Winch Launch Stresses on Vintage Gliders

In message , Mike Schumann writes
Our club is exploring switching from aero tow to winch
launching. Some of our members own older wooden gliders
and have expressed concerns about the increased stress
on the glider's structure resulting from winch launching
vs. aero tow.

Is this a valid concern?

In addition to Robins well made point the pilots need
a certain amount of training and discipline. Bill Daniel
web site on winch launching contains many useful documents
that may be worth reading. See

http://groups.yahoo.com/group/winchd...guid=180793033

You will have to register to down load the infomation
but it is freely available. If you are in the USA make
contact will Bill he is interested in developing winch
launching.

Dave




Just make sure that your winch drivers are trained
properly and don't just launch as though they are coming
off an aircraft carrier. Proper speed control and
suitable weak links and it works fine.

We launch T31s T21s K6s Skylark 2s and Oly 2bs with
now issues at all.
Remember that a lot of older gliders had compromise
hooks which won't
give as high a launch as the more recent designs with
real CofG hooks.

Cheers

Robin
--
Robin Birch

Dave Martin wrote:
In message , Mike Schumann writes
Our club is exploring switching from aero tow to winch
launching. Some of our members own older wooden gliders
and have expressed concerns about the increased stress
on the glider's structure resulting from winch launching
vs. aero tow.

Is this a valid concern?

In addition to Robins well made point the pilots need
a certain amount of training and discipline. Bill Daniel
web site on winch launching contains many useful documents
that may be worth reading. See

http://groups.yahoo.com/group/winchd...guid=180793033

You will have to register to down load the infomation
but it is freely available. If you are in the USA make
contact will Bill he is interested in developing winch
launching.

Dave




Just make sure that your winch drivers are trained
properly and don't just launch as though they are coming
off an aircraft carrier. Proper speed control and
suitable weak links and it works fine.

We launch T31s T21s K6s Skylark 2s and Oly 2bs with
now issues at all.
Remember that a lot of older gliders had compromise
hooks which won't
give as high a launch as the more recent designs with
real CofG hooks.

Cheers

Robin
--
Robin Birch




Mike,

heed all of the above and check the operating manuals for each glider
you intend to launch. You should find a section regarding the required
weak-link strength. Order the proper weak-links from TOST. Contrary to
'home-made' weak links fashioned from hardware store polypropylene
rope, the TOST links are precision engineered devices with a breaking
strength within a few % of the rating. Also, check what type of
releases your gliders have and buy the appropriate rings.
Regarding the extra stress on the glider: a good rule of thumb is that
a normal winch launch imposes a load about equivalent of 2g onto the
glider.
As Dave Martin already stated - join our yahoo winchdesign group for
all your questions regarding safe winch launching.

Uli Neumann