Winch Experts wanted

I think the difference isn't so much height gained, but back calculating
to horsepower based on a 1 "G" acceleration at the start of the launch.
I've flown off a Supacat and while it had good acceleration, it sure
didn't match up to the whopper of a winch that was built by the permian
soaring association. Talk about a zippy launch!

http://members.cox.net/tsample10/SpecialProjects.html

By the way, I think this "unified winch design" concept is a really
great move.



If you have a diesel driving through a fluid flywheel you don't need
that much power: we have a Supacat with a 245 hp Deutz V8 aircooled
industrial diesel and torque converter (no gearbox). This can launch
an ASH-25 or just about any Nimbus. With a 15 m glider, K-21 or Grob
you'd expect 1200-1400 ft on a 1000m run in calm conditions and over
2000 ft if its blowing a bit.

I'd agree with everything you've said about the specialised nature of
a glider winch, the heavy duty engineering and the costs.

--
martin@ : Martin Gregorie
gregorie : Harlow, UK
demon :
co : Zappa fan & glider pilot
uk :

See also: http://www.proximedia.com/local/neth...el/various.htm

Diederik

BTW: I have winched twin astirs, fully loaded, k-8's, T-21 tutor and
prefects with a 350 hp winch. No problem, it's just how you adjust the
throtle


Stefan wrote in message ...
Not exactly what you asked for, but take a look at

http://www.skylaunch.de/album/index.html

It's fun and it may give you some ideas.

Stefan

Yep, it's just not the same when you can match the displacement of an
entire European car engine with the displacement of just 2, maybe 3,
cylinders worth of an American big block motor......

tango4 wrote:

You have to remember folks that these are American horsepower units. About
2:1 is a good ratio against proper European horses!

:-)

Ian

"Kevin Neave" wrote in message
...

Bill,

I think you need to revisit your numbers.

Here at Nympsfield (UK) we have a Supacat winch with
a 250 horse Diesel that easily provides enough power
for the biggest gliders on site (DG505, DuoDT, Nimbus3DT)
(And pretty scary in a Libelle if the winch driver
is *over enthusiastic*)

The previous engine was 180 HP, this was a bit marginal
for the Heavy Glass, but more than enough for any single
seat

(We have a 1000m field & regularly get 1500', even
nil wind)

:-)

KN

At 15:36 19 March 2004, Bill Daniels wrote:

Mark, unfortunately, the physics of a winch launch
says that it takes about
1 kWh or 3,600,000 Joules to launch a glider. The
peak power demand places
yet another constraint on the minimum HP that must
be available. Those
numbers point to a 400 to 500 HP engine to be able
to provide launch service
to any glider in the existing fleet.

"Marc Ramsey" wrote in message
. com...
I think the difference is that Bill is considering operating at much
higher density altitudes. In the western US, there are many glider
operations where summer density altitudes are in the 8000+ foot range.

Marc

Actually, most of the newer and larger diesels are turbocharged and have
electronic controls, including absolute manifold pressure sensors,
electronically controlled fuel injectors, and turbos with waste gates.
These engines will typically make full rated horsepower and torque at
density altitudes above 10,000 feet.

Electronically controlled engines also leave open the possibility of
controlling the engine without the typical manual input to the foot or hand
throttle. The foot pedal in that big diesel behind you on the freeway only
has copper wires between the foot pedal and the engine's ECU (electronic
control unit). It should be quite possible for someone (like you, Marc) to
program such an engine to desired and optimized parameters during each part
of the launch for each type of glider, with perhaps a hand control to
override the automatic settings. The ECU's on the engines already have
cruise control and PTO functions built in, as well as logger functions,
fault logging, fail soft ability, etc. Big trucks today have as much
electronics as cars.
-Bob Korves

Bill Daniels wrote:

"Mark James Boyd" wrote in message

I'd love to see a winch design that uses a 100hp or less engine,
can be easily bolted on the back of an old pickup, and has engine
and parts that are low maintenance and (especially engine) easy
to acquire (either locally or via shipping).

Alternately, how about a "spare tire" that is really a winch drum.
a stable sturdy "jack" and some way to route the cable
to ensure it winds up nice.

Might not work (thoughts of side loads tipping my car
over come to mind!), but it sure is fun to play with the
thuoght!
--

Mark, unfortunately, the physics of a winch launch says that it takes about
1 kWh or 3,600,000 Joules to launch a glider. The peak power demand places

Hmmm...so all gliders are alike? A Gapa or Russia REQUIRES the
same HP as a ballasted LAK-12 or Nimbus 4? Something 400 pounds
vs. 1600 pounds? I know this isn't what you meant...

I read the Marske site and saw the (wt lbs) x (wing loading lbs) x .03 = hp
and it looked like these mini gliders "needed" about 100 hp.

yet another constraint on the minimum HP that must be available. Those
numbers point to a 400 to 500 HP engine to be able to provide launch service
to any glider in the existing fleet. Although the initial cost of a well
engineered winch is high (nearly as much as a tow plane) the long term costs
are only a few percent as much a tug.

A coupla points: well engineered, is limited in how high you
can get, and very hard to move around are winch disadvantages.
The height is tough to get with any winch (8000 ft sightseeing
sled rides ain't gonna happen). But if we assume we'll only fly
500 gross wt. with 6# wing loading, how does this ease the
engineering and building costs, and how mobile is this
new mini-winch?

If we can build four of these things for the price and energy
of a 400hp version, is the launch weight limitation less of a
disadvantage? How about if we can build eight of these for the
same price? How about if we can build 16?

Obviously if you fly 1600 lbs of glider, this does you no good.
And sure, there are non-recurring engineering costs to
making 2, 4, 8, 16 of these. I guess what I'm saying
is I'm not gonna see a big winch that launches 1600 lbs
at MY gliderport in the next 5 years, but I'm gonna bet
I'll see a small, portable, back of the truck winch at
Tehachapi at the Vintage Sailplane Rally in about a month...

I've also seen pictures and know there are dozens (maybe hundreds)
of hugely capable, overengineered (IMHO) winch designs (they seem
to all be custom homebuilts).
For novelty, I'd like to see the juxtaposed minimalist approach.
I've been very impressed by the lighter, smaller gliders
I've seen recently. I'm excited about the idea
of towing them with a 75 hp towplane. I'd like
to see a 100 hp winch, even if it was underpowered, just to
see HOW underpowered...


The good news is that the total energy consumed for one launch (About 1
liter of diesel fuel equivalent) is tiny compared to any other launch method
except bungee launch. (Excluding, of course, the beer you have to provide
the bungee crew.)

Auto tow's about the same, but without the construction costs,
from what I gather. The huge downside (I'm finding out) is that
auto-tow takes a HUGE amount of room/runway...

A glider winch is a highly specialized piece of machinery that needs the
kind of engineering Ulrich is asking for. Please avoid the temptation to
cobble some junk together to make a barely workable winch. That sort of
thing has given winch launch a bad name in the USA.

There's that word "needs" again. ;P Keep in mind you are sharing this
thread with ME, an avid experimenter and no stranger to failure...

A well run winch operation is very attractive to newcomers to the sport. It
shows a lot of ground activity that is visible to the onlookers and the
rides are a real thrill. Lets get winching!

The only winch I know of on the west coast USA that one can
schedule use of is Northwest Soaring an hour east of Seattle.
I called them and it's a May-Oct operation at Cle Elum. Fortunately
the flights out of San Fran area are $130 round trip, so it'll
be cheap to visit there this summer )) .
--

------------+
Mark Boyd
Avenal, California, USA

In article ,
Ulrich Neumann wrote:
(Mark James Boyd) wrote in message news:405aa3e8$1@darkstar...
mat Redsell wrote:
My statement was very confusing... what I really meant was without the winch
I think that we will be in troubles down the road for affordable tows....

And in part I do think that we have taken a wrong road with high wing
loading. for example with the Monarch we are able to tow it aloft with 160
lbs of tension at a speed of about 15 mph with a wind down the runway of
about 10 mph. This requires a very small rope and small horsepower.

http://www.continuo.com/marske/
look under articles for : ultralight design parameters design parameters of
the ultralight glider

I'd love to see a winch design that uses a 100hp or less engine,
can be easily bolted on the back of an old pickup, and has engine
and parts that are low maintenance and (especially engine) easy
to acquire (either locally or via shipping).

Alternately, how about a "spare tire" that is really a winch drum.
a stable sturdy "jack" and some way to route the cable
to ensure it winds up nice.

Might not work (thoughts of side loads tipping my car
over come to mind!), but it sure is fun to play with the
thuoght!

Mark,

a 100HP or less winch? What are you trying to launch - kites or RC
gliders? The Europeans are replacing their winches powered
traditionally by Detroit's finest with big rig Diesels, because ...?
Lets get real here. As nice as it sounds to have your own personal
winch in the trunk, the reality looks more like you could haul your
car around with the winch.

But keep the ideas coming.

Ulrich Neumann

The previous post about the Marske stuff was my reference. Keep in mind
that yes, I AM talking about very lightweight gliders (either
ultralight or close to it). Not necessarily as interesting to the
"soaring enthusiasts" found here, but interesting to me as a
"soaring consumer."

If you wonder where this push comes from, it's from years
of having fellow pilots tell everyone how airplanes cost
"tens of thousands of dollars" and take $5000 to learn how to
fly. I own a $6000 airplane which one could learn to solo
in about 20 flights ($2000).

http://www.cse.ucsc.edu/~mjboyd/cfi/GHFCcharter

A lot of aviation is overkill. Garmin 430, lights, a starter,
flaps, oleo struts, a heater, blah blah blah. And
who needs a PPL? Solo is solo. There's no doubt who's
flying the thing...where did all this complexity come from?
Society, certainly not the aircraft itself...

Do we NEED a 245 hp winch? Is it POSSIBLE to launch
with something smaller and less hassle?

Do we NEED two 40# thrust turbines, or just one and a lighter
glider? ;P
--

------------+
Mark Boyd
Avenal, California, USA

4740' MSL - temperatures in the mid 30s Celcius.
220 HP winch (and that was when it was new fifteen years ago)

We launch Blanik L13, Kestrel 19m etc quite satisfactorily...

One advantage of a relatively low power winch is it is simple to drive. With the
heavier two seaters and the Kestrel it is a case of roll on full power over four
seconds. Leave it there until the time comes to release.

OK - we do have 1800m of wire, and we only get 1500' to 2300' AGL. Our
conditions are good enough that we seldom need a relight during the middle of
the day. Launch after 15:00 and you are taking your chances as always, but I
don't think that a couple of hundred feet AGL will make such a difference then
anyway.

"Mark Zivley" wrote in message
...
Yep, it's just not the same when you can match the displacement of an
entire European car engine with the displacement of just 2, maybe 3,
cylinders worth of an American big block motor......

Not to mention the CO emissions and resource usage ......

Ahh, but what the hell, when all the fish are dead, the sky rains acid, the
cows all have two heads and the crops die off because Monsanto decides to
modify the wrong gene it won't be our problem!

Cynically yours
Ian

We have had several people writing that they have launched heavy glider X
with a low powered winch. I have done it and so have many others, but this
is still not a good idea. There are serious dangers involved.

The best way to look at it is to consider power demand and supply. The
winch engine should be able to supply all the power the glider demands. If
the glider demands more power that is available by pulling up hard, the
airspeed will decay quickly. If the pilot knows this is going to happen, he
can manage it by controlling the pitch attitude carefully. If he doesn't
expect it, the airspeed will decay so quickly that a very dangerous
situation will develop.

The attempt to launch gliders with a low powered winch gets into who is in
control of the launch. I think it goes without saying that who controls the
launch should not be in doubt. The majority view is clearly that the winch
driver should be in charge.

With a low powered winch, the winch driver is in charge early in the launch
but as the glider steepens the climb, the power demand exceeds supply and
speed control shifts to the glider pilot who now must control airspeed with
pitch since the winch is at full throttle. As the glider rises still
further and power demands lessen, airspeed control shifts back to the winch
driver who must reduce power to prevent over speeding the glider. There
are lots of ways this scenario can go badly wrong.

The other area where a low powered winch can cause problems is in the
initial acceleration. The German Aero Club specifies the maximum distance
that a glider can use to reach flying speed to determine the minimum winch
power. Specifically, under all conceivable wind, density altitude and
weight conditions, a glider must reach Vr (rotation speed) in 40 meters or
less - there is no minimum specified. This is a very intelligent
specification. The concern driving this spec is that should a glider's wing
drop to the ground before reaching flying speed, the resulting ground loop
will be very ugly and quite possibly fatal for the glider pilot.

These concerns and the desire to get the highest launch possible, has driven
winch horsepower higher and higher in recent years. Shortening the
accelerate to Vr distance has a powerful effect on the launch height
achievable. Many powerful winches have shortened this to less than 20
meters.

To summarize, I am advocating generous power reserves to permit the winch
driver to maintain control of the launch and to insure the glider reaches
flying speed before a wing can drop.

Bill Daniels

Hi Bill

I respect your views but there are some differences in the way we see things he

Firstly please note that I am not advocating underpowered winches. I do however
maintain that power is not the most important safety issue in winch launching,
and that - for our fleet where the highest wingloading is relatively modest, and
the heaviest glider is a Blanik L13 - a winch with 220Hp is adequate. (maybe 250
would be better)

Bill Daniels wrote:
We have had several people writing that they have launched heavy glider X
with a low powered winch. I have done it and so have many others, but this
is still not a good idea. There are serious dangers involved.

Too low power is dangerous, and we agree entirely that more power is desirable.
Interestingly the most recent National Safety meeting addressed winch launching
as the primary theme.

There were 25 Safety Officers and at least ten Chief Flying Instructors as well
as the SSSA Exco present. One thing that became apparent was that there is no
optimal power winch. In particular - when launching old designs that are light,
high wing with the hook at a considerable vertical displacement from the wing,
there have been numerous dangerous launches where the initial acceleration
exceeds the control authority on the glider. The example given was launching a
Ka8 with the stick hard against the forward stop for most of the launch.

Too much acceleration is as dangerous as too little.

The best way to look at it is to consider power demand and supply. The
winch engine should be able to supply all the power the glider demands. If
the glider demands more power that is available by pulling up hard, the
airspeed will decay quickly. If the pilot knows this is going to happen, he
can manage it by controlling the pitch attitude carefully. If he doesn't
expect it, the airspeed will decay so quickly that a very dangerous
situation will develop.

Agreed, and all of our pilots have to learn to control their demands on the
winch before going solo. In this respect it would be safer and better to have
more power for perhaps 30% of our fleet. Conversely, any piulot who relies on
the generous power reserve of the winch to compensate for pulling back too hard
is dangerous. I am all for the speed decay to warn the pilot. That way, when the
winch falters, he will compensate automatically because he will be used to
monitoring and controlling airspeed carefully.

The attempt to launch gliders with a low powered winch gets into who is in
control of the launch. I think it goes without saying that who controls the
launch should not be in doubt. The majority view is clearly that the winch
driver should be in charge.

Here I differ, the pilot is always in control of his / her destiny. Our process
is that the launch marshal controlls the launch process, and the winch driver
and pilot must work together. A skilled winch driver is in control at all times
within the parameters dictated by physics. If we have a pilot who over rotates
and "bends the pole" a number of things will happen.
With the exception of the Blanik with its flaps deployed the winch driver will
be able to keep the glider above stall speed with full throttle.
The winch driver is still in control and may decide that the probability of a
maximum tension cable break is dangerously high and elect to reduce power until
the pilot takes the pressure off the cable. (even if it results in a low release)
If the pilot is being ham fisted the cable will probably break resulting in a
dangerous recovery and the possibility of landing damage. This probability is
directly proportional to the instantaneous force on the cable, here a powerful
winch is a distinct liability.
In any event an overzealous pilot is going to get a lecture from the CFI...


With a low powered winch, the winch driver is in charge early in the launch
but as the glider steepens the climb, the power demand exceeds supply and
speed control shifts to the glider pilot who now must control airspeed with
pitch since the winch is at full throttle. As the glider rises still
further and power demands lessen, airspeed control shifts back to the winch
driver who must reduce power to prevent over speeding the glider. There
are lots of ways this scenario can go badly wrong.

The other area where a low powered winch can cause problems is in the
initial acceleration. The German Aero Club specifies the maximum distance
that a glider can use to reach flying speed to determine the minimum winch
power. Specifically, under all conceivable wind, density altitude and
weight conditions, a glider must reach Vr (rotation speed) in 40 meters or
less - there is no minimum specified. This is a very intelligent
specification. The concern driving this spec is that should a glider's wing
drop to the ground before reaching flying speed, the resulting ground loop
will be very ugly and quite possibly fatal for the glider pilot.

These concerns and the desire to get the highest launch possible, has driven
winch horsepower higher and higher in recent years. Shortening the
accelerate to Vr distance has a powerful effect on the launch height
achievable. Many powerful winches have shortened this to less than 20
meters.

IF we were launching twin Astirs, or K21s or other heavy two seater I would
concur that you would want more power. But bear in mind that the Blue weak link
is easily overcome by a 200-250Hp winch. If that is the heaviest weak link
specified you are wasting your time on more power.

Again I agree that more initial acceleration is desirable - I HATE slow
acceleration launches in my Cirrus because the chance of a wing drop is higher.
TO overcome this we use gearing on the winch that increases the effective torque
available.

To summarize, I am advocating generous power reserves to permit the winch
driver to maintain control of the launch and to insure the glider reaches
flying speed before a wing can drop.

Bill Daniels


Generous power reserves are desirable. I am just not convinced that the use of
very powerful winches imnproves safety. My experience is that an adequately
powerful winch that is tractable and predictable is safe, even if there are
compromises on height and initial acceleration. In our mixed vintage and glass
setting it would be challenging to have a super powerful winch.

My conclusion is that it is desirable to have generous power reserves and good
torque for fast acceleration of the heaviest aircraft on the fleet. It is also
imperative that the control be adequately calibrated so that power output can be
modulated easily for all of the gliders the winch could be expected to launch.

Bruce