United States. Army. Signal Corps · Washington · leaf 148
t about 16,000 feet is a formation of cloud, sometimes spoken of as the “ Mackerel sky.” This is a calm-weather cloud and is often observed apparently motionless for some time. Fig. 60. Below this are the clouds formed by the ascending currents of air which may be met with from close to the ground… … Flight is secured by driving through the air a surface inclined upward and toward the direction of motion. This surface may be either straight or curved. Chord . — The chord is, for practical purposes, taken to be a straight line from the leading edge of the surface to its trailing edge. For…
Aeronautics, Military
Internet Archive · Smithsonian Libraries · Public domain (published before 1931). Free to use for anything.
