KRONFELD ON GLIDING AND SOARING.pdf - Lakes Gliding Club

236 KRONFELD ON GLIDING & SOARING
a man standing on the step or sitting on the back seat and
looking out through the window at the back. As both
these methods are inconvenient, a good plan is to attach a
trailer to the car. In this the observer sits on a bicycle
saddle, with his back to the driver ; the quick-release to
which the cable is fastened is then fixed to the trailer. This
arrangement also permits the observer to carry a drum in
his trailer which he can brake if necessary as the cable runs
out, and upon which he can wind up the cable after use. A
similar drum arrangement can also be used with an open
car, where it must be placed at the centre of gyration.
For reasons of safety the car must have a quick-release
as well as the glider ; the great disadvantage of the drum
being that it prevents immediate release in cases of emergency.
This defect, however, can be remedied by fastening
the end of the cable on the drum by means of a peg, from
which it will be released the moment its full length runs
out ; this eliminates all possibility of trouble if the quickrelease
on the glider itself fails to loose its end of the cable.
As even such a release must take a certain amount of time
to operate and there is always the possibility of the winch
jamming or the cable becoming tangled, it is advisable to
have some means of cutting the cable in case of emergency.
The best device is an ordinary pair of shears or wire-cutters,
one handle of which is affixed to the winch in a way that
allows the outgoing cable a free passage between the open
blades, while the observer has only to press the other one
if he wants to sever the connection.
On grounds of safety some experts recommend the use of
a hempen rope for machines carrying pupils, because in
case of emergency it breaks more easily than a steel cable.
But the latter stands wear and tear better than the former,
while provided its dimensions are not too great, or an
artificial flaw is created, it will break as easily as a rope in
case of need. I therefore prefer the steel cable, as it is
possible to use the same form of cable for both novices and
advanced pupils. A third alternative is steel wire, which
finds favour on account of its cheapness, but it is awkward
material to handle and does not stand strains too well.
After all, the towing cable need not be made of the expensive