KRONFELD ON GLIDING AND SOARING.pdf - Lakes Gliding Club

50 KRONFELD ON GLIDING & SOARING
Weiss was not afraid to differ from the current opinions
of his day. He sharply criticized Prof. Langley's views
concerning the internal work of the wind on the ground that
the steady ascent of smoke, clouds, or a balloon seriously
contradicted the presence of this inner activity. In this
respect he carried out innumerable experiments, chiefly
with models, from which he gained rich experience. " I
have," said he, " been experimenting with models of
gliders on and off ever since I was a boy, but it is especially
since Lilienthars unfortunate death that I have taken this
up as a regular hobby, and in these past five years alone I
reckon that I have constructed no less than some two
hundred of these models."
The models he designed and the experiments he made
with them are typical features of Weiss's work. None of
his predecessors made so many trials or obtained such good
results with small models that cost hardly anything. He
even succeeded in calm weather in approaching the ground
at an angle of only three degrees, i.e., his model, starting
from a height of three feet, could glide a distance of sixty.
These little artificial birds were possessed of such intrinsic
stability that they could fly by themselves like real birds.
About one of them he says : " I launched it yesterday and
the results were so remarkable that I hardly expect to be
believed ; I do not know that I should believe in them if
I had not seen them myself. There was a north-east wind
blowing at the rate of about twenty miles. I had favourable
circumstances and I launched it about twenty times.
Once it stood for forty seconds quite motionless. It was
launched on the ground, rose to thirty or forty feet, did not
turn, die nor lose its height and remained hovering like a
hawk or a kestrel. It is a positive fact."
There have been and are to this day innumerable theories
concerning the flight of birds. Some of them are most
confused, and many of their exponents believe that Langley's
conceptions are the only acceptable bases for arriving
at the nature of bird flight. Weiss, however, held that
if it was once realized how slight a gliding angle may be
made, how little energy is necessary to change this gentle
downward movement into hovering or even climbing, it