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."

"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. The Margin of Lift will have entirely
disappeared, and there we shall be, staggering along at my tremendous
angle, and only just maintaining horizontal flight."

"And then with luck I'll get my chance," said the Drift. "If he is a bit
worse than green, he'll perhaps still further increase the Angle. Then
the Drift, largely increasing, the Speed, and consequently the Lift,
will become still less, i.e., less than the Weight, and then--what price
pancakes,[3] eh?"

"Thank you," from Efficiency, "that was all most informing. And now will
you tell me, please, how the greatest Speed may be secured?"

"Certainly, now it's my turn," piped the Minimum Angle of Incidence. "By
means of the Elevator, the Pilot places the Aeroplane at my small Angle,
at which the Lift only just equals the Weight, and, also, at which we
shall make greater speed with no more Drift than before. Then we get our
greatest Speed, just maintaining horizontal flight."

"Yes; though I'm out of the horizontal and thrusting downwards,"
grumbled the Propeller, "and that's not efficient, though I suppose it's
the best we can do until that Inventor fellow finds his Mechanics."

"Thank you so much," said Efficiency. "I think I have now at any rate
an idea of the Elementary Principles of Flight, and I don't know that I
care to delve much deeper, for sums always give me a headache; but is