A aviation & planes forum. AviationBanter

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Home » AviationBanter forum » rec.aviation newsgroups » Soaring
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

Life glider hours with winch



 
 
Thread Tools Display Modes
  #11  
Old March 22nd 19, 08:32 AM posted to rec.aviation.soaring
Eric Munk
external usenet poster
 
Posts: 179
Default Life glider hours with winch

As Bob said, the only concern with wooden ships is adequate
maintenance which includes a timely stripdown to bare wood and
inspection of all structural components. Type of glue used is a
major factor, looking at recent issues with common glues like
Kaurit WHK.

GFRP ships like wooden ships have no life limitations based on
use, solely in hours. At least that I know of based on reading
dozena of manuals and type certificates. Looking forward to being
corrected. Have just done a life extension for an ASK21 that had
50,000+ launches and it was in great shape. Just had to replace
the main pins and stab pins as they had reached the end of their
fatigue life of 12,000 hours...

Theoretically, there’s a long fatigue life left in gliders like this when

looking at the calculations Eiri did for the PIK-20s...

At 02:02 22 March 2019, Bob Kuykendall wrote:
What I've read is that the bending forces applied to the wings

and tail
dur=
ing a typical winch launch are roughly equivalent to 3.5g flight.

That is
c=
omfortably 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
operat=
ors did not do so.

Normal winching operations probably has no appreciable effect

on the
compos=
ite parts of a composite glider. However, I believe it was BGA

analysis of
=
repeated winch launch stresses that initiated the service bulletin

on the
s=
teel end-pins ("spigots") on Grob 102, 103 and 109 series

sailplanes.

As for wood sailplanes, my concern would mostly be around the

age and
condi=
tion 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
ca=
n actually sustain after fifty years of operation, repairs, and
deteriorati=
on.

--Bob K.


  #12  
Old March 22nd 19, 12:41 PM posted to rec.aviation.soaring
José Ignacio Otero
external usenet poster
 
Posts: 7
Default Life glider hours with winch

Thansk Martin !!





El jueves, 21 de marzo de 2019, 16:45:08 (UTC-3), Martin Gregorie escribió:
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


  #13  
Old March 22nd 19, 02:15 PM posted to rec.aviation.soaring
José Ignacio Otero
external usenet poster
 
Posts: 7
Default Life glider hours with winch


Hi Bob.

Thanks for the reply, it was what I looking for !!

I think that the pilots how said that, were thinking that because the 3.52 g that the glider "suffer" during the wich start.

Have a nice day, José


El jueves, 21 de marzo de 2019, 23:02:51 (UTC-3), Bob Kuykendall escribió:
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.


  #14  
Old March 22nd 19, 02:24 PM posted to rec.aviation.soaring
José Ignacio Otero
external usenet poster
 
Posts: 7
Default Life glider hours with winch

Hi Erik,

Thanks for your time.

Yes, wooden gliders are in special situation, in my country Argentina, we lower the VNE to the half to make them safe because you never know the glue status.

Have a nice day, José.

El viernes, 22 de marzo de 2019, 4:45:03 (UTC-3), Eric Munk escribió:
As Bob said, the only concern with wooden ships is adequate
maintenance which includes a timely stripdown to bare wood and
inspection of all structural components. Type of glue used is a
major factor, looking at recent issues with common glues like
Kaurit WHK.

GFRP ships like wooden ships have no life limitations based on
use, solely in hours. At least that I know of based on reading
dozena of manuals and type certificates. Looking forward to being
corrected. Have just done a life extension for an ASK21 that had
50,000+ launches and it was in great shape. Just had to replace
the main pins and stab pins as they had reached the end of their
fatigue life of 12,000 hours...

Theoretically, there’s a long fatigue life left in gliders like this when

looking at the calculations Eiri did for the PIK-20s...

At 02:02 22 March 2019, Bob Kuykendall wrote:
What I've read is that the bending forces applied to the wings

and tail
dur=
ing a typical winch launch are roughly equivalent to 3.5g flight.

That is
c=
omfortably 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
operat=
ors did not do so.

Normal winching operations probably has no appreciable effect

on the
compos=
ite parts of a composite glider. However, I believe it was BGA

analysis of
=
repeated winch launch stresses that initiated the service bulletin

on the
s=
teel end-pins ("spigots") on Grob 102, 103 and 109 series

sailplanes.

As for wood sailplanes, my concern would mostly be around the

age and
condi=
tion 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
ca=
n actually sustain after fifty years of operation, repairs, and
deteriorati=
on.

--Bob K.


  #15  
Old March 22nd 19, 04:17 PM posted to rec.aviation.soaring
AS
external usenet poster
 
Posts: 653
Default Life glider hours with winch

On Friday, March 22, 2019 at 9:15:42 AM UTC-4, José Ignacio Otero wrote:
Hi Bob.

Thanks for the reply, it was what I looking for !!

I think that the pilots how said that, were thinking that because the 3.52 g that the glider "suffer" during the wich start.

Have a nice day, José


El jueves, 21 de marzo de 2019, 23:02:51 (UTC-3), Bob Kuykendall escribió:
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.


Guys - let's stop making the winch launch sound like it is a glider shredding method! The force introduced into the glider's structure is limited by a weak-link. The max. breaking strength of these weak-links together with the Vw are determined by the designer and documented in the POH.
I am just referencing two popular two-seat trainers he
ASK-21 - MTOW of 600kg, black weak-link of 1,000kg, ratio 1:1.66
G103 Twin-II - MTOW 580kg, red weak-link of 750kg, ratio 1:1.29
(may the gods of physics forgive me for mixing mass and force units here!)
There is a load added during the launch when the glider transitions from the initial shallow climb into the full climb (akin to performing a small segment of a looping) but all this will not get you near the mentioned 3.5g!
However, all this is predicated on the use of proper weak-links. If you ignore these safety devices, then all bets are off. To the best of my knowledge, there hasn't been a properly maintained glider launched with the correct weak-links, that got pulled apart during the launch!

Uli
'AS'
  #16  
Old March 22nd 19, 04:55 PM posted to rec.aviation.soaring
José Ignacio Otero
external usenet poster
 
Posts: 7
Default Life glider hours with winch

Hi Uli,

I like the idea to use winch luch but I do not know about it, talking with some instructor and pilot of my country (winch is not popular here) I listen many times about this "structure fatigue" but I do not found any about that, and that is the reason of my question.
Your argument is clear and reasonable. Do you have any winch launch procedure file or something similar to know more about it?

Thanks for your time, José.


El viernes, 22 de marzo de 2019, 12:17:47 (UTC-3), AS escribió:
On Friday, March 22, 2019 at 9:15:42 AM UTC-4, José Ignacio Otero wrote:
Hi Bob.

Thanks for the reply, it was what I looking for !!

I think that the pilots how said that, were thinking that because the 3..52 g that the glider "suffer" during the wich start.

Have a nice day, José


El jueves, 21 de marzo de 2019, 23:02:51 (UTC-3), Bob Kuykendall escribió:
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.


Guys - let's stop making the winch launch sound like it is a glider shredding method! The force introduced into the glider's structure is limited by a weak-link. The max. breaking strength of these weak-links together with the Vw are determined by the designer and documented in the POH.
I am just referencing two popular two-seat trainers he
ASK-21 - MTOW of 600kg, black weak-link of 1,000kg, ratio 1:1.66
G103 Twin-II - MTOW 580kg, red weak-link of 750kg, ratio 1:1.29
(may the gods of physics forgive me for mixing mass and force units here!)
There is a load added during the launch when the glider transitions from the initial shallow climb into the full climb (akin to performing a small segment of a looping) but all this will not get you near the mentioned 3.5g!
However, all this is predicated on the use of proper weak-links. If you ignore these safety devices, then all bets are off. To the best of my knowledge, there hasn't been a properly maintained glider launched with the correct weak-links, that got pulled apart during the launch!

Uli
'AS'


  #17  
Old March 22nd 19, 05:36 PM posted to rec.aviation.soaring
AS
external usenet poster
 
Posts: 653
Default Life glider hours with winch

On Friday, March 22, 2019 at 11:55:34 AM UTC-4, José Ignacio Otero wrote:
Hi Uli,

I like the idea to use winch luch but I do not know about it, talking with some instructor and pilot of my country (winch is not popular here) I listen many times about this "structure fatigue" but I do not found any about that, and that is the reason of my question.
Your argument is clear and reasonable. Do you have any winch launch procedure file or something similar to know more about it?

Thanks for your time, José.


El viernes, 22 de marzo de 2019, 12:17:47 (UTC-3), AS escribió:
On Friday, March 22, 2019 at 9:15:42 AM UTC-4, José Ignacio Otero wrote:
Hi Bob.

Thanks for the reply, it was what I looking for !!

I think that the pilots how said that, were thinking that because the 3.52 g that the glider "suffer" during the wich start.

Have a nice day, José


El jueves, 21 de marzo de 2019, 23:02:51 (UTC-3), Bob Kuykendall escribió:
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.


Guys - let's stop making the winch launch sound like it is a glider shredding method! The force introduced into the glider's structure is limited by a weak-link. The max. breaking strength of these weak-links together with the Vw are determined by the designer and documented in the POH.
I am just referencing two popular two-seat trainers he
ASK-21 - MTOW of 600kg, black weak-link of 1,000kg, ratio 1:1.66
G103 Twin-II - MTOW 580kg, red weak-link of 750kg, ratio 1:1.29
(may the gods of physics forgive me for mixing mass and force units here!)
There is a load added during the launch when the glider transitions from the initial shallow climb into the full climb (akin to performing a small segment of a looping) but all this will not get you near the mentioned 3.5g!
However, all this is predicated on the use of proper weak-links. If you ignore these safety devices, then all bets are off. To the best of my knowledge, there hasn't been a properly maintained glider launched with the correct weak-links, that got pulled apart during the launch!

Uli
'AS'



Hello José,

Try this manual for starters, which was put together by Bill Daniels here in the US using data and procedures from various sources:
http://www.pas.rochester.edu/~cline/...20Rev%2012.pdf
I don't know of any similar documents in Spanish but I am sure they exist.
Good luck,


Uli
'AS'
  #18  
Old March 22nd 19, 06:21 PM posted to rec.aviation.soaring
José Ignacio Otero
external usenet poster
 
Posts: 7
Default Life glider hours with winch


Many thanks Uli, it look very complete.

Have a nice weekend, José.



El viernes, 22 de marzo de 2019, 13:36:51 (UTC-3), AS escribió:
On Friday, March 22, 2019 at 11:55:34 AM UTC-4, José Ignacio Otero wrote:
Hi Uli,

I like the idea to use winch luch but I do not know about it, talking with some instructor and pilot of my country (winch is not popular here) I listen many times about this "structure fatigue" but I do not found any about that, and that is the reason of my question.
Your argument is clear and reasonable. Do you have any winch launch procedure file or something similar to know more about it?

Thanks for your time, José.


El viernes, 22 de marzo de 2019, 12:17:47 (UTC-3), AS escribió:
On Friday, March 22, 2019 at 9:15:42 AM UTC-4, José Ignacio Otero wrote:
Hi Bob.

Thanks for the reply, it was what I looking for !!

I think that the pilots how said that, were thinking that because the 3.52 g that the glider "suffer" during the wich start.

Have a nice day, José


El jueves, 21 de marzo de 2019, 23:02:51 (UTC-3), Bob Kuykendall escribió:
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.

Guys - let's stop making the winch launch sound like it is a glider shredding method! The force introduced into the glider's structure is limited by a weak-link. The max. breaking strength of these weak-links together with the Vw are determined by the designer and documented in the POH.
I am just referencing two popular two-seat trainers he
ASK-21 - MTOW of 600kg, black weak-link of 1,000kg, ratio 1:1.66
G103 Twin-II - MTOW 580kg, red weak-link of 750kg, ratio 1:1.29
(may the gods of physics forgive me for mixing mass and force units here!)
There is a load added during the launch when the glider transitions from the initial shallow climb into the full climb (akin to performing a small segment of a looping) but all this will not get you near the mentioned 3..5g!
However, all this is predicated on the use of proper weak-links. If you ignore these safety devices, then all bets are off. To the best of my knowledge, there hasn't been a properly maintained glider launched with the correct weak-links, that got pulled apart during the launch!

Uli
'AS'



Hello José,

Try this manual for starters, which was put together by Bill Daniels here in the US using data and procedures from various sources:
http://www.pas.rochester.edu/~cline/...20Rev%2012.pdf
I don't know of any similar documents in Spanish but I am sure they exist..
Good luck,


Uli
'AS'


  #19  
Old March 22nd 19, 06:22 PM posted to rec.aviation.soaring
Bob Kuykendall
external usenet poster
 
Posts: 1,345
Default Life glider hours with winch

On Friday, March 22, 2019 at 8:17:47 AM UTC-7, AS wrote:

Guys - let's stop making the winch launch sound like it is a glider shredding method!...


ASK-21 - MTOW of 600kg, black weak-link of 1,000kg, ratio 1:1.66...


Let's remember that the critical factor here is wing root bending moment, which relates much more closely to the non-lifting mass than it does to the total mass.

Taking the ASK21 maximum non-lifting mass of 410 kg as our metric, the ratio in question is 1000/410 = 2.43.

True, not the 3.5 I cited, but still a substantial value.

--Bob K.



  #20  
Old March 22nd 19, 06:28 PM posted to rec.aviation.soaring
AS
external usenet poster
 
Posts: 653
Default Life glider hours with winch

On Friday, March 22, 2019 at 1:22:07 PM UTC-4, Bob Kuykendall wrote:
On Friday, March 22, 2019 at 8:17:47 AM UTC-7, AS wrote:

Guys - let's stop making the winch launch sound like it is a glider shredding method!...


ASK-21 - MTOW of 600kg, black weak-link of 1,000kg, ratio 1:1.66...


Let's remember that the critical factor here is wing root bending moment, which relates much more closely to the non-lifting mass than it does to the total mass.

Taking the ASK21 maximum non-lifting mass of 410 kg as our metric, the ratio in question is 1000/410 = 2.43.

True, not the 3.5 I cited, but still a substantial value.

--Bob K.


No doubt, Bob - thanks for that additional clarification! And that's why I am a stickler for the correct weak-link and adherence to Vw during the full climb phase of the launch. :-)

Uli
'AS'
 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
FS/T: Glider Winch Towline Chutes Vicarious Icarus Soaring 6 July 31st 17 10:20 PM
Motorglider hours same as glider? [email protected] Soaring 13 October 1st 15 04:56 PM
Glider Hours Walt Connelly Soaring 18 April 29th 11 10:17 PM
Biggest Glider Ever Launched via Winch? [email protected] Soaring 25 November 22nd 06 11:17 PM
Glider hours count towards ATP? Michael Soaring 1 November 9th 03 03:24 AM


All times are GMT +1. The time now is 09:51 AM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 AviationBanter.
The comments are property of their posters.