New 29 Palms Winchfest Video

Bill Daniels wrote:
"Martin Gregorie" wrote:
I tried it enough times when I was pre-solo, thanks, in both ASK-21 and
Puchacz. Didn't work with them. The only effect I remember it having was
breaking a weak link with the Puchacz in a gust.

I did experience a small speed drop today, also in the Puchacz as it
happens, but from the rate and amount of the decrease that was the driver
adjusting the power by making a small reduction at around 500 ft. After
that the remainder of the launch was smack on Vwinch (59 kts) until he
chopped power at the top and we floated off at 55 kts.

We have two Supacats. One has a 240 hp Deutz aircooled diesel V8
industrial engine and the second a big diesel straight six, probably
around 180 hp: I think we were using the straight six winch today. Both
winches drive the drums with a custom gearbox, in turn driven through a
fluid clutch. There are no gear changes during a launch. AFAIK the gearbox
does the following:
- reduction gear. Drum speed is less than engine RPM (of course)
- drum selection (its a two drum winch)
- oscillating drive for the pay-on system


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

Keep trying it. I think you will find you have control over airspeed.
180 - 240 HP isn't nearly enough power to prevent a big 2-seat glider from
slowing the winch.

I assume Martin flies at the Cambridge Gliding Centre. Their V8 Supacat
could not be slowed by pulling (and in fact sped up at times) through
multiple attempts by myself and an instructor (both of us in the 200+ lb
range) in one of their ASK-21s. The only otherwise unusual outcome was
a premature back release late in one launch. This was done with prior
knowledge and discussion of the fact that it should theoretically be
possible. I'd guess there is no overcoming gobs of torque...

Marc

Bill Daniels wrote:

Keep trying it. I think you will find you have control over airspeed.
180 - 240 HP isn't nearly enough power to prevent a big 2-seat glider from
slowing the winch.

A big two seater may have a small effect on the straight six - we've
only had that winch a year or two. I did all my training on the V8 and I
know from both experience and instructor verbals that nothing in our
club fleet can slow it down enough to make a detectable difference.

An ASH-25 probably could, but although I've seen them winched I've not
been in the winch or the ASH at the time so can't and won't comment
further about that.

I think you're ignoring torque. The 240 hp Deutz is likely to produce
more torque than an automotive V8 of the same or higher power output.
Its a mining engine and designed for high torque at low rpm. Power =
torque * rpm, so for equal power the slower turning engine has
proportionately higher torque. It is, after all, the torque not the
power of the winch that determines whether a glider can affect its speed.

I've looked for engine specs, but although I know it produces peak power
at 2300 rpm, I can't find figures for max torque or the rpm for max
torque. At a guess max torque will be produced at somewhat below 2000 rpm.


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

"Marc Ramsey" wrote in message
et...
Bill Daniels wrote:
"Martin Gregorie" wrote:
I tried it enough times when I was pre-solo, thanks, in both ASK-21 and
Puchacz. Didn't work with them. The only effect I remember it having was
breaking a weak link with the Puchacz in a gust.

I did experience a small speed drop today, also in the Puchacz as it
happens, but from the rate and amount of the decrease that was the
driver adjusting the power by making a small reduction at around 500 ft.
After that the remainder of the launch was smack on Vwinch (59 kts)
until he chopped power at the top and we floated off at 55 kts.

We have two Supacats. One has a 240 hp Deutz aircooled diesel V8
industrial engine and the second a big diesel straight six, probably
around 180 hp: I think we were using the straight six winch today. Both
winches drive the drums with a custom gearbox, in turn driven through a
fluid clutch. There are no gear changes during a launch. AFAIK the
gearbox does the following:
- reduction gear. Drum speed is less than engine RPM (of course)
- drum selection (its a two drum winch)
- oscillating drive for the pay-on system


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

Keep trying it. I think you will find you have control over airspeed.
180 - 240 HP isn't nearly enough power to prevent a big 2-seat glider
from slowing the winch.

I assume Martin flies at the Cambridge Gliding Centre. Their V8 Supacat
could not be slowed by pulling (and in fact sped up at times) through
multiple attempts by myself and an instructor (both of us in the 200+ lb
range) in one of their ASK-21s. The only otherwise unusual outcome was a
premature back release late in one launch. This was done with prior
knowledge and discussion of the fact that it should theoretically be
possible. I'd guess there is no overcoming gobs of torque...

Marc

As I said, try it again with careful observation. You will find it works
though you may have to wait a bit to see the effect.

Bill Daniels

Bill Daniels wrote:
"Marc Ramsey" wrote in message
et...
Bill Daniels wrote:
"Martin Gregorie" wrote:
I tried it enough times when I was pre-solo, thanks, in both ASK-21 and
Puchacz. Didn't work with them. The only effect I remember it having was
breaking a weak link with the Puchacz in a gust.

I did experience a small speed drop today, also in the Puchacz as it
happens, but from the rate and amount of the decrease that was the
driver adjusting the power by making a small reduction at around 500 ft.
After that the remainder of the launch was smack on Vwinch (59 kts)
until he chopped power at the top and we floated off at 55 kts.

We have two Supacats. One has a 240 hp Deutz aircooled diesel V8
industrial engine and the second a big diesel straight six, probably
around 180 hp: I think we were using the straight six winch today. Both
winches drive the drums with a custom gearbox, in turn driven through a
fluid clutch. There are no gear changes during a launch. AFAIK the
gearbox does the following:
- reduction gear. Drum speed is less than engine RPM (of course)
- drum selection (its a two drum winch)
- oscillating drive for the pay-on system


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |
Keep trying it. I think you will find you have control over airspeed.
180 - 240 HP isn't nearly enough power to prevent a big 2-seat glider
from slowing the winch.
I assume Martin flies at the Cambridge Gliding Centre. Their V8 Supacat
could not be slowed by pulling (and in fact sped up at times) through
multiple attempts by myself and an instructor (both of us in the 200+ lb
range) in one of their ASK-21s. The only otherwise unusual outcome was a
premature back release late in one launch. This was done with prior
knowledge and discussion of the fact that it should theoretically be
possible. I'd guess there is no overcoming gobs of torque...

Marc

As I said, try it again with careful observation. You will find it works
though you may have to wait a bit to see the effect.

As I said, we discussed ahead of time what would happen if we were to
pull harder (for a normal launch, only a small amount of back pressure
was needed). We were observing carefully and tried holding the stick on
the back stop for a good portion of the climb. We obviously didn't have
a huge amount of elevator authority (forward CG from two heavy guys), so
maybe we just couldn't generate enough lift on a cold autumn day to
exceed the power output of the winch. Or, perhaps you are used to
winches that are underpowered...

Marc

Marc Ramsey wrote:
As I said, we discussed ahead of time what would happen if we were to
pull harder (for a normal launch, only a small amount of back pressure
was needed). We were observing carefully and tried holding the stick on
the back stop for a good portion of the climb. We obviously didn't have
a huge amount of elevator authority (forward CG from two heavy guys), so
maybe we just couldn't generate enough lift on a cold autumn day to
exceed the power output of the winch. Or, perhaps you are used to
winches that are underpowered...

By the way, I absolutely do not claim to be any sort of winch launch
expert. I am interested in reviving ground launch locally, was in the
UK on business, and chose a number of clubs to visit based primarily on
their winch launch operations. I trained according to BGA standards,
and was signed off to solo on the winch at a couple of clubs. I also
received some training in winch driving, talked to anyone who would
listen, and was generally impressed with equipment and the procedures used.

I recommend that anyone who is interested in using a winch in the US do
the same, we have a lot to learn here...

Marc

Hi Bill,

With our Chevy big block powered Tost winches at Lasham,
you cannot slow down by pulling back - if anything
it has the opposite effect and risks breaking the weak
link. Easing forwards also makes you go faster, so
the only way to slow down is to signal to the winch
driver by wagging the tail with the rudder.

However we tried out a Skylaunch 2 winch for one day
last week with a very similar engine and gearbox, but
with a sophisticated throttle stop system. With that
I could control the speed from the glider, at least
in a K21, by about 5 knots either side of the mean
speed, which was ideal anyway. Maybe this is because
you are being supplied with just the right amount of
power. Unfortunately I didn't get a chance to try this
out with a lighter glider.

Derek Copeland

At 18:36 16 December 2007, Bill Daniels wrote:
Actually guys, you CAN and SHOULD control airspeed
on some winches. There
are few winches that have enough power to prevent a
large, heavy glider from
pulling down the drum RPM. Maybe you guys have one
- maybe not.

If you are a little too fast, pitch up, load the winch
a little and wait to
see what the airspeed does. In most cases, it will
ease back down to the
desired airspeed. If you are a bit slow, lower the
nose which unloads the
winch a bit and wait for the effect. Once you get
the hang of it, it works
sweet.

Many pilots think this won't work becasue they haven't
tried it. Give it a
try and get back to us.

Bill Daniels


'Andreas Maurer' wrote in message
.. .
On Wed, 12 Dec 2007 22:33:24 +0000, Martin Gregorie
wrote:

Speaking for myself, I watched the video and saw a
succession of
launches with right wing low. As wing low launching
is something that,
on my field, would earn you a talk with the duty instructor,
I was
unhappy with the description of this being a 'best
practices' event and
said so.

I agree, Martin.
I've never seen such a series of really critical winch
launches
before. With all due respect - a very serious ground-loop
accident is
going to happen rather sooner than later.


Comment on launch speed. The rules we use a
- after lift off, maintain a shallow climb until the
ASI passes 50 kts
with steady acceleration.
- then and only then rotate slowly. The ideal is to
complete rotation
not less than 5 seconds after lift off.
- we have a high torque, high inertia, fluid clutch
winch. The pilot
cannot and should not attempt to control its speed
except by
signalling the winch driver.
- if you're above Vwinch when the launch starts to
flatten toward the
top (i.e. when the angle is below 35 degrees or
so), release.
- if the speed drops toward 50 kts, lower the nose
to maintain at least
50 kts and monitor the speed.
- if the speed picks up, resume the climb.
- if the nose approaches level and the speed doesn't
rise, release.

The same rules apply for us. Works like a charm.



Bye
Andreas

On Sun, 16 Dec 2007 11:34:33 -0700, "Bill Daniels"
bildan@comcast-dot-net wrote:

Actually guys, you CAN and SHOULD control airspeed on some winches. There
are few winches that have enough power to prevent a large, heavy glider from
pulling down the drum RPM. Maybe you guys have one - maybe not.

If you are a little too fast, pitch up, load the winch a little and wait to
see what the airspeed does. In most cases, it will ease back down to the
desired airspeed. If you are a bit slow, lower the nose which unloads the
winch a bit and wait for the effect. Once you get the hang of it, it works
sweet.

Many pilots think this won't work becasue they haven't tried it. Give it a
try and get back to us.

Hi Bill,

I'm giving this a try since over 20 years and I have to admit that the
influence of pitch attitude on airspeed is negligible with out 280 hp
turbo-diesel winch (even with gliders like ASK-21 and DG-505).

On the other hand - I seldom have the need to control airspeed anyway.
Anything between 90 and 120 kp/h is perfectly ok - if I'm faster or
slower, I decrease pitch attitude. As simple as it gets.


Cheers
Andreas


p.s.:
I think it's usually the response of the winch driver that results in
an airspeed increase: If the winch driver notices a sudden
pitch-decrease (or an abnormal low pitch) of the gilder, he assumes
that the gider is too slow and adds power.
We don't have (and don't need) a voice communication between glider
and winch.







Bye
Andreas

At 13:36 17 December 2007, Del C wrote:
Hi Bill,

With our Chevy big block powered Tost winches at Lasham,
you cannot slow down by pulling back - if anything
it has the opposite effect and risks breaking the weak
link. Easing forwards also makes you go faster, so
the only way to slow down is to signal to the winch
driver by wagging the tail with the rudder.

However we tried out a Skylaunch 2 winch for one day
last week with a very similar engine and gearbox, but
with a sophisticated throttle stop system. With that
I could control the speed from the glider, at least
in a K21, by about 5 knots either side of the mean
speed, which was ideal anyway. Maybe this is because
you are being supplied with just the right amount of
power. Unfortunately I didn't get a chance to try this
out with a lighter glider.

Derek Copeland

Derek,

The Skylaunch system works just as well for very light
gliders and it beats me why other designers have not
copied the elegant simplicity and effectiveness of
the concept of using the progressive torque characterstics
of the GM V8 spark ignition engine combined with properly
researched throttle limitation.

When our club had a Skylaunch for a trial I drove it
under the supervision of their super-experienced winch
man, Pete Salisbury. To my surprise the K8 pilots
were just as complimentary about the suitability and
controllability of their launches as were the pilots
of heavier gliders.

John Galloway

Andeas:


Andreas

p.s.:
I think it's usually the response of the winch driver that results in
an airspeed increase: If the winch driver notices a sudden
pitch-decrease (or an abnormal low pitch) of the gilder, he assumes
that the gider is too slow and adds power.
We don't have (and don't need) a voice communication between glider
and winch.

Bye
Andreas

Despite the danger that Bill Daniels calling me dangerous or some
other unsubstantiated claim, I post here to agree with you 100%.
Playing around with the airspeed should not be the focus of the
launch. It is the winch driver who controls this to the greatest
degree.

Safety and minimizing risk should be the main focus of the pilot.

The incidents mentioned here, are indicative of an increase in risks
during winch launches when trying to influence airspeed as discussed
in this thread. Weak links breaking as you're pulling back to put
strain on the winch or the premature back releases of the cable as
you're pulling are certainly not desirable nor add to safety.

I am with Andreas that from the pilot's point of view, it should be a
simple matter. The winch driver will also get a clue as to what's
happening by observing the glider. However, by pushing and pulling as
discussed here, the winch driver may not be able to figure out what's
going on and perhaps not respond at all or respond in a way that makes
thing worse.

Since the winch driver is the one who has the most control over speed,
you really don't want to confuse him or her.

On Mon, 17 Dec 2007 16:40:49 -0800 (PST), tommytoyz
wrote:


from the pilot's point of view, it should be a
simple matter.

I think that's the main point.

@Bill:
I really love the fact that you are trying to promote winch launching
in the US - but (please correct me if I'm wrong) from the comments
here in this newsgroup I get the impression that you US guys regard
the winch launch as something pretty hazardous that needs a lot of
technology to be safe.
Consequently, your approach to a US winch design looks a little
over-engineered to me, I have to admit. Complex and expensive to
build, hard to set up correctly. Possibly prone to mechanical
problems.

Us European guys seem to see things in a more relaxed way - we tend to
advocate training instead of technological devices to achieve safe
winch operations.

Considering the number of accident-free winch launches per year on my
side of the pond, don't you think that it might be useful to stick
more closely to the KISS-principle ("keep it simple, stupid"), forget
all that high-tech stuff and concentrate on correct training?

Nearly all the winches here are basically very simple.
Anything a winch needs is a strong diesel engine, two drums, 3.500 ft
of cable (be it steel or plastic). No rocket science involved.




Bye
Andreas