Case 1: Heavier-than-Air Flight
In this section, we analyze the invention process of the heavier-than-air aircraft in the nineteenth century largely up and until the maiden flight of the Wrights Flyer. In our analysis, we refrain from discussing the relatively weak technical, conceptual, and functional relationships of heavier-than-air aircraft with exotic aircraft with flapping wings (ornithopters), helicopters, and lighter-than-air aircraft like dirigibles.
In Sect. 3.1, we briefly discuss the emergence and components of what would become the dominant design. In Sect. 3.2, we discuss the contributions of the main inventors in each of the components. In Sect. 3.3, we provide four types of knowledge flows and describe the flows that prominent historians deem the most significant. In Sects. 3.4, 3.5, and 3.6, we discuss the role of institutionalization of inventive activities, how governments have been involved, and how the various inventive activities were fragmented over the globe.
Functionality, Configuration and Design Principle
Although an integrated design and a decomposition into components providing specific aerodynamic functions were articulated early on, the invention materialized only with breakthroughs in control and thrust.
The foundation for aerial navigation was laid by the English baron George Cayley in his work written during the year 1796-1855 (and notably 1799 and 1809). He formulated the aerodynamic principles that flying requires lift greater than gravity and thrust greater than drag. In terms of design, Cayley specified the modern technical configuration with a fixed wing under a dihedral angle, a fuselage to carry the pilot, and an adjustable horizontal and vertical tail for stabilization and control (Jacob 1990).
More than 30 years later, William Henson read Cayley’s work and designed and received a patent on his Aerial Steam Carriage (‘Ariel’), of which technical drawings appeared in newspapers internationally in 1843 (Hallion 2003, p. 113). The aircraft integrated all the quintessential elements of a modern airplane, including a fuselage, propulsion with propellers, well-thought-out wing design, controls, etc. Henson and John Stringfellow set up the ambitious Aerial Transit Company to carry commuters and travelers across the globe. In spite of the consolidation of the aircraft design, the actual materialization of their aviation service was foiled by the many technical problems in various components.
The technological functions to be provided were already known to Cayley; he stated in his “On Aerial Navigation” (1809) that mastering lift, propulsion and control is required for heavier-than-air flight. In the third quarter of the nineteenth century, the system configuration for heavier-than-air aircraft was well-known: (1) a main wing for lift, (2) tail wing for stabilization, (3) power to provide thrust (exceeding drag), (4) control over the direction of the airplane, and (5) the airplane structure including the fuselage to carry the pilot and the load. Interestingly, Alphonse Penaud’s immensely popular toy (designed in 1871) featured most of that: (rubber-band) propulsion, propellers, dihedral angled wings for lateral stability, and a tail with a horizontal stabilizer. The toy was sold worldwide and ultimately inspired many inventors, including the Wright boys.
Confirmation of technical feasibility of certain design elements came only after design experiments. Samuel Langley’s model and Hiram Maxim’s rigged airplane showed that sufficient lift could be generated and that, like in Penaud’s model, aircraft may exhibit lateral and longitudinal stability. However, particularly the step from designing aircraft that have inherent stability (as is required for sustained flight of unmanned models) to control for manned models (and structural support for the weight of the driver) were crucial. By the time the Wrights flew with their “Flyer” in December 1903, they were far ahead of their competitor Langley in that they had both structural integrity and lateral control with wing warping coupled to the rudder. Interestingly, much in line with our process model, this advancement came about by methodically enhancing the system component by component.
Note that there were quite a few competing designs during the nineteenth century, not only for the various components, but also for the whole aircraft. Despite the modern design of the Ariel, other inventors designed aircraft peculiarly mimicking features of flying animals even several decades later, e.g. Clement Ader’s bat-shaped Eole and Avion-III (1890-1897) with bird-feather shaped propeller blades (cf. Champonnois 2009), Otto Lilienthal’s gliders (around 1894), and Alexandre Goupil’s sesquiplane (1883). Despite vast quantities of money spent by Ader, the “slavish imitation of nature” had produced wings with not enough ribs to give sufficient support or uniform lift, ultimately making “the whole machine  most ridiculous” (Quoting words of the Wright brothers in various communications, see Hallion 2003, p. 136-137). Ignorantly, in the development of his aircraft,
Ader ignored and dismissed many developments on other designs and components done before him. Despite his claim to have been the first to realize manned flight, it was very far from a controlled, sustainable flight.