In such a propeller, if the blade is the same
width and pitch at the two points named, the pull
at the tips will be four times greater than at the
intermediate point.
CHAPTER XIV
EXPERIMENTAL GLIDERS AND MODEL AEROPLANES
AN amusing and very instructive pastime is
afforded by constructing and flying gliding machines,
and operating model aeroplanes, the latter
being equipped with their own power.
Abroad this work has been very successful as
a means of interesting boys, and, indeed, men
who have taken up the science of aviation are
giving this sport serious thought and study.
When a machine of small dimensions is made
the boy wonders why a large machine does not
bear the same relation in weight as a small machine.
This is one of the first lessons to learn.
THE RELATION OF MODELS TO FLYING MACHINES.
--A model aeroplane, say two feet in length, which
has, we will assume, 50 square inches of supporting
surface, seems to be a very rigid structure,
in proportion to its weight. It may be dropped
from a considerable height without injuring it,
since the weight is only between two and three
ounces.
An aeroplane twenty times the length of this
model, however strongly it may be made, if
dropped the same distance, would be crushed, and
probably broken into fragments.
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