Can't I do better than that?''
``Yes, indeed,'' spoke up the Propeller, ``though it means
that I must assume a most undignified attitude, for helicopters[[2]]
I never approved of. In order to ascend more
quickly the Pilot will deflect the Elevator, which, by the
way, you see hinged to the Tail. By that means he will
force the whole Aeroplane to assume a greater Angle of
Incidence. And with greater Angle, the Lift will increase,
though I'm sorry to say the Drift will increase also. Owing
to the greater Drift, the Speed through the air will lessen,
and I'm afraid that won't be helpful to the Lift; but I shall
now be pointing upwards, and besides overcoming the Drift
in a forward direction I shall be doing my best to haul
the Aeroplane skywards. At a certain angle known as the
Best Climbing Angle, we shall have our Maximum Margin
of Lift, and I'm hoping that may be as much as almost a
thousand feet altitude a minute.''
[[2]] Helicopter. An air-screw revolving upon a vertical axis.
If driven with sufficient power, it will lift vertically,
but having regard to the mechanical difficulties of such construction,
it is a most inefficient way of securing lift compared with the
arrangement of an inclined surface driven by a propeller
revolving about a horizontal axis.
``Then, if the Pilot is green, my chance will come,'' said
the Maximum Angle of Incidence. ``For if the Angle is
increased over the Best Climbing Angle, the Drift will rush
up; and the Speed, and with it the Lift, will, when my
Angle is reached, drop to a point when the latter will be no
more than the Weight.
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