Auto Tow Information

I am a bit disappointed to see this thread going the
way the Yahoo Winch design group did. I still watch
there and am interested in what comes of it. It started
off (Or so I thought) with the notion of designing
a simple but reliable winch that a small group of people
could afford to build so a small club could fly. It
rapidly evolved into a multi drum, hundreds of horsepower
machine that would make the small club capable of doing
120+ launches of fully loaded ASH-25s and Duo Discuses
a day. Does a small club really need that much power
and more than one on a drum winch?

Let me say, you DO NOT have to use a big engined pickup.
We have towed with a sick V-8 in a donated old Pontiac
Grand Prix, a 6 cylinder Chrysler minivan, a Full size
Chevy Van with a 350, and a Suburban with, I believe,
a 454. And you know what? The altitude gained was
virtually the same for each tow vehicle! A FAR bigger
variable was Pilot Technique. And right behind that,
believe it or not, is CG positioin on the towed glider
(in our case, a 2-33 using the nose hook. Why the
nose hook, you ask? With our 2-33, the CG hook would
hit the ground with the nose skid on the ground and
the right wing down.)

I do agree with the comment about not using a chute
for straight auto towing using rope. It will just
take the end farther from the runway! I have been
able to buy 2000 feet of 3/8th hollow braid Poly for
$200 (plus sales tax). If well taken care of on our
very abraisive paved runway, we can expect to get at
most 100 tows from this. We drive only about 15 to
20 MPH on the return trip, and try to lay the rope
in a grass strip along the runway when we bring it
back. If you can attach an arm to the side of the
towing vehicle to drag the rope back i the grass along
the side of the runway, it will last even longer.

One of our members built up a complete system he installs
in the receiver hitch on his vehicle. It has a 3.5
HP Brigss and Straton motor, the rope reel, hand operated
level wind, throttle and brake for the reel, and a
tow release. Not sure why everyone thinks you need
to use a Tost release for this. The Schweizer releases
we are using work just fine. Whole thing is installed
on swivels, so it always pulls straight on the tow
release. Oh, and since this releas is not on an airplane,
you can make your own that acts like one of the others.
But, you can probably pick up a used Schweizer release
for less than it will cost you to make one of your
own. There aren't many airplanes pulling banners anymore,
so they might be happy to get $100 for that thing on
their tail. He is able to reel in the rope in just
over one minute, then drive quickly back to the launch
end and then star slowly paying ot the rope for the
nex launch. But, even this is probably more than you
are wanting right away.

You don't need a high dollar towplane, you don't need
a high dollar winch, and you don't need a high dollar
tow vehicle in order to get in the air. If you are
not trying to launch an ASH-25 at a 10,000 foot density
altitude, you don't need to size your launching equipment
to do that! What are you looking at launching down
there in Laredo?

Just like the comments about flaps. Well intentioned
auto towing advice, even from people that know what
they are talking about, sometimes gets slanted to their
needs, not yours.

Feel free to contact me directly if you would like
a bit more information about the auto towing we have
done here in Kansas.

Steve Leonard

Sometimes auto tow driver and pilot
1200 plus hours in flaped ships and have never ONCE
had the thing try to float the entire length of the
airport on me so I don't know why the heck you would
ever want to RETRACT the flaps and REDUCE the drag
that is there to slow you down.

"Steve Leonard" wrote in message
...
I am a bit disappointed to see this thread going the
way the Yahoo Winch design group did. I still watch
there and am interested in what comes of it. It started
off (Or so I thought) with the notion of designing
a simple but reliable winch that a small group of people
could afford to build so a small club could fly. It
rapidly evolved into a multi drum, hundreds of horsepower
machine that would make the small club capable of doing
120+ launches of fully loaded ASH-25s and Duo Discuses
a day. Does a small club really need that much power
and more than one on a drum winch?

Let me say, you DO NOT have to use a big engined pickup.

Alright Steve.

I have found more power a detriment. I used to tow my Mini-Nimbus with my
Ford Taurus Wagon. 140 HP on a good day. I could use anyone off the street
for a driver. I just told them to floor it until I was off tow. Worked
great.

With my lighter PW-5 and powerful 200 HP Ford Escape I have to worry about
overspeeding so it is more complicated, with instructions to the driver to
"hold speed."

It is hard for me to imagine a problem with lifting the rear of the tow
vehicle of the ground. Maybe with an ASH-25 or something, but do those guys
do auto tows? I really think those big Ford pickups are overkill.

Larry Pardue 2I

Steve Leonard wrote:
I am a bit disappointed to see this thread going the
way the Yahoo Winch design group did. I still watch
there and am interested in what comes of it. It started
off (Or so I thought) with the notion of designing
a simple but reliable winch that a small group of people
could afford to build so a small club could fly. It
rapidly evolved into a multi drum, hundreds of horsepower
machine that would make the small club capable of doing
120+ launches of fully loaded ASH-25s and Duo Discuses
a day. Does a small club really need that much power
and more than one on a drum winch?

It sounds like you are reading too much into the documents in the Winch
Design Group file section. In reality, the practical design discussions
have all been about two drum winches, mounted on (and obtaining power
from) commonly available large pickups or small trucks with 250 to 300
HP turbo diesels. Discussion has slowed for the past few months, as it
is soaring season in the northern hemisphere.

From a mechanical perspective, the main things that are preventing a
couple of groups from "cutting metal" this fall, are the lack of a
source for inexpensive and reliable split-shaft power takeoff units, and
a simple workable design for drum clutches. If you or anyone else has
any ideas, we'd love to hear them...

Marc

and have never ONCE
had the thing try to float the entire length of the
airport on me

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~

Well, I have. and that was with an approach speed of 50knots on a low
wind day - full flap in a PIK 20B (90 degrees), and it floated and
floated and floated and wouldn't come down. The previouse owner's
technique was to just drive it on, dump the flaps and use the wheel
brake - I thought that was very inelegant. Coming in slower (e.g. 45
knots - which the previous recommended) is deadly if the flare is
started too early, which it was once (no damage done, but my neck [which
is damaged anyway] suffered a bit) - won't do that again!

Rgds,

Derrick Steed

Well, there's cheap and effective and there's just plain cheap. The
difference is critical. US winch launching has suffered a great deal from
the "lets just do it as cheaply as we can" attitude. The result is a lot of
rusting "200HP weed eaters" welded together from junk car parts that
understandably scared the hell out of people and gave winch launch a very
bad name.

I've spent a lot of time looking at the best winches in the world and
examining the cost justification for each feature. I came to appreciate
that winch design is a complex art with profound consequences if you get it
wrong. Nobody is building new single drums winches. Two is the minimum.

My conclusion is that the up front costs, even though they are high, can be
easily justified if the utilization is high enough. If the utilization is
low, you can't justify anything. It's also easy to see that doing it right
the first time is far cheaper in the long run.

Much of the cost of multiple drum winches is in the high-tech cable. A club
can build a multiple drum winch but delay purchase of the cable for all the
drums until the demand is evident.

Multiple drums and high HP results in fast, high launches. There are two
benefits to multiple drums. One is higher utilization and the other is fast
queue's. If you are 6th in line for a launch while the Cu's are popping,
the winch cycle time can't be fast enough.

High HP is both a safety feature and a performance feature. Getting the
glider to a safe climb airspeed quickly reduces the exposure to two types of
accidents - ground loop and stall on the wire. It's much easier to stall a
glider on the wire or let a wing drop with an underpowered winch. Of
course, the glider acceleration must not be so high that the pilot can't
control pitch up.

Higher launches allow more time to search for a thermal. Even a small
increase in release height is a big payoff. If the release height is barely
at pattern entry altitude there is little time to find a thermal. Adding a
few hundred feet to the release height means that a much higher percentage
of launches will contact soarable lift. Given reasonable runway length,
launches above 2000 feet AGL are easy. Much higher launches are possible
with still longer runways.

Auto tow is a very cheap way to go if the room is available. The problem is
that a long rope takes up most of the runway leaving little room for
acceleration and braking of the tow vehicle. For a typical runway, a winch
will get you higher. A winch with multiple drums will launch far faster
than auto tow.

Bill Daniels

The whole idea of winch launch is to reduce launch costs
"Steve Leonard" wrote in message
...
I am a bit disappointed to see this thread going the
way the Yahoo Winch design group did. I still watch
there and am interested in what comes of it. It started
off (Or so I thought) with the notion of designing
a simple but reliable winch that a small group of people
could afford to build so a small club could fly. It
rapidly evolved into a multi drum, hundreds of horsepower
machine that would make the small club capable of doing
120+ launches of fully loaded ASH-25s and Duo Discuses
a day. Does a small club really need that much power
and more than one on a drum winch?

Let me say, you DO NOT have to use a big engined pickup.
We have towed with a sick V-8 in a donated old Pontiac
Grand Prix, a 6 cylinder Chrysler minivan, a Full size
Chevy Van with a 350, and a Suburban with, I believe,
a 454. And you know what? The altitude gained was
virtually the same for each tow vehicle! A FAR bigger
variable was Pilot Technique. And right behind that,
believe it or not, is CG positioin on the towed glider
(in our case, a 2-33 using the nose hook. Why the
nose hook, you ask? With our 2-33, the CG hook would
hit the ground with the nose skid on the ground and
the right wing down.)

I do agree with the comment about not using a chute
for straight auto towing using rope. It will just
take the end farther from the runway! I have been
able to buy 2000 feet of 3/8th hollow braid Poly for
$200 (plus sales tax). If well taken care of on our
very abraisive paved runway, we can expect to get at
most 100 tows from this. We drive only about 15 to
20 MPH on the return trip, and try to lay the rope
in a grass strip along the runway when we bring it
back. If you can attach an arm to the side of the
towing vehicle to drag the rope back i the grass along
the side of the runway, it will last even longer.

One of our members built up a complete system he installs
in the receiver hitch on his vehicle. It has a 3.5
HP Brigss and Straton motor, the rope reel, hand operated
level wind, throttle and brake for the reel, and a
tow release. Not sure why everyone thinks you need
to use a Tost release for this. The Schweizer releases
we are using work just fine. Whole thing is installed
on swivels, so it always pulls straight on the tow
release. Oh, and since this releas is not on an airplane,
you can make your own that acts like one of the others.
But, you can probably pick up a used Schweizer release
for less than it will cost you to make one of your
own. There aren't many airplanes pulling banners anymore,
so they might be happy to get $100 for that thing on
their tail. He is able to reel in the rope in just
over one minute, then drive quickly back to the launch
end and then star slowly paying ot the rope for the
nex launch. But, even this is probably more than you
are wanting right away.

You don't need a high dollar towplane, you don't need
a high dollar winch, and you don't need a high dollar
tow vehicle in order to get in the air. If you are
not trying to launch an ASH-25 at a 10,000 foot density
altitude, you don't need to size your launching equipment
to do that! What are you looking at launching down
there in Laredo?

Just like the comments about flaps. Well intentioned
auto towing advice, even from people that know what
they are talking about, sometimes gets slanted to their
needs, not yours.

Feel free to contact me directly if you would like
a bit more information about the auto towing we have
done here in Kansas.

Steve Leonard

Sometimes auto tow driver and pilot
1200 plus hours in flaped ships and have never ONCE
had the thing try to float the entire length of the
airport on me so I don't know why the heck you would
ever want to RETRACT the flaps and REDUCE the drag
that is there to slow you down.

How long of a runway do you need for an effective / safe winch and/or auto
tow launch environment?

Mike Schumann

"Bill Daniels" wrote in message
...
Well, there's cheap and effective and there's just plain cheap. The
difference is critical. US winch launching has suffered a great deal from
the "lets just do it as cheaply as we can" attitude. The result is a lot
of
rusting "200HP weed eaters" welded together from junk car parts that
understandably scared the hell out of people and gave winch launch a very
bad name.

I've spent a lot of time looking at the best winches in the world and
examining the cost justification for each feature. I came to appreciate
that winch design is a complex art with profound consequences if you get
it
wrong. Nobody is building new single drums winches. Two is the minimum.

My conclusion is that the up front costs, even though they are high, can
be
easily justified if the utilization is high enough. If the utilization is
low, you can't justify anything. It's also easy to see that doing it
right
the first time is far cheaper in the long run.

Much of the cost of multiple drum winches is in the high-tech cable. A
club
can build a multiple drum winch but delay purchase of the cable for all
the
drums until the demand is evident.

Multiple drums and high HP results in fast, high launches. There are two
benefits to multiple drums. One is higher utilization and the other is
fast
queue's. If you are 6th in line for a launch while the Cu's are popping,
the winch cycle time can't be fast enough.

High HP is both a safety feature and a performance feature. Getting the
glider to a safe climb airspeed quickly reduces the exposure to two types
of
accidents - ground loop and stall on the wire. It's much easier to stall
a
glider on the wire or let a wing drop with an underpowered winch. Of
course, the glider acceleration must not be so high that the pilot can't
control pitch up.

Higher launches allow more time to search for a thermal. Even a small
increase in release height is a big payoff. If the release height is
barely
at pattern entry altitude there is little time to find a thermal. Adding
a
few hundred feet to the release height means that a much higher percentage
of launches will contact soarable lift. Given reasonable runway length,
launches above 2000 feet AGL are easy. Much higher launches are possible
with still longer runways.

Auto tow is a very cheap way to go if the room is available. The problem
is
that a long rope takes up most of the runway leaving little room for
acceleration and braking of the tow vehicle. For a typical runway, a
winch
will get you higher. A winch with multiple drums will launch far faster
than auto tow.

Bill Daniels

The whole idea of winch launch is to reduce launch costs
"Steve Leonard" wrote in message
...
I am a bit disappointed to see this thread going the
way the Yahoo Winch design group did. I still watch
there and am interested in what comes of it. It started
off (Or so I thought) with the notion of designing
a simple but reliable winch that a small group of people
could afford to build so a small club could fly. It
rapidly evolved into a multi drum, hundreds of horsepower
machine that would make the small club capable of doing
120+ launches of fully loaded ASH-25s and Duo Discuses
a day. Does a small club really need that much power
and more than one on a drum winch?

Let me say, you DO NOT have to use a big engined pickup.
We have towed with a sick V-8 in a donated old Pontiac
Grand Prix, a 6 cylinder Chrysler minivan, a Full size
Chevy Van with a 350, and a Suburban with, I believe,
a 454. And you know what? The altitude gained was
virtually the same for each tow vehicle! A FAR bigger
variable was Pilot Technique. And right behind that,
believe it or not, is CG positioin on the towed glider
(in our case, a 2-33 using the nose hook. Why the
nose hook, you ask? With our 2-33, the CG hook would
hit the ground with the nose skid on the ground and
the right wing down.)

I do agree with the comment about not using a chute
for straight auto towing using rope. It will just
take the end farther from the runway! I have been
able to buy 2000 feet of 3/8th hollow braid Poly for
$200 (plus sales tax). If well taken care of on our
very abraisive paved runway, we can expect to get at
most 100 tows from this. We drive only about 15 to
20 MPH on the return trip, and try to lay the rope
in a grass strip along the runway when we bring it
back. If you can attach an arm to the side of the
towing vehicle to drag the rope back i the grass along
the side of the runway, it will last even longer.

One of our members built up a complete system he installs
in the receiver hitch on his vehicle. It has a 3.5
HP Brigss and Straton motor, the rope reel, hand operated
level wind, throttle and brake for the reel, and a
tow release. Not sure why everyone thinks you need
to use a Tost release for this. The Schweizer releases
we are using work just fine. Whole thing is installed
on swivels, so it always pulls straight on the tow
release. Oh, and since this releas is not on an airplane,
you can make your own that acts like one of the others.
But, you can probably pick up a used Schweizer release
for less than it will cost you to make one of your
own. There aren't many airplanes pulling banners anymore,
so they might be happy to get $100 for that thing on
their tail. He is able to reel in the rope in just
over one minute, then drive quickly back to the launch
end and then star slowly paying ot the rope for the
nex launch. But, even this is probably more than you
are wanting right away.

You don't need a high dollar towplane, you don't need
a high dollar winch, and you don't need a high dollar
tow vehicle in order to get in the air. If you are
not trying to launch an ASH-25 at a 10,000 foot density
altitude, you don't need to size your launching equipment
to do that! What are you looking at launching down
there in Laredo?

Just like the comments about flaps. Well intentioned
auto towing advice, even from people that know what
they are talking about, sometimes gets slanted to their
needs, not yours.

Feel free to contact me directly if you would like
a bit more information about the auto towing we have
done here in Kansas.

Steve Leonard

Sometimes auto tow driver and pilot
1200 plus hours in flaped ships and have never ONCE
had the thing try to float the entire length of the
airport on me so I don't know why the heck you would
ever want to RETRACT the flaps and REDUCE the drag
that is there to slow you down.

Mike Schumann wrote:

How long of a runway do you need for an effective / safe winch and/or auto
tow launch environment?

I can only talk for winch launch. Safety is not a problem. The problem
is that you must have enough height above the winch to reach a thermal.
How much this is depends on your site.

E.g. at our field, we usually reach about 300-350 metres AGL. This is
usually not enough for us, with few exceptions. 100 metres more would do
it. So we are stuck to aerotow.

Stefan

How long is your runway?

Mike Schumann

"Stefan" wrote in message
...
Mike Schumann wrote:

How long of a runway do you need for an effective / safe winch and/or
auto tow launch environment?

I can only talk for winch launch. Safety is not a problem. The problem is
that you must have enough height above the winch to reach a thermal. How
much this is depends on your site.

E.g. at our field, we usually reach about 300-350 metres AGL. This is
usually not enough for us, with few exceptions. 100 metres more would do
it. So we are stuck to aerotow.

Stefan

We used to autotow (straight, and later reverse pulley) from either of
two good surface hard runways at North Weald, Essex, UK. One was 1 ¼
miles long and we only used less that 1 mile of it for the tow car/cable
run (we landed in the undershoot). The other was ¾ mile and we use
almost its whole length. Launch heights were typically about 7-800 feet
in light winds on the shorter run, and 900-1000 feet on the longer run,
for K13's, two-up. With increasing amounts of wind, up to say 15 knots,
we got 1200+ on the short run and 1400 + on the longer run. Highest I
ever got was about 2000; others got higher, in really strong winds.

Going back to launch vehicles, I would say that straight tow with old
bangers is a cheap and viable way, if you have the runway hard surface
and length, for small numbers of launches, and accepting reliability
issues and not the fastest turnaround. With two cables, two launch cars,
and also two cable retrieve cars, you can speed up the launch rate quite
a lot. The technology is fairly simple, relatively easily learned, and
its all cheap. The cable could be the most expensive part of it. The
driving takes a bit of learning to get the technique right, but it's not
too difficult. To save reinventing, it would be best to get some hints
and tips from those who have done it.

My earlier post about the high cost, super spec. truck, was a direct
response to somebody asking for what seemed like that information. It is
a high cost, high reliability, high turnaround solution. Combining it
with reverse pulley also requires appreciable investment in the pulley
system itself too - but a few thousand, compared with lots of thousands
for a new truck. If you don't want the 9,000 launches per year,
professional-style operation that we had that for, and don't want a top
quality system, fine - that's your choice. Those who didn't want to read
about it, tough.

Both reverse pulley systems, and winches, are really specialist design
projects. Amateurs who take them on rarely, if ever, get them right
first time - I have never seen one such. Both Cotswold Club and Essex
Club took several iterations to arrive at their respective designs of
reverse pulley, and ended up with substantial professional workshop
builds.

I have never seen a good first-time-build winch, either. All the good
professional ones I have seen built in the UK came from ex-amateurs who
learnt from several home-grown prototypes and mistakes before
progressing to good, reliable, and high-capital-cost solutions (Supercat
and Skylaunch). I don't know the history of Tost, but there has been a
long tradition of winching in Germany, and the best Tost winches are
also very good. Several Tost-technology winches have been built in the
UK from greater or lesser proportions of Tost kits. The more local
invention to save capital cost, the greater is the risk of the new short
cuts being worse than the well-developed technology, to put it mildly.

When my own club had to cease truck launches at North Weald, and could
not afford new winches for our new grass site at Ridgewell, we bought
four ex-air cadet winches and fitted the best two of them with
replacement high-power engines and automatic transmissions - the first
one by our own amateurs, the other by a professional engineer who had
built a Tost winch previously for his own gliding club. Our ex-ATC
chassis including winch drums and pay-on gear cost about 800 Sterling
each. The conversions cost (very approximately) about 1-2,000 sterling
for the first, using a used ex-tow-truck powertrain; and about 16,000
sterling for the second including a brand new cab and re-engineered
Chevy (I think) engine/trans combination and LPG conversion. ( They are
not perfect, but the bits that are poorest are the original ATC winch
parts and are very difficult to see how to re-engineer. They work
tolerably well, so we live with them. The main problem, when it happens,
is cables snarling up inside the drum/axle mechanism. But that can
happen even on the high cost professional winches - I saw one such
incident at another club last week, and at a different one again today.)

Chris N.




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"Mike Schumann" wrote in message
nk.net...
How long of a runway do you need for an effective / safe winch and/or auto
tow launch environment?

Mike Schumann

With the old manually controlled winches and steel wire, 30 - 40% of the
runway is achievable as release height. However, there is something of a
revolution in winch technology going on right now.

The new high power, computer controlled winches using ultra light 'plastic'
UHMWPE 4.5mm cord can get up to 50% of the runway length in zero wind
conditions. Launching into a headwind increases the release height quite a
bit more. So a 5000 foot runway might get you 2500 feet AGL. That's
usually enough to contact soarable lift if there is any to be had.

Bill Daniels