Overspeeding on winch launches

Thanks everyone for your feedback. My take aways from this a

1. Speak with the winch driver. I've had fast launches a few times with no reduction in power when signalling.
2. Get the airspeed under control early in the launch.
3. Release early if over speeding past the first 1/2 of the launch.
4. Smooth control inputs and don't give full up elevator towards the top of the launch if over speeding.

Thanks,

Dan

Having a little engine I don't winch launch but reading through
the earlier posts it sounds like little has changed in 40 years:
why, in the 21st Century, don't the pilot and winch driver
communicate by radio? Surely all this waggling the wings
about stuff should long ago have been scrapped?

I would repeat what Scott said above as well. I've done quite a few launches as driver on our winch here at Utah Soaring, and we are always back to 1/3 or 1/4 throttle as the climb rate begins to slow and the glider begins to arc over at the top, and sometimes get all the way to idle by the time the back release engages. The less tension on the line the better the back release works, at least on our Astir.

I assume "signaling" is done by radio? If not, that seems to be a "weak link" in the process chain, as Dave suggests.

Mike

On Tue, 07 Nov 2017 09:00:58 -0800, Mike Hendron wrote:

I would repeat what Scott said above as well. I've done quite a few
launches as driver on our winch here at Utah Soaring, and we are always
back to 1/3 or 1/4 throttle as the climb rate begins to slow and the
glider begins to arc over at the top, and sometimes get all the way to
idle by the time the back release engages. The less tension on the line
the better the back release works, at least on our Astir.

I assume "signaling" is done by radio? If not, that seems to be a "weak
link" in the process chain, as Dave suggests.

Where I fly, glider-winch signalling is visible: lower the nose of the
launch is too slow and use the rudder to wave your tail at the winch if
its too fast.

Our duty launch marshal uses radio, rather than lights, to pass glider
details to the winch driver and to manage the launch, but that doesn't
use an airband frequency and we do not have an airband radio in the
winch.

Our airband frequency is used for glider-tug, glider-glider comms and for
blind calls as we join the circuit. The launch marshal has an airband
receiver to help him maintain situational awareness, but he is primarily
concerned with managing winch launching and co-ordinating launches with
aerotow operations. On a typical day winch launches considerably
outnumber aero tows.

I know that at least one Scandinavian club experimented with using radio
telemetry to display the glider's airspeed to the winch driver, but I
don't know if they still use it or what their conclusions about its
benefits were.


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

On Monday, November 6, 2017 at 1:48:16 PM UTC+1, Dan Schmitz wrote:
I'm wondering what the consequences of overspeeding on winch launches are? I understand that it places stress on the airframe, but to what extent?

I find it near impossible to control the airspeed on the top third of a launch and have found myself over speeding the placarded max. speed by 5 - 10 knots a few times despite signalling to the winch driver.

Should I be taking the approach of releasing at 2/3 of typical launch height (e.g. 700 - 800 foot) if my airspeed isn't under control at this point?

Thanks in advance

Dan - if you are overspeeding in the last third of the launch, your winch driver is inept and needs some supplemental training! He needs to back off the power much more when launching a light single seat glider compared to a heavy K21 or TwinAstir. Ideally, the winch operator retards the engine to the point where the glider over-flies the line and executes a very soft back-release.

Uli
Winchmeister, Carolina Soaring Assoc.

Also electric winchlaunch is getting more common (at least in w. europe)
The cable tension is controlled by the automation of the winch, which leads to a considarable reduction of weak-link breakage and adds to a more safer winch operation.

Eric

On Monday, November 6, 2017 at 7:48:16 AM UTC-5, Dan Schmitz wrote:
I'm wondering what the consequences of overspeeding on winch launches are? I understand that it places stress on the airframe, but to what extent?

I find it near impossible to control the airspeed on the top third of a launch and have found myself over speeding the placarded max. speed by 5 - 10 knots a few times despite signalling to the winch driver.

Should I be taking the approach of releasing at 2/3 of typical launch height (e.g. 700 - 800 foot) if my airspeed isn't under control at this point?

Thanks in advance

I have seen a cable tension display in a modern winch in the UK.
It showed the proper tension for each glider type. It would seem to be the
right way to optimise the launch.

John F.

On Fri, 10 Nov 2017 14:46:00 -0800, john firth wrote:

On Monday, November 6, 2017 at 7:48:16 AM UTC-5, Dan Schmitz wrote:
I'm wondering what the consequences of overspeeding on winch launches
are? I understand that it places stress on the airframe, but to what
extent?

I find it near impossible to control the airspeed on the top third of a
launch and have found myself over speeding the placarded max. speed by
5 - 10 knots a few times despite signalling to the winch driver.

Should I be taking the approach of releasing at 2/3 of typical launch
height (e.g. 700 - 800 foot) if my airspeed isn't under control at this
point?

Thanks in advance

I have seen a cable tension display in a modern winch in the UK.
It showed the proper tension for each glider type. It would seem to be
the right way to optimise the launch.

All Skylaunch winches have a sort of analoge computer: you input the
glider type and windspeed (our winches have an anemometer on the roof)
and that sets a stop at the optimal speed. The driver is still responsable
for initial acceleration and can, IIRC, override the stop, but it
generally gives a pretty consistent launch.

They'll also rebuild almost any other winch (we, CGC, have a Skylaunch
and a Tost they rebuilt) or supply a kit for clubs that want to do their
own work, but they can all have the analogue computer thingy installed.

The glider ASI telemetry is an optional extra that lets the wings driver
see the glider's actual airspeed.


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