The Airplane - Jay Spenser [42]
The Chanute-Herring glider of 1896 combined Lawrence Hargrave’s box kite idea with Octave Chanute’s engineering expertise to create biplane wings.
National Air and Space Museum, Smithsonian Institution
By all accounts, the Chanute-Herring machine surpassed Lilienthal’s best achievements. A trim little design, it was essentially Hargrave’s box kite reimagined with a cruciform tail and wings modified for its new role as a man-carrying glider. But Chanute’s embellishments were what make this human artifact so significant historically.
Chanute’s engineering expertise imbued Hargrave’s breakthrough with a combination of struts and wire bracing that trussed the two wings into a single rigid beam structure. Neither wing alone could have withstood the twisting and flexing forces of flight, but bound together, each lent the other support to create a structure as sturdy as a packing crate.
Here was aviation’s equivalent of the Pratt truss, a method of distributing and supporting heavy loads popular with nineteenth-century civil engineers. The externally braced biplane—history’s first heavier-than-air flight structure—had come into being.
The wings are the most import part of any airplane. They largely determine its performance capabilities and flight characteristics. This is true regardless of the airplane’s configuration.
Biplanes and monoplanes are alike in this regard but differ from a load-bearing standpoint. In biplanes, the wings are the primary structure; all else relies on the rigid beam truss created by these braced lifting surfaces. In contrast, the fuselage is the primary structure in a monoplane because it supports the wings and all else.
In creating the biplane, Chanute had taken Hargrave’s brilliant idea of mutually reinforcing wings and added a masterly understanding of structural load paths. What he had learned over decades of designing bridges and other structures, he now translated aloft. The result was a strength-to-weight ratio that placed manned, powered, heavier-than-air flight well within grasp.
The first beneficiaries of Chanute’s repurposing of the box kite were none other than Wilbur and Orville Wright. In the Chanute-Herring glider, the mechanically minded brothers recognized a design solution combining structural rigidity, light weight, and ample wing area.
Aside from encouragement, this was Chanute’s single contribution to the success of the Wrights. The resemblance of their gliders and flyers to his seminal 1896 machine shows how faithfully the Ohio brothers took its lessons to heart.
In one regard, however, the Wrights would depart from what Hargrave and Chanute had achieved. In a stroke of genius, they deliberately weakened this rigid wing truss to allow the wings to twist for control in the air, as we shall see in a later chapter.
From the time he was tiny, Geoffrey Hargrave had helped his father with his flight experiments. When the new century arrived and airplanes emerged, father and son pored over the press accounts in joyous celebration. It was a matter of pride that the world’s first heavier-than-air flying machines bore the Hargrave stamp.
Then World War I broke out. Australia and New Zealand, dominions of the British Empire, dutifully sent their young men off to fight. Geoffrey Hargrave volunteered and was among the Anzac infantrymen whose lives were senselessly squandered at Gallipoli in Great Britain’s disastrous Dardanelles Campaign. The Turkish bullet that ended young Geoffrey’s life in 1915 broke the elder Hargrave’s heart. Australia’s great aviation pioneer succumbed that same year at age sixty-five.
Even as the structural demands of wings were being figured out, people were also probing their aerodynamic qualities. This began with George Cayley, who postulated for the first time in history that curved surfaces lift more effectively than flat ones. The father of wing theory, Cayley used a whirling arm to methodically conduct the world’s first airfoil tests.
In 1804, George Cayley came up with a fascinating idea. If the wings angled upward