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Hydrodynamic and Aerodynamic Tests of Models of Flying-boat Hulls Designed Flow Aerodynamic Drag - NACA Models 74, 74-A, and 75The present tests illustrate how the aerodynamic drag of a flying boat hull may be reduced by following closely the form of a low drag aerodynamic body and the manner in which the extent of the aerodynamic refinement is limited by poorer hydrodynamic performance. This limit is not sharply defined but is first evidenced by an abnormal flow of water over certain parts of the form accompanied by a sharp increase in resistance. In the case of models 74-A and 75, the resistance (sticking) occurs only at certain combinations of speed, load, and trim and can be avoided by proper control of the trim at high water speeds. Model 75 has higher water resistance at very high speeds than does model 74-A. With constant speed propellers and high takeoff speeds, it appears that the form of model 75 would give slightly better takeoff performance. Model 74-A, however, has lower aerodynamic drag than does model 75 for the same volume of hull.
Document ID
19930081475
Acquisition Source
Legacy CDMS
Document Type
Other
Authors
Truscott, Starr
Parkinson, J B
Ebert, John W , Jr
Valentine, E Floyd
Date Acquired
September 6, 2013
Publication Date
October 1, 1938
Report/Patent Number
NACA-TN-668
Accession Number
93R10765
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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