Winch Experts wanted

You have to remember folks that these are American horsepower units. About
2:1 is a good ratio against proper European horses!

:-)

Ian

"Kevin Neave" wrote in message
...
Bill,

I think you need to revisit your numbers.

Here at Nympsfield (UK) we have a Supacat winch with
a 250 horse Diesel that easily provides enough power
for the biggest gliders on site (DG505, DuoDT, Nimbus3DT)
(And pretty scary in a Libelle if the winch driver
is *over enthusiastic*)

The previous engine was 180 HP, this was a bit marginal
for the Heavy Glass, but more than enough for any single
seat

(We have a 1000m field & regularly get 1500', even
nil wind)

:-)

KN

At 15:36 19 March 2004, Bill Daniels wrote:

Mark, unfortunately, the physics of a winch launch
says that it takes about
1 kWh or 3,600,000 Joules to launch a glider. The
peak power demand places
yet another constraint on the minimum HP that must
be available. Those
numbers point to a 400 to 500 HP engine to be able
to provide launch service
to any glider in the existing fleet.

Yep, it's just not the same when you can match the displacement of an
entire European car engine with the displacement of just 2, maybe 3,
cylinders worth of an American big block motor......

tango4 wrote:

You have to remember folks that these are American horsepower units. About
2:1 is a good ratio against proper European horses!

:-)

Ian

"Kevin Neave" wrote in message
...

Bill,

I think you need to revisit your numbers.

Here at Nympsfield (UK) we have a Supacat winch with
a 250 horse Diesel that easily provides enough power
for the biggest gliders on site (DG505, DuoDT, Nimbus3DT)
(And pretty scary in a Libelle if the winch driver
is *over enthusiastic*)

The previous engine was 180 HP, this was a bit marginal
for the Heavy Glass, but more than enough for any single
seat

(We have a 1000m field & regularly get 1500', even
nil wind)

:-)

KN

At 15:36 19 March 2004, Bill Daniels wrote:

Mark, unfortunately, the physics of a winch launch
says that it takes about
1 kWh or 3,600,000 Joules to launch a glider. The
peak power demand places
yet another constraint on the minimum HP that must
be available. Those
numbers point to a 400 to 500 HP engine to be able
to provide launch service
to any glider in the existing fleet.

4740' MSL - temperatures in the mid 30s Celcius.
220 HP winch (and that was when it was new fifteen years ago)

We launch Blanik L13, Kestrel 19m etc quite satisfactorily...

One advantage of a relatively low power winch is it is simple to drive. With the
heavier two seaters and the Kestrel it is a case of roll on full power over four
seconds. Leave it there until the time comes to release.

OK - we do have 1800m of wire, and we only get 1500' to 2300' AGL. Our
conditions are good enough that we seldom need a relight during the middle of
the day. Launch after 15:00 and you are taking your chances as always, but I
don't think that a couple of hundred feet AGL will make such a difference then
anyway.

We have had several people writing that they have launched heavy glider X
with a low powered winch. I have done it and so have many others, but this
is still not a good idea. There are serious dangers involved.

The best way to look at it is to consider power demand and supply. The
winch engine should be able to supply all the power the glider demands. If
the glider demands more power that is available by pulling up hard, the
airspeed will decay quickly. If the pilot knows this is going to happen, he
can manage it by controlling the pitch attitude carefully. If he doesn't
expect it, the airspeed will decay so quickly that a very dangerous
situation will develop.

The attempt to launch gliders with a low powered winch gets into who is in
control of the launch. I think it goes without saying that who controls the
launch should not be in doubt. The majority view is clearly that the winch
driver should be in charge.

With a low powered winch, the winch driver is in charge early in the launch
but as the glider steepens the climb, the power demand exceeds supply and
speed control shifts to the glider pilot who now must control airspeed with
pitch since the winch is at full throttle. As the glider rises still
further and power demands lessen, airspeed control shifts back to the winch
driver who must reduce power to prevent over speeding the glider. There
are lots of ways this scenario can go badly wrong.

The other area where a low powered winch can cause problems is in the
initial acceleration. The German Aero Club specifies the maximum distance
that a glider can use to reach flying speed to determine the minimum winch
power. Specifically, under all conceivable wind, density altitude and
weight conditions, a glider must reach Vr (rotation speed) in 40 meters or
less - there is no minimum specified. This is a very intelligent
specification. The concern driving this spec is that should a glider's wing
drop to the ground before reaching flying speed, the resulting ground loop
will be very ugly and quite possibly fatal for the glider pilot.

These concerns and the desire to get the highest launch possible, has driven
winch horsepower higher and higher in recent years. Shortening the
accelerate to Vr distance has a powerful effect on the launch height
achievable. Many powerful winches have shortened this to less than 20
meters.

To summarize, I am advocating generous power reserves to permit the winch
driver to maintain control of the launch and to insure the glider reaches
flying speed before a wing can drop.

Bill Daniels

"Mark Zivley" wrote in message
...
Yep, it's just not the same when you can match the displacement of an
entire European car engine with the displacement of just 2, maybe 3,
cylinders worth of an American big block motor......

Not to mention the CO emissions and resource usage ......

Ahh, but what the hell, when all the fish are dead, the sky rains acid, the
cows all have two heads and the crops die off because Monsanto decides to
modify the wrong gene it won't be our problem!

Cynically yours
Ian

Sorry guys

But I think you are all looking in the wrong direction
re diesel winch launches......

I have read the previous 40 something posts on this
subject but no one has mentioned the LPG route, gives
both the acceleration of petrol with the cost savings
of diesel.


www.skylaunch.co.uk is a web site of a manufacturer
of a petrol/LPG driven winch of which I can give a
personal recomendation of being the best winch I have
operated over the last 25 years, as I have flown mainly
from winch sites then I consider myself an expert (
ex as in has been and spert as something under pressure)
I also am expecting at least a bottle of single malt
from my 'friends' at skylaunch ;-))

Ged




At 20:30 21 March 2004, Bill Daniels wrote:

'Craig Freeman' wrote in message
So?
Our setup: 222kW (300hp) turbocharged diesel, 6 drums,
1000m of steel
cable. This winch has handled everything including
a 4DM. Even a
slight tailwind and a ASH25 are no real problem.
Samedan, the highest airport in Europe at over 5600ft
MSL, has the
same winch with four drums. No problems at all. It's
heaven compared
to the voluminous petrol monster they had before.

Just wondering if they had yanked out the engine in
the 'voluminous
petrol monster' and replaced it with some diesel engine
would
they have had a 'voluminous diesel monster' or would
it have been
'heaven'? Point is there is much more to consider
than just powerplant
when it comes to judging a machine. Chances are there
are other things
to consider, like drivetrains, drums, to level wind
or not, operator
comfort, control panels, comunications, cooling systems,
maintainence,
portability, availability of parts, ect. ect. ect.

Craig-
BTW these winches use an average of 0.4 litres of
Diesel per launch.

Credit where credit is due.

Craig Freeman has actually built a winch - a damn good
one - all by himself.
He gets my attention.

Bill Daniels

I second this. My club (Cotswold) has used reverse auto tow, then
Skylaunch. I have flown recently using Supercat. The Skylaunch wins
hand down in both height and reliability/consistency. I also have a
fair amount of experience driving the Skylaunch and know that it is very
flexible and allows good control of light gliders (Ka8), gliders with a
narrow speed range (SHK) and heavy beasts ASH and so on.

LPG also works well in terms of cost and refuelling.

Regards

Robin

In message , Ged McKnight
writes
Sorry guys

But I think you are all looking in the wrong direction
re diesel winch launches......

I have read the previous 40 something posts on this
subject but no one has mentioned the LPG route, gives
both the acceleration of petrol with the cost savings
of diesel.


www.skylaunch.co.uk is a web site of a manufacturer
of a petrol/LPG driven winch of which I can give a
personal recomendation of being the best winch I have
operated over the last 25 years, as I have flown mainly
from winch sites then I consider myself an expert (
ex as in has been and spert as something under pressure)
I also am expecting at least a bottle of single malt
from my 'friends' at skylaunch ;-))

Ged




At 20:30 21 March 2004, Bill Daniels wrote:

'Craig Freeman' wrote in message
So?
Our setup: 222kW (300hp) turbocharged diesel, 6 drums,
1000m of steel
cable. This winch has handled everything including
a 4DM. Even a
slight tailwind and a ASH25 are no real problem.
Samedan, the highest airport in Europe at over 5600ft
MSL, has the
same winch with four drums. No problems at all. It's
heaven compared
to the voluminous petrol monster they had before.

Just wondering if they had yanked out the engine in
the 'voluminous
petrol monster' and replaced it with some diesel engine
would
they have had a 'voluminous diesel monster' or would
it have been
'heaven'? Point is there is much more to consider
than just powerplant
when it comes to judging a machine. Chances are there
are other things
to consider, like drivetrains, drums, to level wind
or not, operator
comfort, control panels, comunications, cooling systems,
maintainence,
portability, availability of parts, ect. ect. ect.

Craig-
BTW these winches use an average of 0.4 litres of
Diesel per launch.

Credit where credit is due.

Craig Freeman has actually built a winch - a damn good
one - all by himself.
He gets my attention.

Bill Daniels






--
Robin Birch

Robin, Ged, for the UK, LPG is the right choice.

In the USA LPG or propane is still used mainly for domestic heating and
cooking and is sold for that purpose. To convert a spark ignition engine to
LPG is an extra $3000 or so and then fuel availability becomes an issue. It
can be done and it would work as well here as in the UK but there's no cost
reason to do it since LPG costs about the same or greater than petrol.

Diesels are reasonably cheap here and the fuel is readily available as
untaxed "red diesel" for as little as $1 per gallon. Biodiesel is a bit
more. In the USA fuel cost for a glider winch is a non-issue contributing
as little as $0.10 per launch. The "big" consumable item in the launch cost
is cable replacement at about $1 per launch. I like turbo diesels mainly
for their flat torque curve and the altitude compensation.

Not related to winches, but I once watched a demonstration of running a
standby diesel generator on natural gas. Basically, they just piped the
natural gas into the engine's air inlet. When they opened the natural gas
valve, the engine governor cut back on the diesel fuel to compensate for the
extra BTU's from the natural gas. The small amount of diesel fuel still
consumed was just for ignition.

Bill Daniels


"Robin Birch" wrote in message
...
I second this. My club (Cotswold) has used reverse auto tow, then
Skylaunch. I have flown recently using Supercat. The Skylaunch wins
hand down in both height and reliability/consistency. I also have a
fair amount of experience driving the Skylaunch and know that it is very
flexible and allows good control of light gliders (Ka8), gliders with a
narrow speed range (SHK) and heavy beasts ASH and so on.

LPG also works well in terms of cost and refuelling.

Regards

Robin

In message , Ged McKnight
writes
Sorry guys

But I think you are all looking in the wrong direction
re diesel winch launches......

I have read the previous 40 something posts on this
subject but no one has mentioned the LPG route, gives
both the acceleration of petrol with the cost savings
of diesel.


www.skylaunch.co.uk is a web site of a manufacturer
of a petrol/LPG driven winch of which I can give a
personal recomendation of being the best winch I have
operated over the last 25 years, as I have flown mainly
from winch sites then I consider myself an expert (
ex as in has been and spert as something under pressure)
I also am expecting at least a bottle of single malt
from my 'friends' at skylaunch ;-))

Ged

The petrol(gasoline)/propane winches at the Midland Club, Long Mynd were
bought new already converted for use with propane. They are large block
General Motors engines intended for marine use, where I understand propane
engines are common. I am practically certain that Skylaunch use the same
engines.

The advantage of petrol(gasoline)/propane engines does not lie only with
fuel cost. The engine itself is cheaper, and it is lighter in weight and
more compact. This means that the whole winch is smaller, lighter and more
compact. The Skylaunch can be towed legally on the road by any decent
4 X4, whereas the Supacat and all the other diesel winches I have seen can
only be moved on the back of a truck, or have to be built onto a truck
chassis. Changing the engine or working on it is also much easier.

Lastly it is much easier to arrange good throttle control and response with
a petrol/propane engine. One important special feature of the Skylaunch is
the throttle arrangement to help the driver get the correct setting for
different gliders and different conditions, the universal experience is that
this works really well.

If there is no cost advantage with propane, all the other reasons for
choosing petrol(gasoline) still apply. I know nothing about altitude
compensation, the Long Mynd is the highest club in the U.K. at
1,400 ft. a.s.l.

The normal size wire used in the U.K. seems to be 4.5 mm, some clubs use
5 mm.

W.J. (Bill) Dean (U.K.).
Remove "ic" to reply.


"Bill Daniels" wrote in message
...

Robin, Ged, for the UK, LPG is the right choice.

In the USA LPG or propane is still used mainly for domestic heating and
cooking and is sold for that purpose. To convert a spark ignition engine
to LPG is an extra $3000 or so and then fuel availability becomes an
issue. It can be done and it would work as well here as in the UK but
there's no cost reason to do it since LPG costs about the same or greater
than petrol.

Diesels are reasonably cheap here and the fuel is readily available as
untaxed "red diesel" for as little as $1 per gallon. Biodiesel is a bit
more. In the USA fuel cost for a glider winch is a non-issue
contributing as little as $0.10 per launch. The "big" consumable item in
the launch cost is cable replacement at about $1 per launch. I like
turbo diesels mainly for their flat torque curve and the altitude
compensation.

Not related to winches, but I once watched a demonstration of running a
standby diesel generator on natural gas. Basically, they just piped the
natural gas into the engine's air inlet. When they opened the natural
gas valve, the engine governor cut back on the diesel fuel to compensate
for the extra BTU's from the natural gas. The small amount of diesel
fuel still consumed was just for ignition.

Bill Daniels


"Robin Birch" wrote in message
...

I second this. My club (Cotswold) has used reverse auto tow, then
Skylaunch. I have flown recently using Supercat. The Skylaunch wins
hand down in both height and reliability/consistency. I also have a
fair amount of experience driving the Skylaunch and know that it is very
flexible and allows good control of light gliders (Ka8), gliders with a
narrow speed range (SHK) and heavy beasts ASH and so on.

LPG also works well in terms of cost and refuelling.

Regards

Robin


In message , Ged McKnight
writes

Sorry guys

But I think you are all looking in the wrong direction
re diesel winch launches......

I have read the previous 40 something posts on this
subject but no one has mentioned the LPG route, gives
both the acceleration of petrol with the cost savings
of diesel.


www.skylaunch.co.uk is a web site of a manufacturer
of a petrol/LPG driven winch of which I can give a
personal recommendation of being the best winch I have
operated over the last 25 years, as I have flown mainly
from winch sites then I consider myself an expert (
ex as in has been and spert as something under pressure)
I also am expecting at least a bottle of single malt
from my 'friends' at skylaunch ;-))

Ged

I've been reading all these posts w/ lots of interest. The basic winch
design is clearly fairly forgiving of specific design details due to the
number of cobbled together winches which are out there. Probably
hundreds worldwide.

Take a frame and a cab and add to that a powerful engine, transmission,
and some cable guides. All of this, while not easy, is straight forward
and parts are readily available for cheap depending on whether you want
to buy new (or rebuilt) or if you go scrounging for deals.

The one trick item that I see which could stand for some specific
development is a way to more effectively modify a rear axle off of a
vehicle so that you maintain a 3/1 ratio from the drive shaft yet can
positively disengage both wheels and then selectively engage either the
right wheel or the left wheel to achieve the dual drum winch.

There either needs to be a way to install a synchronizer type
transmission coupling between the differential and the wheel or
disengage the wheel at the end of the 1/2 shaft. This one part is the
only item that's not already designed for "us".

The Japanese are famous for copying designs which work well and then
continuing to improve upon them. Might as well start with something
that looks a lot like the Skylaunch since I think most of us would agree
that Skylaunch is probably the gold standard out there. Unfortunately,
with the current exchange rate a Skylaunch is well over $100,000 U.S.
Take that basic configuration, improve upon it, but keep it inexpensive.

This project should probably be moved to a slightly different forum like
a yahoo group where people interested in participating can do so without
filling up RAS. This also allows the sharing of files and even voting
on ideas as the project starts to take shape. We're definitely onto
something here, lets get started. We should start by doing some
deciding as to what will be designed. 1 or 2 or more drums.....

Mark

remove duplicate "hot" to reply direct