High-Speed Tests of a Model Twin-Engine Low-Wing Transport Airplane

One of 111 reports in the series: NACA Special Reports available on this site.

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Force tests were made of a 1/8-scale model of a twin-engine low-wing transport airplane in the NACA 8-foot high-speed wind tunnel to investigate compressibility and interference effects at speeds up to 450 miles per hour. In addition to tests of the standard arrangement of the model tests were made with several modifications designed to reduce the drag and to increase the critical speed. The results show serious increases in drag at critical speeds below 450 miles per hour due to the occurrence of compressibility burbles on the standard radial-engine cowlings, on sections of the wing as a result of wing-nacelle ... continued below

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Becker, John V. & Leonard, Lloyd H. April 1, 1940.

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This report is part of the collection entitled: National Advisory Committee for Aeronautics Collection and one other and was provided by UNT Libraries Government Documents Department to Digital Library, a digital repository hosted by the UNT Libraries. It has been viewed 160 times . More information about this report can be viewed below.

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  • Main Title: High-Speed Tests of a Model Twin-Engine Low-Wing Transport Airplane
  • Series Title: NACA Special Reports

Description

Force tests were made of a 1/8-scale model of a twin-engine low-wing transport airplane in the NACA 8-foot high-speed wind tunnel to investigate compressibility and interference effects at speeds up to 450 miles per hour. In addition to tests of the standard arrangement of the model tests were made with several modifications designed to reduce the drag and to increase the critical speed. The results show serious increases in drag at critical speeds below 450 miles per hour due to the occurrence of compressibility burbles on the standard radial-engine cowlings, on sections of the wing as a result of wing-nacelle interference, and on the semi-retracted main landing wheels. The critical speed at which the shock occurred on the standard cowlings was 20 miles per hour lower in the presence of the fuselage than in the presence of the wing only. The drag of the complete model was reduced 25% at 300 miles per hour by completely retracting the landing gear, fairing the windshield irregularities, and substituting streamline nacelles (with allowance made for the proper amount of cooling-air flow) for the standard nacelle arrangement. The values of the critical Mach number were extended from 0.47 to 0.60 as a result of the aforementioned improvements. The principal purpose of the reported tests was to investigate the effect of compressibility on the drag of the component parts of a representative large airplane and on the overall drag of such an airplane. The influence of interference on compressibility effects was also studied. In addition, it was proposed to test several modifications of the standard component parts that gave promise of an improvement in aerodynamic characteristics.

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  • URL: http://hdl.handle.net/2060/20090014136 External Link
  • Report No.: NACA-SR-143
  • Center for AeroSpace Information Number: 20090014136
  • Report No.: NACA-TR-750
  • Archival Resource Key: ark:/67531/metadc65025

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National Advisory Committee for Aeronautics Collection

The National Advisory Committee for Aeronautics (NACA) was a U.S. federal agency founded on March 3, 1915 to undertake, promote, and institutionalize aeronautical research. On October 1, 1958 the agency was dissolved, and its assets and personnel transferred to the newly created National Aeronautics and Space Administration (NASA).

Technical Report Archive and Image Library

This selection of materials from the Technical Report Archive and Image Library (TRAIL) includes hard-to-find reports published by various government agencies. The technical publications contain reports, images, and technical descriptions of research performed for U.S. government agencies. Topics range from mining, desalination, and radiation to broader physics, biology, and chemistry studies. Some reports include maps, foldouts, blueprints, and other oversize materials.

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Creation Date

  • April 1, 1940

Added to The UNT Digital Library

  • Nov. 17, 2011, 5:13 p.m.

Description Last Updated

  • Nov. 30, 2016, 12:38 p.m.

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Becker, John V. & Leonard, Lloyd H. High-Speed Tests of a Model Twin-Engine Low-Wing Transport Airplane, report, April 1, 1940; (digital.library.unt.edu/ark:/67531/metadc65025/: accessed September 22, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.