Almost perfect payout winch launch.

Originally Posted by Bill D

On Friday, May 10, 2013 8:59:22 AM UTC-6, Waveguru wrote:
One of the most important things we teach all glider pilots is that it is there responsibility to keep themselves safe at all times, no matter what happens with the launch vehicle, be it winch, or aerotow. At no time should the pilot put himself in a position that he can't recover from in the event of a launch failure. That means you don't climb until you have sufficient airspeed, you limit the climb angle below 200', you abort the tow with enough runway to land straight ahead if you aren't climbing. No matter what happens to the launch vehicle, it is up to the glider pilot to keep himself in a safe place at all times, with safe options. Maybe you guys train differently? Even if my truck blew up, it just means the glider doesn't get as high as he would have. If the brake fails, it just means the glider doesn't get as high as he might. If my truck fails to get up to speed, the truck goes to the left and the glider lands straight ahead. Our payout system has been very dependable, but we train for launch failures just the same. Contrary to your assumptions, our operation is innovative, simple, safe, and really fun, and it doesn't cost a boat load of money.



Boggs

I have no doubt Gary is a highly responsible pilot and instructor who trains pilots to the best of his ability. He is absolutely correct in describing the pilot's responsibility for his own safety.

That said, I think it may be instructive to examine some of the German DAeC Technical Commission's requirements for winches. (I have a copy translated for me by Ulrich Newmann and I can provide a copy to anyone who requested it.) It's a satisfyingly practical document clearly developed from their vast experience and the results show in their absolutely stellar safety record.

Lets start with power,tension and rope speeds where the DAeC sets minimums.


"In dead calm air, the glider has to be controllable around it's longitudinal axis after less than 15 meters and must reach it's takeoff speed after a maximum of 45 meters."

I think Gary's payout winch can meet this requirement since it only depends on how fast the drum brake is engaged.

Now, here's a tough one - minimum rope speed. This is important because a glider launched in thermic conditions can encounter unexpected tailwind gusts or tailwind layers aloft.

"The drum speed (RPM) has to be chosen such that using the drum core diameter and the power to accelerate the glider according to (above), a rope speed of no less than 1.2 x Va is achievable."

Va on many gliders is in excess of 100 knots so let's say 1.2 x Vw which is typically 70% - 75% of Va but this still may require rope speeds near 100 knots. In the case of a payout winch, one has to add whatever the payout speed is to get the truck speed. I think Gary's pickup truck may have some difficulty with this one since it could mean tow vehicle speeds in excess of 100mph.

Here's a crucial one - minimum release height.

"The power of the winch has to be such that at MTOW in dead calm air, a glider launched at maximum permissible (Vw) airspeed for winch launching can achieve a release altitude of at least 25% of the initial rope length. This must assure safe execution of a normal pattern."

While it's possible Gary's payout winch could achieve this, there may be issues with tow vehicle traction when launching the heaviest gliders. Rope tensions up to a ton may be required at tow speeds.

There are a lot more requirements in the DAeC technical documents on winch design which make good reading.

Hi all

Doing a quick search of the DAeC website to find the document Bill is referencing gives the following information translated by Google

"The speed of the drum must be such that, for
Rated power of the motor to the drum core diameter a
Rope speed in the amount of 1.2 times the lift-off speed
is reached to slow aircraft.
When calculating the drum speed is a surcharge of 10% (for
Operating conditions and weather conditions) to consider.
With more than 1000 m elevation sites of the winds is another
Surcharge of 5% per thousand meters of altitude required."

Even with my imperfect understanding of German or of this translation I don't think they are referring to Va when setting rope speed requirements

:-) Colin

Hangglider and Paraglider pilots have been using payout winches for decades.. Payout winches are a viable, proven way to get horseless flying machines up in the sky. This isn't a singular redneck with a rope and spool, the Germans payout winch launch their paragliders. Nothing new here folks, no witches to burn, you can come out from under your glider trailers now.

On Friday, May 10, 2013 6:09:17 PM UTC-6, gb wrote:
Hangglider and Paraglider pilots have been using payout winches for decades. Payout winches are a viable, proven way to get horseless flying machines up in the sky. This isn't a singular redneck with a rope and spool, the Germans payout winch launch their paragliders. Nothing new here folks, no witches to burn, you can come out from under your glider trailers now.

There is a huge difference in speed between sailplanes and paragliders. So much so there is really no comparison.

On Friday, May 10, 2013 5:11:43 PM UTC-6, Ventus_a wrote:
Bill D;837692 Wrote:

On Friday, May 10, 2013 8:59:22 AM UTC-6, Waveguru wrote:-

One of the most important things we teach all glider pilots is that it

is there responsibility to keep themselves safe at all times, no matter

what happens with the launch vehicle, be it winch, or aerotow. At no

time should the pilot put himself in a position that he can't recover

from in the event of a launch failure. That means you don't climb until

you have sufficient airspeed, you limit the climb angle below 200', you

abort the tow with enough runway to land straight ahead if you aren't

climbing. No matter what happens to the launch vehicle, it is up to the

glider pilot to keep himself in a safe place at all times, with safe

options. Maybe you guys train differently? Even if my truck blew up,

it just means the glider doesn't get as high as he would have. If the

brake fails, it just means the glider doesn't get as high as he might.

If my truck fails to get up to speed, the truck goes to the left and the

glider lands straight ahead. Our payout system has been very

dependable, but we train for launch failures just the same. Contrary to

your assumptions, our operation is innovative, simple, safe, and really

fun, and it doesn't cost a boat load of money.







Boggs-



I have no doubt Gary is a highly responsible pilot and instructor who

trains pilots to the best of his ability. He is absolutely correct in

describing the pilot's responsibility for his own safety.



That said, I think it may be instructive to examine some of the German

DAeC Technical Commission's requirements for winches. (I have a copy

translated for me by Ulrich Newmann and I can provide a copy to anyone

who requested it.) It's a satisfyingly practical document clearly

developed from their vast experience and the results show in their

absolutely stellar safety record.



Lets start with power,tension and rope speeds where the DAeC sets

minimums.





"In dead calm air, the glider has to be controllable around it's

longitudinal axis after less than 15 meters and must reach it's takeoff

speed after a maximum of 45 meters."



I think Gary's payout winch can meet this requirement since it only

depends on how fast the drum brake is engaged.



Now, here's a tough one - minimum rope speed. This is important because

a glider launched in thermic conditions can encounter unexpected

tailwind gusts or tailwind layers aloft.



"The drum speed (RPM) has to be chosen such that using the drum core

diameter and the power to accelerate the glider according to (above), a

rope speed of no less than 1.2 x Va is achievable."



Va on many gliders is in excess of 100 knots so let's say 1.2 x Vw which

is typically 70% - 75% of Va but this still may require rope speeds near

100 knots. In the case of a payout winch, one has to add whatever the

payout speed is to get the truck speed. I think Gary's pickup truck may

have some difficulty with this one since it could mean tow vehicle

speeds in excess of 100mph.



Here's a crucial one - minimum release height.



"The power of the winch has to be such that at MTOW in dead calm air, a

glider launched at maximum permissible (Vw) airspeed for winch launching

can achieve a release altitude of at least 25% of the initial rope

length. This must assure safe execution of a normal pattern."



While it's possible Gary's payout winch could achieve this, there may be

issues with tow vehicle traction when launching the heaviest gliders.

Rope tensions up to a ton may be required at tow speeds.



There are a lot more requirements in the DAeC technical documents on

winch design which make good reading.



Hi all



Doing a quick search of the DAeC website to find the document Bill is

referencing gives the following information translated by Google



"The speed of the drum must be such that, for

Rated power of the motor to the drum core diameter a

Rope speed in the amount of 1.2 times the lift-off speed

is reached to slow aircraft.

When calculating the drum speed is a surcharge of 10% (for

Operating conditions and weather conditions) to consider.

With more than 1000 m elevation sites of the winds is another

Surcharge of 5% per thousand meters of altitude required."



Even with my imperfect understanding of German or of this translation I

don't think they are referring to Va when setting rope speed

requirements



:-) Colin


Your translation doesn't even remotely make sense. 1.2 x liftoff speed wouldn't even allow a safe rotation into climb. Have a professional translate it.

Hi all



Doing a quick search of the DAeC website to find the document Bill is

referencing gives the following information translated by Google



"The speed of the drum must be such that, for

Rated power of the motor to the drum core diameter a

Rope speed in the amount of 1.2 times the lift-off speed

is reached to slow aircraft.

When calculating the drum speed is a surcharge of 10% (for

Operating conditions and weather conditions) to consider.

With more than 1000 m elevation sites of the winds is another

Surcharge of 5% per thousand meters of altitude required."



Even with my imperfect understanding of German or of this translation I

don't think they are referring to Va when setting rope speed

requirements



:-) Colin

Ventus_a

Long live the machine translator - barf.....
Please check Bill's post on that subject - he is referencing the correct translation.

Ulrich Neumann

On Fri, 10 May 2013 06:19:27 -0700, son_of_flubber wrote:

Okay. I do have a few observations/opinions:

1)That the payout winch payouts more line and keeps line tension
constant when the glider hits lift seems an inherent advantage of this
approach when compared to a traditional winch launch.

As Bill says, a payout winch can't easily compensate for sink or a rear
gust at the start of a launch in calm conditions.

2)Don's suggestion that traditional winch launching is proven and that
there is therefore no reason to experiment with payout winching misses
the point. In a country where beefy pickup trucks are common, the
start-up costs for payout winching are much lower than traditional
winching. Secondly, far fewer humans need to be deployed and
coordinated to run a payout winch. The relevant question is "Which is
better to use on a dry lake bed, 1)autotow with payout winch or
2)traditional autotow? What are the tradeoffs?

As Don mentioned, we've been shown videos of payout winches with *no
gillotine fitted*. Its relatively rare, but cases of failures to release
have happened and are highly liable to be fatal without prompt use of the
guillotine. Even with a guillotine, what are the chances of a solo payout
winch driver noticing the problem in time? Even if he does notice, how
fast can he get to the guillotine's release and operate it?

I wouldn't accept a winch or auto-tow launch if there wasn't a functional
guillotine installed so that its release was instantly accessible to the
driver and/or the person monitoring the launch.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

Guillotine? How about simply mounting a release mechanism to the back of
the tow vehicle with the release cable within reach of the driver or
observer? That's the way they do it on the dry lake in Nevada and I was not
the least concerned about accepting ground launches. And, of course,
there's always the weak link at the glider end...


"Martin Gregorie" wrote in message
...
On Fri, 10 May 2013 06:19:27 -0700, son_of_flubber wrote:

Okay. I do have a few observations/opinions:

1)That the payout winch payouts more line and keeps line tension
constant when the glider hits lift seems an inherent advantage of this
approach when compared to a traditional winch launch.

As Bill says, a payout winch can't easily compensate for sink or a rear
gust at the start of a launch in calm conditions.

2)Don's suggestion that traditional winch launching is proven and that
there is therefore no reason to experiment with payout winching misses
the point. In a country where beefy pickup trucks are common, the
start-up costs for payout winching are much lower than traditional
winching. Secondly, far fewer humans need to be deployed and
coordinated to run a payout winch. The relevant question is "Which is
better to use on a dry lake bed, 1)autotow with payout winch or
2)traditional autotow? What are the tradeoffs?

As Don mentioned, we've been shown videos of payout winches with *no
gillotine fitted*. Its relatively rare, but cases of failures to release
have happened and are highly liable to be fatal without prompt use of the
guillotine. Even with a guillotine, what are the chances of a solo payout
winch driver noticing the problem in time? Even if he does notice, how
fast can he get to the guillotine's release and operate it?

I wouldn't accept a winch or auto-tow launch if there wasn't a functional
guillotine installed so that its release was instantly accessible to the
driver and/or the person monitoring the launch.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

On Sat, 18 May 2013 10:03:48 -0600, Dan Marotta wrote:

Guillotine? How about simply mounting a release mechanism to the back
of the tow vehicle with the release cable within reach of the driver or
observer? That's the way they do it on the dry lake in Nevada and I was
not the least concerned about accepting ground launches. And, of
course, there's always the weak link at the glider end...

The guillotine *is* the winch-end release mechanism. What else can you do
but cut the rope if the glider can't release? Jettisoning the drum and
guides, leaving them swinging beneath the glider isn't a good solution!

And, as others have pointed out, if you're not using a stiff 2-3 metre
strop (4.5mm steel cable inside plastic hose) on the glider's end of the
shock rope, then a hesitation or snatch as the take-off run starts can
wrap the cable round your wheel. That's something that's known to prevent
the glider from releasing its end of the cable.

I've just reviewed the video that started this thread and can't see any
sign that such a strop is in use or any indication that the weak link, if
there is one, at the glider end is correct for the glider. In the UK the
weak link housing is an integral part of the strop and the plastic hose
is colour coded to match the weak link: hence the pilot, or anybody else
at the launch point, can visually check that the correct weak is being
used when the cable is accepted prior to launch.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

The rope on a payout winch is on a drum not simply attached to the rear of a truck. Straight auto-tow uses a release. A payout winch needs a guillotine.

On Saturday, May 18, 2013 10:03:48 AM UTC-6, Dan Marotta wrote:
Guillotine? How about simply mounting a release mechanism to the back of

the tow vehicle with the release cable within reach of the driver or

observer? That's the way they do it on the dry lake in Nevada and I was not

the least concerned about accepting ground launches. And, of course,

there's always the weak link at the glider end...





"Martin Gregorie" wrote in message

...

On Fri, 10 May 2013 06:19:27 -0700, son_of_flubber wrote:



Okay. I do have a few observations/opinions:



1)That the payout winch payouts more line and keeps line tension

constant when the glider hits lift seems an inherent advantage of this

approach when compared to a traditional winch launch.



As Bill says, a payout winch can't easily compensate for sink or a rear

gust at the start of a launch in calm conditions.



2)Don's suggestion that traditional winch launching is proven and that

there is therefore no reason to experiment with payout winching misses

the point. In a country where beefy pickup trucks are common, the

start-up costs for payout winching are much lower than traditional

winching. Secondly, far fewer humans need to be deployed and

coordinated to run a payout winch. The relevant question is "Which is

better to use on a dry lake bed, 1)autotow with payout winch or

2)traditional autotow? What are the tradeoffs?



As Don mentioned, we've been shown videos of payout winches with *no

gillotine fitted*. Its relatively rare, but cases of failures to release

have happened and are highly liable to be fatal without prompt use of the

guillotine. Even with a guillotine, what are the chances of a solo payout

winch driver noticing the problem in time? Even if he does notice, how

fast can he get to the guillotine's release and operate it?



I wouldn't accept a winch or auto-tow launch if there wasn't a functional

guillotine installed so that its release was instantly accessible to the

driver and/or the person monitoring the launch.





--

martin@ | Martin Gregorie

gregorie. | Essex, UK

org |

Oops! I was thinking of a straight auto tow. I forgot about the payout
winch part.

You are, of course, correct in the need for a guillotine in this
application.


"Martin Gregorie" wrote in message
...
On Sat, 18 May 2013 10:03:48 -0600, Dan Marotta wrote:

Guillotine? How about simply mounting a release mechanism to the back
of the tow vehicle with the release cable within reach of the driver or
observer? That's the way they do it on the dry lake in Nevada and I was
not the least concerned about accepting ground launches. And, of
course, there's always the weak link at the glider end...

The guillotine *is* the winch-end release mechanism. What else can you do
but cut the rope if the glider can't release? Jettisoning the drum and
guides, leaving them swinging beneath the glider isn't a good solution!

And, as others have pointed out, if you're not using a stiff 2-3 metre
strop (4.5mm steel cable inside plastic hose) on the glider's end of the
shock rope, then a hesitation or snatch as the take-off run starts can
wrap the cable round your wheel. That's something that's known to prevent
the glider from releasing its end of the cable.

I've just reviewed the video that started this thread and can't see any
sign that such a strop is in use or any indication that the weak link, if
there is one, at the glider end is correct for the glider. In the UK the
weak link housing is an integral part of the strop and the plastic hose
is colour coded to match the weak link: hence the pilot, or anybody else
at the launch point, can visually check that the correct weak is being
used when the cable is accepted prior to launch.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |