New 29 Palms Winchfest Video

"Andreas Maurer" wrote in message
...
On Mon, 17 Dec 2007 16:40:49 -0800 (PST), tommytoyz
wrote:


from the pilot's point of view, it should be a
simple matter.

I think that's the main point.

@Bill:
I really love the fact that you are trying to promote winch launching
in the US - but (please correct me if I'm wrong) from the comments
here in this newsgroup I get the impression that you US guys regard
the winch launch as something pretty hazardous that needs a lot of
technology to be safe.
Consequently, your approach to a US winch design looks a little
over-engineered to me, I have to admit. Complex and expensive to
build, hard to set up correctly. Possibly prone to mechanical
problems.

Us European guys seem to see things in a more relaxed way - we tend to
advocate training instead of technological devices to achieve safe
winch operations.

Considering the number of accident-free winch launches per year on my
side of the pond, don't you think that it might be useful to stick
more closely to the KISS-principle ("keep it simple, stupid"), forget
all that high-tech stuff and concentrate on correct training?

Nearly all the winches here are basically very simple.
Anything a winch needs is a strong diesel engine, two drums, 3.500 ft
of cable (be it steel or plastic). No rocket science involved.




Bye
Andreas

Andreas, I have great respect for the long experience you have on that side
of the pond. I have spent years researching just what you do over there.
That's where I got my ideas.

But, there are problems with the very basic KISS principle. If you ask the
winch driver to control the glider's airspeed, you have to give him a way to
to judge how well he does that. If the pilot has an airspeed indicator with
which he judges the quality of a launch but the winch driver has nothing but
"feel", that's unfair to the winch driver since the pilot has MUCH more
information than he does. It's interesting to see that a German company is
now selling an inexpensive airspeed telemetry unit to address this.

If you ask the winch driver to control tension instead of airspeed, he has
several things to help him do that - things like cable sag (if using steel)
throttle setting and the sound and feel of the winch. It's even simpler for
him if there is a tensiometer. It's still better if you can link the
instantaneous cable tension to a throttle control loop so the winch does it
automatically.

The critical point is that neither the pilot or winch driver can control
both airspeed AND tension at the same time. If you tell the pilot to just
"go along for the ride" and task the winch driver with controling both, you
are giving the winch driver an impossible task.

If the winch driver controls only tension, the pilot now has to step up and
control his own airspeed. Once I realized I could do this, launches assumed
a high level of smoothness and consistency. This REALLY works SWEET. The
math shows it works right up to the cable tension that would break the weak
link so winch engine potential power or torque has nothing to do with it.

However, this is a hard concept to teach someone who has been trained
otherwise. I've had people who were jumping up and down with indignation
since they "knew" that pulling harder would make the glider speed up. "Show
me", I said. They lost the bet - every time.

A good analogy is old cars with drum brakes. When they got wet, braking
action vanished until they dried out. There is an almost overpowering
sensation that the car actually speeds up when you step hard on the brakes
and nothing happens.

I'm sure this is what is confusing glider pilots on a winch. As the nose
rises during the rotation, the glider is still accelerating and, since the
airspeed doesn't drop when they pull, they assume pulling on the stick makes
the glider speed up - or at least that they have no control over airspeed.

Once the glider has stabilized in the climb, the old pitch/airspeed
relationship is restored and you can control airspeed. Pitch up to slow and
down to speed up. As the glider nears the top of the launch, the ability to
reduce airspeed is much reduced but releasing back pressure will definitely
make the glider speed up.

There are things that make this hard to see. For one thing, the airspeed
response is not instantaneous - it takes a little time for a pitch input to
result in an airspeed change. For another, if the glider is loaded with the
CG at or even beyond the forward limit, you will likely not have enough up
elevator authority to slow the glider. This is a W&B problem - not a winch
problem. It's is the "two 200+ pounders in a glider with a 380 pound
maximum cockpit load" problem.

So, is this approach unnecessarily complicated? I don't think so. All I am
saying is to give the winch driver the ability to control tension extremely
accurately no matter what. Any driver, any wind, any glider or pilot and
the tension is always exactly right. What's not to like about that?

All you ask of the pilot is to control airspeed with pitch exactly like it
is done in all other flight situations. In other words, "Just fly the
glider". What's complicated about that?

An AOA indicator helps the pilot because his wings are loaded to the
equivalent of 3.5 G's so the "loaded stall airspeed" is much higher than in
1G flight. Glider's have stalled while on the wire with disastrous results.
A safe AOA indication is an absolute guarantee that you won't stall - no ASI
indication gives that level of assurance.


Bill Daniels

Bill,

accidents don't happen because somebody is missing a gadget.

Accidents happen because people are not aware about the situation they are
in. On a winch launch, and more so during free flight, you have lots of
indications about what is going on (speed, attitude, feel, sound).

Whenever somebody lacks situational awareness, he is an accident waiting to
happen, and the lack of awareness is the main cause of accidents. It's not
the missing AoA which is fatal..

Somebody who doesn't pay attention to what is going on will not benefit from
an AoA because he obviously doesn't care about all the information he
already gets.

I am a profound believer that you can increase safety only by training (both
mental and on the stick), and by increasing situational awareness. Adding
gadgets is an engineering approach to something which can't be solved by an
engineering approach. Somebody who doesn't get the fact that he is about to
stall will find another way to die, once you've added the AoA (and he cares
to look).

Bert

"Bill Daniels" bildan@comcast-dot-net wrote in message A safe AOA
indication is an absolute guarantee that you won't stall - no ASI
indication gives that level of assurance.


Bill Daniels

At 17:18 18 December 2007, Bill Daniels wrote:

All you ask of the pilot is to control airspeed with
pitch exactly like it
is done in all other flight situations. In other words,
'Just fly the
glider'. What's complicated about that?

An AOA indicator helps the pilot because his wings
are loaded to the
equivalent of 3.5 G's so the 'loaded stall airspeed'
is much higher than in
1G flight. Glider's have stalled while on the wire
with disastrous results.
A safe AOA indication is an absolute guarantee that
you won't stall - no ASI
indication gives that level of assurance.


Bill Daniels


A typical winch launch will put up to a 2G load on
the wings. If you're using the proper techniques and
equipment, the load is limited to a maximum of about
2.5G, depending on the glider.

The AoA increases as the glider flies up the wire.
Its therefore easier to use a calculated minimum safe
speed during the full climb which you know will keep
the AoA below the critical angle, even at the top of
the launch. This also ensures that the AoA is comfortably
below the critical angle at low level where a stall/spin
would be particularly dangerous.

Edward

"Edward Lockhart" wrote in message
...
At 17:18 18 December 2007, Bill Daniels wrote:

All you ask of the pilot is to control airspeed with
pitch exactly like it
is done in all other flight situations. In other words,
'Just fly the
glider'. What's complicated about that?

An AOA indicator helps the pilot because his wings
are loaded to the
equivalent of 3.5 G's so the 'loaded stall airspeed'
is much higher than in
1G flight. Glider's have stalled while on the wire
with disastrous results.
A safe AOA indication is an absolute guarantee that
you won't stall - no ASI
indication gives that level of assurance.


Bill Daniels


A typical winch launch will put up to a 2G load on
the wings. If you're using the proper techniques and
equipment, the load is limited to a maximum of about
2.5G, depending on the glider.

The AoA increases as the glider flies up the wire.
Its therefore easier to use a calculated minimum safe
speed during the full climb which you know will keep
the AoA below the critical angle, even at the top of
the launch. This also ensures that the AoA is comfortably
below the critical angle at low level where a stall/spin
would be particularly dangerous.

Edward


From this I assume you would rather fly gliders that weren't designed by
'engineers'.

No one who understand the use of an AOA indicator will call it a "gadget".

Having done winch launches with an AOA indicator, I can assure you that the
AOA does, in fact, remain constant throughout a well flown launch.

Yes, you can use airspeed but only as an abstraction of the real thing which
is AOA. Airspeed and AOA are not the same thing. You can stall a glider at
any airspeed but only at one AOA.

I can also assure you that the maximum loads on the wing is much nearer 3.5G
than 2.5.

Bill Daniels

Bill,
I think the resistance your seeing is due to this:

Pilot Adjusted Airspeed
The acceptable airspeed range on a winch launch for any given wing
loading on practically any glider is fairly wide. Say +/- 30 knots. So
what then is the point of pushing and pulling to change the airspeed
for a few knots here and there, if it is even possible on some set
ups?

If the airspeed is in the acceptable range, there is no point to doing
this. It will only possibly confuse the winch driver creating a
negative feedback loop between pilot/driver actions.

Think about your statement:
"All you ask of the pilot is to control airspeed with pitch exactly
like it
is done in all other flight situations. In other words, "Just fly the
glider". What's complicated about that? "

As has been reported here, different winch set ups react differently.
So you would need to fly and train differently for each set up. That's
not good.

Also, as has been reported here, which you seem not to believe, is
that it is dangerous, such as breaking the weak link, say on a gust,
just as your pulling the most. Think about that situation.

All this just to control airspeed a few knots here and there?

It doesn't sound like a good practice to base standard practices on
and train people that way. If you want to do it yourself after much
experience, that's another matter. But it should not be taught this
way across the board. On some winch setups it might produce the exact
opposite effects for all anyone knows.

Experimenting by experienced pilots is one thing, especially if you're
willing to get closer to the weak link breakage point that necessary
during launch. But it should not be standard practice, IMHO.

I'm really tempted not to answer but here goes anyway.

"tommytoyz" wrote in message
...
Bill,
I think the resistance your seeing is due to this:

Pilot Adjusted Airspeed
The acceptable airspeed range on a winch launch for any given wing
loading on practically any glider is fairly wide. Say +/- 30 knots. So
what then is the point of pushing and pulling to change the airspeed
for a few knots here and there, if it is even possible on some set
ups?

Because being at the optimum airspeed is both safer and results in higher
launches.

If the airspeed is in the acceptable range, there is no point to doing
this. It will only possibly confuse the winch driver creating a
negative feedback loop between pilot/driver actions.

If your winch driver get confused so easilly, maybe you need to find another
one.


Think about your statement:
"All you ask of the pilot is to control airspeed with pitch exactly
like it
is done in all other flight situations. In other words, "Just fly the
glider". What's complicated about that? "

I stand by that.

As has been reported here, different winch set ups react differently.
So you would need to fly and train differently for each set up. That's
not good.

The laws of physics are the same everywhere in the universe. Train to the
physics.


Also, as has been reported here, which you seem not to believe, is
that it is dangerous, such as breaking the weak link, say on a gust,
just as your pulling the most. Think about that situation.

Breaking a weak link is inconvenient, not dangerous. If you think it's
dangerous, maybe you need more training in emergencies.


All this just to control airspeed a few knots here and there?

It doesn't sound like a good practice to base standard practices on
and train people that way. If you want to do it yourself after much
experience, that's another matter. But it should not be taught this
way across the board. On some winch setups it might produce the exact
opposite effects for all anyone knows.

I say, train to the physics . That accomodates all differences. If you
train to some standard other than the basic physics, that is REALLY
dangerous.

Experimenting by experienced pilots is one thing, especially if you're
willing to get closer to the weak link breakage point that necessary
during launch. But it should not be standard practice, IMHO.

No one is experimenting, This is how it works.

Bill Daniels

Bill's statement #1
"Breaking a weak link is inconvenient, not dangerous."

My Response
And even this is good? You want to risk incurring a breakage more
often, just to get a slightly higher launch altitude? I don't think
it's a good trade off and at a minimum, it does not add to safety in
any case either.

And being at optimum airspeed is not safer than being slightly outside
but still in the acceptable airspeed range. Only being at the edge is
unsafe, specifically at the low end. That's when everyone advocates
changing the attitude by lowering the nose, in case it continues and
an abort becomes necessary, and as you know, to maintain good AoA.

Bill's statement #2
"The laws of physics are the same everywhere in the universe. Train
to the
physics."

I say:
Your statement is not false all by itself. But it fails to make your
point as winch launch training. It excludes to consider the fact that
not all winch setups are the same. Some have vastly more torque than
others and the weight and type of ship being launched also makes a
difference in how the airspeed will or will not react if you push or
pull. Driver training also matters. You can not assume all these
factors are the same at all times. They're not.

It also matters at what speed you initiate the attitude changes. Lots
a variables. All just to get slightly higher? How much do you think
you'll gain anyway? Experienced winch pilots may play around with this
but is should not be taught as best practices.

I respectfully disagree with your advice that it is good practice. I
think it's bad practice, especially for clubs here in the USA trying
to establish best practices.

If you haven't done so already, I suggest you fly off several winches
in Europe. I hear (since I've never flown winches here) that the
winches in the USA are very different.

On Dec 18, 12:36 pm, "Bill Daniels" bildan@comcast-dot-net wrote:

I can also assure you that the maximum loads on the wing is much nearer 3.5G
than 2.5.

Spar bending moment, yes. Aerodynamic load, no.

If the wing loading was 3.5G, the stall speed would be in excess of 60
knots and there would be a lot more dead pole benders.

So, tommytoys, are you in the USA or Europe? Why is it that you are afraid
to use your real name?


"tommytoyz" wrote in message
...
Bill's statement #1
"Breaking a weak link is inconvenient, not dangerous."

My Response
And even this is good? You want to risk incurring a breakage more
often, just to get a slightly higher launch altitude? I don't think
it's a good trade off and at a minimum, it does not add to safety in
any case either.

Dont' waffle. You said unsafe and that's BS.


And being at optimum airspeed is not safer than being slightly outside
but still in the acceptable airspeed range. Only being at the edge is
unsafe, specifically at the low end. That's when everyone advocates
changing the attitude by lowering the nose, in case it continues and
an abort becomes necessary, and as you know, to maintain good AoA.

Bill's statement #2
"The laws of physics are the same everywhere in the universe. Train
to the
physics."

I say:
Your statement is not false all by itself. But it fails to make your
point as winch launch training. It excludes to consider the fact that
not all winch setups are the same. Some have vastly more torque than
others and the weight and type of ship being launched also makes a
difference in how the airspeed will or will not react if you push or
pull. Driver training also matters. You can not assume all these
factors are the same at all times. They're not.

Physics is the whole enchilada. Winch setups may be different but the
operating physics are the same. Train to the physics and winch setup
differences won't matter.

Are you saying that every 'different' winch operation should have a
different training syllabus? That's really nuts.



It also matters at what speed you initiate the attitude changes. Lots
a variables. All just to get slightly higher? How much do you think
you'll gain anyway? Experienced winch pilots may play around with this
but is should not be taught as best practices.

I can't make any sense of this paragraph. All the variables are simple and
easily exlainable. Which one confuses you?


I respectfully disagree with your advice that it is good practice. I
think it's bad practice, especially for clubs here in the USA trying
to establish best practices.

I think it's not that you disagree but that you just don't understand it.


If you haven't done so already, I suggest you fly off several winches
in Europe. I hear (since I've never flown winches here) that the
winches in the USA are very different.

I have flown from many winches of many different types but far more
important, I've studied the physics. Go read the papers by Goulthrope and
Moore. Read the information provided by Hydrostart at www.Hydrostart.nl

Winch launch is not an art, it's a science and not a very complicated one.

Bill Daniels

Bill,
I am not confused at all. I don't know why you come off so defensive
and aggressive.

In that vein, have never explained why you said I should ground myself
and that I'm dangerous. Thats was a ridiculous statement and a cop out
to not answer - and you know it. Owning up to it wold be a good start,
IMHO.

Anyway, I am of the KISS school. You advocate the pilot push or pull
to try and oscillate attitude to control airspeed. I say the pilot
should not. Why is that so difficult for you to understand? This is
the only point we disagree on. Does this call for insults and crazy
statements? We mostly agree.

"Train to the physics and winch setup differences won't matter."

You forget that the winch driver is main factor, which you repeatedly
leave out and that's not a physics issue. Having been launched by many
different winch drivers off the same winch, I can tell you there are
differences.

Instructors will often ask who is driving the winch. There is a reason
for this.

So if you think that oscillating by pushing and pulling with
a) different winch set ups
b) different aircraft and
c) different winch drivers
will always give the same results with your technique, be my guest. I
know otherwise.

Your oscillating technique is just not best practices for pilots to
learn to launch with a variety of variables. Perhaps for one
particular set up, yes. But not as general standard.

Premature back releases and tempting weak link breaks with high nose
up attitudes in the name of slightly higher (and even this is
questionable) release altitudes is not best practices. A steady climb
profile when the speed is acceptable and steady is better than pushing
and pulling to supposedly get higher. Perhaps you actually release
lower, if the winch driver doesn't react well to this technique? Ever
thought of that?

But you think different, and I have no problem with that. Be my guest.
Oscillate away on your launches.
Tom Vallarino