Comparison of Three Exit-Area Control Devices on an N.A.C.A. Cowling, Special Report Page: 7 of 12
[11] p. : ill.View a full description of this report.
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values of Ap/q, however, the rapid decrease in 1o
max
is largely chargeable to the fact that large exit areas
increase the form drag by disturbing the flow over the
nacelle.
CONCLUD NG REMARKS
The results indicate that the adjustable cowling flap
and the bottom opening with adjustable flap are about
equal in merit on the basis of pressure obtainable and
that both are more effective than the adjustable-length
cowling skirt.
For equal cooling-air flow, the maximum net effi-
ciency obtained for the adjustable cowling flaps and for
the adjustable-length cowling skirt was about 1 percent
greater than that obtained for the bottom opening with
adjustable flap,
No measurements were made of the distribution of flow
through the cowling. Such measurements will be necessary
before definite conclusions can be drawn concerning the
relative cooling qualities of the arrangements tested.
Langley Memorial Aeronautical Laboratory,
National Advisory Committee for Aeronautics,
Langley Field, Va., March 12, 1940.
REFERENCES
I. Weick, Fred E., and Wood, Donald H.: The Twenty-Foot
Propeller Research Tunnel of the National Advisory
Committee for Aeronautics, T.R. No. 300, N.A.C.A.,
1928.
2. Theodorsen, Theodore, Brevoort, M. J,, and Stickle,
George W.: Full-Scale Tests of N.A.C.A. Cowlings.
T,R. No. 592, N.A.C.A., 1937.
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McHugh, James G. Comparison of Three Exit-Area Control Devices on an N.A.C.A. Cowling, Special Report, report, May 1940; (https://digital.library.unt.edu/ark:/67531/metadc65123/m1/7/: accessed April 24, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.