SAFE Winch Launching
Derek Copeland
You may have got the impression from some recent correspondence on this
site that winch launchings is about as risky as bungey jumping or joining
a Kamikaze squadron!
In fact we do many tens of thousands, if not hundreds of thousands, of
winch launches in Europe with only the very occasional accident. Even the
ones we do have are largely avoidable.
Most of the serious winch launching accidents come into the following
categories:
1) Ground loop or cartwheel after catching a wingtip on the ground.
2) Flick spin due to over-rotating after lift off.
3) Stall/spin after a cable break or other launch failure.
These can be avoided respectively by:
a) Pulling the cable release knob if a wing drops.
b) Monitoring the airspeed and controlling the rate of rotation to not
more than 10 degrees/second.
c) Lowering the nose to the recovery attitude and regaining a safe
airspeed before attempting any further manoeuvres. Also learning the most
suitable options for landing safely from various heights.
Things happen much more quickly during a winch launch than they do during
an aerotow, so you do need to engage your brain before you start moving,
not halfway up the launch.
There is starting to be more interest in winch launching in the States,
due to rising fuel and maintenance costs for tug aircraft. However I have
found it somewhat disappointing that some of the leading US protagonists
seem to want to ignore any advice from European clubs and winch builders,
who have a wealth of experience in this method. It's the 'good ol' US
of A always knows best' syndrome. As a result you have already suffered a
fatality and two serious injuries this year from a fraction of the number
of launches that we would do in Europe in the same period.
You already have the most of the basics for winch launching in the US. You
have many vehicles fitted with large and powerful V8 engines and good
automatic gearboxes that can be cannibalised to make decent winches.
Please note that you must disable any kick down arrangement on the
automatic gearboxes. If you join a Yahoo group called 'Winch Design' you
will find a document written by the BGA winching advisor called 'Proven UK
specification' which gives you most of the information needed to build a
good winch. You don't need very fancy and expensive, but as yet unproven,
diesel-hydraulic or electric winches that the above protagonists seem to
think are essential.
Derek Copeland
bildan
Written by someone who thinks British automobiles with Lucas electrics
are reliable transportation.
Brian Goodspeed
>Written by someone who thinks British automobiles with Lucas electrics
>are reliable transportation.
>
Written by someone who always claims to know everything about everything -
except that Lucas no longer exist. They were taken over and bankrupted by
a U.S. company!
rlovinggood
Ray Lovinggood
Carrboro, North Carolina, USA
PS: LUCAS: Prince of Darkness
Also, why do Brits drink warm beer? They have Lucas refrigerators...
vic20owner
while I have never winch launched and only just recently soloed I have
been a member of that group for a while now simply because I knew I
would learn a thing or two about winch launching by just lurking and
paying attention.
Derek Copeland
>
>Written by someone who thinks British automobiles with Lucas electrics
are reliable transportation.
>
Having in the past owned several rather unreliable Ford cars, which is an
American Corporation, I have for the last 15 years or so bought
British/French Peugeots and Citroens, most of which have been totally
reliable over big annual mileages. Fords seem to last for 60,000 miles and
then everything goes wrong with them!
A number of my friends have British Rover cars (probably with some Lucas
components), and they also seem to be much more reliable than Fords.
Unfortunately that company went into liquidation and was eventually bought
by the Chinese.
Derek Copeland
Surfer!
<delco...@tiscali.co.uk> writes
<snip>
>
>Most of the serious winch launching accidents come into the following
>categories:
>
>1) Ground loop or cartwheel after catching a wingtip on the ground.
>2) Flick spin due to over-rotating after lift off.
>3) Stall/spin after a cable break or other launch failure.
>
>These can be avoided respectively by:
>
>a) Pulling the cable release knob if a wing drops.
>b) Monitoring the airspeed and controlling the rate of rotation to not
>more than 10 degrees/second.
And not starting to rotate unless the winch is managing to accelerate
the glider. When that happens, pull off, and aviate back to the ground.
The issues I know of in that situation are lowering the nose to far and
slamming into the ground, and pulling the airbrakes too early (before
the glider is at a normal approach speed) and again slamming into the
ground.
>c) Lowering the nose to the recovery attitude and regaining a safe
>airspeed before attempting any further manoeuvres. Also learning the most
>suitable options for landing safely from various heights.
<Snip>
--
Surfer!
Email to: ramwater at uk2 dot net
Surfer!
<6c6860e3-55dc-4c28...@h18g2000yqj.googlegroups.com>,
rlovinggood <rlovi...@bellsouth.net> writes
<snip>
>
>Also, why do Brits drink warm beer?
It's not warm, it's cellar temperature - about 55F - and it tastes best
at that temperature if it's kept properly. Other beers / lagers have to
be chilled to kill the 'taste'.
Dave Martin
Warm beer......
It is a fairly simple process we drink our beer warm so we can taste it.
The residue, is pumped from the urinal into large vats and frozen, it is
then resold as lager or American beer to people with no taste
Dave
Bruce
As an aside it is perhaps ironic that much of the world's beer
production comes from a South African company (SAB Miller)
Can't say whether it is better or worse than average, warm or cold since
I never got past the "this all tastes like cat pee" stage. ;-)
Alistair Wright
mentioned auto towing. The 'reverse auto tow' is the most efficient launch
method I have ever encountered. We used it at the Essex Club at North Weald
while I instructed there.
You need a nice long runway, about 6000ft is ideal but shorter will do. The
ingredients are:
1) Two large automatic cars of about 100BHP - we used retired V6 Ford
Zephyrs - we will call them car1 and car2. A driver and observer (who
watches the glider) are required.
2) A large grooved pulley about six feet in diameter on a rotatable gimbal
and anchored firmly to the ground. The pulley is at the opposite end of the
runway to the launch point.
3) A piece of single strand piano wire the length of the runway.
4) Gliders with pilots.
The wire is passed over the pulley and attached to car 1 which is sitting at
the pulley and the other end to the glider via the usual rope, parachute,
and weak link. Car 2 is sitting at the launch point. Slack is taken up, and
at the all out signal car 1 sets off down the runway towards the glider
which most obligingly lifts off, and sets off up what is now effectively a
winch launch. Meanwhile car 2 sets off following the glider towards the
pulley avoiding car 1, of course, which is driving at about 35- 40 mph
towards the launch point. Glider releases, (we often got nearly 2000ft on a
good day), and car 1 carries on the launch point while car 2 arrives at the
pulley. The cable has launching tackle on both ends, so the next glider is
coupled on and car 2 is connected to the cable and does the next launch ...
need I go on? We used to get 20 launches an hour using this method. No time
is wasted retrieving cables. No need to buy an expensive winch, and the
cheap cable lasted a long time. Ford Zephyrs were also fairly cheap from the
scrap yard, and we had people in the club adept at fixing them. As quite of
lot of American clubs seem to have access to runways I cannot see why they
cannot try this method of launching. I recommend it.
Alistair Wright
Frank Whiteley
Having launched with EGC at North Weald a couple of occasions many
years ago, my experience was a bit different. We got maybe 800ft in
the K13, but I think the normal launch cars were broken down and a
manually shifted Vauxhall was in use. Each time it shifted, the
drogue chute was over the nose of the glider. I got 1200ft in the SHK
on the other day. IIRC, airspace was limited to 2200ft until about
five miles north. (Have to dig out an old chart that's archived
somewhere). On the days I was there, only one vehicle was in use and
on the first day, there was a wire snarl up on the pulley system (two
big wheels) that delayed things for well over an hour.
However, I do agree that the system may be very efficient. To that
end, the old Cotswold GC system was, IMVHO, more elegant and required
less people to operate
http://www.coloradosoaring.org/thinking_pages/ground_launching/reverse_pulley/default.htm
In addition to the long runway, CGC insisted on a lateral 2000ft clear
zone around the pulley. Piano wire is nasty stuff when it breaks
under tension. They also used rather more substantial tow vehicles
and you couldn't launch modern K-21's, DG-50X's and 1000's and single
seaters with Zephyr's. You can't discount the cost of powerful tow
vehicles. We did okay at Enstone GC with an XJ6 Jag on auto tow.
After many years, Cotswold GC reverted to winching.
http://www.cotswoldgliding.co.uk/ They formerly had a history page
about the reverse pulley, but I don't find anything on their web site
now. They do mention that learning to glide is cheaper than learning
to drive though;^)
We do have some long runways in the US, but few are lacking runway
lights or other obstacles that are too close to entertain reverse
pulley launching. On these same runways, it's quite feasible to winch
using the UHMWPE ropes.
Regards,
Frank Whiteley
johngalloway
Seems to be a non sequitor considering that Derek was advocating US
not UK engines for winches.
bildan
Written by someone who actually knows how to use Google.
BTW, I think Lucas was bought by DARPA who was looking for the secret
of light bulbs that emit darkness.
Del C
>
>Seems to be a non sequitor considering that Derek was advocating US not
UK engines for winches.
>
Well I would, but most UK cars do not have huge gas guzzling V8 engines
that are big and powerful enough to power a winch, due to our
Government's excessiveand historical taxation of road vehicle fuels.
Possibly V12 Jaguar or Rolls Royce engines would do. if you can find them
cheaply enough second hand. If you want a new engine, then the GM Marine
engines, as used by Skylaunch, are as good and cheap as anything.
Derek Copeland
P.S. Lucas made their initial fortune by selling reversing lights for
Italian tanks in WW2. They worked perfectly!
chipsoars
My understanding is that Lucas, Prince of Darkness, was also
responsible for the invention of intermittent windshield wipers.
I couldn't resist.............
Chip F. - who loves a good winch launch.
vaughn
"chipsoars" <ch...@fitzpatrick-family.org> wrote in message
news:aa2586ad-09ee-47fb...@y17g2000yqn.googlegroups.com...
My understanding is that Lucas, Prince of Darkness, was also
responsible for the invention of intermittent windshield wipers.
Well, sort of. They just weren't supposed to be intermittent at the
time.
History seems to assign the invention of true intermittent windshield
washers to Robert Kearns.
http://www.theautochannel.com/news/2005/02/25/005398.html
I seem to remember a movie...
Vaughn
Chris Nicholas
(UK):
There were at least three different generations of Ford trucks used
for launching at North Weald, with the Ford Zodiac cars as a brief
interlude. The Vauxhall that Frank mentions must have been on a day
during the old generations of second hand vehicles which were
certainly not the best. Somebody must have used their own private car
for launching – I do not recall the club ever had a Vauxhall between
1970 when I started and 1991 or thereabouts when we had to stop wire
launches at North weald.
For anyone to judge the capability of reverse pulley launching by a
sight of one off day in the 1970’s is not a fair comparison.
I joined the club in 1970, and they were using ex-US or Canadian
service Ford F100 trucks. A few years later, the second-hand supply of
these ran out, and old Mark IV Ford Zodiac’s were tried as an
affordable alternative with sufficient power.
In 1978 we undertook a major re-equipment. As well as two K13s and a
tug, we bought two brand new Ford F100 trucks. They had 5.8 L V8
engines and propane gas tanks. (We still have one of the engines. It
went on for a life after death, as a replacement engine in an ex-ATC
Eagle-type winch, which we still have as a backup winch at Ridgewell.)
In 1988, these were wearing out. We and Lasham ordered new Ford F250
trucks. We had two, but I can’t remember how many Lasham ordered at
that time. They had 7.5 L V8 engines, supercooling, LPG conversion,
and cost £10,251.25 each including delivery and VAT. This was the
net price after I was able to arrange a healthy discount through my
connections with Ford at that time, which included from time to time
arranging publicity photographs at North Weald with gliders in the
background when they wanted to launch a marketing campaign for a new
vehicle.
These were the last tow trucks we used for launching at North Weald.
(In the early 1990s, the council which had bought the aerodrome banned
wire launching at the request of powered aircraft operators at the
aerodrome. They had concerns about mixing wire and their aircraft at
the same time.)
The last version of the “pulley” that we used had two wheels on a
pivoting frame, with a short straight between them which formed an
anvil. A Guillotine arrangement ran through the horizontal pivot, so
we could meet the requirement to be able to chop the cable during a
launch if necessary. As far as I know, the Aston Down device did not
permit such a safety arrangement.
As a general comment on life, launching, and the universe, I would add
that there are two ways (at least) to contemplate a technique that you
have not used before.
1. Invent it from the beginning yourself and make the same mistakes as
everybody else did.
2. Learn from people who eventually got it right and do it similarly.
Yours in a spirit of friendship and cooperation.
Chris N.
Del C
merits of tasty warm British beer against that cold p*ss water the Yanks
drink, an attack on the late lamented Lucas car component company, and the
merits or otherwise of reverse pulley autotowing.
In the same period as Chris describes below, we did straight autotowing at
Lasham using various models of US Ford F series pick up trucks. This was
mainly because the winches available at the time were so poor. Once Tost,
Supacat and Skylaunch started building decent quality winches, it was
realised that you could get get much higher and safer launches, so the
changeover was made in the mid 1980's. I believe that only two UK clubs
still autotow in any form.
Derek Copeland
At 12:04 06 July 2009, Chris Nicholas wrote:
>Just to put the record straight about pulley launching at North Weald
>(UK):
>
>There were at least three different generations of Ford trucks used
>for launching at North Weald, with the Ford Zodiac cars as a brief
>interlude. The Vauxhall that Frank mentions must have been on a day
>during the old generations of second hand vehicles which were
>certainly not the best. Somebody must have used their own private car
>for launching =96 I do not recall the club ever had a Vauxhall between
>1970 when I started and 1991 or thereabouts when we had to stop wire
>launches at North weald.
>
>For anyone to judge the capability of reverse pulley launching by a
>sight of one off day in the 1970=92s is not a fair comparison.
>
>I joined the club in 1970, and they were using ex-US or Canadian
>service Ford F100 trucks. A few years later, the second-hand supply of
>these ran out, and old Mark IV Ford Zodiac=92s were tried as an
>affordable alternative with sufficient power.
>
>In 1978 we undertook a major re-equipment. As well as two K13s and a
>tug, we bought two brand new Ford F100 trucks. They had 5.8 L V8
>engines and propane gas tanks. (We still have one of the engines. It
>went on for a life after death, as a replacement engine in an ex-ATC
>Eagle-type winch, which we still have as a backup winch at Ridgewell.)
>
>In 1988, these were wearing out. We and Lasham ordered new Ford F250
>trucks. We had two, but I can=92t remember how many Lasham ordered at
>that time. They had 7.5 L V8 engines, supercooling, LPG conversion,
>and cost =A310,251.25 each including delivery and VAT. This was the
>net price after I was able to arrange a healthy discount through my
>connections with Ford at that time, which included from time to time
>arranging publicity photographs at North Weald with gliders in the
>background when they wanted to launch a marketing campaign for a new
>vehicle.
>
>These were the last tow trucks we used for launching at North Weald.
>(In the early 1990s, the council which had bought the aerodrome banned
>wire launching at the request of powered aircraft operators at the
>aerodrome. They had concerns about mixing wire and their aircraft at
>the same time.)
>
>The last version of the =93pulley=94 that we used had two wheels on a
Del C
PROS:
1) A new professionally built winch will probably cost less than a new
towing aircraft. If you build your own from scrap automobile/truck parts
it will cost considerably less.
2) A winch doesn't require a highly qualified and certificated driver,
Certificates of Airworthiness, 50 hour checks, etc, etc. Some routine
maintenance is required though.
3) Low carbon footprint. A winch launch consumes less than a fifth of the
fuel required for an aerotow
4) No aircraft noise complaints.
5) Given proper training and pilot awareness, it's pretty safe.
6) Winch launching is cheap; at our club less than a third of the cost of
a 2000ft aerotow, even with professional winch drivers. So ideal for
training and circuit bashing. A decent soaring pilot can usually get away
from the sort of heights achieved, in the right conditions.
7) You don't have to learn accurate formation flying behind a tug.
8) You are unlikely to kill the winch operator, as opposed to a tug pilot
who can be killed if you get too high or too out of position.
9) Above all IT'S FUN.
CONS:
1) Launch height is limited by by the length of the cable run and the
headwind component. On a still day you will at best get about 45% of the
cable run. Launching directly into a headwind will improve this.
2) You can't get towed to a source of lift, such as a cumulus cloud or a
ridge. You always end up right over the winch.
3) Pilots need to be fairly well trained and switched on to deal with
launch failures and cable breaks.
4) Winch Cables may conflict with power flying at a mixed operation site.
Derek Copeland
Derek Copeland
I tried to reply to your questions directly, but your spam filter doesn't
seem to like my tiscali email address. So the answers are:
1) How high you get depends on the length of the run, the power of the
winch (ours are Skylaunches with plenty of power and good control) and the
headwind component. At my club we typically get about 1600ft in no wind and
2000ft launching into a 10 knot headwind. Our standard aerotows are 2000ft,
but you can go as high as you like, depending on your needs and the depth
of your wallet.
2) A wingtip touching the ground during an aerotow ground run is not
normally an issue for aerotowing, provided that it's on a smooth surface
or very short grass. Having said that I once did �5.5k's worth of damage
to my glider trying to aerotow out of a cowfield with rather clumpy grass,
when I caught a wingtip in a particularly lush clump before I could get the
wing up and groundlooped violently. With a winch launch, because you are
putting in a lot of energy very quickly, a cartwheel can develop very
quickly; hence the need to abort the launch if a wing drops.
You also have to fly the glider in such a way that you can always recover
from a launch failure, which basically involves a short initial safety
climb and controlling the rate of rotation. If you pull up like a Saturn
rocket taking off, you are in severe danger or either flick spinning on
the cable, or stalling heavily into the ground if the cable breaks or the
winch fails early on!
3) It's surprising how often you find a thermal straight off the top of a
winch launch. I suppose this is because the heat generated by the winch
engine triggers off a thermal. Otherwise you head off to the nearest
cumulus cloud, or look for birds or other gliders circling. It is
considered polite to move out of the way before the next glider is ready
to launch and not to circle low down in the base leg area, but that often
allows 5 minutes or so in which to climb, by which time you may be high
enough not to conflict.
4) When training new members we normally start them off with aerotows to
get them used to being in the air and to learn how to control the glider
before transferring to the winch. Having said that, many UK clubs do all
their training by winch.
5) For obvious reasons you have to have a system in place that prevents
aerotows and other aircraft from taking off at the same time as a winch
launch is taking place. We have an appointed 'launch point controller'
whose job it is to coordinate all movements by radio. We also place the
winch launch point about 500 yards in from the downwind boundary and on a
grass area away from the main runway, so most gliders, tugs and light
aircraft can land short of there without conflicting with the cables.
Unfortunately this costs us some potential launch launch height. If we use
the full length of the airfield (1900yards) we can get 2500ft winch
launches even in nil wind. We sometimes do this when things are quiet, but
then you have to stop launching whenever there is an aircraft or glider on
approach. Also the higher you take the cables, the more likely they are to
drift over something expensive after a cable break.
Regards,
Derek Copeland
bildan
At my club we typically get about 1600ft in no wind and
> 2000ft launching into a 10 knot headwind. Our standard aerotows are 2000ft,
> but you can go as high as you like, depending on your needs and the depth
> of your wallet.
This week we were getting as high as 1900' from 3900 feet of rope at
9000 feet density altitude with little wind with the Hydrowinch. With
no gear shifting at all, the Hydrowinch is MUCH smoother than any
winch with an automatic transmission.
Skylaunches are just like old Gerhleins with new paint - they use
exactly the same components. They are not particularly well
controlled since they use road vehicle torque converters and automatic
transmissions free to shift gears when they please. The old junk
Gerhleins around most US clubs are probably the only winches in the
world worse than a Skylaunch - but they are a LOT cheaper.
BTW, notice how Derek has to reply to himself to get any conversation
at all?
T8
That you, Lennie?
-T8
Derek Copeland
assumptions. The figures I gave are for a K13, which winch launches less
well than a K21 because the belly hook is too far forward. K21's get
about 200 feet higher, especially when flown solo.Also Bill Daniel's
winch is using synthetic Dyneema cable which adds about 150 feet to the
launch compared with the 4.5mm stranded steel cable we use.
Dynema cable is superb stuff, but unfortunately 5 times more expensive
than steel. As cable replacement is one of the major costs in winch
launching, this makes it less economic.
The Skylaunch winch gives well controlled, correctly speeded launches for
every type of glider from slow old vintage single seaters up to big heavy
two-seat DG1000 turbos. It is also very easy to drive (I am a winch
driver). The gear change all occur during the ground run and are totally
smooth and imperceptible from the glider end.
If you build a winch with an automatic gearbox, you have to disable the
kick down function and tweak the box so that it changes up at fairly low
revs. I agree with Bill that you can't just stick an unmodified automatic
gearbox into a winch without encountering the sort of problems that seem to
beset Gerhlein winches. It is also important to get the overall gearing
correct.
For a good quality Skylaunch launch of a K21 to 2300ft into about a 5 knot
headwind see:
http://www.youtube.com/watch?v=4ArI5_1PE_Y
BTW. My reply was genuine in response to an email from a gent called Alan
Larson. I tried twice to reply by email, but got delivery failure
notifications with the text:
The following message to <email address> was undeliverable.
The reason for the problem:
5.1.0 - Unknown address error 550-'5.0.0 All tiscali sends is spam'
OK Tiscali is not the best ISP in the world for keeping out spam, but even
so.....? I have removed Alan's actual email address to prevent him getting
any spam.
Derek Copeland
At 13:36 11 July 2009, bildan wrote:
Berry
<0959abb8-34e3-474c...@g31g2000yqc.googlegroups.com>,
bildan <bil...@comcast.net> wrote:
My club used to have a very good winch. It was a one-off called the
"Eagle Winch" and was designed and built by one of our members. He got
his initial glider training in Germany and had knowledge of quality
winches. That winch is now with the Philadelphia Glider Council, I
believe. We were forced to let go of it because we moved to a municipal
airport that was incompatible with winch operations (crossing runways).
The Eagle winch has an automatic transmission. However, in our operation
it was locked into 2nd gear for normal conditions. In strong wind, we
used 1st gear. No gear changes necessary. It was very easy to operate
and became even more so after the steel cable was swapped our for plasma
rope by the second owners at the Memphis club. At our original field,
with 4000 feet of cable out, we could easily launch our single seaters
to 2000 feet if we had any headwind.
johngalloway
This account of the performance of the Skylaunch winch is, as Bill has
repeatedly been told previously elsewhere by pilots who actually
operate or launch on Skylaunch winches, utterly false and his
obsessive denigration of it is disgraceful. Our club had a Skylaunch
winch for evaluation for six days a couple of weeks ago. The
smoothness of launch is faultless and a vast improvement over Supacat
and Tost winches
The fact that the automatic transmission can shift gears "when they
please" is a complete non issue. The gear changes up at the start of
the launch occur within the first 2-3 seconds (timed by me) and before
the glider has rotated into the climb. The gear changes are
completely imperceptible in the glider. None of numerous pilots on
the ground near the winch during launches note the upwards gear
changes without being prompted to listen out for them - an even then
there was soe debate about whether they could be detected.
Occasionally the autobox changes down to second during the mid launch
when under load but at no time was any of the many pilots launched
aware of any gear change.
The operational mechanisms of the Skylaunch are not designed to
"control" the launch so it is not surprising that it does not do so.
What it does have is an interconnected maximum throttle position guide
that takes into account the type of the glider and the headwind
component. This means that each glider is effectively provided with a
winch with an appropriately powered engine for itself and the wind
conditions in the mid launch. The winch driver still has to control
the start and end of the launch - by advancing the throttle control at
an appropriate rate at the start (about 3 seconds IMHO) and backing
off the power at the top. The predictable response of the good old GM
V8 to load means that the plot can pull into a steep climb without
fear of overspeeding.
The new US winches may turn out to be brilliant but Bill's emotional
bias invalidates him as an objective reporter in my opinion.
John Galloway
Frank Whiteley
The Hydrowinch is currently fitted with Spectra 12-strand, not Dyneema
nor Plasma-12.
Having now driven some number of launches and having trained another
to drive the Hydrowinch, I'd say it has some very nice features.
There are a some others that I've suggested to the developers.
There've been a couple of set backs, one of which led to a three month
delay. These folks have day jobs also and since some of the team
comes from overseas, it does slow things a bit. I'd like to put it on
line today, but that's not my decision to take. They aren't so
compromising, but it's close.
Frank Whiteley
Jon Marshall
and a second hand 454 cid chevvy big block and standard truck autobox,
running 4.5mm stranded wire.
The engine was imported second hand from USA three years ago It seems to
be a mid seventies perhaps early eighties truck motor with associated
gearbox, sourced from a scrapyard and fitted with a few mods but NO
alterations save to disable kickdown and to run with lpg we did not look
inside the engine and it used less than 5 litres of oil in 3000 launches.
It is very smooth partly due to all the rollers and associated bearings
being renewed. As John noted the gearchanges on this standard autobox are
imperceptible and completed by approx 10' AGL . Driving is much the same
as before but less variable owing to the throttle guide system.
The old engine was a 425 cid oldsmobile engine with stock autobox which
was finally retired spewing oil and rattling but still launching. The
biggest differences arose with the new rollers and LPG both make these big
winches much smoother.
Simple cheap and very effective
Jon
Dorset Gliding Club, UK
Del C
>
>This account of the performance of the Skylaunch winch is, as Bill has
>repeatedly been told previously elsewhere by pilots who actually
>operate or launch on Skylaunch winches, utterly false and his
>obsessive denigration of it is disgraceful. Our club had a Skylaunch
>winch for evaluation for six days a couple of weeks ago. The
>smoothness of launch is faultless and a vast improvement over Supacat
>and Tost winches
>
>The fact that the automatic transmission can shift gears "when they
>please" is a complete non issue. The gear changes up at the start of
>the launch occur within the first 2-3 seconds (timed by me) and before
>the glider has rotated into the climb. The gear changes are
>completely imperceptible in the glider. None of numerous pilots on
>the ground near the winch during launches note the upwards gear
>changes without being prompted to listen out for them - an even then
>Occasionally the autobox changes down to second during the mid launch
>when under load but at no time was any of the many pilots launched
>aware of any gear change.
>
>The operational mechanisms of the Skylaunch are not designed to
>"control" the launch so it is not surprising that it does not do so.
>What it does have is an interconnected maximum throttle position guide
>that takes into account the type of the glider and the headwind
>component. This means that each glider is effectively provided with a
>winch with an appropriately powered engine for itself and the wind
>conditions in the mid launch. The winch driver still has to control
>the start and end of the launch - by advancing the throttle control at
>an appropriate rate at the start (about 3 seconds IMHO) and backing
>off the power at the top. The predictable response of the good old GM
>V8 to load means that the plot can pull into a steep climb without
>fear of overspeeding.
>
>The new US winches may turn out to be brilliant but Bill's emotional
>bias invalidates him as an objective reporter in my opinion.
>
>John Galloway
>
the Hydrowinch is based costs an astonishing 500,000 Euros, so it ought to
be damn good! Makes a Skylaunch 2 at 90,000 Euros sound very good value,
and it is a tried and tested design. And remember that they do a cut down
and simplified version called the Skylaunch 3 for a lot less than that,
if you can do without air conditioned cabs etc.
Until recently we had a demo Skylaunch with a GM 502 High Torque engine.
On that you could open the throttle up to the preset as fast as the gas
strut would allow you to. However we have just bought two new winches with
the High Power engine and I initially got some complaints about banging the
tails of K13s down a bit hard at the start of the ground run, so I have
slowed down opening the throttle to about 3 seconds, as you suggest. You
also have to start backing off the throttle for the last third of the
launch to avoid overspeeding the glider. As long as you know that you have
to do this it is not difficult.
What the Skylaunch does brilliantly in my opinion, is to give a very
consistent ground run and rotation, whatever type of glider you are
flying. With our old Tost winches you could get anything from a
dangerously fast snatch into the air to a slow and ponderous ground run
with a risk of a wing drop. If a launch starts right it tends to stay
right, so we get consistently higher launches from them, if only for that
reason.
Derek Copeland
bildan
> In article
> <0959abb8-34e3-474c-ae1b-3f7f0497d...@g31g2000yqc.googlegroups.com>,
Germany is a good place to learn about winches. Plasma rope is like
night and day compared to steel. Steel cable is evil stuff. If you
have a winch actually designed for Plasma - unlike the Skylaunch and
Gerhlein - it will outlast steel by as much as 5x making it actually
cheaper in the long run.
Did you actually lock your transmission in 2nd or just place the gear
selector in 2nd? It's an important question since a standard tranny
will still make the 1-2 upshift causing a power oscillation. We see
a lot of tension traces showing tension oscillations from these
winches.
Anyone considering an automatic transmission for a gilder winch really
needs to understand how they work. Automatics are highly developed
for road vehicles whose requirements are diametrically opposed to
those of a glider winch. If a road vehicle encounters an increasing
load, such as a hill, it is designed to help the driver maintain speed
by increasing torque to the wheels to meet the higher load, doing what
it can to reduce the loss of speed. Cresting the hill and starting
down, it reduces torque and tends toward coasting. Both actions
increase vehicle performance and minimize fuel consumption.
If a glider encounters a thermal during a launch, the rope tension
will increase which the automatic transmission will see as a "hill"
causing it to increase torque to the drum. This increases rope
tension still more as it tries to pull the glider down through the
thermal. If the glider hits sink, the automatic transmission will
slack off the torque just when the glider needs more power. A good
winch operator can overcome these to a degree with constant throttle
adjustments - if he can tell what is going on in the glider but it's
hard, skilled work. It's definitely not "set and forget".
A tension controlled winch will do the opposite - decreasing power in
thermals letting lift do the work and increasing it in sink leaving
the pilot to control speed with pitch. The pilot sees a very smooth
launch regardless of wind or thermals. The winch operator doesn't
need to do anything at all.
It's wonderful to never need speed signals again.
Andreas Maurer
wrote:
>A tension controlled winch will do the opposite - decreasing power in
>thermals letting lift do the work and increasing it in sink leaving
>the pilot to control speed with pitch. The pilot sees a very smooth
>launch regardless of wind or thermals. The winch operator doesn't
>need to do anything at all.
>
>It's wonderful to never need speed signals again.
... yet thousands of clubs in Europe with much, much more winch
experience than any club in the US don't see the need for such a
system.
Dave Martin
description of how it constant tension works and why it would be
beneficial.
Why don't we in Europe adopt this technology -- quite simply cost.
Without private finance of money/time/labour/parts few clubs if any can
afford to scrap their current winches and buy the new technology.
Dave
At 00:29 12 July 2009, Andreas Maurer wrote:
>On Sat, 11 Jul 2009 17:07:50 -0700 (PDT), bildan
>wrote:
>
>>A tension controlled winch will do the opposite - decreasing power in
>>thermals letting lift do the work and increasing it in sink leaving
>>the pilot to control speed with pitch. The pilot sees a very smooth
>>launch regardless of wind or thermals. The winch operator doesn't
>>need to do anything at all.
>>
>>It's wonderful to never need speed signals again.
>
>
>.... yet thousands of clubs in Europe with much, much more winch
Andreas Maurer
wrote:
>Bills explanation a couple of posts ago is an excellent and simple
>description of how it constant tension works and why it would be
>beneficial.
>
>Why don't we in Europe adopt this technology -- quite simply cost.
>Without private finance of money/time/labour/parts few clubs if any can
>afford to scrap their current winches and buy the new technology.
If constant tension was really necessary for a good winch launch, many
clubs would already have one.
But the standard system (Tost, Skylaunch, whatever) is good enough for
the majority aof the clubs here.
It's definitely nicve to have - but Bill would probably have an easier
job if he advertized a more simple and much cheaper winch design to
the US clubs... ;)
Marian Aldenhövel
>> A tension controlled winch will do the opposite
> ... yet thousands of clubs in Europe with much, much more winch
> experience than any club in the US don't see the need for such a
> system.
Some do.
When I was trained as a winch driver I was taught to judge cable tension
and use that as the input parameter to the control loop. The only way of
doing that without special sensors is to look at the cable sag. Works
during the main portion of the launch, but is not very accurate of course.
I think if the winch, or winch driver, has the means to control tension
and the pilot controls airspeed winch launches become more efficient and
even safer. Reports suggest that, I have no experience of my own.
Also you would propably get much more consistent launch performance
across different conditions and much more important, different drivers.
Today we get launches like being shot from a carrier deck and the
lumbering wingrunner-testing type all in the same day depending on who
is manning the winch. The first launches of the day, or after a driver
swap, or when conditions change would no longer need to be different
than those by a well-adapted driver.
I am all for it.
Ciao, MM
Don Johnstone
>If a glider encounters a thermal during a launch, the rope tension
>will increase which the automatic transmission will see as a "hill"
>causing it to increase torque to the drum. This increases rope
>tension still more as it tries to pull the glider down through the
>thermal. If the glider hits sink, the automatic transmission will
>slack off the torque just when the glider needs more power. A good
>winch operator can overcome these to a degree with constant throttle
>adjustments - if he can tell what is going on in the glider but it's
>hard, skilled work. It's definitely not "set and forget".
>
>A tension controlled winch will do the opposite - decreasing power in
>thermals letting lift do the work and increasing it in sink leaving
>the pilot to control speed with pitch. The pilot sees a very smooth
>launch regardless of wind or thermals. The winch operator doesn't
>need to do anything at all.
>
>It's wonderful to never need speed signals again.
I think the difference in design concept between Europe/ USA is that over
the years we have leaned to design things which work for a minimal cost.
We have tried to avoid the expensive solution designed to kill you. I can
think of nothing more dangerous in a winch design than a tension sensitive
drive.
It may be wonderful to not need signals again, which if you are dead of
course you don't need, we prefer the safe option over here even if it
means a little more work.
bildan
For the record, I have no financial or managerial connection with
either US winch manufacturer but I strongly support and encourage
both. Both chose the best solutions based on very careful
investigation of winch launch dynamics. Neither chose to spend money
on excessively complicated solutions without extremely good cause.
Do I have an emotional bias against crappy engineering? Damn right I
do - especially when it's being sold as the 'perfect' solution.
The use of an automobile engines and automatic transmissions has only
one advantage - they're cheap and they 'work' after a fashion but it's
far from an ideal solution. There is quite a bit of field data to
support this. Once the underlying dynamics is fully investigated, it
become clear that this is not the way to go. Automatic transmissions
are a particularly evil choice.
To repeat yet again, automatic transmissions are highly developed and
uniquely adjusted for each vehicle in which they are installed. To
transplant them into a glider winch with diametrically opposite
requirements brings out the worst in the device. They are designed
for a wildly different purpose.
People can get used to anything and will learn to compensate for the
shortcomings of a winch based on automobile parts. They may not even
realize they are compensating unless there is a point of comparison.
You may not notice the transmission shifting or tension/speed errors
until you launch from a winch that does not shift and automatically
adjusts for air motion - then it's a revelation.
I strongly suggest doubters read George Moore's article in July
Soaring and the following article in the September issue. Thanks to
George, we now know EXACTLY how winch physics work. It's no surprise
that such knowledge leads to new and better winch designs.
bildan
Check your geography. Tension controlled winches were developed in
Europe. Check your engineering facts. Tension controlled winches are
FAR safer than any other alternative.
How can a winch be safe when the operator must control glider airspeed
with throttle WHEN HE HAS NO KNOWLEDGE OF IT? Actually, Skylaunch
indirectly acknowledges this by offering airspeed telemetry as an
option.
The only reason for this loud controversy is a single English winch
manufacturer in who uses cheap American auto parts and sells the
product - essentially a 2-drum Gerhlein - for $145,000 USD at last
check. It's a great business model as long as there are suckers.
People tend to get upset when you point out the Emperor has no
clothes.
Yes I know it's a MARINE GM V8 but that's the same engine core as used
in a pick-up trucks with a few different accessories. Last check,
they wholesale for about $2,500. The stock GM TH400 sells for about
$1200 USD.
Andreas Maurer
wrote:
>How can a winch be safe when the operator must control glider airspeed
>with throttle WHEN HE HAS NO KNOWLEDGE OF IT?
It is safe. Period. Even if you don't believe that.
All the best
Andreas
Andreas Maurer
<asd...@asfsafsd.ua> wrote:
>> ... yet thousands of clubs in Europe with much, much more winch
>> experience than any club in the US don't see the need for such a
>> system.
>
>Some do.
Indceed some do - but very, very few.
If there really was an urgent need we'd have more than a couple of
such winches in Europe by now, don't you agree?
>When I was trained as a winch driver I was taught to judge cable tension
>and use that as the input parameter to the control loop. The only way of
>doing that without special sensors is to look at the cable sag. Works
>during the main portion of the launch, but is not very accurate of course.
But sufficiently accurate, isn't it?
Contrary to the believe of some people here it doesn't matter if the
speed during the winch launch is 5 kts faster or slower (although the
perfect speed certainly increases launch height).
>I think if the winch, or winch driver, has the means to control tension
>and the pilot controls airspeed winch launches become more efficient and
>even safer. Reports suggest that, I have no experience of my own.
Efficiency? Definitely.
Safety? I doubt it.
I havent't been able to find even one accident report that was caused
by inappropriate power setting by the winch driver, yet there are
comparably many accidents caused by rope breaks or complete power
losses of the winch - things that cannot be prevented by tension
controlled speed.
>Also you would propably get much more consistent launch performance
>across different conditions and much more important, different drivers.
Indeed. Nice to have. :)
>Today we get launches like being shot from a carrier deck and the
>lumbering wingrunner-testing type all in the same day depending on who
>is manning the winch. The first launches of the day, or after a driver
>swap, or when conditions change would no longer need to be different
>than those by a well-adapted driver.
Typical problem of winch driver training. Once we started to re-train
our winch drivers who had problem scontroling the speed, we got rid of
this problem.
Viele Gr��e
Andreas
David Chapman
to strong head winds increasing rapidly part way up the launch. I can
imagine it is better, but I am not an expert.
Winch safety is mostly in the hands of the pilot, the winch is not
relevant to a good launch, but the trained pilot must be able to react to
any scenario.
But other nonsense posted here . please help me, ...
A standard car auto gearbox has some magic power to automatically adjust
the torque to the car wheels on reaching a hill, without changing gear,
road speed or engine setting? What magic is that?
David.
At 18:45 12 July 2009, Andreas Maurer wrote:
>On Sun, 12 Jul 2009 12:45:08 +0200, Marian Aldenh�vel
David Chapman
the winch is relevant to a good launch, but the pilot is responsible for
the safety,
Del C
come I got 55knots on the nail (perfect speed) for every winch launch I
did on a Skylaunch today while instructing in a K13 in quite windy, rough
and gusty conditions? No oscillations, no over or underspeeds, no weak
link breaks and no unwanted gear changes.
Derek Copeland
bildan
wrote:
> But other nonsense posted here . please help me, ...
>
> A standard car auto gearbox has some magic power to automatically adjust
> the torque to the car wheels on reaching a hill, without changing gear,
> road speed or engine setting? What magic is that?
>
That 'magic' is called a torque converter which begins to slip and
multiply torque under increasing load. Stock units can double torque
to the wheels.
Modern transmissions use a torque converter locking clutch allowing an
even greater torque multipication factor after the clutch disengages
under load. The effect can be 4:1 or greater.
For basic info, see: http://en.wikipedia.org/wiki/Torque_converter
In addition, automobile engine torque curves have peak torque lower
than cruise RPM. As the vehicle encounters a load such as a hill, the
torque output actually increases as the RPM is pulled down by the
increasing load. The typical V8 used in glider winches has a torque
peak at about 1800 RPM.
The engine/transmission combination acts in exact opposition to what
is needed in a glider winch.
bildan
> >>>Andreas
Because you operate at low throttle settings and you have no clue what
turbulent air is. Try flying in the desert sometime.
bildan
> On Sun, 12 Jul 2009 12:45:08 +0200, Marian Aldenhövel
> Andreas
By those standards, starting cars with hand cranks was 'adequate' and
electric starters would be 'nice to have'.
In fact, tension control is relatively new technology based on vastly
increased knowledge of winch launch dynamics. It certainly has the
potential to increase safety in those cases where unexpected weather
or a human winch operator creates unexpected conditions.
Don Johnstone
>
>In fact, tension control is relatively new technology based on vastly
>increased knowledge of winch launch dynamics. It certainly has the
>potential to increase safety in those cases where unexpected weather
>or a human winch operator creates unexpected conditions.
>
In fact it has the potential to be the most dangerous suggestion ever
encountered in glider winching.
Why is it that for years winches have been developed and used in the UK
and Europe with no real problems and all of a sudden someone comes up
with probably the most moronic suggestion ever and that is that if the
tension on the cable is increased the winch slows down to compensate.
So I leave the ground and the glider starts to rotate to the climb,
increasing the tension on the cable so it slows down. Brilliant, it takes
a real towering intellect to think that one through. I suppose the
explanation will be that there is some clever electronic gizzmo to
compensate. The problem with high technology systems is they do not tend
to be robust and they require regular maintainace to ensure their correct
operation, (MVG Winch is a perfect example, most of the advanced features
don't work) whereas a well trained winch driver can do the necessary
compensation using good old fashioned judgement far more safely.
I would far rather place my trust in a basic winch with a well trained
driver that rely on dubious untried engineering solutions driven by the
unknowing.
Skylaunch, Tost, Supercat and MVG winches perform very well with very few
problems. Skylaunch, or Skylaunch re-engined winches are probably now the
most popular winch in use in the UK. We like them and the many years of
experience that has gone into them.
PS We do not have deserts in the UK, and we don't cancel comps just
because 2 or 3 people don't get away either.
bildan
Don, you have so utterly misunderstood the concept, it's difficult to
start a reply.
A tension controlled winch maintains tension, the pilot controls
speed. He does that in exactly the same way as in free flight - nose
up to slow, nose down to speed up. No matter what he does, the
tension remains at the same high percentage of the weak link
strength. The pilot cannot change the tension, only the speed. The
tension cannot exceed the weak link strength.
It's exactly like an airplane. Rope tension is the equivalent of
thrust. The winch provides the power and the pilot flies the glider.
The beauty is that no mater the turbulence wind layers or thermals,
airspeed remains under the pilots total control.
With an airplane on takeoff, even a powerful one, if you raise the
nose, the airspeed will decrease. If you lower the nose, the airspeed
will increase. It's how it works - hundreds of thousands of times a
day. A tension controlled winch does exactly the same thing.
Airplane pilots understand the concept instantly.
Derek Copeland
>
>
>A standard car auto gearbox has some magic power to automatically adjust
>the torque to the car wheels on reaching a hill, without changing gear,
>road speed or engine setting? What magic is that?
>
>David.
>
works! As far as I am concerned, it is a device to allow a motor vehicle
to move off from rest, to smoothly change gears, and to stop without
stalling the engine, without a driver operated mechanical clutch. It is
not cruise control!
In that changing gear with a mechanical gearbox and clutch would give
dangerous short term losses of power, an automatic gearbox is an essential
component for any winch or towcar.
Derek Copeland
Dave Martin
The arguments are now in an endless repetative cycle fired by the theories
you propose and the convenient practicalities of the European systems, also
used by older US winches - still in use today.
There is only one solution the challenge is there -- get the winch built
with the new technology and at a competetive price and put it on the
market.
Like new glider technology if it works people will use it.
Sadly much as we would like to do it we cannot change overnight.
Look how long it has taken to get the EB28 technology into a practical
aircraft --- but at what cost and how many of us can actually afford it?
Dave
Del C
power out of a mechanical device (such as an automatic gearbox) than you
put in. You can gear that power down to get more torque, but the Skylaunch
winch depends on supplying the right amount of power (related to throttle
setting) for the given glider type and headwind component. The automatic
gearbox is only useful to provide some extra torque at low revs to get the
glider moving at the start of the ground run without stalling the engine.
Derek Copeland
At 22:45 12 July 2009, bildan wrote:
>On Jul 12, 3:30=A0pm, David Chapman
>wrote:
>
>> But other nonsense posted here . please help me, =A0...
Jim Beckman
>Do I have an emotional bias against crappy engineering? Damn right I
>do - especially when it's being sold as the 'perfect' solution.
My club in New Jersey used to operate a winch. It was before my time
(hard to believe anything was before my time, but there you are). It was
made from a Model A Ford chassis. One rear axle was welded solid and a
drum (probably made from an old truck wheel) was mounted on the other axle
with the launch rope wrapped around it. They launched down the side of a
hill and had one helluva lot of fun doing it.
OK, this was back in the 1930s, as I've heard the tales.
We'd all like to have the ultimate winch to launch with. We'd also like
to all have Ferraris to drive. Most of us settle for what we can afford,
and try to avoid letting the perfect become the enemy of the good.
Jim Beckman
bildan
The only strange part is your inability to read and understand
technical manuals. No one except yourself used the term "cruise
control". Automatic transmissions are extremely complicated devices
with complex behaviors that cannot be understood in your simple terms.
bildan
We are doing exactly that - and it's working! It's what has the Brits
so agitated.
Bob
has spilled out into RAS, I think this public (and personal) argument
is doing harm to potential winch activity in the U.S. There are many
glider pilots in the U.S. who believe that winch launching is more
dangerous than aerotow… and this endless debate, about the merits of
one technology over another, just fuels that skepticism.
Engineers, by personality and training, want clear-cut black and white
answers to a problem. The fact is that there is a lot of gray involved
in what works with winch equipment. Regardless of the merits of new
winch technology, Europe has been effectively winch launching for many
decades with “traditional” mechanical technology. Setting the
engineering skirmish aside, the old technology is proven to work over
the course of hundreds of thousands of launches. Maybe the “new”
technology is better, but keeping it in context – it is a potential
alternative to the proven traditional technology, not *THE* definitive
answer. This is what is being lost in this ongoing point and counter-
point dialog.
There are many of us who believe in the merits of winch launching; and
that U.S. glider pilots would benefit from the widespread adoption of
the technique. However, from a management standpoint these ongoing
inscrutable arguments are a winch advocate’s public relations
nightmare. The fact is that traditional automotive-based winch
technology works, as proven by decades of successful use. The
developing new technology may be an improvement, but that in no way
negates the wide-spread use of lower cost existing technology.
It would benefit the soaring community if the polarized principals in
this personal disagreement would spend their time advocating winch
launching as a method, rather than publically arguing over technical
details that may or may not be relevant. For most of us involved in
winching, the debate is somewhat amusing (if not distressing), but
what is does do is to support anti-winch sentiment in the U.S.
Just as we can effectively train new pilots in a K-13 or a DG-1000, we
can effectively and safely winch launch with automotive-based hardware
or new technology hardware. If we could re-focus this obsessive, bias,
and argumentative dialog into promoting the use of ground launching it
would be of greater benefit to the soaring community at large.
Anyone agree?
Bob Lacovara
(Winch pilot, winch driver, winch advocate)
bildan
In fact, with an automatic transmission in the drive line, it's
impossible to ever get the rope tension exactly right - certainly not
with something as simple minded as a throttle stop.
Most of what an automatic actually does in a glider winch is either
unnecessary or detrimental. Only the auto-clutch action at idle is
useful and there are far better ways to do that. The only
justification for using an automatic in a winch is that it's cheap and
comes with the engine.
The idea that low starting gears are necessary with a glider winch is
absurd. Tost gutted their automatics - even while saying automatics
were dangerous - to eliminate everything but the torque converter
leaving the box in it's straight through 1:1 ratio. Simple torque
calculations show that 3rd gear is capable of breaking the strongest
weak link during acceleration. Stepping through 1st and 2nd gears
only makes it more difficult to achieve accurate acceleration.
Wayne Paul
I really wish this thread would change its' tone, or move back to the WinchDesign group.
.
Del C
automatic gearboxes, the ground run acceleration for the heavier two
seater was somewhat ponderous, although they could still rocket launch
lightweight K8 single seaters. They also tended to overheat the gearbox
oil, despite being fitted with big oil coolers with electric fans.
This was also why you had to apply full throttle to get the gliders moving
and then back off as the gliders entered the full climb, to avoid a huge
overspeed. From a winch driver's point of view, it was hard to get this
right, which was probably the cause of some of the awful launches we used
to have to endure in that era.
Derek Copeland
At 14:49 13 July 2009, bildan wrote:
>On Jul 13, 6:30=A0am, Del C wrote:
>> Unless Bill has invented a perpetual motion machine, you can't get
more
>> power out of a mechanical device (such as an automatic gearbox) than
you
>> put in. You can gear that power down to get more torque, but the
>Skylaunc=
>h
>> winch depends on supplying the right amount of power (related to
>throttle
>> setting) for the given glider type and headwind component. The
automatic
>> gearbox is only useful to provide some extra torque at low revs to get
>th=
>e
>> glider moving at the start of the ground run without stalling the
>engine.
>>
>> Derek Copeland
>>
>> At 22:45 12 July 2009, bildan wrote:
>>
>> >On Jul 12, 3:30=3DA0pm, David Chapman
>> >wrote:
>>
>> >> But other nonsense posted here . please help me, =3DA0...
>>
>> >> A standard car auto gearbox has some magic power to automatically
>> adjust
>> >> the torque to the car wheels on reaching a hill, without changing
>> gear,
>> >> road speed or engine setting? What magic is that?
>>
>> >That 'magic' is called a torque converter which begins to slip and
>> >multiply torque under increasing load. =A0Stock units can double
torque
>> >to the wheels.
>>
>> >Modern transmissions use a torque converter locking clutch allowing
an
>> >even greater torque multipication factor after the clutch disengages
>> >under load. =A0The effect can be 4:1 or greater.
>>
>> >For basic info, see:http://en.wikipedia.org/wiki/Torque_converter
>>
>> >In addition, automobile engine torque curves have peak torque lower
>> >than cruise RPM. =A0As the vehicle encounters a load such as a hill,
>the
>> >torque output actually increases as the RPM is pulled down by the
>> >increasing load. =A0The typical V8 used in glider winches has a
Bob
Bob Lacovara
bildan
Look, I didn't start this thread. You don't have a perfect winch and
neither does anybody else. There's a LOT of room for improvements in
every aspect of winch design. Keep an open mind.
If you think that automatic gear changes don't matter, put a tension
logger on yours for a few launches. The results will astonish you.
What gets my dander up is "emotional" opposition to all attempts at
innovation based on the idea that your domestic winch is 'perfect'.
Del C
>After watching this thread deteriorate, it reminds me why I stopped =
>participating in the WinchDesign Yahoo news group. The discussions =
>became personal, agressive, angry, and absent of civility.
>
>WinchDesign group.
>
I started this thread off trying to promote winch launching as a safe,
environmentally friendly and low cost means of launching gliders. Most
gliding clubs in Germany, Holland, the UK and the Eastern European
countries do the majority of their launches this way.
The problem is Bill Daniels. I have no idea what his true agenda is: Maybe
to build up a US winch building empire? However the BGA winching advisor,
who knows everything there is to know about winch launching, has also
given up posting on the Winch Design Group in disgust.
Derek Copeland
Del C
>
>Look, I didn't start this thread. You don't have a perfect winch and
>neither does anybody else. There's a LOT of room for improvements in
>every aspect of winch design. Keep an open mind.
>
>If you think that automatic gear changes don't matter, put a tension
>logger on yours for a few launches. The results will astonish you.
>
>What gets my dander up is "emotional" opposition to all attempts at
>innovation based on the idea that your domestic winch is 'perfect'.
>
problems your alleged 'tension spikes' actually cause? We just don't
seem to get weak link or cable breaks associated with gearchanges. Even if
they do exist, there is enough elasticity in a 1km plus winch cable to
absorb them. As you have been told repeatedly by everyone with a decent
quality automatic gearbox winch, the gear changes are totally smooth and
imperceptible at the glider end.
And can you prove that your mega expensive superwinches will do any better
in rough conditions with a wobbly student pilot at the controls of the
glider?
Derek Copeland
Wayne Paul
"Del C" <del.co...@tiscali.co.uk> wrote in message news:7c1406F...@mid.individual.net...
I concur that the US needs an economical way to launch sailplanes. As elsewhere in the world, a good winch seems to be the answer.
I don't have a ground-launch endorsement in my log book; however, I hope to get the training in the near future.
In order for the endorsement to have any value, I will need to install a CG hook on my HP-14 and travel to a facility with a winch. There are a couple of auto/truck ground launching operation less then 300 mile; however, I will have the travel about 700 mile to use a winch. This should give you some sense of the US lack of winch launch accessibility.
I can remember asking a simple naive question on the WinchDesign group and being attacted by two Europeans who thought I was taking sides in a long standing argument. I was new to the group and didn't realize I was expected to read every posting on the News Group so as to be enlightened both technically and politically before being allowed to speak. As I watched I realized that emotion was driving the threads and engineering had almost vanished in the background. So... I left.
With sadness, I see the same thing happening here. I do not have the background to take sides; however, I see that the same emotionally charged cast of characters have simply moved their fight from the Yahoo News Group to here. It is sad, because in the name of enlightening the US soaring community to the value of using a good winch system, they are planting seed of doubt as to whether any winch can really be considered safe.
I just wish for all concerned that this thread would die.
Marc Ramsey
Uh, no, we don't want this in the Winch Design group, either, I've had
to resort to moderating away further discussion of this particular topic.
At the moment, we're having a rather informative discussion on various
techniques for fabricating drums...
Marc
Derek Copeland
It seems to me that you need to build up a critical mass of expertise, and
clubs with winch launching facilities in the US. In the UK I can visit 4
other clubs within a 50 mile radius of my home club who also winch launch,
so we can share experience and learn from each other. Germany is very
similar.
As I and others have pointed out before, you already have most of the
necessary ingredients to build good quality winches in the States,
particularly lots of vehicles with big powerful V8 engines and good
automatic gearboxes that can be transplanted into winches. We in Europe
actually import such things from you. Most of our winches use big block
Chevys or big secondhand diesel engines from trucks or earth movers.
Even with an almost technically perfect winch (nothing is ever totally
perfect), you will still have the occasional cable break, weak link break,
technical failure, or driver error, not to mention wing drops due to gusts.
Safe winch launching is basically about being mentally prepared to deal
with such problems as they arise. In the UK our pre-flight check list
includes an E for Eventualities, where you pre-brief yourself as to how to
deal with all the likely failures and problems that might occur during any
sort of launch, including aerotows.
Suggest that you have a read of:
http://www.gliding.co.uk/bgainfo/safety/safewinchlaunching.htm
By the way, I learnt wire launching by autowing, where about every fifth
launch was a cable break, especially as the cables became worn from
dragging them along an asphalt runway. This was far from a technically
perfect solution, but I got very good at dealing with launch failures and
never came close to killing myself. I actually had a launch failure on my
first and third solos on the same day, with only the second one going full
term to a vaguely respectable height of about 1000 feet. If anyone tells
you that autotowing is a great way of launching gliders, they are lying!
We get at least 1600 feet from our winch launches off a much shorter run.
It was still good fun though. Once we had gone solo we were also expected
to drive the towcars, after a little bit of training.
Cheers,
Derek Copeland
At 16:42 13 July 2009, Wayne Paul wrote:
>
>
>I concur that the US needs an economical way to launch sailplanes. As =
>elsewhere in the world, a good winch seems to be the answer. =20
>
>I don't have a ground-launch endorsement in my log book; however, I hope
=
>to get the training in the near future. =20
>
>In order for the endorsement to have any value, I will need to install a
=
>CG hook on my HP-14 and travel to a facility with a winch. There are a
=
>couple of auto/truck ground launching operation less then 300 mile; =
>however, I will have the travel about 700 mile to use a winch. This =
>should give you some sense of the US lack of winch launch accessibility.
>
>I can remember asking a simple naive question on the WinchDesign group =
>and being attacted by two Europeans who thought I was taking sides in a
=
>long standing argument. I was new to the group and didn't realize I was
=
>expected to read every posting on the News Group so as to be enlightened
=
>both technically and politically before being allowed to speak. As I =
>watched I realized that emotion was driving the threads and engineering
=
>had almost vanished in the background. So... I left.
>
>With sadness, I see the same thing happening here. I do not have the =
>background to take sides; however, I see that the same emotionally =
>charged cast of characters have simply moved their fight from the Yahoo
=
>News Group to here. It is sad, because in the name of enlightening the
=
>US soaring community to the value of using a good winch system, they are
=
>planting seed of doubt as to whether any winch can really be considered
=
Wayne Paul
You have identified a major problem in the first paragraph. It is hard to create a "critical mass" when the state where you live covers 83,642 square miles and only has a population density of 15.64 people/sq mile. The area of England is only 50,346 square mile; however, has a population density of 1,015/sq mile. Our density is only 1.6 percent of England's.
As a result of the low population density it is hard to form a viable club. Locally forming a club has been tried on at least three separate occasions all of which resulted in failure. Consequently all the local gliders are privately owned.
The large geographic provides a great opportunity to fly cross-country. All the local pilots fly cross-country. As a result we seldom have more then 10 launches a day. This makes aero-tows the most practical launch form.
Maybe this will help you understand why the Western US has not embraced the wench as our primary launch mode.
Respectfully,
Wayne
http://www.soaridaho.com/
"Derek Copeland" <delco...@tiscali.co.uk> wrote in message news:7c1ga1F...@mid.individual.net...
Don Johnstone
>Derek,
>Maybe this will help you understand why the Western US has not embraced
=
>the wench as our primary launch mode.
>
>Respectfully,
>
>Wayne
We gave up on that idea long ago, trying to get our ladies to run that
fast proved beynd our capabilities so we built winches instead.
bildan
This is just more rabble rousing. You know the answer, you've seen
the data from winches in your own country. Seeing tension oscillate
by 80% of the tension limits is very scary and it does lead to
problems including wire and weak link breaks. You actually begged me
once not to publish the tension charts or even mention the problem.
(I saved the e-mail in case you deny it.) I have a LOT more tension
charts - really ugly ones. You don't want me to publish them either.
All the current winches are priced within a few thousand dollars of
each other so there are no "mega expensive winches" - except they're
unfortunately all too expensive.
My agenda is simple; help build the best winches in the world without
constant and distinctly unwelcome interference from people with
nothing constructive to add. In all the years you've been posting
about winch construction, you've never added a single new idea. But
you've campaigned loudly and often against any every offered by anyone
else.
I've read every BGA publication on winch launch that's ever been
published. I've read every training BGA syllabus - and I've read ALL
your accident reports. Your accident record is far from the best.
It's in a three ring binder about 4" thick on my bookshelf. Your
stuff is OK but no better than other sources.
So, here's an offer. Stop attacking everything we do and I won't
comment about the Skylaunch. We are going to build, publicly test and
write detailed articles about our winches. I expect no derogatory
commentary from you.
We are not British Subjects and certainly not your students.
Wayne Paul
"Don Johnstone" <gp3...@okbloggs.co.uk> wrote in message news:7c2044F...@mid.individual.net...
LOL, ... and I had tried so hard to avoid making that specific typographical error!!
Frank Whiteley
> "Del C" <del.copel...@tiscali.co.uk> wrote in messagenews:7c1406F...@mid.individual.net...
> > At 15:01 13 July 2009, Wayne Paul wrote:
> >>After watching this thread deteriorate, it reminds me why I stopped =
> >>participating in the WinchDesign Yahoo news group. The discussions =
> >>became personal, agressive, angry, and absent of civility.
>
> >>I really wish this thread would change its' tone, or move back to the =
> >>WinchDesign group.
>
> > I started this thread off trying to promote winch launching as a safe,
> > environmentally friendly and low cost means of launching gliders. Most
> > gliding clubs in Germany, Holland, the UK and the Eastern European
> > countries do the majority of their launches this way.
>
> > The problem is Bill Daniels. I have no idea what his true agenda is: Maybe
> > to build up a US winch building empire? However the BGA winching advisor,
> > who knows everything there is to know about winch launching, has also
> > given up posting on the Winch Design Group in disgust.
>
> > Derek Copeland
>
> I concur that the US needs an economical way to launch sailplanes. As elsewhere in the world, a good winch seems to be the answer.
>
> I don't have a ground-launch endorsement in my log book; however, I hope to get the training in the near future.
>
> In order for the endorsement to have any value, I will need to install a CG hook on my HP-14 and travel to a facility with a winch. There are a couple of auto/truck ground launching operation less then 300 mile; however, I will have the travel about 700 mile to use a winch. This should give you some sense of the US lack of winch launch accessibility.
>
Wayne,
I was talking with Bill Corbin today about the prospect of finding a
winch for King Mountain. Any old Gehrlein model 62's languishing
about out there readers? We may be launching with one starting
Tuesday. I spent 8 hours on the tractor mowing the launch and
recovery area and runways today, such is the rain we've had in
Colorado this year.
Frank Whiteley
Don Johnstone
I am struggling to understand what cable tension has to do with anything.
I have been winch launched 10000 times and have driven a winch for many
more launches than that over 50 years and the only thing that concerns me
is the speed of the cable retrieval at the delivery end. Yes I use the bow
in the cable to keep the speed constant but this is a relative thing, not
an absolute. I accelerate quicker than most drivers to keep the ground run
as short as possible and to give the pilot aerodynamic control as quickly
as possible. I also reduce the speed at the top of the launch often
causing the glider to back release.
It really does not matter how it is done but the important thing is that
the control applied by the winch driver is reflected in the response of
the winch to his input at the business end.
I can think of few, if any accidents that have been caused by "tension
spikes" whatever they are, and a lot caused by varying amounts of a lack
of skill.
It is a real shame that people are being denied an economic alternative
launch procedure by ignorance. It does not have to be complicated, in fact
given the use to which it is put the simpler the better.
The winches we have in the UK work, and they work well. Reading some of
the postings about tension control has been interesting in an amusing sort
of way, well actually it's been a hoot.
Learn from the mistakes of the Munster Van Gelder winch, an excellent
winch with many advanced features, most of which are switched off in
normal operation. The servicing overhead is massive and the only people
able to run them, with one exception is the RAF. Yes it gives an
excellent launch, probably the best I have ever had but at a huge cost in
maintenance overheads. Why, because it is too complicated with too many
advanced features even when driven by what are really proffesional winch
drivers.
I am also struggling to understand why so much notice is being taken of
someone who obviously knows so little about the practical operation of
glider winches. As Wayne has said, almost no winching is carried out in
the USA so I would have thought it sensible to consult those who do
operate winches rather than some crackpot with wild ideas and zero
knowledge.
Wayne Paul
I believe that John Kangas is also mowing the King Mountain Glider Park
"Frank Whiteley" <frank.w...@gmail.com> wrote in message news:c791f538-0756-4330...@k26g2000vbp.googlegroups.com...
Wayne Paul
John Kangas mowed the King Mountain Glider Park (http://www.kingmountaingliderpark.com/) last week end. He also installed tie-downs getting ready for the Aug 17 "grand opening" . (Are you planning to attend?)
As you know, one of John's goals is the installation of a winch. He feels the field's proximity to the mountain and associate know areas which generate thermals will make flying cross-country from a winch a "piece of cake." I am sure he would be interested in knowing about an old Gehrlein that is languishing somewhere here in the US. (There is also a glider operation "start up" in Baker City, OR that is looking for an old winch.)
I flew my Gold 300km triangle out of Mackay, Idaho and one of the turnpoints was the King Mountain Glider Park coordinates. (http://www.soaridaho.com/Flights/6F_Gold_Distance.html)
With the proximity of both the King Mountain Glider Park and Baker City, a CG hook for my HP-14 is on my winter project list.
Wayne
http://www.soaridaho.com/
"Frank Whiteley" <frank.w...@gmail.com> wrote in message news:c791f538-0756-4330...@k26g2000vbp.googlegroups.com...
Frank Whiteley
be able to come to Idaho.
Frank
On Jul 14, 6:12 am, "Wayne Paul" <wa...@soaridaho.com> wrote:
> Frank,
>
> I believe that John Kangas is also mowing the King Mountain Glider Park"Frank Whiteley" <frank.white...@gmail.com> wrote in messagenews:c791f538-0756-4330...@k26g2000vbp.googlegroups.com...
Bob Whelan
> <Snip...>
> Maybe the �new�
> technology is better, but keeping it in context � it is a potential
> alternative to the proven traditional technology, not *THE* definitive
> answer. This is what is being lost in this ongoing point and counter-
> point dialog.
- - - - - -
> There are many of us who believe in the merits of winch launching; and
> that U.S. glider pilots would benefit from the widespread adoption of
> the technique.
And I'm one of 'em. Soaring as an activity is sufficiently arcane and
the group (worldwide) that practices it sufficiently thinly spread that
internecine warfare fits the "foot shot" definition, in my book.
- - - - - -
> It would benefit the soaring community if the polarized principals in
> this personal disagreement would spend their time advocating winch
> launching as a method, rather than publicly arguing over technical
> details that may or may not be relevant.
"Roger that!" (What a concept!!!)
- - - - - -
> <Snip>... If we could re-focus this obsessive, bias,
> and argumentative dialog into promoting the use of ground launching it
> would be of greater benefit to the soaring community at large.
>
> Anyone agree?
"Ayup..."
- - - - - -
> Bob Lacovara
> (Winch pilot, winch driver, winch advocate)
Ditto your sig-line and tack-on 'engineer/*soaring* advocate.' (Sadly,
sometimes that last does NOT go without saying!) :-)
Bob - all soaring is good - W.
Gary Emerson
Are you making them at the weak link??
Are you making these measurements at the winch end of things?
I'd really like to know...
Don Johnstone
That is the question that is puzzling me too. The tension sensed by the
winch will, and should be constantly changing during the launch, measuring
that would be, how can I put it, useless.
The tension at the glider release hook will be relatively constant but
measuring that introduces the problem of the addional weight of the device
that does it and a reliable transmission of data to the ground.
Marc Ramsey
I'm going to throw in my two cents here. I've been trying to get hard
data and information from first hand experiences for several years, now,
there just isn't much real stuff publicly available. There is, however,
a growing body of theory (which is good), speculation (not so good), and a
lot of bold statements that I have been, so far, unable to verify.
First, as far as I find out, the only tension/torque controlled winches
currently in day to day use use either electric or hydraulic drive
systems. For an electric winch, the torque applied to the drum can be
controlled based on drive current and drum speed. In the hydraulic case,
torque control is achieved by adjusting hydraulic pressure. In both
cases, this allows applying a specific amount of torque to the drum, which
approximates the desired amount of tension on the rope. In neither case is
the actual rope tension being measured. Drum inertia, rope oscillations,
etc., will also affect the rope tension. Apparently, though, at least
some of these winches provide tension controlled launches on a practical
basis.
There is one winch with an automated controls system under development in
the US, which uses a diesel engine and automatic transmission, with a
running line tensiometer (RLT) at the winch end. I have not been able to
obtain any information on whether the tension control program is actually
in use, and whether it is resulting in any real improvement over more
conventional winch launches.
One group in the UK has flown with a recording load cell to collect data
during a dispute with the manufacturer of their (conventional) winch. The
load cell was apparently placed at the weak link end of the rope. I've
seen about 10 distinct graphs produced by this device, and they look
terrible (large excursions in tension). However, despite loud
proclamations that "hundreds" of similar flights have been recorded on
several winches, I've never been able to get hold of any further data. I
also have been unable to obtain information on the device itself, how it
was calibrated, the circumstances under which the data was recorded, and
whether there were electrical, mechanical, driver, and/or pilot related
issues that could affect the data.
It does look rather straightforward to put a recording or wireless load
cell at the glider end of the rope, or use an RLT or even measure the load
directly from the winch axle (which I'll have provision for in the winch
I'm designing). So, I expect we'll be seeing more data in the future.
That's all I know at the moment, if there is anyone lurking out there
with solid data, I'd love to hear about it...
Marc
Derek Copeland
seem to gloss over. How do you measure tension in a long and thrashing
cable that is being wound into a winch at up to 70 knots as the glider
lifts off? There are gadgets called running line tensiometers that are
used in underground cable laying, but they don't work at the sort of
speeds required.
The other approach is to mount a load cell at the glider end and transmit
the data back to the winch in some way, such as a radio link.
Even if you can directly measure tension in the cable, you have to bear in
mind that the glider has to pull against that tension and that changes in
its pitch angle due to pilot inputs or gusts will temporarily increase or
reduce the tension. You would therefore have to damp the system or it
would tend to hunt. I know as a glider pilot and winch driver myself, that
the less you can change the pitch angle of the glider and the throttle
setting of the winch, the steadier the launch becomes. If the pilot is
trying to control the airspeed with the stick at the same time that the
winch is trying to sense and maintain a constant tension, there is a risk
that they will end up chasing each other, especially when separated by a
long, sagging (even Dyneema sags slightly) and slightly elastic cable.
In practice the Skylaunch approach of limiting the power setting as
appropriate to the glider type, headwind component and weak link strength
seems to work well. If the pilot pulls back harder, or the glider runs
into a thermal, it slows the winch engine down by just the right amount.
Easing forward or hitting sink allows the engine to speed up. Since we
replaced Tost winches with Skylaunches, broken weak links have almost
become a thing of the past and the vast majority of the launches are
correctly speeded given correct pilot inputs. The pilot can control the
airspeed by changing the pitch angle.
Derek Copeland
tommytoyz
the wheel. Conventional winches already do that. IF the power setting
is retained constant in conventional winches with a torque converter,
the tension will be constant excluding the inertia factor. Every winch
will have inertia and delay and none will be able to respond
instantaneously to changes in wire load.
A tension meter can be installed in any type of winch, electric,
hydraulic or conventional. There is no difference between the
different types there and power can be controlled by one if desired.
The issue is, does it make sense? Is the approximation calculated by
the British design good enough? Or do we need a real time tension
control winch? Would the inertia i the system even make this possible
or desirable?
I would say that setting the desired tension according to type and
conditions by approximation, ala Skylaunch, and not worrying about the
fluctuations is plenty good enough. The main reason is because
designing a winch to be truly controlled in real time by the actual
and current tension, micro second by microsecond, is probably very
expensive, unproven and would not solve the inertia delay issue of the
winch. Trying to chase the gusts so to speak - how would that work? A
conventional winch type already lets the drum slow down and/or pulls
the engine revs down if the cable tension increases due to a gust or
thermal - thus reducing the tension - this is already a mechanically
built in constant torque effect.
This is by no means perfect, but certainly good enough to give mostly
smooth launches. In gusty conditions, there is no winch in the world,
not even on paper, that can react fast enough to dampen away the
oscillations in cable tension and airspeed, due to the time delay in
reacting to the changes in cable tension.
We just need to figure out how to make a cheap reliable winch and find
places to use them at. At $10-$15 a launch, a glider club or operator
would quickly make a nice income, like European clubs do. The real
cost of a winch launch is something like $3-5 per launch including
maintenance, reserves and replacements. 30 launches a week x $10
profit = $1,200 extra a month. That's one very nice glider upgrade
every 5 years. This is one of the main reasons why European clubs have
such nice equipment.
Tom
Marc Ramsey
At 04:19 15 July 2009, tommytoyz wrote:
>We just need to figure out how to make a cheap reliable winch and find
>places to use them at. At $10-$15 a launch, a glider club or operator
>would quickly make a nice income, like European clubs do. The real
>cost of a winch launch is something like $3-5 per launch including
>maintenance, reserves and replacements. 30 launches a week x $10
>profit = $1,200 extra a month. That's one very nice glider upgrade
>every 5 years. This is one of the main reasons why European clubs have
>such nice equipment.
There are winches already in operation in the US, there are groups who
want to operate them, and there are groups trying to design and
manufacture them. I think we need all of the above.
I'm part of a wanna-be operating group, with limited funds. That pretty
much means either finding a rebuildable Gehrlein, importing an inexpensive
used winch from Europe, or homebrewing a new winch (based on the UK spec).
I prefer the latter, as I think there is still plenty of room for
optimization, both in fabrication and operation. While I respect those
who are trying to push the envelope with advance power systems and launch
automation, a simple single drum winch based on automotive components will
be good enough for our local group get started.
If you aren't a member of the Yahoo Winch Design group, please consider
joining. While we have our share of spats, there is progress being made
towards coming up with component designs for a cheap reliable
non-automated winch...
Marc
Bruce
Which is why I suggested we think about metrics. If there were not big
changes in tension at the Winch end you would have a REAL problem. Go
check it - on our 2km run the glider has not moved before the winch is
1-1.5s into power up - until then there is a lot of tension going into
the cable at the winch and zero happening at the glider end.
We have had a ham fisted learner winch driver snap the cable neatly
(1880KN breaking strain cable) at the drum without even moving the chute
at the launch point.
So - The place it has to be reasonably gentle (smooth curve) is at the
glider hook.
Now we get into a whole new debate about the relative advantage of
UHMDPE (Spectra / Dyneema etc.) and steel cable.
Steel has much more elasticity and inertia to absorb those transient
loads. The spring steel wire acts like a spring storing energy and
smoothing loads. Inconveniently this means that when it breaks under
tension you get a backlash that can result in big overwinds and injuries.
The plastic rope is - counter-intutively given the name, far less
elastic and very light. Result is that winches so equipped may need to
have smoother delivery. And (I am not a good enough engineer here) it is
possible that the tension at the winch on these is similar to that
experienced by the aircraft hook. Would depend on hysteresis and all
sorts of other things that are probably best measured rather than
calculated / guessed.
Any one with facts?
tommytoyz
importing an inexpensive used winch from Europe, or homebrewing a new
winch (based on the UK spec). I prefer the latter, as I think there is
still plenty of room for optimization, both in fabrication and
operation. While I respect those who are trying to push the envelope
with advance power systems and launch automation, a simple single drum
winch based on automotive components will be good enough for our local
group get started. "
I agree, however, I suggest a retrieve winch set up if you guys are
going for a single drum as otherwise, launch rate will be too slow.
Last year I flew from a 6 drum winch and it was aircraft carrier
style. From reading, I gather that with a single drum winch with a
retrieve winch set up can achieve a rate of 20 launches an hour. How
many tow planes would it take to achieve 20 launches/hour to 2,000
feet per launch? My guess is two tow plane. With only 1 tow plane that
many launches would take 2 hours - much more if they stray far from
the airport. The economics of winching are staggering compared to
aerotows - and above all - much more fun. This includes hunting for
that first lift at low altitude AGL. Even with multiple relights, it's
still cheaper and more fun.
Tom
Del C
start of a winch launch is to open the throttle wide before all of the
slack has been taken out of the cable, so that you get a sudden snatch.
I have launched on both stranded steel and UHMWPE cable on a conventional
Tost winch with a changing automatic gearbox, and couldn't honestly feel
any real difference, except that you don't get any jolts from cleated
repairs going through the rollers with the synthetic cable. These
generally occured near the top of the launch, where we were most likely to
break cables with the Tosts, and are more down to the way we repair broken
steel cables, rather than the cables themselves.
I personally much prefer synthetic cables, because they give smoother and
higher launches, but the club management said no, due to the much higher
cost of the stuff!
Dyneema is definitely safer in that it has less tendency to spring back
after a break and no sharp ends to cut anybody who is unlucky or stupid
enough to stand in the way. My club has had a couple of minor injuries
that way.
Derek Copeland
Andreas Maurer
<tommy...@gmail.com> wrote:
> The real
>cost of a winch launch is something like $3-5 per launch including
>maintenance, reserves and replacements. 30 launches a week x $10
>profit = $1,200 extra a month. That's one very nice glider upgrade
>every 5 years. This is one of the main reasons why European clubs have
>such nice equipment.
Unfortunately this is not the reason...
There might be a few clubs in Europe that charge the prices you
mentioned, but all the clubs I know charge between 2 and 5 Euro,
sufficient only to cover the costs.
Cheers
Andreas
Chris Reed
USD10 or more. Winch launching makes a surplus, aerotowing tends to run
at a deficit, at the smaller clubs at least.
tommytoyz
At my old club in Germany there were several prices depending if you
were a youth, club member in club aircraft, club member with your
private aircraft or non club member with your private aircraft. The
cheapest rates are as you mentioned. It also makes a big difference
that the German clubs have way more launches than 30 a week. It's more
like 150 a week or more. So the spread can be less.
Of course there are other criteria that the government supports these
clubs and some members to a small degree and they also charge by the
hour for their aircraft - though a small fee - but a fee none the
less. Their set up is just totally different, but my point is that
you can make good money as a club here in the USA with a winch where
you really can't with a tow plane. The tow plane is just very
expensive if operated by the club and if using an FBO, no money comes
back to the club.
All this changes, with a club owned winch and even charging the
astronomical fee (for a winch launch) of $15 per launch, it's a good
money maker which can be put to good use in a non profit 501 (c)(3)
club to buy aircraft, equipment, hangars, etc.....Even at $10 a launch
it's a good money maker. Perhaps the launch fees can be charged as in
the German clubs, depending on club status and aircraft. This would
encourage club membership as well as it's cheaper to launch as a club
member.
Z Goudie
Even with multiple relights, it's
>still cheaper and more fun.
>Tom
Not if you finish up at the back of a queue of 20 gliders as the sea
breeze blows through and the launch point has to be moved to the other end
of the runway....
bildan
As you point out, the mfg, spec's call for about 1.5% elongation at
failure for UHMWPE (Spectra/Dyneema) That is much stiffer than
steel. And yes, any roughness or variability in winch power output
does get passed to the glider. That said, rope launches seem much
smoother than with steel cable.
A misconception seems to be that a tension controlled winch goes
instantly from 0 to 100% tension at the beginning of the takeoff
roll. In fact, tension ramps up smoothly and only becomes constant
during the main climb. That's why it's called a "tension controlled
winch" rather than a constant tension winch.
The steady tension make it far easier for the pilot to maintain good
airspeed control. There is much less effect from thermals and gusts.
It's a quieter, smoother easier launch. Because the "area under the
curve" is greater with constant tension in the main climb, more net
energy gets transferred to the glider than in the case of varying
tension so launches are higher with no increase in maximum climb
angle.
Tension through the ground roll and rotation phase follows essentially
the same profile as with an excellent conventional winch launch.
There are limits set to preclude too rapid acceleration and the
tension cannot reach the weak link or rope breaking levels. The
automation make one launch pretty much like the next with little
variation due to the winch operator.
By the way, tension control is nothing new. I recall an article in
Sailplane and Gliding from the 1960's on the subject. Soaring
Magazine had an article on an auto tow system using a tensiometer made
from a hydraulic master cylinder and a pressure gauge from about the
same time. Many of today's hang glider winches and auto tow systems
use tension control.
Don Johnstone
>A misconception seems to be that a tension controlled winch goes
>instantly from 0 to 100% tension at the beginning of the takeoff
>roll. In fact, tension ramps up smoothly and only becomes constant
>during the main climb. That's why it's called a "tension controlled
>winch" rather than a constant tension winch.
>
>The steady tension make it far easier for the pilot to maintain good
>airspeed control. There is much less effect from thermals and gusts.
>It's a quieter, smoother easier launch. Because the "area under the
>curve" is greater with constant tension in the main climb, more net
>energy gets transferred to the glider than in the case of varying
>tension so launches are higher with no increase in maximum climb
>angle.
How can you possibly know that without measuring the "tension" at the
release hook. You certainly cannot measure the increased tension caused by
a thermal at the winch as the inertia of the steel cable is the main cause
of the increase in tension experienced at the release hook. This
"tension spike" cannot be measured at the winch. From a point at which
the cable is at 45 degrees to the ground the "tension" imparted to the
glider, through the cable release, is increasingly provided by the weight
of the cable, and therefore measuring tension at the winch has no meaning
whatsoever, in fact the tension there should be almost 0.
>
>Tension through the ground roll and rotation phase follows essentially
>the same profile as with an excellent conventional winch launch.
>There are limits set to preclude too rapid acceleration and the
>tension cannot reach the weak link or rope breaking levels. The
>automation make one launch pretty much like the next with little
>variation due to the winch operator.
You may get good results by serendipidy but you certainly won't get them
through control of tension. What you are measuring at the winch bears
absolutely no direct relationship to what is experienced at the glider
end, and that is what counts.
With a good qualified winch driver you get consistent launches, sounds to
me you are worrying far too much about not being able to train your winch
drivers properly, and given some of the theories expounded that is perhaps
understandable.
What you are trying to achieve in a complicated way we solve by using
robust equipment and trained winch drivers who do understand what they are
doing.
bildan
> At 23:52 15 July 2009, bildan wrote:
>
> >A misconception seems to be that a tension controlled winch goes
> >instantly from 0 to 100% tension at the beginning of the takeoff
> >roll. In fact, tension ramps up smoothly and only becomes constant
> >during the main climb. That's why it's called a "tension controlled
> >winch" rather than a constant tension winch.
>
> >The steady tension make it far easier for the pilot to maintain good
> >airspeed control. There is much less effect from thermals and gusts.
> >It's a quieter, smoother easier launch. Because the "area under the
> >curve" is greater with constant tension in the main climb, more net
> >energy gets transferred to the glider than in the case of varying
> >tension so launches are higher with no increase in maximum climb
> >angle.
>
> How can you possibly know that without measuring the "tension" at the
> release hook. You certainly cannot measure the increased tension caused by
> a thermal at the winch as the inertia of the steel cable is the main cause
> of the increase in tension experienced at the release hook. This
> "tension spike" cannot be measured at the winch. From a point at which
> the cable is at 45 degrees to the ground the "tension" imparted to the
> glider, through the cable release, is increasingly provided by the weight
> of the cable, and therefore measuring tension at the winch has no meaning
> whatsoever, in fact the tension there should be almost 0.
First, we're not using steel cable, we're using UHMWPE (Specra/
Dyneema). Lightweight "plastic" rope only weighs about 1 pound per
hundred feet and has very little inertial at all. Tension measured at
the winch is within a percent or so of that at the glider and has
essentially no effect on tension measurement.
> >Tension through the ground roll and rotation phase follows essentially
> >the same profile as with an excellent conventional winch launch.
> >There are limits set to preclude too rapid acceleration and the
> >tension cannot reach the weak link or rope breaking levels. The
> >automation make one launch pretty much like the next with little
> >variation due to the winch operator.
>
> You may get good results by serendipidy but you certainly won't get them
> through control of tension.
Gee, I must be dreaming But we seem to be getting exactly what I'm
telling you we're getting - with tension control. This isn't theory,
we're actually doing it. There must be some sort of magic effect no
one knows about. Or maybe the laws of physics are different over here.
bildan
Most people are using a "logger" that works like a GPS logger except
that it measures tension with a load cell and records the data on
flash memory card at a few samples per second for later readout on a
PC. With it's protective padding, It's about the size of a toy
football or a liter soft drink bottle and weighs less than a pound.
It's placed in the winch line near the parachute. I'm not an EE, but
I'm told they are easy to make using off the shelf components - any
"sparky" can build one. It's nice since you can use it on any winch.
You can also measure it at the winch if it's hydraulic or electric or
you use a Running Line Tensiometer (RLT).
A large drum has relatively little rope build-up during a launch so
the effective radius can be estimated pretty closely as a function of
time. With a hydraulic winch, the torque at the drum is directly
related to the oil pressure at the hydraulic motor. With those data,
the rope tension can be calculated to more than good enough accuracy.
It's the same with an electric winch except you measure electrical
values.
No matter how you get it, a tension trace is very useful in diagnosing
problems with a winch - or a winch driver. I'd want to make my own
trace on any winch before I bought it.
Frank Whiteley
You mention gov't support in Germany, but in effect that's what a 501c
(3) tax determination provides in the US. That is, the non-profit tax
determination is a means to keep the size of government at bay, yet
support your voluntary efforts for something that might not exist
locally apart from that volunteerism. The benefit comes from the
donors, and the donors benefit also and it reduces taxes.
A US club could do 150 per week, but you have to work at recruiting to
the sport and plan for the results of your efforts.
Club's are generally good at keeping logs of glider time, so why not
charge for air time. In the UK, they charged by the minute at the
clubs I joined. In the RAF clubs, the first ten minutes were free and
the meter was running (very modestly) after that. The book keeping is
hardly difficult these days.
Frank Whiteley
Del C
Just out of interest, who are these 'most people' and do they have a
design for a tension logger that could published? I know of only one club
in the UK who have tried using one, which was the source of your infamous
'ugly tension spikes' claim.
I have looked at these logs and they tend to show momentary troughs rather
than spikes, and the weak link strengths were generally not exceeded.
Without knowing what the meteorological conditions where at the time, or
how smooth the winch driver and the glider pilot where in their actions,
it is difficult to draw any conclusion from them. I haven't yet seen a
trace from your 'US superwinches', so can you prove they would do any
better in the same circumstances and with the tension logger mounted in
the same place?
Derek Copeland
At 03:50 16 July 2009, bildan wrote:
Derek Copeland
giving smooth and imperceptible gear changes during a winch launch, see if
you can hear the gearchanges in this video of a new Skylaunch winch in
action at Lasham?
http://www.youtube.com/watch?v=riqhzcXZqzg
Derek Copeland
At 19:34 11 July 2009, johngalloway wrote:
>On 11 July, 14:36, bildan wrote:
>>
>> This week we were getting as high as 1900' from 3900 feet of rope at
>> 9000 feet density altitude with little wind with the Hydrowinch.
=A0With
>> no gear shifting at all, the Hydrowinch is MUCH smoother than any
>> winch with an automatic transmission.
>>
>> Skylaunches are just like old Gerhleins with new paint - they use
>> exactly the same components. =A0They are not particularly well
>> controlled since they use road vehicle torque converters and automatic
>> transmissions free to shift gears when they please. =A0The old junk
>> Gerhleins around most US clubs are probably the only winches in the
>> world worse than a Skylaunch - but they are a LOT cheaper.
>>
>> BTW, notice how Derek has to reply to himself to get any conversation
>> at all?
>
>This account of the performance of the Skylaunch winch is, as Bill has
>repeatedly been told previously elsewhere by pilots who actually
>operate or launch on Skylaunch winches, utterly false and his
>obsessive denigration of it is disgraceful. Our club had a Skylaunch
>winch for evaluation for six days a couple of weeks ago. The
>smoothness of launch is faultless and a vast improvement over Supacat
>and Tost winches
>
>The fact that the automatic transmission can shift gears "when they
>please" is a complete non issue. The gear changes up at the start of
>the launch occur within the first 2-3 seconds (timed by me) and before
>the glider has rotated into the climb. The gear changes are
>completely imperceptible in the glider. None of numerous pilots on
>the ground near the winch during launches note the upwards gear
>changes without being prompted to listen out for them - an even then
>there was some debate about whether they could be detected.
>Occasionally the autobox changes down to second during the mid launch
>when under load but at no time was any of the many pilots launched
>aware of any gear change.
>
>The operational mechanisms of the Skylaunch are not designed to
>"control" the launch so it is not surprising that it does not do so.
>What it does have is an interconnected maximum throttle position guide
>that takes into account the type of the glider and the headwind
>component. This means that each glider is effectively provided with a
>winch with an appropriately powered engine for itself and the wind
>conditions in the mid launch. The winch driver still has to control
>the start and end of the launch - by advancing the throttle control at
>an appropriate rate at the start (about 3 seconds IMHO) and backing
>off the power at the top. The predictable response of the good old GM
>V8 to load means that the plot can pull into a steep climb without
>fear of overspeeding.
>
>The new US winches may turn out to be brilliant but Bill's emotional
>bias invalidates him as an objective reporter in my opinion.
>
>John Galloway
>
bildan
> Just to emphasize John's point about a properly set up automatic gearbox
> giving smooth and imperceptible gear changes during a winch launch, see if
> you can hear the gearchanges in this video of a new Skylaunch winch in
> action at Lasham?
>
> http://www.youtube.com/watch?v=riqhzcXZqzg
>
> Derek Copeland
Opening the throttle like a little old lady will mask shifts on any
transmission. This obviously depends a great deal on the winch
operator opening the throttle very gingerly.
johngalloway
Bill,
You are implying that if the throttle of a Skylaunch winch is advanced
rapidly then the autobox changes will become obvious or a problem or
whatever. This is simply not the case.
At various times I have test driven a Skylaunch, been inside and
outside the winch looking out for gear changes (because this was
something I was initially wondering about too), and been launched. I
have seen the throttle advanced rapidly to maximum or advanced slowly
over 3 seconds and it makes no difference to appreciation of
gearchanges. As a personal example I had a launch recently in which
the driver (watched by a friend in the cab) for some reason pushed the
throttle rapidly through the throttle stop guide for my type and gave
me a very overpowered initial acceleration. There was absolutely no
detectable gear change effect during the initial (very rapid)
acceleration.
John Galloway
Del C
the Skylaunch winch from zero to lift off speed (50-60mph) in about 3
seconds, which is little slower than Bill claims for his US superwinch.
Any faster than this can be dangerous for some types of glider, because it
can cause excessive pitch up rates. Excessive acceleration can also bang
down the tails of those gliders that set on their nose wheels or skids
pretty hard onto the ground, with a risk of structural damage!
Derek Copeland
At 18:31 19 July 2009, johngalloway wrote:
>On 19 July, 16:54, bildan wrote:
>> On Jul 19, 4:30=A0am, Derek Copeland wrote:
>
>> > Just to emphasize John's point about a properly set up automatic
>gearbo=
>x
>> > giving smooth and imperceptible gear changes during a winch launch,
>see=
> if
>> > you can hear the gearchanges in this video of a new Skylaunch winch
in
>> > action at Lasham?
>>
>> >http://www.youtube.com/watch?v=3DriqhzcXZqzg
>>
>> > Derek Copeland
>>
>> Opening the throttle like a little old lady will mask shifts on any
>> transmission. =A0This obviously depends a great deal on the winch
>> operator opening the throttle very gingerly.
>
>Bill,
>
>You seem to have difficulty coping with the fact that whatever
>preconceived idea comes into you mind is not necessarily a fact.
>
>The fact is that
>
Don Johnstone
>On 19 July, 16:54, bildan wrote:
>> Opening the throttle like a little old lady will mask shifts on any
>> transmission. =A0This obviously depends a great deal on the winch
>> operator opening the throttle very gingerly.
>
>Bill,
I am a little mystified by this, can you tell us Bill exactly how many
Skylaunch winches you have seen, which particular types, and how many
launches you have witnessed being made by a Skylaunch winch?
Don Johnstone
>On a very still day the gliders up to DG1000Ts were being accelerated by
>the Skylaunch winch from zero to lift off speed (50-60mph) in about 3
>seconds, which is little slower than Bill claims for his US superwinch.
>Any faster than this can be dangerous for some types of glider, because
it
>can cause excessive pitch up rates. Excessive acceleration can also bang
>down the tails of those gliders that set on their nose wheels or skids
>pretty hard onto the ground, with a risk of structural damage!
>
>Derek Copeland
>
faster the acceleration to flying speed the safer the launch, having
effective controls makes all the difference. Being towed down the field on
the ground accelerating slowly is a recipe for disaster.