FLYING MACHINES TODAY "Hitherto aviation has been almost monopolized by that much-overpraised and much-overtrusted person, 'the practical man.' It is much in need of the services of the theorist--the engineer with his mathematical calculations of how a flying machine ought to be built and of how the material used in its construction should be distributed to give the greatest possible amount of strength and efficiency." --From the _New York Times_, January 16, 1911. [Illustration: THE FALL OF ICARUS] FLYING MACHINES TODAY BY WILLIAM DUANE ENNIS _Professor of Mechanical Engineering in the Polytechnic Institute of Brooklyn_ _123 ILLUSTRATIONS_ [Illustration: VAN NOSTRAND LOGO] NEW YORK D. VAN NOSTRAND COMPANY 23 MURRAY AND 1911 27 WARREN STS. _Copyright, 1911, by_ D. VAN NOSTRAND COMPANY THE · PLIMPTON · PRESS · NORWOOD · MASS · U · S · A To MY MOTHER PREFACE Speaking with some experience, the writer has found that instruction in the principles underlying the science and sport of aviation must be vitalized by some contemporaneous study of what is being accomplished in the air. No one of the revolutionizing inventions of man has progressed as rapidly as aerial navigation. The "truths" of today are the absurdities of tomorrow. The suggestion that some grasp of the principles and a very fair knowledge of the current practices in aeronautics may be had without special technical knowledge came almost automatically. If this book is comprehensible to the lay reader, and if it conveys to him even a small proportion of the writer's conviction that flying machines are to profoundly influence our living in the next generation, it will have accomplished its author's purpose. POLYTECHNIC INSTITUTE OF BROOKLYN, NEW YORK, April, 1911. CONTENTS PAGE THE DELIGHTS AND DANGERS OF FLYING.--Dangers of Aviation.--What it is Like to Fly 1 SOARING FLIGHT BY MAN.--What Holds it Up?--Lifting Power.--Why so Many Sails?--Steering 17 TURNING CORNERS.--What Happens when Making a Turn.-- Lateral Stability.--Wing Warping.--Automatic Control.-- The Gyroscope.--Wind Gusts 33 AIR AND THE WIND.--Sailing Balloons.--Field and Speed 43 GAS AND BALLAST.--Buoyancy in Air.--Ascending and Descending.--The Ballonet.--The Equilibrator 57 DIRIGIBLE BALLOONS AND OTHER KINDS.--Shapes.-- Dimensions.--Fabrics.--Framing.--Keeping the Keel Horizontal.--Stability.--Rudders and Planes.--Arrangement and Accessories.--Amateur Dirigibles.--The Fort Omaha Plant.--Balloon Progress 71 THE QUESTION OF POWER.--Resistance of Aeroplanes.-- Resistance of Dirigibles.--Independent Speed and Time-Table.--The Cost of Speed.--The Propeller 101