.
>
>Spectra/Dyneema doesn't ball up and tangle like steel
>so you use much
>lighter braking force. In fact, with tension control
>used for braking, very
>light reverse torque is more than enough to prevent
>problems so very, very
>little force is needed to pull out a Spectra cable
>from a winch designed to
>take advantage of Spectra/Dyneema.
>
>To get all the benefits of Spectra/Dyneema, you have
>to not only modify the
>winch, you have to change operational techniques.
>Just throwing it on an
>old steel cable winch and using steel cable operating
>techniques is
>guaranteed to fail - as it did at Lasham.
>>
>>>
>>> The cost of Spectra is more like three times the cost
>>>of steel not 5
>>> times -
>>> I checked the prices this morning. It takes a LOT
>>>of power to pull steel
>>> cable across an airfield - I can pull a mile of Spectra
>>>with one finger.
>>>
>>> We need verifiable data from retrieve winches. Your
>>>tests at Lasham are
>>> not
>>> verifiable since you did no controlled experiments.
>>
>> Having been to Lasham myself and talked to people
>>there (though not
>> yet witnessed the retrieve winch itself operating),
>>I'm perfectly
>> satisfied that what Derek says about the performance
>>of both UHMWPE
>> and retrieve winches is correct.
>>
>
>Derek says Dyneema doesn't work because it's too expensive,
>wears out faster
>than steel and doesn't provide any aditional height.
> Evedence from many
>other sites successfuly using Dyneema is to the contrary
>on all points. The
>difference is that successful sites did their homework
>and made all the
>neccessary changes.
>
>Bill Daniels
>
>
>
>
>

Bill Daniels

November 29th 07, 11:25 PM

"Dan G" > wrote in message
...
> On Nov 29, 5:38 pm, "Bill Daniels" <bildan@comcast-dot-net> wrote:
>> Yes, they certainly pull against the heavy payout brake - they have to,
>> they're using steel cable. You have to keep steel under tension to
>> prevent
>> tangles. Spectra/Dyneema doesn't need that tension.
>
> The pay-out brake is not to keep the line under tension, it's to stop
> the drum when the retrieve stops, or the drum keeps turning and paying
> out cable which forms great big loops hanging down from the drum. A
> drum of UHMWPE will of course be much lighter than a steel one, but
> the drum itself is heavy enough. If the brake is weak you have to tow
> very slowly, which is frustrating.

I bet it's frustrating. Why don't you re-engineer it so it works right.

You need to re-think tension. Steel needs to be kept under tension any time
you are moving it. If it is just laying in the grass, it's still under a
little tension due to friction with the grass.

If it takes 70hp to pull out the cable, you're using way too much brake.
Tension control winches use the hydraulic motor to provide light reverse
torque, not a brake. It takes very little reverse torque to prevent over
runs with UHMWPE.

>
>
>> Derek says Dyneema doesn't work because it's too expensive, wears out
>> faster
>> than steel and doesn't provide any aditional height. Evedence from many
>> other sites successfuly using Dyneema is to the contrary on all points.
>> The
>> difference is that successful sites did their homework and made all the
>> neccessary changes.
>
> Lasham isn't the only club that tried UHMWPE and abadonded it.
> Pocklington tried it too - with a brand new Skylaunch winch - and also
> abandoned it. Another club I know well is only using up their current
> stock of it before reverting to steel. A number of sites had initially
> very favourable results with UHMWPE but I've never seen any follow-up
> results, which were promised by the BGA but have never materialised
> (afaik).
>

The start of this thread was about some very talented folkes in Belgium who
set a release height record using UHMWPE on a winch designed for it. UHMWPE
is a spectacular success as a winch rope. It beats steel on all counts
including wear and life. In fact it lasts long enough to actually be
cheaper than steel on a per launch basis. BUT, you have to understand it
AND you winch has to be designed for it.

Skylaunch is a great steel cable winch. However, it would need a lot of
modifications to make it a successful UHMWPE winch. I sincerely hope they
do this since it would be easier than trying to convince the world that
UHMWPE doesn't work.

UHMWPE has never failed anyone but some people trying to use it have failed
to use it properly. If you want to know how to use it right, talk to the
people who succeeded not the ones who failed. Make a call to Belgium.

Bill Daniels

Bill Daniels

November 29th 07, 11:32 PM

"Del C" > wrote in message
...
> Er, did you actually read what I wrote Bill?

No. I usually don't since I've found it's mostly BS.

Del C

November 29th 07, 11:34 PM

The K21 seems to climb as well as anything on a winch
launch, despite being a bit big and heavy. Probably
only a K8 will beat it.

We have a couple of DG1000s and they don't climb quite
as well. If you pull the stick well back, a sort of
pitching motion seems to set in as though the elevator
is stalling.

Del Copeland

At 21:18 28 November 2007, Dan G wrote:
>On Nov 28, 6:22 pm, 'S=F6nke Gutzlaff' wrote:
>> 950m steel cable + 350hp winch + 20km/h wind + ASK21
>>=3D 750m or 78%.
>> More high was possible, but airspace class C begins
>>at 750m above our
>> airfield so I had to release the cable.
>>
>> I think the ASK21 gets the best high on winchlaunch.
>>Our DG1000 always get=
>s
>> 25% less high.
>>
>> Greetings,
>> S=F6nke
>
>S=F6nke, what speed do you fly at on the winch, and
>how much back
>pressure do you apply to the stick?
>
>
>Dan
>

Dan G

November 30th 07, 12:17 AM

On Nov 29, 10:24 pm, "Sönke Gutzlaff" > wrote:
> I've learned that 100km/h is fast enough, our instructors even say 90km/h
> ist the perfect speed for the 21 to gain maximun high.
> I had lot of cable breaks this year and no problems with the speed. You've
> only to react fast enough. And the 21 is a very friendly flying plane (with
> our other planes, especially the ASW19 I prefer higher speeds on winch
> launch) and you normaly are not pulling the stick full back before you reach
> the safety high.

What do your instructors say about using back-stick in the K21?

I just did my annual winch-launch checks and mine wouldn't let me use
any back-stick at all. A K21 will still launch perfectly well like
that but I *know* that I'm not getting the best out the launch like
that. On the other hand my instructor did play a neat trick on me - he
distracted me by suddening say "look at that plane!" and pulling the
release at the same time. I *did* hesitate in getting the nose down
and even though it was only a small delay by the time I'd finished the
push-over to the recovery attitude there was only 40 knots on the
clock. Took a fair few seconds to get the speed back up before braking
down to a straight-ahead landing.

That was a bit of an eye-opener, to be honest.

Dan

Dan G

November 30th 07, 12:22 AM

On Nov 29, 11:34 pm, Del C
> wrote:
> The K21 seems to climb as well as anything on a winch
> launch, despite being a bit big and heavy. Probably
> only a K8 will beat it.

I agree although last weekend it was so windy the K8 was just getting
blown about all over the place and in the hands of several pilots,
including our DCFI, was only getting 1,500', compared to 1,900-2,000'
for the K21 (assuming the weak link didn't break on the way up). In
calmer conditions the 8 usually has the edge.

What does Lasham teach on stick position for the 21 during launch?

> We have a couple of DG1000s and they don't climb quite
> as well. If you pull the stick well back, a sort of
> pitching motion seems to set in as though the elevator
> is stalling.

I had that in a K13 once - it's definitely the tailplane stalling.
Quite an interesting experience.

Dan

Bert Willing[_2_]

November 30th 07, 08:54 AM

Well, if you have the stick fully back (which I often have, and don't object
to with my students), you
1) are above safety altitude
2) pay attention.

Bert

"Dan G" > wrote in message
...
On Nov 29, 10:24 pm, "Sönke Gutzlaff" > wrote:
> I've learned that 100km/h is fast enough, our instructors even say 90km/h
> ist the perfect speed for the 21 to gain maximun high.
> I had lot of cable breaks this year and no problems with the speed. You've
> only to react fast enough. And the 21 is a very friendly flying plane
> (with
> our other planes, especially the ASW19 I prefer higher speeds on winch
> launch) and you normaly are not pulling the stick full back before you
> reach
> the safety high.

What do your instructors say about using back-stick in the K21?

I just did my annual winch-launch checks and mine wouldn't let me use
any back-stick at all. A K21 will still launch perfectly well like
that but I *know* that I'm not getting the best out the launch like
that. On the other hand my instructor did play a neat trick on me - he
distracted me by suddening say "look at that plane!" and pulling the
release at the same time. I *did* hesitate in getting the nose down
and even though it was only a small delay by the time I'd finished the
push-over to the recovery attitude there was only 40 knots on the
clock. Took a fair few seconds to get the speed back up before braking
down to a straight-ahead landing.

That was a bit of an eye-opener, to be honest.

Dan

Peter Hermann

November 30th 07, 09:18 AM

"S??nke Gutzlaff" > wrote:
>
> >"Dan G" > schrieb im Newsbeitrag
> >moment's hesitation you could end up very nose-high without much
> >speed...

best precondition to safely fly a hammerhead while actively releasing
remainder of cable since you certainly strictly adhered to:

> launch) and you normaly are not pulling the stick full back before you reach
> the safety high.

http://en.wikipedia.org/wiki/Aerobatic_maneuver

John Smith

November 30th 07, 11:05 AM

Dan G wrote:

> What do your instructors say about using back-stick in the K21?

The same as in any other glider: Use as needed to keep your target speed.

Dan G

November 30th 07, 03:40 PM

On Nov 30, 11:05 am, John Smith > wrote:
> Dan G wrote:
> > What do your instructors say about using back-stick in the K21?
>
> The same as in any other glider: Use as needed to keep your target speed.

That's what I think but I put this specifically to the full cat* I was
flying with and he disagreed, saying "you'll risk spinning on the
wire" if you use "any" back stick in the K21, and that you should ride
the speed with the elevator neutral throughout the launch until you
need to wave-off (signal the winch driver to slow down by waggling the
tail).

< shrugs >.

Dan

*in the UK there are three categories of instructor: "full" is the
highest, the others being "basic" and "half"

Andreas Maurer

November 30th 07, 06:21 PM

On Fri, 30 Nov 2007 09:54:16 +0100, "Bert Willing"
> wrote:

>Well, if you have the stick fully back (which I often have, and don't object
>to with my students), you
>1) are above safety altitude
>2) pay attention.

- already have a significant nose-down force by cable tension because
of your height

Bye
Andreas

Del C

December 1st 07, 09:04 AM

At Lasham for the K21 we teach holding the stick about
two-thirds of the way forward for the ground run and
safety climb and then easing back to give the correct
climb angle with the wingtips about 45 degrees to the
horizon. You don't have to pull back quite so hard
to achieve this as you do in our K13 basic trainers,
and you shouldn't be right on the back stop.

Incidentally the K21 will do a perfectly acceptable
(although not optimal) winch launch if you just hold
the stick in the centre of the elevator range and leave
it there throughout the launch. It is probably the
easiest and safest glider to winch launch there is,
with a very wide speed range (anywhere between 50 and
81 knots will do), and very benign stalling characteristics.

Del Copeland

At 00:24 30 November 2007, Dan G wrote:
>On Nov 29, 11:34 pm, Del C
> wrote:
>> The K21 seems to climb as well as anything on a winch
>> launch, despite being a bit big and heavy. Probably
>> only a K8 will beat it.
>
>I agree although last weekend it was so windy the K8
>was just getting
>blown about all over the place and in the hands of
>several pilots,
>including our DCFI, was only getting 1,500', compared
>to 1,900-2,000'
>for the K21 (assuming the weak link didn't break on
>the way up). In
>calmer conditions the 8 usually has the edge.
>
>What does Lasham teach on stick position for the 21
>during launch?
>
>> We have a couple of DG1000s and they don't climb quite
>> as well. If you pull the stick well back, a sort of
>> pitching motion seems to set in as though the elevator
>> is stalling.
>
>I had that in a K13 once - it's definitely the tailplane
>stalling.
>Quite an interesting experience.
>
>
>Dan
>

John Smith

December 1st 07, 10:52 AM

Del C wrote:

> At Lasham for the K21 we teach holding the stick about
> two-thirds of the way forward for the ground run and
> safety climb and then easing back to give the correct
> climb angle with the wingtips about 45 degrees to the
....

I consider this mechanical approach completely wrong.

On the ground run, use the stick as needed to keep the glider on the
ground. (This may or may not be 2/3 forward.) (Personally, I start with
the stick fully forward and then ease it slowly back until the glider
begins to fly. I have no idea at which stick position this happens.)

On initial climb, use the stick as needed to do a smooth transition, and
watch your speed.

On climb, use the stick as needed to keep your target speed. (If this
means neutral or at the back stop, so be it.)

Your target speed dictates the climb angle, and this may or may not be
45 dgrees, depending on the winch and the glider and probably a lot of
other things.

If you teach a mechanical apporach, then you are going to be in big
trouble if sometimes you happen to fly at a different location.

Del C

December 1st 07, 12:07 PM

John,

With the Tost winches we use at Lasham, the pilot has
no control over the speed, unlike the torque or tension
controlled Supacat or MEL winches. Nethertheless he
is still expected to monitor the airspeed, especially
during the safety climb, and not to initiate the rotation
until it is adequate. After that we expect him to hold
a steady attitude and allow the winch driver to control
the speed and power. If the airspeed gets too high
the pilot signals to the winch driver by waggling the
tail with the rudder. If it gets too slow, he lowers
the nose slightly to reduce the risk of stalling and
also to signal to the driver that more power is required.
The pilot could also of course be a she.

The original question from Dan G was what do we teach
at Lasham, where we have very powerful winches (as
does his own club). You may have to climb more gently
with less powerful winches. The point you make is a
good one.

Del Copeland

At 10:54 01 December 2007, John Smith wrote:
>Del C wrote:
>
>> At Lasham for the K21 we teach holding the stick about
>> two-thirds of the way forward for the ground run and
>> safety climb and then easing back to give the correct
>> climb angle with the wingtips about 45 degrees to
>>the
>....
>
>I consider this mechanical approach completely wrong.
>
>On the ground run, use the stick as needed to keep
>the glider on the
>ground. (This may or may not be 2/3 forward.) (Personally,
>I start with
>the stick fully forward and then ease it slowly back
>until the glider
>begins to fly. I have no idea at which stick position
>this happens.)
>
>On initial climb, use the stick as needed to do a smooth
>transition, and
>watch your speed.
>
>On climb, use the stick as needed to keep your target
>speed. (If this
>means neutral or at the back stop, so be it.)
>
>Your target speed dictates the climb angle, and this
>may or may not be
>45 dgrees, depending on the winch and the glider and
>probably a lot of
>other things.
>
>If you teach a mechanical apporach, then you are going
>to be in big
>trouble if sometimes you happen to fly at a different
>location.
>

Martin Gregorie[_1_]

December 1st 07, 07:20 PM

Del C wrote:
> John,
>
> With the Tost winches we use at Lasham, the pilot has
> no control over the speed, unlike the torque or tension
> controlled Supacat or MEL winches.
>
Exactly the same applies to a V-8 diesel Supacat with its high torque
output - an Ash-25 might control the winch speed but a K-21 has no chance.

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

John Smith

December 1st 07, 08:19 PM

Del C wrote:

> With the Tost winches we use at Lasham, the pilot has
> no control over the speed,

We have a Tost winch, too, and the pilot has definitely some degree of
control over the speed. The winch driver gives the tension depending on
how much the pilots pulls. But then the winch driver holds that tension
and the pilot makes the fine adjustments. No way a winch driver could
adjust precisely and quickly enough.

It's like a dialogue between the winch driver and the pilot. It requires
a certain experience and feeling from both to yield good results.

But having winched at many sites, I know that there are huge differences
among the "winch cultures". A pilot must be able to immediately feel how
he is winched and to adopt accordingly.

Bill Daniels

December 1st 07, 09:08 PM

"John Smith" > wrote in message
...
> Del C wrote:
>
>> With the Tost winches we use at Lasham, the pilot has
>> no control over the speed,
>
> We have a Tost winch, too, and the pilot has definitely some degree of
> control over the speed. The winch driver gives the tension depending on
> how much the pilots pulls. But then the winch driver holds that tension
> and the pilot makes the fine adjustments. No way a winch driver could
> adjust precisely and quickly enough.
>
> It's like a dialogue between the winch driver and the pilot. It requires a
> certain experience and feeling from both to yield good results.
>
> But having winched at many sites, I know that there are huge differences
> among the "winch cultures". A pilot must be able to immediately feel how
> he is winched and to adopt accordingly.

Winch culltures and varying winch driver techniques is one reason computer
controlled cable tension is such a good idea. It puts the airspeed control
firmly in the hands of the pilot. You get a near perfect launch every time
in every glider pretty much regardless of conditions.

Bill Daniels

Del C

December 1st 07, 10:44 PM

You don't say what engine you have in your Tost winch
John, but ours are fitted with powerful 8.2 litre,
410hp Chevy marine engines. Except for the very heaviest
two seater gliders, pulling back harder on the stick
will not reduce the airspeed and may even have the
opposite effect due to increasing the vertical speed
vector - the so called 'water skier' effect. Easing
the stick forward may momentarily reduce the speed
for the same reason (reduces the vertical speed component)
but will signal to the driver that more power is required
so you will still speed up again! The only way to slow
down if the launch gets too fast is to signal to the
winch driver by wagging the tail with the rudder.
Having said all that, we have very well trained winch
drivers who nearly always provide correctly speeded
launches.

I have launched on a number of low powered, 'torque
controlled' diesel engined winches where speed is supposed
to be controllable from the glider end, but I wonder
if this is just because pulling back harder slows the
winch engine down and easing forward allows it to speed
up again? These winches seem to become less easily
controllable by the glider when re-fitted with more
powerful engines, as has been confirmed by another
correspondent.

Maybe the answer is to provide just the right amount
of power to launch the specific glider type in the
prevailing wind conditions. In this respect throttle
tabs as found on the latest Skylaunch winches may be
the KISS (Keep It Simple Stupid) way to go, rather
than very expensive and complicated tension controlled
diesel-hydraulic or electric winches.

Del Copeland

At 20:24 01 December 2007, John Smith wrote:
>Del C wrote:
>
>> With the Tost winches we use at Lasham, the pilot
>>has
>> no control over the speed,
>
>We have a Tost winch, too, and the pilot has definitely
>some degree of
>control over the speed. The winch driver gives the
>tension depending on
>how much the pilots pulls. But then the winch driver
>holds that tension
>and the pilot makes the fine adjustments. No way a
>winch driver could
>adjust precisely and quickly enough.
>
>It's like a dialogue between the winch driver and the
>pilot. It requires
>a certain experience and feeling from both to yield
>good results.
>
>But having winched at many sites, I know that there
>are huge differences
>among the 'winch cultures'. A pilot must be able to
>immediately feel how
>he is winched and to adopt accordingly.
>