Using Plasma Rope For Winch Tows

Chris Reed wrote:
...
In my experience the K8 pitch-up was near uncontrollable when winching. If
you had winched it previously you learnt the theoretically correct
procedure, which was:

a. Stick back to get the nose skid up.

b. Stick central to run on the main wheel; and then

c. (*Immediately the main wheel left the ground) Knuckles hard into the
instrument panel and wait for the pitch to become controllable.


I have no experience with the K8, but the general procedure
I learnt for any glider is: stick full forward *before* start.
I don't know if this will prevent the nose skid of a K8 to lift,
but it doesn't prevent the nose wheel of a K21 to lift. At the
very beginning of the launch, the aerodynamic forces are weak
compared to the inertial forces (accelaration near 1g implies
inertial forces have the same order of magnitude as the weight
of the glider), so when acceleration just begins, the main forces
are the cable traction and the inertial force at CG, making
a pitching up moment. If later the aerodynamic force due to
the elevator becomes sufficient to override this moment, it
is now time to pull the stick avoiding a nose drop.

The K8 in question had a replacement wing from a different glider and some
other repairs - maybe the CG hook was not ideally placed relative to the
revised CG? The glider has now gone, so can't check this out.

"Bert Willing" wrote in
message ...
I learnt flying gliders on a Ka7/Ka8 combo (only winching), later
instructing, and I never came across a behaviour of a Ka8 as you describe
it. Completely simple and controlable.

--
Bert Willing

ASW20 "TW"

I have flown a K8 from a winch launch several dozen
times and never experienced a 'pitch up' as you describe.
I was trained for winch launching on a Ka-7 and then
was moved into the K8. I loved it! The winch, a Tost
unit, I think, was powered by a General Motors V-8
gasoline engine which was mounted on an ancient Mercedes
truck of maybe 5 ton capacity.

The winch was great for launching the single-seaters.
My best altitude at release height was 700 meters
in the K8. The winch could have used a bit more grunt
for launching the Grob 103, but it still managed to
get to 400 meters or so.

Could the weight and balance been out of limits on
the K8 you were launching?

I wish our club had a winch! Then, I would get to
drive the 'Lepo' again!

Ray Lovinggood
Carrboro, North Carolina, USA
LS-1d, 'W8'

At 12:06 11 August 2003, Chris Reed wrote:
'Andreas Maurer' wrote in message
.. .
On Thu, 7 Aug 2003 07:52:53 -0600, 'Bill Daniels'
wrote:



The boundary on the high side of acceleration is the
tendency of some
gliders with high CG's, low hooks and limited down
elevator authority to
pitch-up uncontrollably when a threshold acceleration
is exceeded.

Please tell me the names of these gliders. I have
NOT heard of a
single one yet that showed this behaviour. Not one.

In my experience the K8 pitch-up was near uncontrollable
when winching. If
you had winched it previously you learnt the theoretically
correct
procedure, which was:

a. Stick back to get the nose skid up.

b. Stick central to run on the main wheel; and then

c. (*Immediately the main wheel left the ground) Knuckles
hard into the
instrument panel and wait for the pitch to become controllable.

On anything but the softest of take-ups (a) and (b)
disappeared, as the
glider was flying before you could react, so the *real*
procedure was stick
full forwards as soon as the glider moved.

Once full pitch control was re-established the rest
of the launch was fine,
but the first two seconds were only semi-controlled,
and that only if you
knew what to expect. I never saw a first flight in
the K8 where the pilot
reacted in time to prevent an uncontrolled pitch-up
as soon as the main
wheel left the ground. And our winch was not any kind
of high-powered
monster.

All the glass gliders I've seen winching behaved well,
but the K8 was ...
interesting.

I guess that it was something like this, because Ka8's are somewhat the
reference for very, very easy gliders in all circumstances.
With a glide ratio of almost a PW5.

--
Bert Willing

ASW20 "TW"


"Chris Reed" a écrit dans le message de
...
The K8 in question had a replacement wing from a different glider and some
other repairs - maybe the CG hook was not ideally placed relative to the
revised CG? The glider has now gone, so can't check this out.

"Bert Willing" wrote in
message ...
I learnt flying gliders on a Ka7/Ka8 combo (only winching), later
instructing, and I never came across a behaviour of a Ka8 as you
describe
it. Completely simple and controlable.

--
Bert Willing

ASW20 "TW"

"Chris Reed" wrote in message ...
"Andreas Maurer" wrote in message
...
On Thu, 7 Aug 2003 07:52:53 -0600, "Bill Daniels"
wrote:



The boundary on the high side of acceleration is the tendency of some
gliders with high CG's, low hooks and limited down elevator authority to
pitch-up uncontrollably when a threshold acceleration is exceeded.

Please tell me the names of these gliders. I have NOT heard of a
single one yet that showed this behaviour. Not one.

In my experience the K8 pitch-up was near uncontrollable when winching. If
you had winched it previously you learnt the theoretically correct
procedure, which was:

a. Stick back to get the nose skid up.

b. Stick central to run on the main wheel; and then

c. (*Immediately the main wheel left the ground) Knuckles hard into the
instrument panel and wait for the pitch to become controllable.

On anything but the softest of take-ups (a) and (b) disappeared, as the
glider was flying before you could react, so the *real* procedure was stick
full forwards as soon as the glider moved.

Once full pitch control was re-established the rest of the launch was fine,
but the first two seconds were only semi-controlled, and that only if you
knew what to expect. I never saw a first flight in the K8 where the pilot
reacted in time to prevent an uncontrolled pitch-up as soon as the main
wheel left the ground. And our winch was not any kind of high-powered
monster.

All the glass gliders I've seen winching behaved well, but the K8 was ...
interesting.

Chris,

there had to be something wrong with this Ka-8. I soloed on the winch
in a Ka-13 and transitioned to the Ka-8 long before taking up
aero-towing. Unless your winch operator was a graduate of the Naval
Cat-shot school, the launches were very controllable. Our procedure
had us lift off with the stick somewhat forward depending on your
weight and the rudder full left to compensate for the off-center tow
hook. As soon as you lifted off, the rudder went back to neutral (or
wherever it had to go to compensate for cross-wind) and you would
continue in a shallow climb to about 150' before easing the stick back
slightly aft of neutral to assume the steep climb attitude. We would
typically achieve 12-1500' on an average windy day.
Too bad that not more clubs operate winches in the US. Would someone
be able to offer an explanation for this?

Ulrich Neumann
Libelle 'GM'

Too bad that not more clubs operate winches in the US. Would someone
be able to offer an explanation for this?

Ulrich Neumann
Libelle 'GM'

It is interesting, that no one has picked up on this.
Every body appears to be concerned about the decline of
member ship and how important it is to get young people into
gliding. Here is a way to substantially reduce the cost in North America,
for young aspiring Glider Pilots.
Regards
Udo

The club, 'DJK' in Landau in der Pfalz, Germany, had
many GREAT winch operators! The only instrument, I
think (hey, this was from 1983 till 1986), was a tach
and maybe a engine coolant temperature gauge. I think
they operated mainly by sight and sound. Yep, they
were great operators! I think their rules stipulated
at least 100 operations with an instructor before they
could operate solo.

Ray Lovinggood
Carrboro, North Carolina, USA
(who misses winch launching in the Land of Aero Tows)

At 13:48 12 August 2003, Bill Daniels wrote:
Let me add that if the winch driver provides the right
acceleration, the
pilot of a K-8, or any similar glider, will be unaware
of the pitch-up
tendency. Ray, you were blessed with the services
of a good winch driver.
Bill Daniels

'Jonathan Gogan' wrote in message
...
Ray;
Ka8 well known for pitch-up on winch-launch with
lighter (ladies or small/medim men) pilots but still
well within W&B
limits.
I have no such problem being f*t g*t but that is not
altogether a good
thing
;-)
J.


'Ray Lovinggood' wrote in message
...
I have flown a K8 from a winch launch several dozen
times and never experienced a 'pitch up' as you describe.
I was trained for winch launching on a Ka-7 and then
was moved into the K8. I loved it! The winch, a
Tost
unit, I think, was powered by a General Motors V-8
gasoline engine which was mounted on an ancient Mercedes
truck of maybe 5 ton capacity.

The winch was great for launching the single-seaters.
My best altitude at release height was 700 meters
in the K8. The winch could have used a bit more grunt
for launching the Grob 103, but it still managed to
get to 400 meters or so.

Could the weight and balance been out of limits on
the K8 you were launching?

I wish our club had a winch! Then, I would get to
drive the 'Lepo' again!

Ray Lovinggood
Carrboro, North Carolina, USA
LS-1d, 'W8'

At 12:06 11 August 2003, Chris Reed wrote:
'Andreas Maurer' wrote in message
.. .
On Thu, 7 Aug 2003 07:52:53 -0600, 'Bill Daniels'
wrote:



The boundary on the high side of acceleration is
the
tendency of some
gliders with high CG's, low hooks and limited down
elevator authority to
pitch-up uncontrollably when a threshold acceleration
is exceeded.

Please tell me the names of these gliders. I have
NOT heard of a
single one yet that showed this behaviour. Not one.

In my experience the K8 pitch-up was near uncontrollable
when winching. If
you had winched it previously you learnt the theoretically
correct
procedure, which was:

a. Stick back to get the nose skid up.

b. Stick central to run on the main wheel; and then

c. (*Immediately the main wheel left the ground) Knuckles
hard into the
instrument panel and wait for the pitch to become
controllable.

On anything but the softest of take-ups (a) and (b)
disappeared, as the
glider was flying before you could react, so the *real*
procedure was stick
full forwards as soon as the glider moved.

Once full pitch control was re-established the rest
of the launch was fine,
but the first two seconds were only semi-controlled,
and that only if you
knew what to expect. I never saw a first flight in
the K8 where the pilot
reacted in time to prevent an uncontrolled pitch-up
as soon as the main
wheel left the ground. And our winch was not any kind
of high-powered
monster.

All the glass gliders I've seen winching behaved well,
but the K8 was ...
interesting.

"Ulrich Neumann" wrote in message

Too bad that not more clubs operate winches in the US. Would someone be
able to offer an explanation for this?

Ulrich Neumann
Libelle 'GM'

This whole thing about uncontrollable pitch-up occurs outside the normal
winch launch profile. It also usually requires a winch with an automatic
transmission in need of service. Mentioning the K-8 as an example of a
glider that pitches up was not intended as a criticism of this fine, docile
glider.

For whatever reason, all gliders are likely to have some acceleration value
above which the launch is not comfortable. This value is almost always
above what is considered "normal" acceleration. All well trained winch
drivers are well aware of this danger.

Most people have at one time or another driven a car with an automatic
transmission that won't start smoothly where the engine revs before the
transmission "thunks" into first gear, jerking the car forward. Should this
happen with a winch, the glider may get snatched into the air before the
pilot has enough down elevator authority to stop the pitch-up. Once an
automobile engine/transmission is installed in a winch, it is difficult to
evaluate the health of the transmission since testing protocols all require
a test drive of the original automobile.

As for why winches are uncommon in the USA, I suspect that it has to do with
the fact that most glider operations in the country are at public airports.
Winching on a public runway that is shared with power traffic is problematic
at best.

There is also the fear of the unknown. Almost all US pilots were trained
with airtow or in powered aircraft and, to them, the sight of a glider in a
45 degree climb near the ground looks like an incredibly dangerous thing.
It's almost impossible to convince them that winch launch is actually as
safe or even safer than airtow.

Bill Daniels

I do not understand why winch launch is not popular in the USA.

Its cheap, safe, fast and FUN. Winch launching gliders combines the
rollercoaster first 50 seconds, with all the nice quiet peaceful stuff
for the rest of the flight. Best of both worlds...

Only disadvantage is it needs an extra person on the winch and some
radio co-ordination.


Udo Rumpf wrote:
Too bad that not more clubs operate winches in the US. Would someone
be able to offer an explanation for this?

Ulrich Neumann
Libelle 'GM'


It is interesting, that no one has picked up on this.
Every body appears to be concerned about the decline of
member ship and how important it is to get young people into
gliding. Here is a way to substantially reduce the cost in North America,
for young aspiring Glider Pilots.
Regards
Udo

"Jeff Goodenough" wrote...
Bruce Greeff wrote:

Only disadvantage is it needs an extra person on the winch and some
radio co-ordination.

As opposed to an extra person in an aircraft in front of you, you mean? :-)

Using aerotow you can launch with two people, one in the tow plane and one in
the glider. Would you do a winch launch with with only the operator and the
pilot?

Marc