New 29 Palms Winchfest Video

Speed is not controlled by the pilot on a conventional winch. Though
you can temporarily speed up by pulling on certain winches, that is
only a temporary effect, as the tension increases and the glider is
accelerated for a short burst.

However, that is really not a technique or effect that has much
practical meaning, one way or the other.

If the speed is too slow, the pilot has to slack off and be prepared
to release. How can the pilot know the reasons for the lack of
power?......pulling more just assumes it's only a winch driver related
issue - when it could be any number of reasons for the slow speed.

So yes, pulling will increase speed temporarily but only slightly and
pushing will decrease it, again only slightly depending on the
particulars of the winch - the effects are really not very noticeable
on a conventional winch. Pulling will reduce motor and drum RPM,
reducing the water skier effect.

Pushing will also not really reduce airspeed too much or perhaps not
at all depending on the winch, because motor and drum ROM will
increase when pushing.

But this is the wrong area to focus on in any case and can vary from
one winch set up to another - depending on the engine torque, glider
weight and engine RPM at which point the push or pull happens. But
again, it's academic and not practical from a pilot point of view:

I was taught this way:

- Wings level, not matter the wind direction
-Take off when sufficient air speed is reached with wings level
- If a wing drags on the ground for more than 1second - release
-Gradually rotate and increase rate of climb to normal climb attitude
within the safety zone to 200ft as airspeed remains constant or
increases
-If airspeed falls bellow a certain speed, be ready to push forward
and release ( In that order!)
-If airspeed falls even lower, quickly push forward and then release
-On the last 25% or so of the launch, gradually decrease the stick
back pressure. Remember that the launch is an arc with a constantly
changing climb angle relative to the horizon. So at the top of the
launch, the pitch is almost horizontal - so the aircraft nose should
also be almost horizontal there.

There has never been a case of a glider over stressing due to
excessive speed on winch launch, so that is not really a danger point.
But if it seems excessive, one can always just release and I've seen
that happen a few times, though rare. In any case, that is what the
weak link is for.

The only quick pitch movement should be when pushing over to release
in an aborted launch due to lack of winch power and speed. Otherwise
the pitch changes should always be smooth.

Keep it simple and do not try to micromanage the launch from the
pilot's point of view. There is no way the pilot can know what the
troubles are, if any - so he can not possibly know what effect
pushing, pulling or signaling will have.

This is all just my 2 cents.

Discussing this brought more memories and perhaps I should fine tune
this by discussing some sceanrio's:

If the airspeed never picks up enough, but not low enough for a
release, just do not go into full climb mode even above the safety
altitude, just remain in a shallow climb till either the airspeed
increases or it falls further, where you push over and release if it
does fall off. But keep some tension on the rope so that the chute
doesn't open. So don't follow the rope or level off completely unless
you're aborting and releasing.

The signal to the winch driver that the airspeed is too slow is the
fact that the glider is in a shallow climb mode. The winch driver may
or may not add power. In no case can the pilot know. So the pilot
should not pull more and increase climb rate to speed up. That's
dangerous.

The same is when the speed starts falling off bellow a certain point.
I'm not talking about when it fluctuates and starts falling. But only
when it falls bellow a certain point. Then, for safety reasons, you
gradually shallow the climb angle when it falls too low, in case the
power dies or there is some other problem. If power picks up again,
you can resume the climb angle.

This is done for safety reasons and not to influence the air speed.
The winch driver can see if you're shallow or haven't started climbing
normally yet. Then again maybe he can't..............

But the reasons for the lack of power can be totally outside the fault
of the winch and the driver. For instance there can be strong and
sudden wind shears at certain altitudes at the beginning of the day
that nobody knows of, or when wind conditions change during the day.

There might also be a traffic conflict with another plane somehow that
the winch driver sees, but the pilot does not...............

This can result in a crappy launch with a low release altitude. So
what? Get another launch! It's cheap. Bad launches are fixed by
talking to the winch driver. In Germany, the winch drivers usually
called up to ask when that happens so they can make adjustments.

So pilots trying to influence speed is a good practice. The airspeed
will vary during a winch launch anyway. The best practice in this
regard is to have well educated winch drivers who know what power
settings are required for the different types of gliders being
launched and on the known wind conditions.

If this results in a crappy launch anyway, inform the winch driver of
the problem you had, (..."at 300ft the speed increased/decreased 15
knots, at 1,000ft it reversed again...") , and the driver can adjust
the power settings throughout the launch accordingly for good launches
there after for all types.

Of course tension controlled winches do not have these problem, but
there are none in the U.S and few even in Europe.

It's not the launching pilot who can really control the airspeed or
power application on a conventional winch. So please, do not pull to
increase speed as the low speed may be due to some problem you are not
aware of and where pulling may not help - rather you'll only increase
the risk should something else then happen - which you also can not
predict.

I erroneously said:
"So pilots trying to influence speed is a good practice"

I wanted to say:
"So pilots trying to influence speed is NOT a good practice"

I fly off a powerful winch and pulling back has never sped it up. It
increases the tension and, with the throttle held constant at the
winch, simply slows the engine down.

I've never pushed forwards on a launch unless the speed has been
falling away (not very clever to be nose-up with no speed). In the UK
winch drivers are trained to notice a glider "nosing over" and thus
gently feed in more power until the glider returns to a normal climb.

I think someone suggested buying a copy of the BGA Instructor's
Handbook and having it shipped to the US. That sounds a good idea. You
can buy a copy he

http://www.gliding.co.uk/shop/produc...products_id=65

It covers both theory and practicalities of winch launching well.


Dan

Dan G wrote:
I fly off a powerful winch and pulling back has never sped it up. It
increases the tension and, with the throttle held constant at the
winch, simply slows the engine down.

The one time I consciously tried to slow down by pulling was in a K21 on
a Supacat 8. Airspeed kept increasing, but that may have had more to do
with the wind gradient that day...

Marc

Winch launch has nothing to do with free flight, and "angle of attack for
best L/D" has no meaning. On a winch launch, you simply try to fly at
Ca/max.
On my 1,200+ winch launches, I never felt the need of an AoA meter (nor did
I after releasing).

"Marc Ramsey" wrote in message
...
3. Pilots were told that while on winch launch they
are flying at zero angle of attack. Is this possible?

Not zero, but at a normal (i.e., not 45 degrees) positive AOA, ideally
that for best L/D. Hence the interest in AOA meters.

Marc

tommytoyz wrote:

[an over slow launch] can result in a crappy launch with a low
release altitude. So what? Get another launch! It's cheap. Bad
launches are fixed by talking to the winch driver. In Germany,
the winch drivers usually called up to ask when that happens so
they can make adjustments.

A very good point, and one that is seldom if ever mentioned here.

If you have a bad launch, talk to the winch driver and calmly discuss
the problem with him. Equally important, if he gets it spot on, let him
know! He'll appreciate that and remember what he did the next time he
launches you or another glider of the same type.

For instance, those of us flying 1st generation glass very often get
over fast launches because the drivers are used to heavier, more highly
loaded gliders. In my club the only 1st Gen glass is a pair of Libelles,
but we also have two SZD Juniors, which all our drivers are very
familiar with. The Junior has a similarly light wing loading to a
Libelle but is draggier and has a Vwinch of 70 kts against the Libelle's
65. A request to a winch driver who hasn't launched me for a while to
"launch me like a Junior, but 5-10 kts slower" gets a good launch every
time.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

At 13:06 11 December 2007, Martin Gregorie wrote.

If you have a bad launch, talk to the winch driver
and calmly discuss
the problem with him. Equally important, if he gets
it spot on, let him
know! He'll appreciate that and remember what he did
the next time he
launches you or another glider of the same type.

For instance, those of us flying 1st generation glass
very often get
over fast launches because the drivers are used to
heavier, more highly
loaded gliders.

I have been reading with great interest the past few
months the threads about winches and launching on them.
And just a small observation about our own club in
Prescott is that we have a medium powered winch. Which
gives the heavier gliders, ie the Blanik and 2-33 fully
loaded, a full power launch with the pilot pushing
to increase speed once the winch driver has reached
full power and the lighter ones, 1-26 with light pilot,
a 60%or so power launch.

But what I havent heard here in these threads is any
one communicating via radio to the winch driver during
the launch? We use a simple method on the radio by
calling out the speed we are seeing. In other words
we start by telling the winch operator who, what, how
fast, and ready for launch. Then during launch we call
out our speed and the winch driver adjusts accordingly.
Example:

Blanik to winch, I am fully loaded, wings are level,
traffic pattern is clear, I am ready for a tow at 55
(short for 55mph).

Winch to blanik, roger, here we go tow at 55, no delay.

(after intial saftey climb to 200 feet and rotation
into 45 degree climb angle)

blanik says: five zero, five zero
(winch reacts with full throttle and says): Full power.

blanik says: Roger. (and decreases angle of attack
to increase airspeed to target of 55).

We then continue to call out airspeed every few 5 or
6 hundred feet. Until the winch driver tells us to:
Stand by------level off level off.

At which point we level off and release. Winch driver
then waits to see the chute and announces: I have the
chute.

There are many scenarios with different gliders and
weights but you get the picture. I have driven the
winch and this seems to work very well. You get an
idea of where the throttle has to be to start with
each glider and it usually is a small if any adjustment
throughout the launch.

I have not flown on any other winches, only car tows,
so my question is why no communication?

I have not flown on any other winches, only car tows,
so my question is why no communication?

Did a similar thing in Oklahoma, using noise canceling headsets on the
winch and traffic frequency for speed hacks, but this was a new winch
and some new pilots, so had to shake things out. Works okay in a
remote area with today's low volume of transient power traffic. So
you visit or move to another club. Now, forget what you've used and
learn standard techniques. As a frequent winch driver, I'd rather
everyone was practiced in standard signals and is well ahead of the
glider and the process on each and every launch. Radio calls may not
work well at a big site where multiple winches or aero towing
operations are operating in parallel, or where the traffic frequency
is otherwise cluttered. I am also concerned about pilots in singles
using a hand held radio or mic for this, and even in two seaters, as
there may be very little time to react if something goes pear-shaped,
as there's the ever present danger of dropping either into a control
at the worst possible time. Sod's law. If you have boom or headset
mics and push buttons on the stick, okay, but this is generally no the
case in trainers and many singles. Some may not even have radios. We
use GMRS radios and/or flags to keep off 123.3 for staging and
starting the launch (as there are plenty of other users of the
frequency out there), but use the visual signals for speed control
during the launch.

One day soon, perhaps we'll have additional tools for this.

Frank Whiteley

Bert Willing wrote:
Winch launch has nothing to do with free flight, and "angle of attack for
best L/D" has no meaning. On a winch launch, you simply try to fly at
Ca/max.

I don't agree. Common sense (and the mathematics) make it clear that
the most effective (highest altitude) launch is achieved by maximizing
the lift and minimizing the drag given the varying cable tensions
delivered during the climb phase of the launch. For a specific cable
tension, that speed will be equivalent to the best L/D for the polar
adjusted to the effective loading resulting from that cable tension.
The AOA for best L/D, however, is independent of the effective loading.
So, the optimal speed could be maintained during climb by keeping the
AOA at best L/D (which also, of course, keeps one below the stall AOA).

On my 1,200+ winch launches, I never felt the need of an AoA meter (nor did
I after releasing).

Well, in my 20+ winch launches I haven't been much concerned with
anything beyond getting to release without breaking anything. From a
training perspective, however, particularly in places (like the US)
where there isn't much overall experience with winch launching, an AOA
meter should be a great deal of help with learning to fly the launch
optimally.

Marc