Record height for a winch launch?

On Monday, 5 March 2001 00:00:08 UTC, MHende6388 wrote:
Curious what the highest sailplane launch from a winch has ever been for the
longest cable.

Michael

My personal record is 3,400' in a T-21 at Feltwell back in the mid-1960s using a barrage balloon winch but that was kiting and we hung on until there was no cable left on the drum. There was a huge bow in the cable apparently.
Best straight launch is about 2,300'.

At 19:35 14 April 2020, wrote:
On Monday, 5 March 2001 00:00:08 UTC, MHende6388 wrote:
Curious what the highest sailplane launch from a winch has ever
been for
the
longest cable.

Michael

My personal record is 3,400' in a T-21 at Feltwell back in the mid-
1960s
using a barrage balloon winch but that was kiting and we hung on
until
there was no cable left on the drum. There was a huge bow in the
cable
apparently.
Best straight launch is about 2,300'.

Probably not the best idea in the world. If using 4mm steel cable the
weight of that amount of cable would be around 1400lbs. 5mm cable
would be 2180lbs, pretty close to a ton. That is all supported by the
frame to which the release is mounted, and of course the wing roots. If
the T21 had a GoG hook it is bolted to the frame which supports the
seat. The things we did when we were young and stupid.

At 21:15 14 April 2020, Don Johnstone wrote:
At 19:35 14 April 2020, wrote:
On Monday, 5 March 2001 00:00:08 UTC, MHende6388 wrote:
Curious what the highest sailplane launch from a winch has ever
been for
the
longest cable.

Michael

My personal record is 3,400' in a T-21 at Feltwell back in the mid-
1960s
using a barrage balloon winch but that was kiting and we hung on
until
there was no cable left on the drum. There was a huge bow in the
cable
apparently.
Best straight launch is about 2,300'.

Probably not the best idea in the world. If using 4mm steel cable the
weight of that amount of cable would be around 1400lbs. 5mm cable
would be 2180lbs, pretty close to a ton. That is all supported by the
frame to which the release is mounted, and of course the wing roots. If
the T21 had a GoG hook it is bolted to the frame which supports the
seat. The things we did when we were young and stupid.

Only because our elders let us and even encouraged us by word and
example!

Incidentally, with a 1000lb weak link, which was the norm in those days,
why
did it not break with 2000+lbs of cable suspended?

On Tue, 14 Apr 2020 21:15:58 +0000, Don Johnstone wrote:

Probably not the best idea in the world. If using 4mm steel cable the
weight of that amount of cable would be around 1400lbs. 5mm cable would
be 2180lbs, pretty close to a ton. That is all supported by the frame to
which the release is mounted, and of course the wing roots. If the T21
had a GoG hook it is bolted to the frame which supports the seat. The
things we did when we were young and stupid.

There used to be a couple of videos on YouTube of an MDM Fox being
winched to 1500m and then doing aerobatics all the way down, but it seems
to have vanished. Took around 2.5 minutes on the winch to get to the top.

One of the videos was shot from the back seat in the Fox and the other
watched the reel on the Tost winch as it steadily filled right up.

IIRC this was connected with an aerobatic comp somewhere in Germany.


--
Martin | martin at
Gregorie | gregorie dot org

The Utah Soaring Association built a pretty amazing winch that was designed to handle up to 9000' of winch rope! Yes, we spent a lot of energy on designing the drum to withstand the crazy crushing forces. We have only tried up to 7000' of rope so far but we were getting some pretty great high launches. Here is a fun video showing what it is like getting high on a winch launch at Nephi:

https://youtu.be/VrUTjWEfbcI

Cheers!
Bruno - B4

That was in Fürstenfeldbrug near Munich on a military runway with 10'000 ft of Spectra rope.

On Tuesday, April 14, 2020 at 3:30:05 PM UTC-6, Don Johnstone wrote:
At 19:35 14 April 2020, wrote:
On Monday, 5 March 2001 00:00:08 UTC, MHende6388 wrote:
Curious what the highest sailplane launch from a winch has ever
been for
the
longest cable.

Michael

My personal record is 3,400' in a T-21 at Feltwell back in the mid-
1960s
using a barrage balloon winch but that was kiting and we hung on
until
there was no cable left on the drum. There was a huge bow in the
cable
apparently.
Best straight launch is about 2,300'.

Probably not the best idea in the world. If using 4mm steel cable the
weight of that amount of cable would be around 1400lbs. 5mm cable
would be 2180lbs, pretty close to a ton. That is all supported by the
frame to which the release is mounted, and of course the wing roots. If
the T21 had a GoG hook it is bolted to the frame which supports the
seat. The things we did when we were young and stupid.

Don,

I think your napkin calcs need another go. 3/16" (4.75mm) 7/7 galvanized steel wire rope weighs 6.1lbs/100ft. We used 5400ft on our winch run. That weighed 330lbs. We now use 3/16" Amsteel Blue, which weighs 54lbs. So, a glider at our site on a 2000ft launch would be lifting about 125lbs of steel wire rope, plus few pounds of strop and parachute.

4mm-5mm steel would weight a bit more or less, but nothing like what you've calculated. Something got inverted in your calcs.

Frank Whiteley

New people always ask about release altitudes. The more relevant question is the rate of launches. We learn to fly and gain proficiency through repetition, we gain altitude in thermals. Ever ask the guy doing pattern work in a 172 how high he got?

On Thursday, April 16, 2020 at 5:27:22 PM UTC-4, wrote:
New people always ask about release altitudes. The more relevant question is the rate of launches. We learn to fly and gain proficiency through repetition, we gain altitude in thermals. Ever ask the guy doing pattern work in a 172 how high he got?

Right on, Doug!
Another question I get from just about everyone who learns that there are hardly any single drum winches in Europe but most of them have two or even up to six drums: Wow - isn't that a bit close to launch that many gliders so close to each other? [insert the sound the little birdie makes when it comes out of the clock here]

Uli
'AS'

On Fri, 17 Apr 2020 06:14:28 -0700, AS wrote:

On Thursday, April 16, 2020 at 5:27:22 PM UTC-4,
wrote:
New people always ask about release altitudes. The more relevant
question is the rate of launches. We learn to fly and gain proficiency
through repetition, we gain altitude in thermals. Ever ask the guy
doing pattern work in a 172 how high he got?

Right on, Doug!
Another question I get from just about everyone who learns that there
are hardly any single drum winches in Europe but most of them have two
or even up to six drums: Wow - isn't that a bit close to launch that
many gliders so close to each other? [insert the sound the little birdie
makes when it comes out of the clock here]

OK, I'll bite:

My club does a lot of winching, usually off a 1km x 175m grass runway
that is fairly well aligned with the prevailing winds (04/22) and use a
two drum Skylaunch winch. Launches are generally to 1400ft but can be a
lot higher given a strong breeze with a good gradient. We have a grass
triangle of runways, but the other two runs are 16/34 and 09/27 are much
narrower and launch rates on them are a lot slower because landings block
those runways until the glider can be towed back to the launch point.

It is possible to get 18 launches an hour with this rig on 22 or 04, but
that needs a big crew. As well as a launch marshal and winch driver you
need:

- a dedicated driver in the Hilux cable truck, who'd chase the first
launch down the field and wait by the winch to bring both cables back.

- a couple of people with golf buggies getting landed gliders off
the landing area, which is behind and to one side of the launch point,
so landing rolls don't normally end up in front of the launch point.

- another one or two people keeping the launch queue moved up to the
launch points (one for each cable, on either side of the control
point table).

- an absence of instructors briefing students at the front of the
launch queue

I understand this setup and its limitations: back when we used a launch
list and I was a new solo, working on Bronze and Silver in the club's
Juniors, there was a gang of us in the same position, so periodically
we'd all get stuck in and push the launch rate, but no matter how we
tried, we never managed more than 18 launches per hour.

These days we use booked training slots and in consequence there just
aren't enough people around the launch point to push the launch rate much
above 10-12 launches/hour.

The London club had a four drum van Gelder winch and tried the same
tricks, but they told me that they also hit a barrier at 18 launches/
hour, probably because, back in the days of steel cable, they used a
tractor to fetch cables rather than the Hiluxes we use - I imagine that a
Hilux would have problems dragging four steel cables at once, especially
on damp or wet grass.


--
Martin | martin at
Gregorie | gregorie dot org