III. Theoretical Models

Trevor Pinch and Wiebe Bijker make a number of useful observations about SCOT in their essay “The Social Construction of Facts and Artifacts” (Bijker, Hughes, and Pinch). For example, Pinch and Bijker note that social groups, which may or may not be homogenous, define which technological issue or “artifact” is a problem to be addressed (Bijker, Hughes, and Pinch, pp. 30 and 33–34). Similarly, specific parts of a technological system may be imbued with different functions or meanings by different groups or individuals, and hence a technological controversy is closed through public opinion, not by technically "solving" the issue (Bijker, Hughes, and Pinch, pp. 40–42 and 44). Overall, this approach to SCOT contextualizes technological artifacts though the meanings given to them by social groups (Bijker, Hughes, and Pinch, p. 46).

In terms of the Shuttle example, Pinch and Bijker’s analysis applies to the four goals of the Shuttle. It is instructive to consider who wanted which capability on the Shuttle. The Shuttle, like many other technologies, means different things to different people. Attempting to be all things to all parties virtually ensures that not all the goals of a particular technology will be achieved. This is certainly true with the Shuttle, where some of the goals such as low cost and human rating are at odds. Certainly there is more to consider in any technological system than its technical components.

Similarly, the concept of “heterogeneous engineering” encompasses not only physical materials and equations in any technological endeavor, but also the social, political, and economic enterprises behind the scenes (MacKenzie in Bijker, Hughes, and Pinch, p. 198, citing Law in Bijker, Hughes, and Pinch). MacKenzie also argues that “[o]ften, the heterogeneous engineering required from those pushing a new technology is the creation of the sense of a need for that technology” (MacKenzie in Bijker, Hughes, and Pinch, p. 205—emphasis in the original). Thus, entrepreneurship is essential to creating an economic market for a new technological invention. Conversely, sometimes an organization or individual may dictate specific characteristics for a new technology before buying economically or accepting politically a product in development.

Beyond this general theoretical discussion of SCOT, it may be useful to consider two specific examples of social construction in aeronautics technology. This paper will look first at the application of SCOT theory in the case of retractable airplane landing gear during the 1930s (Vincenti passim); it will then examine how aeronautical engineers largely chose to build planes from metal, rather than wood, starting in the 1920s and 1930s (Schatzberg passim).

In the 1930s, there were five generally recognized goals for airplane landing gear: aerodynamic performance, weight, cost, reliability, and maintenance. These five criteria involved multiple tradeoffs. If, for example, one wanted an airplane with maximum aerodynamic efficiency, retractable landing gear was the best option, but this increased the weight, and thus an airplane outfitted with retractable landing gear would need more thrust to take off and maneuver (Vincenti, p.8). Aviation pioneer Jack Northrop, however, was able to design more stable fixed landing gear with a “pants-type” streamlining that, surprisingly enough, performed virtually as well aerodynamically as retractable gear in wind-tunnel tests at relatively low speeds (Vincenti, pp. 9–10). In addition, retractable gear raised significant logistical problems in the 1930s. Initially, a pilot had to raise the landing gear by hand cranking; later, retractable landing gear used electric motors that often leaked fluid (Vincenti, p. 19). Vincenti does not even fully address the issue of how rugged landing gear must be to retract and extend flawlessly (Sotham, passim). So why did retractable gear become so prevalent?

The simple answer is that at higher speeds of approximately 200 miles per hour, retractable gear performed significantly better than fixed gear in the wind tunnel (Vincenti, p. 16). Once planes began flying at these higher speeds, the choice was clear. Even today, many low-speed planes employ fixed gear, although most planes now fly fast enough to justify the more technologically complex retractable gear system for the sake of aerodynamics. Vincenti thus contends that the engineers of the early 1930s “agreed in their goal of higher speeds; their crystal ball for how best to get there, however, was unavoidably clouded” (Vincenti, p. 19) until the aerodynamic benefits of retractable gear at higher speeds were proven.

Vincenti’s main thesis is that although “social considerations had little or nothing to do with” the choice of landing gear, the definition of the problem was shaped by society’s desire for faster airplanes for military, racing, and commercial purposes (Vincenti, p.28). Once the need for speed was socially established, aeronautical engineers set to work on various subsystems, such as landing gear, to produce the most aerodynamically efficient, and thus fastest, airplanes possible. Vincenti also explicitly acknowledges the SCOT literature embodied by Pinch and Bijker by noting again that social factors, as well as narrow “technical” considerations, dictate how engineering problems are defined and addressed (Vincenti, p. 26).

A second application of aeronautical social construction is in the choice between metal and wooden airplanes (Schatzberg, passim). During roughly the same time period as the landing gear debate, the 1920s and 1930s, aircraft designers moved gradually but surely from wooden to metal airplanes. During World War I, approximately 170,000 airplanes were built, mostly from fabric-covered wood. But the Germans had successfully experimented with metal, and after the war, word spread quickly (Schatzberg, p. 37). Although metal is clearly a more durable material for aircraft such as seaplanes, this could not “explain the nearly universal support for metal structures in all types of aircraft” (Schatzberg, p. 52). Proponents of metal airplanes claimed a number of advantages such as fire safety, weight efficiency, manufacturing costs, and durability (Schatzberg, p. 40). Schatzberg explains how each of these factors did not necessarily always favor metal over wood. For example, although wood may burn more easily than metal, in the 1920s, the real fire safety problem was improperly isolated combustible fuel. Similarly, supposedly stronger metal supports tended to buckle because they were made of long, thin cross-sections to reduce weight (Schatzberg, pp. 41, 44).

Interestingly, Schatzberg describes how the National Advisory Committee for Aeronautics (NACA), the predecessor organization to NASA, devoted significant resources to solving certain problems with metal, such as aluminum’s tendency to corrode, but did not fully address similar kinds of problems associated with wood, such as the durability of glued joints (Schatzberg, pp. 50, 61–63). If it wasn’t so clear that metal was superior to wood for airplane construction before the advent of high-performance aircraft and advanced synthetic materials, then why did engineers tackle the metal problems more aggressively than the wood problems? Schatzberg argues that the reason for this is that the preference for metal was socially constructed.

Specifically, he contends that engineers were enamored of metal for two social reasons. For one thing, they viewed metal as a material of progress and of science (Schatzberg, p. 53). In the early twentieth century, technology’s affect on American life seemed to be increasing. Builders had recently learned how to use metal to construct tall buildings and long bridges, so this material seemed to exemplify technological advancement. In addition, many engineers saw wood as a material that was used by craftsmen, whereas metal seemed to be the domain of more rigorously, academically trained engineers; hence viewing metal in this way was a method for engineers to gain status in the eyes of their scientific counterparts (Schatzberg p. 52).

Schatzberg tries to push his argument further by explicating the reason behind this social construction. He attempts to explain why the aeronautical community embraced this “progress ideology” of metal so readily by tying this notion’s origins to very broad cultural trends of the late nineteenth and early twentieth centuries (Schatzberg, p. 66–69). For example, he claims that by “the late [nineteenth] century, almost all Americans embraced technical change as the key to human progress” (Schatzberg, p. 67). Whether or not such broad cultural explanations are valid, Schatzberg’s argument about the socially constructed value of metal versus wood in building airplanes is worth considering as a model.

Updated April 5, 2001
Steven J. Dick, NASA Chief Historian
Steve Garber, NASA History Web Curator
For further information, e-mail histinfo@hq.nasa.gov

Designed by Douglas Ortiz and edited by Lisa Jirousek
NASA Printing and Design