Portal de Periódicos da CAPES

The Retractable Airplane Landing Gear and the Northrop “Anomaly”: Variation-Selection and the Shaping of Technology

1994; Johns Hopkins University Press; Volume: 35; Issue: 1 Linguagem: Inglês

10.1353/tech.1994.0116

1097-3729

Walter G. Vincenti,

Mechanical Engineering and Vibrations Research

The Retractable Airplane Landing Gear and the Northrop ‘Anomaly”: Variation-Selection and the Shaping of Technology WALTER G. VINCENTI Airplane designers today routinely provide their high-performance aircraft with a landing (and takeoff) gear that retracts inside the vehicle in flight. Few people apart from the designers give attention to that fact. As with other devices that attract little notice, however, the retractable landing gear has a history of more than incidental interest. Looked at deliberately, its story contains lessons about the processes of learning and change in engineering. This article does not pretend to a full history of the retractable gear. Such a task would call for a book.1 Though I aim to put the story in context, I shall focus primarily on an episode in the United States in the first half of the 1930s, when the retractable gear was entering prominently and permanently into airplane design. In that period, as retractable gear were appearing on a series of innovative airplanes, a succession of high-performance craft from the noted designer John Northrop continued to exhibit a streamlined fixed undercarriage. These beautifully trim aircraft are certain to be remembered by any observer of the aeronautical scene at the time—as was I as an aviation enthusiast in high school. Thinking back on them prompted me to wonder: How was it that Northrop, who led the way in other respects, was apparently so slow to adopt retraction? An answer to this Mr. Vincenti is a member of the Department of Aeronautics and Astronautics at Stanford University. He thanks the host ofpeople who helped collect and comprehend the material in this article: Richard Allen, Gerald Baker, Glenn Bugos, Ira Chart, Edward Constant, Fred Culick, David Edge, the late Edward Heinemann, Nicholas Hoff, Thomas Hughes, John Kimball, Stephen Kline, Ilan Kroo, Gerald Landry, Edwin Layton, Mark Levinson, Robert McGinn, Anne Millbrooke, Russell Robinson, Eric Schatzberg, Paul Seaver, Richard Shevell, Richard Smith, and a Technology and Culture referee. 'For a brief outline of the history of the airplane landing gear, both fixed and retractable, see C. Ellam, “Developments in Aircraft Landing Gear, 1900-1939,” Transactions of the Newcomen Society 55 (1983—84): 48—51.© 1994 by the Society for the History of Technology. All rights reserved. 0040-165X/94/3501-0004$01.00 1 2 Walter G. Vincenti question, I hoped, might supply evidence concerning the variationselection model for the growth of engineering knowledge put for­ ward in my recent book.2 The story turned out more instructive than I anticipated. Beyond its significance for the variation-selection model, it has implications—cautionary, I believe—for the social study of technology. I will take up these matters following a narrative of the Northrop episode and its context. The Usual View Adoption of retractable gear contributed to whatJohn Rae calls the “airframe revolution” of the early 1930s. As discussed in the volumes by Rae and by Ronald Miller and David Sawers, American designers combined this and other innovations—aluminum stressed-skin struc­ ture, wing flaps, and the controllable-pitch propeller—into what would remain the dominant configuration for both military and civil purposes for the next twenty years. This synthesis is seen as coming about through a series of ten or so key land-based aircraft, beginning with the Boeing Monomail and Northrop Alpha, single-engine com­ mercial designs of 1930, and culminating in the well-known Douglas twin-engine airliners, the DC-1, -2, and -3 of 1933-36. The various innovations, introduced in different combinations as the series grew, came together as a whole in the DC-1. Of the series, the Monomail (fig. 1) and the Lockheed Orion, an advanced but still wood-structured transport of 1931 (fig. 2), are often pointed to as pioneering use of retractable gear. Since this airframe revolution, the retractable under­ carriage has been an accepted and essential element of highperformance land-based aircraft.3 To the extent they have examined the issue, historians tend to see the introduction of the retractable gear as an essentially reasoned and ordered affair. Lawrence Loftin, in his detailed and technically informed book Quest for Performance, compares the numerical drag coefficient of the Orion with that of Lockheed...