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Show Fljimig FliYYer Is Now Assured a flying machine glides, or volplanes, to the vertical distance It lowers itself in doing so ; meanwhile retaining its "flying speed," or normal rate at which it remains under full control of the pilot. The ratio of six to one Is a conservative con-servative average figure for airplanes. That is to say, an average airplane with Its motor shut off at an altitude of 1,000 feet ctin volplane a horizontal distance of 6,000 feet under control before It comes to land. An efficient glider has as good an angle of glide as an efficient airplane. But the important difference Is that the glider travels more slowly. Assuming As-suming In the foregoing rase, for instance, in-stance, that the airplane would normally nor-mally glide to the earth, through the 0,000 feet from a height of 1,000. In one minute, the glider, with the same gliding angle, but much less speed, might take two, or even three, minutes to glide the same distance. The difference dif-ference Is due to the varying flying speed. The flying speed of an airplane or glider Is the minimum mini-mum speed It must maintain in order to fly forward on a level under full control. It Is, therefore, practically practi-cally the same as the speed of the craft at the moment It takes off, when the speed Just begins to provide "lift" enough to overcome the weight of the machine. Flying speed nut only varies with different types of pianos, according accord-ing to design and ratio of wing area ' to weight, but also varies from time to time In an Individual phine, according to loading and to the condition of the wings and other essential parts at the moment. An airplane with n flying speed of ,ri0 miles an hour with pilot only abonrd will necessarily require a slightly higher flying speed with a passenger also aboard. Mere speed must be attained to supply the additional lift. A plane with Its wings newly "tuned up" to afford maximum max-imum efliclency will gradually require a higher flying speed thereafter, as the wings sag and warp out of best alignment align-ment under the strain of usage. Flying Speed. Flying speed in general Is governed by the ratio of wing area to weight. The larger the total wing surface Is In proportion to the weight of the airplane air-plane or glider, the less Is the flying speed. The less number of pounds that each squnre foot of wing surface has to sustain the slower the wing must pass through the air. The object In glider construction, therefore. Is to provide as great wing area as possible In proportion with weight. This makes for low flying speed, which facilitates fa-cilitates the gliding ami climbing. It permits such low flying speed that gilders, gild-ers, much more frequently than airplanes, air-planes, do the trick of seeming to fly backward, as the Dewoltlne machine did at Koosevelt Held. This Is due merely to gliding or flying headed Into a wind with a velocity greater than the flying speed of the craft so that, while the craft Is moving forward fast enough to keep balance, It is moving backward relatively to the earth. The flying lllyver, like Its Immediate parent the glider, seems fated to become be-come a sporting and pleasure machine, rather than a practical commercial vehicle ve-hicle of general usefulness. The glider gli-der has already become a popular "play toy." In Switzerland and In the llnrfz mountains In (iermnny, gliding was a familiar pastime last winter. The snow-covered hillsides were good places for taking olT, with skids Instead In-stead of heavier wheels on the machines; ma-chines; and the snow-covered valleys afforded equally good landing places. With Its possible very low cost, and with Its range of performance considerably consid-erably greater than that of the gilder, the Hying flivver will perhaps soon become be-come a successful compel it or of the automobile runabout and the motor boat, as a tiling of sport. Hut Its slg-iillleauce slg-iillleauce scarcely exceeds Hint, because be-cause the gliding feature Is available only under rare aerial conditions, and at that In few locations. New York Times. j New Invention Is Expected to Put Plane Within. Reach of Every Family. The "flymg flivver" has literally and suddenly come into the sky. Although the pioneer was wrecked, aeronautic experts believe that flying flivvers 60on will become as plentiful, relatively, relative-ly, as their namesakes. The new experiment ex-periment in human flight proved Itself before it crashed upon a Jersey tree in an attempted flight from Is'ew York to Washington. The nickname of the Dewoitine cross between a glider and a regular airplane Is befitting In respect of weight, size, fuel requirements, relative speed and probable construction cost, Emil Dewoitine is quoted as having 6aid that the machine can and will be manufactured in quantity at a retail price of 5400. Georges Barbot, the pilot, pi-lot, has said that the craft would cover cov-er 125 miles on a gallon of gasoline. But in respect to practical usefulness, as a means of aerial transportation of persons or goods, the flying flivver gives no promise of living up to the flivver reputation. In the opinion of aviation experts. The Dewoitine machine is different from a motorless glider chiefly In that it has a motor. To withstand the vibration vi-bration of the engine, the wing surfaces sur-faces and skeletons and the body had to be constructed more strongly than In the case of a glider. This meant additional weight, and, together with the weight of the motor Itself said to be only forty pounds made the whole craft considerably heavier than a glider. gli-der. The total "tonnage" of the flying fly-ing flivver was about 400 pounds, without with-out the pilot, which Is double the average av-erage weight of man-carrying gliders. And successful man-carrying gliders have been made weighing even lass than the average of 200 pounds. The Dewoitine craft Is different from a regular airplane mainly In that the motor Is of much lower horse power pow-er and the whole machine is smaller and lighter. The motor mounted In the flying flivver Is a two-cylinder Cler-guet Cler-guet of twelve horsepower. Ordinary Ordi-nary small airplanes carry 100 horsepower horse-power motors, on the average; though constant improvements In propeller and wing design are gradually lowering lower-ing the horsepower requisite In proportion pro-portion to the weight of machines. The Sperry fast messenger plane, recently re-cently tested over Long Island, has a BO-horsepower engine. This plane Is one of the smallest In the country, however. In point of size the Dewoitine Invention In-vention measures 40 feet from wing tip to tip and 15 feet over all In length. The craft Is a monoplane, and even with the 40-foot spread Its wing area Is less than the average airplane. It Is Just about equal, however, to the total wing surface of many small types of comparatively high seed one-sealer planes, which have more powerful motors, mo-tors, weigh much more, hut can sustain sus-tain their weight with the small wings by virtue of their swiftness. Extends Power of Gliders. The power equipment of the flying flivver, small though It be, Is enough to do away with the limitations peculiar pe-culiar to motorless gliders. Its additional addi-tional weight, however, Is not too great to prevent powerless gliding. A glider cannot start flight from level ground. Ordinary glider flights arc begun from hilltops, by rolling the craft downhill until they pick up "Hying speed" and take olT from the slope. Where hillsides hill-sides are less steep or long, calapiilt devices have been used to help supply the Initial Hying speed, but vvllli little wiccchh on the whole. II. J. N nd m n n uned an elastic rope to propel bis "sailplane" "sail-plane" Into the air from the highest mound at the golf links near liayslde, 1j. I., In a recent series ol' flights. The seemingly Impossible feat of making a motorlcMH winged era ft climb up In the sl,y Is possible because of the presence of upward movements of the air. The fact that air currents do move upward and downward as well, Is often overlooked because such currents cur-rents are rarely encountered near the earth's surface, and never In areas where the surface Is flat and smooth. Obviously, a down-moving current is deflected when it nears the earth, and spreads out in a sort of radial wind movement. It Is plain, too, that an up-moving up-moving current cannot originate just at the earth's flat surface, because It would cause a vacuum there. The currents by virtue of which gilders gil-ders can keep their altitude or even climb, are not called winds, usually defined as horizontal natural movements move-ments of air. They are sometimes technically known as "winds with a vertical component." Soaring birds, such as hawks and eagles, the natural gilders, take advantage of these upward-flowing vertical or Inclined movements move-ments of air, to fly and climb for hours at a time without flapping their wings or exerting themselves In any way except ex-cept to' maintain their balance and steer in areas where the air move- I ment Is favorable. There is no doubt, though, of course, there Is no direct proof, that these soaring birds have an Instinctive sense of rising or falling a sort of exceedingly sensitive natural nat-ural altimeter by which they pick out the upward-moving areas of air. Oil-ding Oil-ding Is merely man's way of Imitating the soaring birds. And man must use his common sense and Intelligence and judgment In place of the soaring birds' instinctive sense of rising or falling, to spot the correct place to glide. Some aeronauts prefer to call these motorless aircraft "sailplanes" Instead of gliders, which Is the term more commonly com-monly applied. II. J. Nordman, Inventor Inven-tor of the craft that recently made several flights over golf links near Bayslde, refers to his machine as a sailplane. Downward Air Currents. Glider pilots have to guard In particular par-ticular against the downward nlr currents. cur-rents. It is obvious that In the total of all air movements over the eaith's surface the speed and volume of the rising currents equal the speed and volume of the falling currents. The fulling currents are what, In the pioneer pio-neer days of aviation, were known as "air pocket.s," regarded with dread. The slow-flying airplanes of those days, like the Dewoitine flying flivver, were more subject to downwnrd eddies of wind nnd were less safe for that reason. rea-son. The faster a plane Is moving through the air, the less effect will It feel In reaction to air eddies, or "bumps," as the aviators call them. This fact Is somewhat of an obstacle to the future popularity of flying flivvers, fliv-vers, which must he a relatively slow craft when not gliding, lf It Is to com bine the elements of gilding and of powered flight. The flying flivver's power equipment Is Just sufficient to give the craft a start from level ground, without the1 aid of n catapult or any other starting device. And In the air the motor makes It possible to continue flight. In aerial conditions that do not permit powerless power-less gliding. The flying flivver driver can fly In still air, or even in moderate downward currents, and seek out areas favorable to gliding. This I lie gilder of course cannot do. When the Hying flivver pilot, reaches an area In which the air Is rising, he can throttle down or even perhaps "kill" Ills motor, and fly bis wasplike machine as a glider. A regular airplane can do the same tiling, to be sure; but not nearly so well. The larger mnlor of the; ordinary ordi-nary plane makes Unit much more dead weight. And the relatively smaller small-er wing area of the airplane built fur speedy flight Is Incapable of gliding without "losing altitude" at a much faster rate Hum Hie slower glider er Hying flivver, and correspondingly Ioh-Ing Ioh-Ing the advantage of the upward air currents. In tills Instance, Hie slowness slow-ness of hi' Hying flivver and the glider Is Hie essential factor. The "gliding angle" Is the ratio of Hie horizontal distance through wbrch |