Francis Wenham (an engineer who was also interested in microscopy, photography, optics and engine design) first became actively interested in aerial research while on a trip to Cairo, Egypt, in 1858 and wrote a report on his findings in 1859. He examined birds' wings and determined that it was the curve, the camber, of the birds' wings which generated the maximum lift and further, that the greatest amount of lift existed near the front edge, the leading edge, of the wing. He also concluded that while the mechanical principles involved in bird flight must be utilized, "all imitations of natural wings" must be repudiated. He also wrote that "... in designing a flying-machine, any deviations (NOTE: from the design of natural bird wings) are admissible, provided the theoretical conditions involved in flight are borne in mind." In 1866 Wenham presented his paper "Aerial Locomotive" to the first meeting of the Aeronautical Society in London, England. At the close of Wenham's presentation, the Society's Chair, The Duke of Argyll, made the following comment
|"I think the paper just read is one of great interest and importance, especially as it points out the true mechanical explanation of the curious problem, as to how and why it is that birds of the most powerful flight always have the longest and narrowest wings."|
It was this one paper which established Wenham as a significant figure in aeronautical research, for his conclusions were published in the Aeronautical Society's journal, presented in Octave Chanute's 1894 "Progress In Flying Machines" and reprinted, in 1895, in James Means' "Aeronautical Annual" and again in 1910 by the Aeronautical Society of Great Britain, all of which were widely distributed and widely read.
One of Wenham's suggestions was that aerial research should begin with a thorough study of "kites," meaning small winged structures, or model flying machines (a point which Lawrence Hargrave took to heart). He also managed to demonstrate that wings of greater span generate more lift than wings of greater depth (chord), even though the total surface area of both such wings are the same, and suggested that lifting surfaces might be superimposed to reduce overall width. Wenham also understood that to turn a flying machine in flight, more lift should be generated on one side than on the other, contrary to the then-prevailing opinion that a rudder, akin to that on a ship, was necessary to turn a flying machine. In addition to his very important 1866 research paper, Wenham and John Browning designed and constructed what was almost certainly the world's first wind tunnel, in 1871, and obtained results which established the relationship between pressure and velocity.
In "Aerial Locomotion" Wenham presented possible configurations for gliding machines, as shown above: Figure 1. is the top view of a gliding machine, illustrating the total surface area required to sustain aloft a human of average weight; Figure 2. is the rear view of the same design, showing the prone position which Wenham suggested for the gliding machine's operator; Figure 3. is a front view of a multi-winged gliding machine trussed with "thin bands of iron" (c) and vertical wing struts (d); Figure 4. represents a more refined design, incorporating small wing-like propellers on each end, operated by motion of the operator's feet and arranged so that the propellers could be operated more on one side or the other ("... thus enabling the machine to turn..." by generating more lift on one side than one the other) or together; Figure 5. shows an even more refined design, with wing-like propellers at the ends of long arms (reminiscent of Hargrave's later "Trochoided planes"), a cellular wing structure with vertical supports (struts), wing trussing, and a horizontal position for the operator; Figure 6. is a side view of the machine depicted in Figure 5.
Francis Wenham's keen observations and superb deductive reasoning permitted him to understand the requirements and underlying mechanics of flight in a way which, apparently, no one had previously. Wenham's "Aerial Locomotion" can be seen as standing, in a theoretical sense, between George Cayley and Lawrence Hargrave, two other major figures in aeronautical history. The widespread availability of "Aerial Locomotion" during the mid-1890's, just prior to the period of great aerial research activity between 1895 and 1903, probably encouraged many experimenters to pursue and refine their research.
It is striking to note that at least four significant aerial vehicle design elements suggested by Wenham in 1866 can be seen on the series of successful Wright gliders and on the 1903 Wright Flyer: 1) superimposed wings, 2) vertical upright supports between the superimposed wings, 3) the prone position of the operator, as in Wenham's design with superimposed wings, and 4) that turning in flight ought be accomplished by means of generating more lift on one side of the aerial vehicle than on the other, rather than through the use of a simple rudder. It is also important to restate that Wenham's paper "Aerial Locomotion" was readily available to Wilbur Wright (as well as to Orville) in the 1895 "Aeronautical Annual" which the Smithsonian Institution recommended to Wilbur Wright in June of 1899 (along with other aeronautical reading material), and which he soon thereafter obtained and read.