View Single Post
  #7  
Old March 22nd 04, 05:43 PM
Bill Daniels
external usenet poster
 
Posts: n/a
Default


"Shawn Curry" wrote in message
news:9zE7c.58429$JL2.758827@attbi_s03...
JS wrote:

Bill, excellent point!

I have always considered the winch drivers job to be more dangerous than


the

glider pilots. I tell people that each time I reach for the throttle, I
think about the 300 pounds of steel wire that is about to come straight

at
me doing 70 MPH.

Steel wire mesh or screen is totally inadequate to protect the driver.


The

winch cab windows should be 3/4" polycarbonate (Lexan) which, I'm told,


will

stop a 9mm bullet fired point blank. Yes, Lexan will get scratched
eventually but it's not that expensive to replace. The rest of the cab
should be at least .125 inch steel sheet.

Spectra will reduce the danger somewhat but the rest of the hardware

will
still be there and present the same dangers.

I would prefer a winch cab that is armored, weather tight and air
conditioned.

Bill Daniels



What about chanching the rotation direction of the cable reels, would it
make the lose cable end hitting the ground instead of drivers cabin?

js



Would Spectra or some other synthetic cable improve this? How much does
it stretch? My thought being that, there would still be a lot of energy
in a stretched light weight cable (imagine a 1000 foot rubber band
pointing at the driver) despite the lower weight and mass-to-drag while
falling.
Also, is the problem with steel wire/cable the elastic energy stored
from the launch, the mass of the falling steel, or a combination, that
creates the danger?

Shawn


Spectra improves the situation a lot. The lack of "whipback" is the primary
reason the marine and construction industries have adopted Spectra as a
wholesale replacement for wire rope. Spectra stretches less than 1% before
failure and the stretch and recovery is so slow it is called "creep". The
"rubber band" concept just does not apply to Spectra.

Falling spectra poses no problem whatsoever (as long as it falls on the
airport) but the steel hardware does. There will still be carabiners and
weak links attached to the glider end of the rope that pose a danger.

Bill Daniels