Excerpt from Air-Screws: An Introduction to the Aerofoil Theory of Screw Propulsion<br><br>The problem of determining the form of air flow generated by an aerofoil, moving through still air, is one that has so far defied mathematical analysis. This problem, which applies equally to water and other fluids, is one for which a solution has only been obtained when the aerofoil is a flat plate of infinite span) The analytical results however do not conform with those obtained by experiment, and it would seem that the still more complex problem of the curved surface is 'beyond the reach of present-day analysis.<br><br>The mathematical theory makes the pressure on a flat surface vary as the 'square of the general velocity of the stream, and experiment has shown that between fairly large limits in velocity this holds good.<br><br>Briefly, if an aerofoil be exposed to a moving current of air or, what is the same thing, if an aeroplane wing be moving through still air, the resultant air pressure on the aerofoil may be expressed by the formula (r where (s) denotes the area of the aerofoil surface, and (v) the velocity of flight of the aerofoil relative to the air. (it) is a constant the numerical value of which depends upon the units employed in the measurements of the quantities (r), (s), and (v).<br><br>About the Publisher<br><br>Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com<br><br>This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.