THE ELEMENTARY PRINCIPLES AIR THEIR GRIEVANCES
The Lecture Hall at the Royal Flying Corps School for Officers was deserted. The pupils had dispersed, and the Officer Instructor, more fagged than any pupil, was out on the aerodrome watching the test of a new machine.
Deserted, did I say? But not so. The lecture that day had been upon the Elementary Principles of Flight, and they lingered yet. Upon the Blackboard was the illustration you see in the frontispiece.
I am the side view of a Surface, it said, mimicking the tones of the lecturer. Flight is secured by driving me through the air at an angle inclined to the direction of motion.
Quite right, said the Angle. Thats me, and Im the famous Angle of Incidence.
And, continued the Surface, my action is to deflect the air downwards, and also, by fleeing from the air behind, to create a semi-vacuum or rarefied area over most of the top of my surface.
This is where I come in, a thick, gruff voice was heard, and went on: Im the Reaction. You cant have action without me. Im a very considerable force, and my direction is at right-angles to you, and he looked heavily at the Surface. Like this, said he, picking up the chalk with his Lift, and drifting to the Blackboard.