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National Advisory Committee for Aeronautics, Report - Drag and Cooling with Various Forms of Cowling for a 'Whirlwind' Radial Air Cooled Engine, II

This report gires the results of the second portion of an investigation in the Twenty-Foot Pro-
peller Research Tunnel of the National Advisory Committee for Aeronautics, on the cowling and
cooling of a “ Whirlwind” J-fi radial air-cooled engine. The first portion, which is reported in
N. A. C. A. Technical Report No. 313, pertains to tests with a cabin fuselage. This report covers
tests with several forms of cowli-ng, including'concentional types, individual fairings behind the
cylinders, individual hoods orer the cylinders, and the new N. A. 0. A. complete cowling, all on an
open cockpit fuselage. Drag tests were also made with a conventional engine nacelle, and with a
nacelle having the new complete cowling.

In the second part of the investigation the rewlts found in the first part were substantiated.
It was also found that the reduction in drag with the complete cowli-ng over that with conre-ntional
cowling is greater with the smaller bodies than with the cabin fuselage, in fact the gain in the case
of the completely cowled nacelle is over twice that with the cabin fuselage. The indi-m'dual fairings
and hoods did not prove efectice in reducing the drag. The results of flight tests on an ATfiEA
airplane (reported in the appendix to N. A. C. A. Technical Report No. 313) hare been analyzed
and found to agree very well with the results of the wind tunnel‘tests.

This report covers the second and final portion of an investigation of the cowh'ng and cooling
of radial air-cooled engines The first portion, which dealt with the cowling of a “Whirlwind”
engine in a cabin fuselage, has been reported m N. A. C. A. Technical Report No. 313 (Refer-
ence 1).