The Airplane - Jay Spenser [44]
Unfortunately, this line of experimentation proved an outright failure. The glider wouldn’t fly, and the whole frustrating experience drove home to Wenham just how little was actually known to help experimenters such as himself. Fortunately for posterity, he did something about it.
In 1866, he became a founding member of the Aeronautical Society of Great Britain, predecessor to today’s Royal Aeronautical Society. Created to help advance the quest for human flight, this engineering society boasted among its membership many of the leading scientific and engineering luminaries of the day.
Called on to give the society’s first annual lecture, Wenham presented a paper titled “On Aerial Locomotion and the Laws by Which Heavy Bodies Impelled Through Air Are Sustained.” A masterly blend of observation and deductive reasoning, this talk addressed bird flight, assessed the state of flight research, identified and examined technical issues, advocated for kite and glider experiments, and presented speculations on glider design and construction.
As always, Wenham spoke with reverent fascination of the natural world and the clues to be gleaned from it. For example, he described having seen a flock of spoonbills skimming low over the Nile. “Let one circumstance be marked—though they have fleeted past at a rate of near thirty miles per hour,” he told his audience, “so little do they disturb the element in which they move that not a ripple of the placid bosom of the river, which they almost touch, has marked their track.”6
Of course, Wenham shared his conviction that long, narrow wings lift more effectively than short, stubby ones. Aeronautical engineers call this relationship between a wing’s length (span) and front-to-rear measurement (chord) its aspect ratio. Long, slender wings have higher aspect ratios than short, broad ones. If a particular wing’s span is seven times its average chord, its aspect ratio is 7:1. Aspect ratio is in fact one of the most important parameters of wing design. Sailplanes generally have the highest aspect ratios and jet fighters the lowest. (Not all wings have parallel leading and trailing edges, of course; some wings are elliptical, and others, such as swept wings, taper as they extend outward. In such cases, the average chord length is used to calculate aspect ratio.)
The Aeronautical Society published “On Aerial Locomotion” in 1867. Lilienthal, Hargrave, Langley, and Chanute were among the flight researchers influenced by it. Hargrave particularly applauded Wenham for his advocacy of kite experimentation and “superposed lifting surfaces” (multiplane wing configurations).
To further disseminate this Englishman’s seminal ideas, Chanute paraphrased parts of his paper in the pages of Progress in Flying Machines. About the same time, a wealthy Bostonian named James Howard Means reprinted the entire paper in the 1895 edition of his Aeronautical Annual, a compendium of writings “devoted to the encouragement of experiment with aerial machines.”7
The Wrights first became familiar with Wenham’s ideas when Wilbur wrote to the Smithsonian Institution in 1899 asking for information about and a bibliography of flight. Igor Sikorsky was another likely beneficiary of Wenham’s thinking; if so, it explains how Sikorsky knew to give his giant Grand and Ilya Muromets airplanes such high-aspect-ratio wings.
As stated, it bothered Francis Wenham that a dearth of knowledge had sabotaged his efforts to build a working glider. There had been too few answers and too much guesswork as he cobbled the craft together. By the time the pragmatic Englishman gave his Aeronautical Society lecture in June 1866, he had arrived at a decision of profound consequence. “I propose shortly,” he informed those assembled, “to try a series of experiments by the aid of an artificial current of air of known strength, and to place the Society in possession of the results.”8
The result of this public commitment