Quest for Performance: The Evolution of Modern Aircraft
Chapter 4: Design Revolution 1926-39
[77] The pace of aircraft development began to accelerate by the middle 1920's. Policies were established within the United States that assured consistent, although somewhat small, yearly appropriations for the procurement and development of new military aircraft. In an attempt to improve the poor aviation safety record and thus enhance the image of aviation as a serious means of transportation, laws were enacted that required the licensing of civil aircraft and pilots. Airworthiness standards were developed for the aircraft, and proficiency requirements were established for the licensing of pilots. The aircraft airworthiness requirements opened a market for the development of new types of general aviation aircraft. War surplus aircraft, such as the Jenny, either could not meet the new requirements or their certification would have proved economically unfeasible. The airmail that had been carried by Government aircraft for many years reverted to private contractors. Thus began the airline industry, albeit in a small way. Under the stimulus of these influences, the aircraft industry began to grow.
The pace at which advanced aircraft can be developed is closely coupled to the generation of new and advanced technology. The results of research investigations by the Langley Memorial Aeronautical Laboratory of the National Advisory Committee for Aeronautics (NACA) began to play an increasingly important part in providing the new technology necessary for the development of advanced aircraft. Investigations in aerodynamics, stability and control, propulsion, loads, dynamics, and structures formed the research program of NACA. Wind tunnels, laboratories, flight research, and analytical studies were the means by which new technology was developed. The results of NACA's research investigations were made available to the industry in the form of technical reports. Bound volumes of these reports, covering the [78] entire lifespan of NACA from 1915 to 1958, are a part of most good technical libraries. Indexes such as those cited in reference 74 give a complete bibliography of research publications by NACA. Years subsequent to 1949 are covered in additional indexes. Brief accounts of the significant research activities of NACA are contained in references 49, 56, and 73.
The universities played an important role in educating young aeronautical engineers and in various aspects of aeronautical research. Schools of aeronautical engineering sponsored by the Guggenheim Foundation were particularly important. These schools existed at the Massachusetts Institute of Technology, the California Institute of Technology, New York University, the University of Michigan, the Georgia Institute of Technology, Stanford University, and the University of Akron. The contributions of the Guggenheim Foundation to the development of aeronautics in the United States are described in reference 70.
The military services played an extremely important role not only in the generation of new technology but in sponsoring the application of that technology in the development of new and useful operating systems. Thus, the development and operation of new military equipment provided a highly significant foundation of proven components, such as engines, for use in new civil aircraft. A summary of the contributions of military aeronautical research and development to the development of advanced commercial aircraft throughout the thirties, forties, and fifties is contained in reference 104. A close relationship can frequently be found between the development of advanced military aircraft and new commercial aircraft that employed not only many of the design features of military aircraft but also hardware and concepts that had been proved in military aviation.