New winch height record

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

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

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

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

"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

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

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

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

"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

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