Part 8 (2/2)

Such a fall is known as ”stalling” or ”pancaking.”

=NOTE.--The golden rule for beginners: Never exceed the Best Climbing Angle. Always maintain the flying speed of the aeroplane.=

SUMMARY.

_Essentials for Maximum Climb._

1. Low velocity.

2. Large surface.

3. Large angle relative to propeller thrust.

4. Large angle relative to direction of motion.

5. Large camber.

_Essentials for Maximum Velocity._

1. High velocity.

2. Small surface.

3. Small angle relative to propeller thrust.

4. Small angle relative to direction of motion.

5. Small camber.

It is mechanically impossible to construct an aeroplane of reasonable weight of which it would be possible to vary the above opposing essentials. Therefore, all aeroplanes are designed as a compromise between Climb and Velocity.

As a rule aeroplanes are designed to have at low alt.i.tude a slight margin of lift when the propeller thrust is horizontal. By this means, when the alt.i.tude is reached where the margin of lift disappears (on account of loss of engine power), and which is, consequently, the alt.i.tude where it is just possible to maintain horizontal flight, the aeroplane is flying with its thrust horizontal and with maximum efficiency (as distinct from engine and propeller efficiency).

The margin of lift at low alt.i.tude, and when the thrust is horizontal, should then be such that the higher alt.i.tude at which the margin of lift is lost is that alt.i.tude at which most of the aeroplane's horizontal flight work is done. That ensures maximum velocity when most required.

Unfortunately, where aeroplanes designed for fighting are concerned, the alt.i.tude where most of the work is done is that at which both maximum velocity and maximum margin of lift for power are required.

Perhaps some day a brilliant inventor will design an aeroplane of reasonable weight and drift of which it will be possible for the pilot to vary at will the above-mentioned opposing essentials. Then we shall get maximum velocity, or maximum margin of lift, for power as required.

Until then the design of the aeroplane must remain a compromise between Velocity and Climb.

[Footnote 14: See Newton's laws in the Glossary at the end of the book.]

[Footnote 15: See ”Aerofoil” in the Glossary.]

CHAPTER II

STABILITY AND CONTROL

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