Life glider hours with winch

Hi all.

I listened from some pilots that the glider life hours reduce if you use winch start.

Is that true? I looked for some data about and I did not found.

have a nice day, José.

At 17:14 21 March 2019, wrote:
Hi all.

I listened from some pilots that the glider life hours reduce if you
use
wi=
nch start.

Is that true? I looked for some data about and I did not found.

have a nice day, Jos=C3=A9.


I know this is true for the Blanik and maybe other dural gliders.
Certainly not any GFRP or wooden types.

At 17:14 21 March 2019, wrote:
Hi all.

I listened from some pilots that the glider life hours reduce if you
use
wi=
nch start.

Is that true? I looked for some data about and I did not found.

have a nice day, Jos=C3=A9.


Blanik, yes. Other dural gliders maybe. Others don’t think so.

At 17:14 21 March 2019, wrote:
Hi all.

I listened from some pilots that the glider life hours reduce if you
use
wi=
nch start.

Is that true? I looked for some data about and I did not found.

have a nice day, Jos=C3=A9.


Blanik, yes. Other dural gliders maybe. Others don’t think so.

On Thursday, March 21, 2019 at 11:14:42 AM UTC-6, wrote:
Hi all.

I listened from some pilots that the glider life hours reduce if you use winch start.

Is that true? I looked for some data about and I did not found.

have a nice day, José.

Any life adjustment issues should be in the POH or the maintenance manual. There were adjustment factors on our L-23 for winch launches, flying with the wing tip extensions, solo/dual flight, or for aerobatic flight.

Frank Whiteley

El jueves, 21 de marzo de 2019, 14:31:08 (UTC-3), Frank Whiteley escribió:
On Thursday, March 21, 2019 at 11:14:42 AM UTC-6, wrote:
Hi all.

I listened from some pilots that the glider life hours reduce if you use winch start.

Is that true? I looked for some data about and I did not found.

have a nice day, José.

Any life adjustment issues should be in the POH or the maintenance manual.. There were adjustment factors on our L-23 for winch launches, flying with the wing tip extensions, solo/dual flight, or for aerobatic flight.

Frank Whiteley


Hi Frank,

Thanks for reply, L-23 is an special situation with the AD in the wing roots.

What about K-13, Ka-6, Libelle, Std Austria, Lak-12, Std Cirrus, ASW-20...

El jueves, 21 de marzo de 2019, 14:30:05 (UTC-3), Eric Munk escribió:
At 17:14 21 March 2019, wrote:
Hi all.

I listened from some pilots that the glider life hours reduce if you
use
wi=
nch start.

Is that true? I looked for some data about and I did not found.

have a nice day, Jos=C3=A9.


I know this is true for the Blanik and maybe other dural gliders.
Certainly not any GFRP or wooden types.

Hi Erik,

Thanks fro reply, L-23 is speciall situation...

On Thu, 21 Mar 2019 11:52:53 -0700, José Ignacio Otero wrote:

El jueves, 21 de marzo de 2019, 14:31:08 (UTC-3), Frank Whiteley
escribió:
On Thursday, March 21, 2019 at 11:14:42 AM UTC-6,
wrote:
Hi all.

I listened from some pilots that the glider life hours reduce if you
use winch start.

Is that true? I looked for some data about and I did not found.

have a nice day, José.

Any life adjustment issues should be in the POH or the maintenance
manual. There were adjustment factors on our L-23 for winch launches,
flying with the wing tip extensions, solo/dual flight, or for aerobatic
flight.

Frank Whiteley


Hi Frank,

Thanks for reply, L-23 is an special situation with the AD in the wing
roots.

What about K-13, Ka-6, Libelle, Std Austria, Lak-12, Std Cirrus,
ASW-20...

There is nothing my Std Libelle's POH about launch method affecting
airframe lifetime. AFAIK they are fitted as standard with both CG and
nose hooks. Mine was, and so are the other two others based at the club.
Re-life inspection is at 3000 hours regardless of launch method.


--
Martin | martin at
Gregorie | gregorie dot org

At 18:54 21 March 2019, José_Ignacio_Otero wrote:
El jueves, 21 de marzo de 2019, 14:30:05 (UTC-3), Eric Munk
escribi=C3=B3:
At 17:14 21 March 2019, wrote:
Hi all.

I listened from some pilots that the glider life hours reduce if
you=20
use
wi=3D
nch start.

Is that true? I looked for some data about and I did not found.

have a nice day, Jos=3DC3=3DA9.

=20
I know this is true for the Blanik and maybe other dural gliders.=20
Certainly not any GFRP or wooden types.

Hi Erik,

Thanks fro reply, L-23 is speciall situation...


Hi for the L13 the shortest airframe life is to winch launch two persons
on board and make it an aerobatic flight, longest airframe life aerotow
launch flown solo no aerobatics, by the manual all flights should be loged
according to each flight type launch,crew number, aerobatics or no
aerobatis if like our worn out L13 none of the details required about it's
flight use could be corolated when it came to how mutch airframe life
remained
so the fuz ended up as a flight simulator, the rest of the loose rivets
scrap metal.

What I've read is that the bending forces applied to the wings and tail during a typical winch launch are roughly equivalent to 3.5g flight. That is comfortably below the load limit of every common glider. However, it is high enough that repeated launches will eventually shorten the service life of an aluminum glider. The Blanik designers understood this very well, and the original service documentation was quite explicit about logging operations carefully so the service life could be tracked. Unfortunately, most operators did not do so.

Normal winching operations probably has no appreciable effect on the composite parts of a composite glider. However, I believe it was BGA analysis of repeated winch launch stresses that initiated the service bulletin on the steel end-pins ("spigots") on Grob 102, 103 and 109 series sailplanes.

As for wood sailplanes, my concern would mostly be around the age and condition of the structure, since many wood gliders are now half a century old. Since you don't feel the added stresses of winch launching the way you feel the g of vertical acceleration, it would be easy to get into the gray area between what the structure was originally built to sustain, and what it can actually sustain after fifty years of operation, repairs, and deterioration.

--Bob K.