Winch Launching

This has been discussed here many times, and if you search the archieves
you'll find plenty of material. Anyway, a short summary:

Pro:
- it is safe *if* done properly. Be sure to get thorough instruction by
experienced people.
- cheaper than aerotow
- "greener" than aerotow
- it is fun!

Con:
- it mixes poorly with power traffic (but it is doable if you have a
plan and everybody cooperates)
- boring for the winch driver
- needs more ground staff
- limited in height and distance, i.e. you can't tow to that thermal 10
miles away if there's none nearby

On Jan 4, 3:59 pm, John Smith wrote:
This has been discussed here many times, and if you search the archieves
you'll find plenty of material. Anyway, a short summary:

Pro:
- it is safe *if* done properly. Be sure to get thorough instruction by
experienced people.
- cheaper than aerotow
- "greener" than aerotow
- it is fun!

Con:
- it mixes poorly with power traffic (but it is doable if you have a
plan and everybody cooperates)
You only need the airspace over the airfield for less then a minute so
if you keep everybody advised on CTAF, there's no real problem. Pull
the rope out on the grass between the asphalt and the runway edge
lights where it's out of everyone's way. Many winch groups operate
from fairly busy single runway public airports.

- boring for the winch driver
Well, it's fun for me.

- needs more ground staff
You do need a wing runner with a CG hook, but otherwise, it's the same
number of people as aero tow (either the wing runner or winch driver
can pull out the rope) - of course, you can use more people with a
winch
..
- limited in height and distance, i.e. you can't tow to that thermal 10 miles away if there's none nearby
The practical reality is that you rarely actually know there is a
thermal 10 miles away. If there's lift around, you can find it with a
2000'AGL winch launch - if there's no lift around, why consider an
aero tow?

Bill Daniels

bildan wrote:

- limited in height and distance, i.e. you can't tow to that thermal 10 miles away if there's none nearby

The practical reality is that you rarely actually know there is a
thermal 10 miles away. If there's lift around, you can find it with a
2000'AGL winch launch - if there's no lift around, why consider an
aero tow?

This depends on the location. At our site, we seldom can reach a thermal
from the winch, and even on those rare days not reliably. So as much as
we'd like to use it for cross country launches (heck, it *is* cheaper
and more fun!), winch launches are pretty much limited to student
instruction.

On the other hand, we often *do* know that there's that thermal 10 miles
away. First, because it is always there, and second, because of the
forming cumulus. But between our site and that thermal, there are 10
miles of sink. Agreed, on most days there eventually will grow thermals
near the airfield, but only at noon, when those pilots who did a aerotow
have already 2 hours under their belt and are 100 miles away. Agreed,
you can fill that gap with a sustainer, but then, you can as well
aerotow. Most airports weren't planned by glider pilots!

I wonder if one of the new generation winches like the Hydrowinch with
a 4000ft launch would make a difference. Most winch operations I have
read about all end with a 2K+ launch which does not give you a lot of
time before starting a landing pattern. Just imagine a 4K launch
without any lift, it still ends up being a perfect training flight of
15-25 minutes. I really want to go out to Colorado and test out the
new prototype and see if it is for real. Too bad they cost so much $$$
$$.

flyingmr2 wrote:
I wonder if one of the new generation winches like the Hydrowinch with
a 4000ft launch would make a difference.

The limiting factor is not the winch, but the rope length which in turn
is related to the available runway length. A rough estimate is that the
height with no wind is about half the rope length.

Here's what you can do with a perfectly conventional tost winch and 3000
meters of spectra rope: http://www.youtube.com/watch?v=-VlRd9-wxQI (note
that the altimeter is in meters and the vario im m/s)

The limiting factor is not the winch, but the rope length which in turn
is related to the available runway length. A rough estimate is that the
height with no wind is about half the rope length.

Super cool video with an awesome launch. The hydrowinch site says
they have enough room on the spool for 10K of Spectra rope. I guess
if you have a 10k runway available,. you could get launched into
space! Well, not quite, but it would sure seem high compared to a
regular 2k launch.

flyingmr2 wrote:

if you have a 10k runway available,. you could get launched into
space! Well, not quite, but it would sure seem high compared to a
regular 2k launch.

Just be sure to publish a NOTAM. Nobody expects a winch rope above, say,
3000 feet AGL.

On Jan 5, 8:46 am, flyingmr2 wrote:
The limiting factor is not the winch, but the rope length which in turn
is related to the available runway length. A rough estimate is that the
height with no wind is about half the rope length.

Super cool video with an awesome launch. The hydrowinch site says
they have enough room on the spool for 10K of Spectra rope. I guess
if you have a 10k runway available,. you could get launched into
space! Well, not quite, but it would sure seem high compared to a
regular 2k launch.

The question of just how high a winch launch could go has come up
several times. There is a small group of extreme kite flyers who have
flown L/D ~4 kites up to 30,000 feet using the same Spectra rope used
by glider winches. That suggests that launching a glider to the floor
of Class A airspace would be possible given enough runway and wind. I
expect that someone will do that fairly soon.

If the glider can be launched into a 50 knot wind layer, a tension
controlled winch would automatically reverse the drum rotation
direction and pay out rope - the glider would in effect be a high L/D
kite. The possible release height would then depend on the length of
the rope, not the length of the runway.

Finding a long enough strip is exceedingly difficult in some parts of the
country.

At 23:59 04 January 2009, John Smith wrote:
This has been discussed here many times, and if you search the archieves

you'll find plenty of material. Anyway, a short summary:

Pro:
- it is safe *if* done properly. Be sure to get thorough instruction by
experienced people.
- cheaper than aerotow
- "greener" than aerotow
- it is fun!

Con:
- it mixes poorly with power traffic (but it is doable if you have a
plan and everybody cooperates)
- boring for the winch driver
- needs more ground staff
- limited in height and distance, i.e. you can't tow to that thermal 10

miles away if there's none nearby

On Jan 4, 9:00*pm, Nyal Williams wrote:
Finding a long enough strip is exceedingly difficult in some parts of the
country.

Spoken by one in a club that recently moved and purchased an airport.
But as I understand it your club apparently does have an option to
extend your length enough to adopt winching with some bartering.

A winch can be parked some distance from the end of the runway.
Overruns at municipal airports are usually at least 500ft. Runway
light of concern are usually easily removed for the day. Granted,
CCSC is rather short for 'performance' winching, and Red Stewart
airport (1.5miles distant), where the winch proponents did a
significant number of launches this past year is a bit longer, however
at that airfield there may be an opportunity to park the winch well
past the airfield boundary, an option that doesn't exist at the CCSC
site. Mixed operations are quite manageable, mostly it's
communications, communications, communications.

Thinking 'way outside the box', 16.1 miles distant is Wilmington Air
Park, owned by DHL, who is pulling out of the US market. Two runways,
(4250' separation), of 9000' and greater length but 150' wide. Opt
for the shorter one and share the airport with UPS or FEDEX or whoever
may want to serve Cincinnati from there. This may be a golden
opportunity, but it would take 5-day operations most of the season to
make it happen. Of course, Wilmington Air Park doesn't have the park-
like ambiance of CCSC's present site. To gain 1200 more feet at the
present site, CCSC would have to acquire land and close a road; two
big and expensive challenges. There appears to be some type of
easement or right of way to the south that might become a new road and
high tension lines to the far east beyond the houses that could
parallel new private lanes.

Winching is quite safe unless you simply must get everyone involved in
driving the winch. CCSC already has a team concept at work and
extending this to winching would seem trivial. The boring bit about
winch driving is waiting while some instructors and students are doing
ground school at the launch point. If the glider is ready when the
rope arrives, a single drum winch can keep up with a tow plane. A two-
drum winch will outrun any tow plane in terms of vertical feet per
day. Few, if any, tow ten miles to lift. Most club boards would put
high fees on twenty minute turn arounds in flat country. I think
that's more common in the mountain west where the tach hour charges
apply for long, high tows. Not clear from the web site about the
actual fees. There seems to be some discrepancies between the rate/
100ft on the web and the schedule and the hook up charge. This would
seem to need re-thinking for winching, that is, the ratio of hook-up
charge to launch charge.

Frank Whiteley