Winch Launch Extreme 5200 ft

Just to confirm what Bill writes, have a look at the
following link:

http://www.youtube.com/watch?v=-VlRd9-wxQI

You will see that the vario reads a steady 1500 metres/min
up for some time during the winch launch. That is over
4500 ft/min (or 45 knots) for those who can't think
in metric units. There are also some good aerobatics
on the way down in the Fox two-seater.

Derek Copeland

At 02:48 02 December 2006, Bill Daniels wrote:

A typical launch will have the glider climbing at
a 45 degree angle and 60
knots. That works out to a little over 42 knots vertical
speed. Of course,
that the peak climb rate. The average on a high launch
can be around 35
knots. The stresses are about the same as mild aerobatics.

There are a number of GPS logs on the web that show
rates of climb about the
same as these figures.

If you want to work out the stress for yourself, the
peak cable tension will
roughly equal the flying weight of the glider. The
cable pull vector will
start horizontal and swing down to 70 degrees during
the launch. At
approximately 70 degrees, the CG hook will automatically
'back-release' the
cable.

Serious fun.

Bill Daniels

Derek Copeland schrieb:

http://www.youtube.com/watch?v=-VlRd9-wxQI

You will see that the vario reads a steady 1500 metres/min

Actually, it reads 15 m/s.

Whoops, quite right Stefan, but then I'm used to instruments
calibrated in knots and feet. In that case the climb
rate will be 900 metres/minute or just under 3000ft/minute
(30 knots).

Most UK varios stop at 10 knots or 1000ft/min, so I
only know that that I'm normally climbing faster than
that for the majority of the winch launch.

At Lasham a 1500 ft winch launch takes about 35 seconds
including the ground run, so 3000 ft/min would be about
right with a sufficiently powerful winch.

Derek Copeland


At 15:06 02 December 2006, Stefan wrote:
Derek Copeland schrieb:

http://www.youtube.com/watch?v=-VlRd9-wxQI

You will see that the vario reads a steady 1500 metres/min

Actually, it reads 15 m/s.

Derek Copeland schrieb:

At Lasham a 1500 ft winch launch takes about 35 seconds
including the ground run, so 3000 ft/min would be about
right with a sufficiently powerful winch.

The video shows that the climb rate of 15m/s (around 3000ft/min, the
rule of thumb for the conversion is a factor 2 and a couple of zeros at
the right place) is reached only at an altitude of around 300m (=1000ft)
AGL. As the flight in the video was done with a Fox, I guess that the
climb was initiated extra carefully, but still. BTW, the Fox was flown
with a speed of around 145km/h (80 knots).

You'll find more infos he http://www.segelkunstflug.mediacluster.de/193

I hear that a winch is being prepared for a release height record attempt in
the US. The drum can hold more than 5Km of 3mm UHMWPE rope. It will be up
to the builders to announce this officially.

It's interesting to speculate about the maximum release height theoretically
possible. The limit is not the weight of the rope since UHMWPE is so light
nor the winch power since really large engines are available. The limiting
factor will be the aerodynamic drag on the rope.

There are always new high strength fibers being introduced which would allow
still thinner rope diameter. Given ATC clearances, it may be possible to
eventually winch a glider into Class A airspace. Very large kites have
reached 35,000 feet.

How about an unballasted open class glider and 10 Km of winch rope operating
from a remote desert dry lake?

Bill D

"Stefan" wrote in message
. ..
Derek Copeland schrieb:

At Lasham a 1500 ft winch launch takes about 35 seconds
including the ground run, so 3000 ft/min would be about
right with a sufficiently powerful winch.

The video shows that the climb rate of 15m/s (around 3000ft/min, the rule
of thumb for the conversion is a factor 2 and a couple of zeros at the
right place) is reached only at an altitude of around 300m (=1000ft) AGL.
As the flight in the video was done with a Fox, I guess that the climb was
initiated extra carefully, but still. BTW, the Fox was flown with a speed
of around 145km/h (80 knots).

You'll find more infos he http://www.segelkunstflug.mediacluster.de/193

Stefan wrote:
Derek Copeland schrieb:

http://www.youtube.com/watch?v=-VlRd9-wxQI

You will see that the vario reads a steady 1500 metres/min

Actually, it reads 15 m/s.

Which is approx 30 kt or 3,000 ft per minute

Bill Daniels wrote:

How about an unballasted open class glider and 10 Km of winch rope operating
from a remote desert dry lake?

Why waste the rope (or is it string at that diameter) by reeling it in.
Use auto tow. A new type of record for Boneville salt flats?

Andy

while there are no special forces for the glider
there are special requirements for the winch.
The drums have to withhold bigger forces due
to the flexibility of the plastic cable.

Some explanations and photos at this site:
http://www.sagach.ch/Deutsch/Windenstart.htm
for english translate it from german
http://translate.google.com/translat...language_tools
have fun
Swiss Chris



"Walter Kronester" wrote in message
...
Hi,
ever heared of winch launches up to 5200 ft (1590m)?
in the forum of www.segelflug.de I read the following. It might be of
interest for you
(short form translation):
During a glider acrobatic meeting in Fuerstenfeldbruck (Germany/Bavaria),
pilots from
Bavaria and Austria had the possibility to try a new launch method. Mostly
double
seaters were launched up to 5200 ft. (1590m). Acro pilots were
enthusiastic
after 29
launches, because they could fly their full program out of the winch after
an only
90 seconds lasting start.
This was made possible by the winch manufacturer Tost (Assling, Germany).
They supplied a specially modified winch. Karl Hoeck from
Friedberg/Germany
did the technical calculations and the design of the drum of the winch.
This drum had to withstand a pressure of 3 million lb (1400 metric tons)
from the 9842 ft
(3000m) of Dyneema rope with 0.18 inches diameter (4.5mm).
Organizing clubs were Bundeswehr Sportflieger Gemeinschaft
Fürstenfeldbruck
e.V.
and Akademische Fluggruppe München. Munich control was involved.

With headwinds between aprox. 6 and 11 knots (10 - 20 km/h) following
altitudes have been reached:
ASK 21 and ASK 13 double seated: 5216 ft (1590m)
FOX double seated: 4594 ft (1400m)
Mue 28 single seated: 3937 ft (1200m)

regards
Walter