What the Helicopter Is.
The helicopter gets its name from being fitted with vertical
propellers or helices (see illustration) by the
action of which the machine is raised directly from the ground into the
air. This does away with the necessity for getting the machine under a
gliding headway before
General Outline of Helicopter Machine.
[Description: Black and white illustration: Cross-section of helicopter
machine, with two propellers above and one at rear.]
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