The big propellers were of course outside the cabin, and in the
rear, where was located the horizontal rudder, for guiding the craft
to right or left. At the rear was also an auxiliary vertical
rudder, for elevating or lowering the craft. The main elevation
rudder was in front, and this was of a new shape, never before used,
as far as Mr. Vardon knew.
There was another feature of the Abaris that was new and one which
added much to the comfort and safety of those aboard her. This had
to do with the starting of the motor and the operation of the big
wooden propellers.
In most aeroplanes, whether of the single or double type, the
propeller, or propellers, are directly connected to the motor. In
some monoplanes the motor, especially the Gnome, itself rotates,
carrying the blades with it. In biplanes, such as the Burgess,
Wright or Curtiss, it is the custom to operate the propellers
directly from the motor, either by means of a shaft, or by sprocket
chains.
But, in any case, the starting of the engine means the whirling of
the propellers, for they are directly connected. This is why, when
once the engine stops in mid-air, it can not be started again. Or
at least if it is started it is mostly a matter of chance in getting
it to go under compression or by the spark. There is no chance for
the aviator to get out and whirl the propellers which are, in a
measure, what a flywheel is to an automobile.
Also that is why the aviator has to be in his seat at the controls,
and have some other person start his machine for him, by turning
over the propeller, or propellers until the motor fires.
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