Winch rope 1/4 inch poly

With all the talk about Spectra for winch wire replacement, one thing
comes to mind. COST! I just replaced our armored cable with 7X19
3/16 inch stranded steel cable. The cost for a five thousand foot
spool was $500. If the Spectra costs 40 cents per foot that equals
$2000. I recently heard of a club that was using standard poly rope
to replace their wire. They were claiming 2000 foot tows on a 4000
foot runway. Does anyone know where this operation is and if they
were using 1/4 inch poly or a beefer size? I wouldn't think that 1/4
inch poly would last very long.

The Auckland Gliding Club in NZ has been using 1/4 inch poly on their
winch for at least two years -- contact them for comments through

http://www.gliding.co.nz/

Robert Curry wrote:
With all the talk about Spectra for winch wire replacement, one thing
comes to mind. COST! I just replaced our armored cable with 7X19
3/16 inch stranded steel cable. The cost for a five thousand foot
spool was $500. If the Spectra costs 40 cents per foot that equals
$2000. I recently heard of a club that was using standard poly rope
to replace their wire. They were claiming 2000 foot tows on a 4000
foot runway. Does anyone know where this operation is and if they
were using 1/4 inch poly or a beefer size? I wouldn't think that 1/4
inch poly would last very long.

I've asked for some more information on this. The polypropylene rope specs
I find for 1/4inch are too low for safe winch launching, nominally 1150lbs,
which is less than the recommended weak link for say an L-23 or G-103. On
gliderforum.com, Pete Mulhare from the Whangarei GC describes the migration
from wire rope to a product described as spectra (but otherwise suggested to
maybe have been dacron in another thread though the images appear to be
Spectra) to poly rope. However, this is
3-strand 8mm, which is a tick more than 5/16inch, and a breaking strength of
1710lbs, according to specs I've found. Splicing is supposed to reduce
strength, however, from our experience with Spectra, the splices never
broke.

From a performance aspect, if we're seeking 2000-2500ft launches as the
norm, 3/16inch wire rope hangs about 32-40sqft of surface into the equation.
My rough estimate is that the total drag of the wire and tackle is at least
equal to and likely greater than a fully-loaded G-103 under the tension of
launch to 2000ft and substantially more above that release height. The
higher the launch, the greater the effect of the rope diameter. 5/16inch
may be fine for short runs and moderate launch heights, but there even more
rope drag effect if high launches are the goal. Amsteel Blue would seem to
be the product of choice, but it's smallest available diameter is 3/16inch.
There are a couple of other products with 2800lb breaking strength at
1/8inch diameter. The cost of most products can be accomodated IF a length
will go 1000 launches. The weight advantages are a given.

Frank Whiteley
Colorado

"Charles Yeates" wrote in message
...
The Auckland Gliding Club in NZ has been using 1/4 inch poly on their
winch for at least two years -- contact them for comments through

http://www.gliding.co.nz/

Robert Curry wrote:
With all the talk about Spectra for winch wire replacement, one thing
comes to mind. COST! I just replaced our armored cable with 7X19
3/16 inch stranded steel cable. The cost for a five thousand foot
spool was $500. If the Spectra costs 40 cents per foot that equals
$2000. I recently heard of a club that was using standard poly rope
to replace their wire. They were claiming 2000 foot tows on a 4000
foot runway. Does anyone know where this operation is and if they
were using 1/4 inch poly or a beefer size? I wouldn't think that 1/4
inch poly would last very long.

My club has converted to poly and been running it for nearly 2 yrs now
I am not directly involved in the winch operation and most of the club
is away on the summer camps at present so I can only relate what I
have heard and will get the people who organise the winch system to
reply.
The club had wire but we have 3300ft(3100ft usable) of runway and it was
marginal
as a result usage was way down.When news of spectra type of ropes
became available, interest in the winch was stirred up because our
towplane is getting old (Pawnee manf in 50s)and requires more expensive
maintenance these days and replacement was being considered.
It was cheaper to see if spectra was going to help on getting more height
off the winch before buying a new towplane.
The experiment was a success, heights improved dramatically enough
that the majority of launches were getting away without problems.
The spectra is not made locally and the rope cost was a big part of the
operation budget.The winch still made a bigger per launch profit
than the towplane
Poly was suggested as it was very cheap in comparison and locally available,
no supply problems as we had with spectra.
Rope diameter started with smaller then switched larger ,I dont know the
actual rope diameter.
Splices require 2 extra tucks as they slowly slip and let go at the
recommended
number.
The biggest difference is the elasticity which has a number of effects on
the
launch practises and the equipment.
The hub of the drums had to be strengthened considerably as the rope was
slowly crushing them as it shrank back to normal length..
The winch driver radios the pilot and says nose down and generally stops the
drum
totally until released to stop releases under tension sending loops down to
the
winch and snagging and breaks occurring .
We have not had pay on guides but are considering it to stop over and under
loops
on the drum releasing suddenly during pulling out the ropes and snagging and
breaking
The big difference at the glider end is a very strong acceleration as the
winch can
be at full power taking stretch up in the rope then you are often airborne
in 20-30 feet
as the rope almost bungees you
The pilot MUST maintain tension on the rope ,if you ease the tension too
rapidly .a
slow/fast/slow/fast pio starts to occur and you have to bung off.
Once you get used to the very rapid acceleration to flying and maintain the
tension
then you get very good launches in comparison to wire .
Opinion seems to be that the big gain is in the acceleration and being able
to rotate
to full climb very quickly as you have a lot of energy available and the
large V8 pulling
does not slow down much, if at all (except maybe with the Duodiscus turbo)
Heights depend on all the usual variables but often single seaters will get
35-50%+ of
cable length in our case 3100ft length in still to 10kts, and increases with
wind speed .
Our site lies parallel to a small 700-800ft ridge and seabreeze is often
present ,most
launches are crosswind so the majority of launches have only a small
headwind component
Other clubs have come to see our operation and are changing or in the
process of changing
because of good launches and more profit per launch.
gary
Auckland Gliding Club


"Robert Curry" wrote in message
m...
With all the talk about Spectra for winch wire replacement, one thing
comes to mind. COST! I just replaced our armored cable with 7X19
3/16 inch stranded steel cable. The cost for a five thousand foot
spool was $500. If the Spectra costs 40 cents per foot that equals
$2000. I recently heard of a club that was using standard poly rope
to replace their wire. They were claiming 2000 foot tows on a 4000
foot runway. Does anyone know where this operation is and if they
were using 1/4 inch poly or a beefer size? I wouldn't think that 1/4
inch poly would last very long.

Other info now obtained
poly is 10 millimetres diameter and with use shrinks to 8ml
Durability is 1000-1500 launches on grass field being dragged out
by 4wd from stationary winch
Our local cost is $245US for 1000metres of rope.DO THE MATH.ITS CHEAP
We charge round $8US per launch this to help fund another winch
The winch motor is a 5.7ltr V8 petrol driving through an auto box to an
old truck axle with diff modified to drive one side at time (your common
winch)
The difference is the drums.The drums have a centre core cut from the old
front wheel
of a road roller 12ml thick hardened steel (we got it for free)and the side
plates
10ml thick with a welded on bevel at the top to act as a guide.
All this to stop the crushing effects.of the stretched rope
I have the email of one of the main members who helped in the
experimentation stage
and is on the instructor,s panel so can explain the changes to the flight
training on
winch launching with our style of winch.
Another club has also switched to this method and is having the same success
as we are on a similar strip length.Most single seaters are getting close to
or +50% of
rope length in height.
Trials at another club with 5400ft of runway found that the sag in the rope
with longer
lengths tended to get premature releases in top third of launch as angle of
the rope
into the release was not as flat.
This was a limited number of launches.
gary


"goneill" wrote in message
...
My club has converted to poly and been running it for nearly 2 yrs now
I am not directly involved in the winch operation and most of the club
is away on the summer camps at present so I can only relate what I
have heard and will get the people who organise the winch system to
reply.
The club had wire but we have 3300ft(3100ft usable) of runway and it was
marginal
as a result usage was way down.When news of spectra type of ropes
became available, interest in the winch was stirred up because our
towplane is getting old (Pawnee manf in 50s)and requires more expensive
maintenance these days and replacement was being considered.
It was cheaper to see if spectra was going to help on getting more height
off the winch before buying a new towplane.
The experiment was a success, heights improved dramatically enough
that the majority of launches were getting away without problems.
The spectra is not made locally and the rope cost was a big part of the
operation budget.The winch still made a bigger per launch profit
than the towplane
Poly was suggested as it was very cheap in comparison and locally
available,
no supply problems as we had with spectra.
Rope diameter started with smaller then switched larger ,I dont know the
actual rope diameter.
Splices require 2 extra tucks as they slowly slip and let go at the
recommended
number.
The biggest difference is the elasticity which has a number of effects on
the
launch practises and the equipment.
The hub of the drums had to be strengthened considerably as the rope was
slowly crushing them as it shrank back to normal length..
The winch driver radios the pilot and says nose down and generally stops
the
drum
totally until released to stop releases under tension sending loops down
to
the
winch and snagging and breaks occurring .
We have not had pay on guides but are considering it to stop over and
under
loops
on the drum releasing suddenly during pulling out the ropes and snagging
and
breaking
The big difference at the glider end is a very strong acceleration as the
winch can
be at full power taking stretch up in the rope then you are often airborne
in 20-30 feet
as the rope almost bungees you
The pilot MUST maintain tension on the rope ,if you ease the tension too
rapidly .a
slow/fast/slow/fast pio starts to occur and you have to bung off.
Once you get used to the very rapid acceleration to flying and maintain
the
tension
then you get very good launches in comparison to wire .
Opinion seems to be that the big gain is in the acceleration and being
able
to rotate
to full climb very quickly as you have a lot of energy available and the
large V8 pulling
does not slow down much, if at all (except maybe with the Duodiscus turbo)
Heights depend on all the usual variables but often single seaters will
get
35-50%+ of
cable length in our case 3100ft length in still to 10kts, and increases
with
wind speed .
Our site lies parallel to a small 700-800ft ridge and seabreeze is often
present ,most
launches are crosswind so the majority of launches have only a small
headwind component
Other clubs have come to see our operation and are changing or in the
process of changing
because of good launches and more profit per launch.
gary
Auckland Gliding Club


"Robert Curry" wrote in message
m...
With all the talk about Spectra for winch wire replacement, one thing
comes to mind. COST! I just replaced our armored cable with 7X19
3/16 inch stranded steel cable. The cost for a five thousand foot
spool was $500. If the Spectra costs 40 cents per foot that equals
$2000. I recently heard of a club that was using standard poly rope
to replace their wire. They were claiming 2000 foot tows on a 4000
foot runway. Does anyone know where this operation is and if they
were using 1/4 inch poly or a beefer size? I wouldn't think that 1/4
inch poly would last very long.

"goneill" wrote in message
...
Other info now obtained
poly is 10 millimetres diameter and with use shrinks to 8ml
Durability is 1000-1500 launches on grass field being dragged out
by 4wd from stationary winch
Our local cost is $245US for 1000metres of rope.DO THE MATH.ITS CHEAP
We charge round $8US per launch this to help fund another winch
The winch motor is a 5.7ltr V8 petrol driving through an auto box to an
old truck axle with diff modified to drive one side at time (your common
winch)
The difference is the drums.The drums have a centre core cut from the old
front wheel
of a road roller 12ml thick hardened steel (we got it for free)and the
side
plates
10ml thick with a welded on bevel at the top to act as a guide.
All this to stop the crushing effects.of the stretched rope
I have the email of one of the main members who helped in the
experimentation stage
and is on the instructor,s panel so can explain the changes to the flight
training on
winch launching with our style of winch.
Another club has also switched to this method and is having the same
success
as we are on a similar strip length.Most single seaters are getting close
to
or +50% of
rope length in height.
Trials at another club with 5400ft of runway found that the sag in the
rope
with longer
lengths tended to get premature releases in top third of launch as angle
of
the rope
into the release was not as flat.
This was a limited number of launches.
gary

Gary,

Thanks for the information. Now, if the poly could be spliced ~50/50 or so
with something like 1/8" Validator 12
http://www.samsonrope.com/admin/data...dator12_LR.pdf ,
(Vectran) http://www.pelicanrope.com/peli05c.htm both the bungee and sag
effects could be reduced with some cost benefits. This could be a solution
for long runs. When we launched with 1000ft of Spectra on the end of the
wire rope, we didn't pull the Spectra through the rollers. Two synthetics
with a reasonable join might work well as a hybrid solution.

Vectran is stronger than Spectra with a higher critical temperature, but
with somewhat less abrasion resistence.

There are some interesting 1/4" vectran sheathed products
http://www.pelicanrope.com/new04.htm
for improved abrasion resistence.

And Plasma 12
http://www.cortlandcable.com/psrope/...PlasmaRev9.pdf
Spectra in a variety of sizes.

Frank Whiteley
Colorado

Big point ,the bungee effect is VERY DESIRABLE at the initial acceleration
and rotation into the full climb,this is where the extra height is coming
from ,
no wasted field length ,the penalty for the bungee effect is at the top of
the
launch where the the winch needs to have the release with no tension
so the rope does not catapult at the winch and snag in the feed guide.
A number of single seaters are requesting 70 knots on the winch and
dipping the nose for release then pulling up with the residual speed often
getting 1600-1700ft.
Overall the good effects outweigh the few minor problems created ,these
problems are negated by operational changes
gary
"F.L. Whiteley" wrote in message
...

"goneill" wrote in message
...
Other info now obtained
poly is 10 millimetres diameter and with use shrinks to 8ml
Durability is 1000-1500 launches on grass field being dragged out
by 4wd from stationary winch
Our local cost is $245US for 1000metres of rope.DO THE MATH.ITS CHEAP
We charge round $8US per launch this to help fund another winch
The winch motor is a 5.7ltr V8 petrol driving through an auto box to an
old truck axle with diff modified to drive one side at time (your common
winch)
The difference is the drums.The drums have a centre core cut from the
old
front wheel
of a road roller 12ml thick hardened steel (we got it for free)and the
side
plates
10ml thick with a welded on bevel at the top to act as a guide.
All this to stop the crushing effects.of the stretched rope
I have the email of one of the main members who helped in the
experimentation stage
and is on the instructor,s panel so can explain the changes to the
flight
training on
winch launching with our style of winch.
Another club has also switched to this method and is having the same
success
as we are on a similar strip length.Most single seaters are getting
close
to
or +50% of
rope length in height.
Trials at another club with 5400ft of runway found that the sag in the
rope
with longer
lengths tended to get premature releases in top third of launch as angle
of
the rope
into the release was not as flat.
This was a limited number of launches.
gary

Gary,

Thanks for the information. Now, if the poly could be spliced ~50/50 or
so
with something like 1/8" Validator 12
http://www.samsonrope.com/admin/data...dator12_LR.pdf ,
(Vectran) http://www.pelicanrope.com/peli05c.htm both the bungee and sag
effects could be reduced with some cost benefits. This could be a
solution
for long runs. When we launched with 1000ft of Spectra on the end of the
wire rope, we didn't pull the Spectra through the rollers. Two synthetics
with a reasonable join might work well as a hybrid solution.

Vectran is stronger than Spectra with a higher critical temperature, but
with somewhat less abrasion resistence.

There are some interesting 1/4" vectran sheathed products
http://www.pelicanrope.com/new04.htm
for improved abrasion resistence.

And Plasma 12
http://www.cortlandcable.com/psrope/...PlasmaRev9.pdf
Spectra in a variety of sizes.

Frank Whiteley
Colorado

goneill wrote:

Big point ,the bungee effect is VERY DESIRABLE at the initial
acceleration and rotation into the full climb,this is where the extra
height is coming from ,

There is a small club in South Africa using a low cost plastic fibre
rope for auto towing.

Their operation is different in that they lay out the rope, then
deliberately loop back a specific distance (about 50m I think) on the
tow car end of the rope. When the launch commences the tow car
accelerates at full power. When the rope becomes taught, the tow car is
already moving at speed. The elasticity in the rope over its entire
length absorbs the shock of the take up. The pilot experiences rapid
acceleration and take off, not unlike a good winch launch. By the time
the glider has rotated into a normal climbing attitude the car and
glider are moving at constant speed and the launch proceeds normally.

The advantage of the method is that it eliminates the long ground run
associated with auto tow and there are no hesitations from gear changes
etc.

I believe they fly mainly K6 and sometimes K7. The reports I have heard
are positive, but I have not seen the operation and I don't have any
details. I can't comment on how effective or safe it is.

Happy New Year.

Ian

1. with a hybrid solution on a LONG (=5000ft) run, you still get 2500ft of
bungee effect at the beginning of the launch (not sure that 5000ft of bungee
effect is wanted)
2. then ELIMINATE the sag as the launch gets higher using the lighter and
thinner and more expensive rope

I'm not suggesting this for launch runs of 1000m, but those about 1400m
length or greater where someone has already demonstrated that 10mm poly has
issues of weight and drag.

Frank

"goneill" wrote in message
...
Big point ,the bungee effect is VERY DESIRABLE at the initial acceleration
and rotation into the full climb,this is where the extra height is coming
from ,
no wasted field length ,the penalty for the bungee effect is at the top of
the
launch where the the winch needs to have the release with no tension
so the rope does not catapult at the winch and snag in the feed guide.
A number of single seaters are requesting 70 knots on the winch and
dipping the nose for release then pulling up with the residual speed often
getting 1600-1700ft.
Overall the good effects outweigh the few minor problems created ,these
problems are negated by operational changes
gary
"F.L. Whiteley" wrote in message
...

"goneill" wrote in message
...
Other info now obtained
poly is 10 millimetres diameter and with use shrinks to 8ml
Durability is 1000-1500 launches on grass field being dragged out
by 4wd from stationary winch
Our local cost is $245US for 1000metres of rope.DO THE MATH.ITS CHEAP
We charge round $8US per launch this to help fund another winch
The winch motor is a 5.7ltr V8 petrol driving through an auto box to
an
old truck axle with diff modified to drive one side at time (your
common
winch)
The difference is the drums.The drums have a centre core cut from the
old
front wheel
of a road roller 12ml thick hardened steel (we got it for free)and the
side
plates
10ml thick with a welded on bevel at the top to act as a guide.
All this to stop the crushing effects.of the stretched rope
I have the email of one of the main members who helped in the
experimentation stage
and is on the instructor,s panel so can explain the changes to the
flight
training on
winch launching with our style of winch.
Another club has also switched to this method and is having the same
success
as we are on a similar strip length.Most single seaters are getting
close
to
or +50% of
rope length in height.
Trials at another club with 5400ft of runway found that the sag in the
rope
with longer
lengths tended to get premature releases in top third of launch as
angle
of
the rope
into the release was not as flat.
This was a limited number of launches.
gary

Gary,

Thanks for the information. Now, if the poly could be spliced ~50/50 or
so
with something like 1/8" Validator 12
http://www.samsonrope.com/admin/data...dator12_LR.pdf ,
(Vectran) http://www.pelicanrope.com/peli05c.htm both the bungee and sag
effects could be reduced with some cost benefits. This could be a
solution
for long runs. When we launched with 1000ft of Spectra on the end of
the
wire rope, we didn't pull the Spectra through the rollers. Two
synthetics
with a reasonable join might work well as a hybrid solution.

Vectran is stronger than Spectra with a higher critical temperature, but
with somewhat less abrasion resistence.

There are some interesting 1/4" vectran sheathed products
http://www.pelicanrope.com/new04.htm
for improved abrasion resistence.

And Plasma 12
http://www.cortlandcable.com/psrope/...PlasmaRev9.pdf
Spectra in a variety of sizes.

Frank Whiteley
Colorado

Actually, I'm not sure the economic effect would be positive. The rope that
winds onto the drum first doesn't see much wear so the effect of using cheap
rope might not be significant. Looking at the big picture, the cost
difference per launch for cable replacement might not be worth the hassle of
using two kinds of rope. The price of high-strength synthetics is coming
down anyway.

All the engineering data I have says Spectra will outlast lesser synthetics
by a factor of 10 or more. Nothing wrong with experimenting with cheaper
materials though. If you want a "bungee effect", then nylon would be a
better material than poly.

The bungee effect is a way to store engine power and then release it at the
point of peak power demand with the result that a smaller engine can do the
work for a larger one. My gut reaction is that it would be better to use a
larger engine and no bungee effect - an engine is controllable and the
bungee effect is not. A stretchy rope is a step away from precise control
of the launch.

In my experience, most problems that arise in winch operations come from
poorly thought out efforts to save money up front. The best way to save
money is to do the thing right the first time.

Bill Daniels

"F.L. Whiteley" wrote in message
...
1. with a hybrid solution on a LONG (=5000ft) run, you still get 2500ft
of
bungee effect at the beginning of the launch (not sure that 5000ft of
bungee
effect is wanted)
2. then ELIMINATE the sag as the launch gets higher using the lighter and
thinner and more expensive rope

I'm not suggesting this for launch runs of 1000m, but those about 1400m
length or greater where someone has already demonstrated that 10mm poly
has
issues of weight and drag.

Frank

"goneill" wrote in message
...
Big point ,the bungee effect is VERY DESIRABLE at the initial
acceleration
and rotation into the full climb,this is where the extra height is
coming
from ,
no wasted field length ,the penalty for the bungee effect is at the top
of
the
launch where the the winch needs to have the release with no tension
so the rope does not catapult at the winch and snag in the feed guide.
A number of single seaters are requesting 70 knots on the winch and
dipping the nose for release then pulling up with the residual speed
often
getting 1600-1700ft.
Overall the good effects outweigh the few minor problems created ,these
problems are negated by operational changes
gary
"F.L. Whiteley" wrote in message
...

"goneill" wrote in message
...
Other info now obtained
poly is 10 millimetres diameter and with use shrinks to 8ml
Durability is 1000-1500 launches on grass field being dragged out
by 4wd from stationary winch
Our local cost is $245US for 1000metres of rope.DO THE MATH.ITS
CHEAP
We charge round $8US per launch this to help fund another winch
The winch motor is a 5.7ltr V8 petrol driving through an auto box to
an
old truck axle with diff modified to drive one side at time (your
common
winch)
The difference is the drums.The drums have a centre core cut from
the
old
front wheel
of a road roller 12ml thick hardened steel (we got it for free)and
the
side
plates
10ml thick with a welded on bevel at the top to act as a guide.
All this to stop the crushing effects.of the stretched rope
I have the email of one of the main members who helped in the
experimentation stage
and is on the instructor,s panel so can explain the changes to the
flight
training on
winch launching with our style of winch.
Another club has also switched to this method and is having the same
success
as we are on a similar strip length.Most single seaters are getting
close
to
or +50% of
rope length in height.
Trials at another club with 5400ft of runway found that the sag in
the
rope
with longer
lengths tended to get premature releases in top third of launch as
angle
of
the rope
into the release was not as flat.
This was a limited number of launches.
gary

Gary,

Thanks for the information. Now, if the poly could be spliced ~50/50
or
so
with something like 1/8" Validator 12
http://www.samsonrope.com/admin/data...dator12_LR.pdf ,
(Vectran) http://www.pelicanrope.com/peli05c.htm both the bungee and
sag
effects could be reduced with some cost benefits. This could be a
solution
for long runs. When we launched with 1000ft of Spectra on the end of
the
wire rope, we didn't pull the Spectra through the rollers. Two
synthetics
with a reasonable join might work well as a hybrid solution.

Vectran is stronger than Spectra with a higher critical temperature,
but
with somewhat less abrasion resistence.

There are some interesting 1/4" vectran sheathed products
http://www.pelicanrope.com/new04.htm
for improved abrasion resistence.

And Plasma 12
http://www.cortlandcable.com/psrope/...PlasmaRev9.pdf
Spectra in a variety of sizes.

Frank Whiteley
Colorado