KRONFELD ON GLIDING AND SOARING.pdf - Lakes Gliding Club

248 KRONFELD ON GLIDING & SOARING
aeroplane towed flights, the drum carried in the aeroplane
should be provided with a peg off which the cable will slip
as soon as it has run out to its full length. As in the case of
towed starts by motor-car, the cable should be rendered
resilient by attaching a piece of rubber shock-cord at one
or both ends, while it is always advisable to affix flags to the
cable in order to render its position visible during a flight.
Too much stress cannot be laid on the advantage of telephonic
communication between the two pilots.
(2)
THE TOWED GLIDER
If gusts should lift the glider high above the aeroplane
towing it, the former is likely to find itself carrying some
portion of the latter's weight. This places too great a
strain on the glider and may easily lead to a broken wing.
Another danger factor is an excessive towing speed.
Hence it is our endeavour to reach a compromise between
safety measures and flying efficiency. As, in my opinion,
the towed flight is more suitable for instructional purposes
than for cross-country flights, it seems to me unwise to
deviate greatly from the strength and weight found necessary
for normal sailplanes, which should, therefore, be
towed only by aeroplanes of slow speed and light enginepower.
For special " stunts " or for long overland flights
gliders with special modifications must be used, but it must
be remembered that all such are generally made at the
expense of performance in free gliding flight. The demands,
with regard to the position for the quick-release, the
view for the pilot and controllability, are more or less
similar to those desirable for towed starts by cars. The
cable should be about four hundred and fifty to six hundred
feet long and from one-eighth to seven-thirty-seconds of
an inch in diameter.
The best method of imparting instruction in aeroplane
towed flight is in conjunction with a course of car towed
starts. In each case the same principles apply to the
start.