Page:Popular Science Monthly Volume 91.djvu/48

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The Strength of Human Wings

One hundred and twenty-two people can stand on the wings of a big biplane

��IF the men who lost their lives in the early years of the flying machine's develop- ment could come back to life and gaze upon the picture which accompanies this article, they would first gasp in astonish- ment and then they would approve en- thusiastically the construction which made it possible for sixty people to crowd upon one.Thalf.of-a huge biplane's wings without breaking, them. For, let it never be for- gotten/ that some of the early martyrs who dropped to a terrible" x death from great heights, went to their doom because the builders.. of;, their machines had no concep- tion of .the structural * strength required to buffet turbulent winds at high speed. . Study, the pictured well. Note that the wing section. of a biplane here depicted is supported from a. heavy wooden frame and not . from the.' floor. The wirig section is held" only, on one side and extends freely from that side into the air. Judging from their size, the wings are , those of any

��enormous flying yacht. Although the sup- porting surfaces of this yacht could evi- dently sustain the weight of some one hundred and twenty-six passengers, they have not, of course, that amount of lifting power. The crew of the vessel probably amounts to four. Hence, the weight for one hundred and twenty-two people is available for the boat body, rudders, engines, propellers and supplies, something like over eight and one-half tons. More- over, the human freight here pictured clearly does notoverstrain the wings.

The picture is an object lesson in reserve strength. The stoutest storm-sails of an old-fashioned sailing ship were never sub- jected to such strains as those which must be endured by that fabric of linen, wires, and lattice-work of which the wings of a modern flying-machine are composed. A sail needs strength to resist mere tearing alone. A flying-machine's wings must in addition be so rigid that they will keep its shape in the worst hurricane. Only the pilot of an airplane knows how his wings are strained when he drops at a steep angle from a height of five thousand feet in a swift downward glide for home. It must bend no more than if it were made of cast iron. To this stiffness the modern airplane owes its superior stability.

Testing the wings of the great biplane by crowding upon it a maximum human load

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