KRONFELD ON GLIDING AND SOARING.pdf - Lakes Gliding Club

238 KRONFELD ON GLIDING & SOARING
provided that its construction is strong enough to stand
the strain and its speed approximates to the normal speed
of the motor-car towing it. The heavier type of machine
naturally gathers speed more slowly and requires a longer
run before it can be released. Gliders of the type known
as the light-wind sailplanes can be towed by smaller cars,
but care must be taken not to put too much strain on their
light frames. The " Zogling " was never designed for such
purposes, but machines such as the " Priifling " and the
"Falke," which are built with normal fuselages, have been
found quite adaptable to it. The best type is, however,
the " Utility Glider/' specially designed by the brothers
Franklin for towed starts. This fulfils one of the most
important demands made on the types used for towed starts
in that it is highly sensitive and responds readily to all its
controls.
Such machines must also be designed so that they readily
assume their proper flying angle and can quickly rise from
the ground. Most soaring gliders would be found wanting
in this respect.
The towed machine must likewise " taxi " well. Judging
by the experience of instructors, the best type of machine
for such purposes runs on a central wheel and answers
readily to all controls when moving along the ground at a
pace less than its flying speed. The wheel or wheels must
not be set too far below the fuselage, otherwise the
machine is likely to capsize, but perhaps a machine provided
with a wheel running in a divided skid is the best solution
of this problem. It is also advisable to have a wheel brake
that will prevent the machine running too far and enable it
to be landed either with or against the slope in hilly country,
in the latter case it is necessary to guard against the glider
running backwards after it has landed, and for this a wheel
brake is most useful.
A machine with an enclosed cockpit gives the pupil a
greater sense of security and enables him to accustom himself
from the beginning to the types which he will afterwards
be expected to fly. A machine employed for instructional
purposes should also be built more solidly than one intended
for soaring only ; it thus gains in strength, while the extra