Winch rope 1/4 inch poly

[Robert Curry]

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.

[Charles Yeates]

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.

[F.L. Whiteley]

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.
>

[goneill]

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]

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.
>
>

[F.L. Whiteley]

"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/datasheets/pdf/Validator12_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/catalogpdf/NewPlasmaRev9.pdf
Spectra in a variety of sizes.

Frank Whiteley
Colorado

[goneill]

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/datasheets/pdf/Validator12_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/catalogpdf/NewPlasmaRev9.pdf
> Spectra in a variety of sizes.
>
> Frank Whiteley
> Colorado
>
>
>

[Ian Forbes]

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

[F.L. Whiteley]

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/datasheets/pdf/Validator12_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/catalogpdf/NewPlasmaRev9.pdf
> > Spectra in a variety of sizes.
> >
> > Frank Whiteley
> > Colorado
> >
> >
> >
>
>

[Bill Daniels]

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/datasheets/pdf/Validator12_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/catalogpdf/NewPlasmaRev9.pdf
> > > Spectra in a variety of sizes.
> > >
> > > Frank Whiteley
> > > Colorado
> > >
> > >
> > >
> >
> >
>
>

[goneill]

There is talk of trying a hybrid to eliminate line sag for longer runs,have
to
wait and see on that one.
The point about the rope storing energy equal to a bigger engine, well we
are
already using a 5.7 ltr V8 with performance mods to get high output,to get
more pull is going to cost a lot in terms of the engine verses $250US for
1000 metres of poly.
The second part of this is the club 1.5hrs drive south of us had their winch
motor
stolen because it was very highly tweaked up and a prize worth stealing
gary

"Bill Daniels" > wrote in message
hlink.net...
> 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/datasheets/pdf/Validator12_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/catalogpdf/NewPlasmaRev9.pdf
> > > > Spectra in a variety of sizes.
> > > >
> > > > Frank Whiteley
> > > > Colorado
> > > >
> > > >
> > > >
> > >
> > >
> >
> >
>

[Bill Daniels]

I have nothing against cheap rope, if the long term economics work. But, if
you reduce the question to how much extra it costs for each launch, an all
spectra rope would likely add less than $1 US per launch and return an extra
25% in height achieved, at least on long (5000 feet+) winch runs. (Don't
expect to see that much extra height on short runs.)

For me, adding $1 to the launch costs for a higher, sweeter, more reliable
launch is well worth it.

Tweaking an ex-automobile engine for more output is an expensive way to go
in the long run since it tends to make for a peaky torque curve and less
reliability. What seems to work best for a winch is an engine with a flat
power curve and a huge torque reserve. Every automobile power train that I
have seen used in glider winch had problems of one kind or another - usually
inadequate control of the launch because of the transmission shifting to
accommodate the peaky torque curve.

Getting an engine stolen is a security issue, not a winch design issue.
But, if the engine had been a 3000 pound diesel, the bandits would have
probably left it alone.

Bill Daniels

"goneill" > wrote in message
...
> There is talk of trying a hybrid to eliminate line sag for longer
runs,have
> to
> wait and see on that one.
> The point about the rope storing energy equal to a bigger engine, well we
> are
> already using a 5.7 ltr V8 with performance mods to get high output,to get
> more pull is going to cost a lot in terms of the engine verses $250US for
> 1000 metres of poly.
> The second part of this is the club 1.5hrs drive south of us had their
winch
> motor
> stolen because it was very highly tweaked up and a prize worth stealing
> gary
>
> "Bill Daniels" > wrote in message
> hlink.net...
> > 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/datasheets/pdf/Validator12_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/catalogpdf/NewPlasmaRev9.pdf
> > > > > Spectra in a variety of sizes.
> > > > >
> > > > > Frank Whiteley
> > > > > Colorado
> > > > >
> > > > >
> > > > >
> > > >
> > > >
> > >
> > >
> >
>
>

[Doug Taylor]

Vectran would not be a very suitable winch rope. It tends to fatigue
relatively rapidly with bending. It is useful as standing rigging on
sailboats but isn't used for running rigging. Technora is about the
same tensile strength and modulus (both have very high modulus)
without the fatigue problem. I don't have any proof of this but was
told this by someone who appeared to know quite a lot about all the
various new fibers being used in rope.

> >
> 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/datasheets/pdf/Validator12_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/catalogpdf/NewPlasmaRev9.pdf
> Spectra in a variety of sizes.
>
> Frank Whiteley
> Colorado

[goneill]

I was not present at the original trials but I believe the extra height from
Spectra
type rope was about the same as the poly.
The one other effect of poly is its memory seems to be only to shrink into
its own
length and if released under tension pulls away from the glider and only
throws
loops towards the winch but they do not reach the winch if the drum is
stopped
no tendency for the ends to whip .
I saw a suggestion about nylon earlier in the thread to create the bungee
effect
but correct me if I am wrong but nylon does tend to whip out
gary
"Bill Daniels" > wrote in message
link.net...
> I have nothing against cheap rope, if the long term economics work. But,
if
> you reduce the question to how much extra it costs for each launch, an all
> spectra rope would likely add less than $1 US per launch and return an
extra
> 25% in height achieved, at least on long (5000 feet+) winch runs. (Don't
> expect to see that much extra height on short runs.)
>
> For me, adding $1 to the launch costs for a higher, sweeter, more reliable
> launch is well worth it.
>
> Tweaking an ex-automobile engine for more output is an expensive way to go
> in the long run since it tends to make for a peaky torque curve and less
> reliability. What seems to work best for a winch is an engine with a flat
> power curve and a huge torque reserve. Every automobile power train that
I
> have seen used in glider winch had problems of one kind or another -
usually
> inadequate control of the launch because of the transmission shifting to
> accommodate the peaky torque curve.
>
> Getting an engine stolen is a security issue, not a winch design issue.
> But, if the engine had been a 3000 pound diesel, the bandits would have
> probably left it alone.
>
> Bill Daniels
>
> "goneill" > wrote in message
> ...
> > There is talk of trying a hybrid to eliminate line sag for longer
> runs,have
> > to
> > wait and see on that one.
> > The point about the rope storing energy equal to a bigger engine, well
we
> > are
> > already using a 5.7 ltr V8 with performance mods to get high output,to
get
> > more pull is going to cost a lot in terms of the engine verses $250US
for
> > 1000 metres of poly.
> > The second part of this is the club 1.5hrs drive south of us had their
> winch
> > motor
> > stolen because it was very highly tweaked up and a prize worth stealing
> > gary
> >
> > "Bill Daniels" > wrote in message
> > hlink.net...
> > > 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/datasheets/pdf/Validator12_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/catalogpdf/NewPlasmaRev9.pdf
> > > > > > Spectra in a variety of sizes.
> > > > > >
> > > > > > Frank Whiteley
> > > > > > Colorado
> > > > > >
> > > > > >
> > > > > >
> > > > >
> > > > >
> > > >
> > > >
> > >
> >
> >
>

[Bill Daniels]

How about this "bungee effect" scenario:

You accelerate the glider smartly and stretch the rope. The glider lifts
off normally but encounters a strong headwind layer at 100 feet AGL. The
pilot frantically signals for less speed and the winch driver promptly
reduces power, but the "bungee effect" just keeps pulling the glider faster
until the stored energy is depleted. Then the glider airspeed sags as the
reduced winch engine power is felt. The pilot signals for more speed and
the winch engine throttle is again advanced, but the additional power is
absorbed in stretching the rope before the glider sees the additional speed.
Then repeat cycle.

I once tried auto tow with 3000 feet of 5mm nylon and this is what I
encountered. We never did tame the launch so we went back to steel wire.
_______

This is a very bad way to control a launch unless the winch power is set
very low so the glider pilot controls airspeed with pitch attitude. I don't
like the idea of winch rope that stretches any more than needed to damp
vibrations. I like the idea of instantaneous airspeed response to throttle
changes. Spectra stretches less than 1% at the failure point. Spectra is
pretty much a "drop in" replacement for steel wire except that it is 90%
lighter.

It's much better to have reserve power from a large, high torque engine and
a winch line with little stretch. My dream winch is a powerful one that has
a telemetry link to the glider. The winch pulls the glider to the desired
airspeed at the maximum safe acceleration and holds it precisely there while
the pilot pulls up to tension the rope to 80 - 90% of the weak-link breaking
point. That is the definition of an optimized launch.

Bill Daniels

[goneill]

First line of your reply is the wrong way round, the full power signal is
given and about 1-2 seconds stretching later the glider accelerates very
rapidly
and is airborne 1-2 fuse lengths, depending on which glider and winch
power setting has been used you have a very short initial climb phase
and have to rotate to full climb or you will overspeed ,the winch reduces
his
power setting as you rotate into the full climb arc.
We are not talking a huge effect here and your reference to your use of
nylon
as a launch rope ,if I am correct nylon has far more spring in it than poly.
Autotow we do here for fun every now and again and the acceleration is
slower
The other thing to remember is this club and other clubs have dialed up
many
thousands of launches on this poly rope and it has shown to be consistant
and predictable in the bungee effect
gary
"Bill Daniels" > wrote in message
link.net...
> How about this "bungee effect" scenario:
>
> You accelerate the glider smartly and stretch the rope. The glider lifts
> off normally but encounters a strong headwind layer at 100 feet AGL. The
> pilot frantically signals for less speed and the winch driver promptly
> reduces power, but the "bungee effect" just keeps pulling the glider
faster
> until the stored energy is depleted. Then the glider airspeed sags as the
> reduced winch engine power is felt. The pilot signals for more speed and
> the winch engine throttle is again advanced, but the additional power is
> absorbed in stretching the rope before the glider sees the additional
speed.
> Then repeat cycle.
>
> I once tried auto tow with 3000 feet of 5mm nylon and this is what I
> encountered. We never did tame the launch so we went back to steel wire.
> _______
>
> This is a very bad way to control a launch unless the winch power is set
> very low so the glider pilot controls airspeed with pitch attitude. I
don't
> like the idea of winch rope that stretches any more than needed to damp
> vibrations. I like the idea of instantaneous airspeed response to
throttle
> changes. Spectra stretches less than 1% at the failure point. Spectra is
> pretty much a "drop in" replacement for steel wire except that it is 90%
> lighter.
>
> It's much better to have reserve power from a large, high torque engine
and
> a winch line with little stretch. My dream winch is a powerful one that
has
> a telemetry link to the glider. The winch pulls the glider to the desired
> airspeed at the maximum safe acceleration and holds it precisely there
while
> the pilot pulls up to tension the rope to 80 - 90% of the weak-link
breaking
> point. That is the definition of an optimized launch.
>
> Bill Daniels
>

[Martin Gregorie]

On Fri, 2 Jan 2004 17:39:28 +1300, "goneill" >
wrote:

>We are not talking a huge effect here
>
Agreed. I was watching launches at Auckland a few weeks ago and didn't
notice any gross bungee effects. All the launches I saw looked pretty
smooth.

One question: I saw that you were using a long plastic covered strop
between the drogue and glider, but could not see either a weak link or
a set of colour coded strops. Did I miss something?


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

[goneill]

The weak link is there between chute and strop
so when the pilot pulls the bung there is something
relatively large to find attached to the rings.
The strop seems to come down slower than just the rings
gary
"Martin Gregorie" > wrote in message
...
> On Fri, 2 Jan 2004 17:39:28 +1300, "goneill" >
> wrote:
>
> >We are not talking a huge effect here
> >
> Agreed. I was watching launches at Auckland a few weeks ago and didn't
> notice any gross bungee effects. All the launches I saw looked pretty
> smooth.
>
> One question: I saw that you were using a long plastic covered strop
> between the drogue and glider, but could not see either a weak link or
> a set of colour coded strops. Did I miss something?
>
>
> --
> martin@ : Martin Gregorie
> gregorie : Harlow, UK
> demon :
> co : Zappa fan & glider pilot
> uk :
>

[Martin Gregorie]

On Sat, 3 Jan 2004 08:36:59 +1300, "goneill" >
wrote:

>The weak link is there between chute and strop
>so when the pilot pulls the bung there is something
>relatively large to find attached to the rings.
>
.....makes sense


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

[Bruce Hoult]

In article >,
Martin Gregorie > wrote:

> On Fri, 2 Jan 2004 17:39:28 +1300, "goneill" >
> wrote:
>
> >We are not talking a huge effect here
>
> Agreed. I was watching launches at Auckland a few weeks ago and didn't
> notice any gross bungee effects. All the launches I saw looked pretty
> smooth.

I took a couple of winch launches at Puhipuhi in a Janus on I think poly
rope last week. Seemed pretty smooth, and I didn't notice bad effects
from stretching. Not that I got much height from my own pathetic
attempt (less than 1000 ft), but it was enough to get away...

-- Bruce

[Martin Gregorie]

On Mon, 12 Jan 2004 20:35:06 +1300, Bruce Hoult >
wrote:

>In article >,
> Martin Gregorie > wrote:
>
>> On Fri, 2 Jan 2004 17:39:28 +1300, "goneill" >
>> wrote:
>>
>> >We are not talking a huge effect here
>>
>> Agreed. I was watching launches at Auckland a few weeks ago and didn't
>> notice any gross bungee effects. All the launches I saw looked pretty
>> smooth.
>
>I took a couple of winch launches at Puhipuhi in a Janus on I think poly
>rope last week. Seemed pretty smooth, and I didn't notice bad effects
>from stretching. Not that I got much height from my own pathetic
>attempt (less than 1000 ft), but it was enough to get away...
>
I cheated last time I flew: poly rope all right, but attached to a
Cessna 182, not a winch. We got away too, thanks to being dropped at
2500 on a ridge across the valley from Omarama. I was in the DG-1000
and spent the next three hours learning the first steps to mountain
flying from Hugh. Fantastic! Worth every penny.

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

[Robert Curry]

(Doug Taylor) wrote in message >...
> Vectran would not be a very suitable winch rope. It tends to fatigue
> relatively rapidly with bending. It is useful as standing rigging on
> sailboats but isn't used for running rigging. Technora is about the
> same tensile strength and modulus (both have very high modulus)
> without the fatigue problem. I don't have any proof of this but was
> told this by someone who appeared to know quite a lot about all the
> various new fibers being used in rope.
>
> > >
> > 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/datasheets/pdf/Validator12_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/catalogpdf/NewPlasmaRev9.pdf
> > Spectra in a variety of sizes.
> >
> > Frank Whiteley
> > Colorado

OK, I can see that their are many ideas & successes on the polyrope.
Can anyone give me an idea as to the height advantage. For example.
Four thousand foot runway no wind. With wire we usually climbed to
1000 feet and with poly we averaged 1200? Does anyone know of a web
site where this info may have been posted?

Robert Curry
Ohio

[goneill]

Your heights seem to be a bit low off 4000ft on poly ,I would have
expected 1500 as an average
On 3300ft we are averaging 1300-1600ft with single seaters
Have you adapted the launch profile to take advantage of the rope.
gary
"Robert Curry" > wrote in message
om...
> (Doug Taylor) wrote in message
>...
> > Vectran would not be a very suitable winch rope. It tends to fatigue
> > relatively rapidly with bending. It is useful as standing rigging on
> > sailboats but isn't used for running rigging. Technora is about the
> > same tensile strength and modulus (both have very high modulus)
> > without the fatigue problem. I don't have any proof of this but was
> > told this by someone who appeared to know quite a lot about all the
> > various new fibers being used in rope.
> >
> > > >
> > > 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/datasheets/pdf/Validator12_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/catalogpdf/NewPlasmaRev9.pdf
> > > Spectra in a variety of sizes.
> > >
> > > Frank Whiteley
> > > Colorado
>
> OK, I can see that their are many ideas & successes on the polyrope.
> Can anyone give me an idea as to the height advantage. For example.
> Four thousand foot runway no wind. With wire we usually climbed to
> 1000 feet and with poly we averaged 1200? Does anyone know of a web
> site where this info may have been posted?
>
> Robert Curry
> Ohio