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Wind-Tunnel Tests of Several Model Tractor-Propeller and Pusher-Propeller Wing Extension-Shaft Arrangements, Special ReportTests were made in the 20-foot propeller-research tunnel to investigate the possibility of obtaining increased net efficiencies of propeller-nacelle units by enclosing the engines in the wings and by using extension shafts. A wing of 5-foot chord was fitted with a propeller drive assembly providing for several axial locations of tractor propellers and pusher propellers. A three-blade 4-foot propeller and a three-blade 3 1/2-foot propeller of special design were tested in this wing with spinners and fairings ranging in diameter from 6 to 16 inches. A 16-inch NACA cowling was tested for comparative purposes. Two types of cuffs were also employed. It was found that the net efficiency of a conventional round-shank propeller mounted on an extension shaft in front of or behind a wing increased with an increase in the diameter of the spinner and the shaft housing within the scope of the tests. The largest spinner used had a diameter that might favorably compare with that of a radial engine cowling. The efficiencies for the pusher position appeared to be more critically affected by spinner size than those for the tractor position. The spinners with large diameters for the pusher position resulted in a higher efficiency than those for the corresponding tractor arrangements; the reverse was true for the small spinners. The use of propeller cuffs in combination with a spinner of small diameter generally resulted in net efficiencies that were comparable with those found for the large-spinner combinations.
Document ID
20090016321
Acquisition Source
Legacy CDMS
Document Type
Other
Authors
Harmon, Hubert N.
(National Advisory Committee for Aeronautics. Langley Aeronautical Lab. Langley Field, VA, United States)
Date Acquired
September 7, 2013
Publication Date
June 1, 1941
Subject Category
Aircraft Propulsion And Power
Report/Patent Number
NACA-SR-196
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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