Winch Launch Safety Study

At 19:00 28 March 2009, David Chapman wrote:
A Yahoo groups forum on Glider Winch engineering. Some posts review
tension
control, ?? .......
http://dir.groups.yahoo.com/group/wi...eer/message/36
http://dir.groups.yahoo.com/group/wi...eer/message/38

and even one thinking about using battery power?
http://dir.groups.yahoo.com/group/wi...eer/message/40
Did anyone get a electric battery launch before?

There is a German made electric winch called the ESW2B that essentially
runs on battery power, albeit an array of 12 volt lead-acid ones. They
need to be constantly charged up while in use, either from the mains or a
portable generator. I believe that you can't do too many launches per
hour without boiling the battery acid.

A winch needs at least 300hp or 230kW to launch a modern two-seater
glider, so it's a bit too much for normal mains electricity!

Derek Copeland

On 22 Mrz., 03:24, bildan wrote:

And just as often I've challenged you to produce ANY engineering data
to support your mere opinion. *You have not and I believe you cannot.

That seems like elementary rigid body mechanics to me. In this case
calculations trump measurements due to the well-understood nature of
the
physics and the inherent errors of any measurement.

A simple longitudinal simulation model should be well sufficient to
gain
good insight into these types of accidents. Would be an interesting
subject
for a followup article.

Best regards
--Gerhard Wesp

On 26 Mrz., 02:55, wrote:
What the initial tension, measured in G that you consider ideal on
initial launch? Are you afraid to answer this question that I am now
asking of you for the third time already? You can't complain about
others not providing data (which is not true) if you refuse to even
begin to do so yourself. So put up already.

Ahem... Tension is measured in Newton, not in G. G == acceleration,
or m/s^2. Yes, the forward acceleration of the glider in the initial
takeoff run
can be measured in G, but the connection between the cable tension and
acceleration involves glider and cable mass and wind, so there's no
one-to-one correspondence.

Best regards
--Gerhard Wesp