COMBINING MONOPLANE AND BIPLANE FORMS
Although the regular biplane form is exceedingly difficult to manage
in small models, there is great advantage in combining it with the
monoplane forms (Plate 26). The biplane makes an excellent lifting
plane, and when the model combines with it a broad monoplane for
stability, surprisingly long flights may be made. The model here
illustrated has flown 218 feet 6 inches.
Despite its size, the model is exceedingly light. It is made almost
entirely of dowel sticks braced with piano wire. Still another
advantage of the biplane form is the action of the supporting surface
when it comes to descend. The model settles easily to the ground, in
contrast to many monoplane models which come down with a dislocating
shock. The skids of this model are simple and effective. In a model of
this form it is obviously best to have the propellers drive rather than
pull it.
An ingenious young aëronaut has reversed the above order and placed his
biplane in the rear, using the monoplane for lifting (Plate 27). His
model is unusually large, having a spread of four feet. The biplane is
square, with lateral stability planes on either side. The elevating
planes appear small in proportion, but they serve to keep the craft on
an even keel. The most striking feature of this model is its extreme
lightness. Although unusually large, it weighs but nine ounces. The
frame, except for the braces is built of reed. The planes are covered
with parchment. The model is driven by two rather small propellers. The
position of the propellers will appear, at first glance, to be rather
low, but it must be remembered that the extreme lightness of the model
brings the center of gravity very far down. The model has flown more
than two hundred feet.
[Illustration: PLATE IX. An Interesting Experiment Along New Lines.]
The stability of the models thus combining the monoplane and biplane
forms comes as a surprise. Both the models in question rise easily from
the ground, which is more than can be said of many aëroplanes big or
little, and once aloft maintain a steady horizontal flight, which is
still more unusual. An interesting field of experiment is suggested
by these combinations. These successful experiments have been made
with perfectly flat planes. Suppose now we try them out with flexed
planes. If the stability thus gained may be combined with the increased
soaring quality of the curved plane, we may be on the way to making
some remarkable flights. In the summer of 1909 a number of boys built
and flew model aëroplanes in New York, when many interesting and well
constructed models were brought out, and the longest flight was only
sixty feet. Less than one year later the same boys succeeded in flying
their machines for more than two hundred feet. The new models were no
larger, the motors no more powerful, but the machine had become more
shipshape and efficient. It is reasonable to suppose that each year
will bring a similar advance.