Overspeeding on winch launches

I don't agree with:

", i.e. when the climb
starts to flatten, you should release immediately if you're even slightly
above the placarded max winch speed. "

I do agree of course that exceeding the placarded limit is not a problem earlier in the launch when the cable is pulling the glider more forward than down, but that the load on the glider (and the weak link) is more critical towards the end of the launch. However, rather than releasing, I think that safety (and not breaking the weak link) can be achieved by relaxing the back pressure.

The correct weak link should prevent any glider from suffering structural failure, and probably does. But has anyone ever heard of any accident caused by exceeding a placarded maximum launch speed?

On Mon, 06 Nov 2017 16:33:03 -0800, waremark wrote:

The correct weak link should prevent any glider from suffering
structural failure, and probably does. But has anyone ever heard of any
accident caused by exceeding a placarded maximum launch speed?

Not that I've heard of, but that's pretty much a direct quote from any of
the instructors at GRL - especially w.r.t. the Puchacz.

I tend to apply it pretty rigidly to my Libelle because she's an old
lady, 48 this year, and I feel that I should be kind to her.

Actually, Libelles would appear to have a better protection than the weak
link: I was at Eden Soaring at the end of September, where pole-bending
is pretty much de rigeur thanks to a somewhat short field (940m winch to
launchpoint) and the need to get to the hill, 2.5 km away, at least 900ft
above the airfield, so you hear words from the instructor if you're
climbing out at less than 45 degrees during a site check in their K13.
Anyway, I soon found out that doing the same in my Libelle tends to back
release a little before I'd normally pull the bung and certainly before
the weak link went. They have good winch drivers: good brisk acceleration
at the start and spot on 65 kts in the top half of the launch.


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

At 00:33 07 November 2017, waremark wrote:
I don't agree with:

", i.e. when the climb=20
starts to flatten, you should release immediately if you're even
slightly=
=20
above the placarded max winch speed. "

I do agree of course that exceeding the placarded limit is not a
problem
ea=
rlier in the launch when the cable is pulling the glider more
forward than
=
down, but that the load on the glider (and the weak link) is more
critical
=
towards the end of the launch. However, rather than releasing, I
think
that=
safety (and not breaking the weak link) can be achieved by
relaxing the
ba=
ck pressure.

The correct weak link should prevent any glider from suffering
structural
f=
ailure, and probably does. But has anyone ever heard of any
accident
caused=
by exceeding a placarded maximum launch speed?

I watched a fatal winch launch accident happen ,and it still haunts
me.
The climb was not steep but the pilot got into a PIO while trying to
sort it out .1 wing broke off near the root and it came down
side ways.
There were structural faults in the glider wing and the weak link was
doubled,BUT the experienced winch driver said there was little load
on the cable.
We put it down to the change in angle of attack at high speed, the
load hits the wing first, then the hook, it is not until all the bow is
taken from the cable that the load it on the weak link and the driver
feels it.
max winch means max.
However I have not let it stop me, but I never have full back stick at
near max winch speed and I try to be smooth .
Jon May