Flight Investigation at High Speeds of the Drag of Three Airfoils and a Circular Cylinder Representing Full-Scale Propeller Shanks Page: 3 of 7

                                
FLIGHT INVESTIGATION AT HIGH SPEEDS OF 'HE DRAG OF THREE AIRFOILS AND A CIRCULAR CYLINDER

FmiurE -Location of models and wake-surrey rake below lower surface of wing of
XP-51 airplane.

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FIoUa 6.-CIrcular cylinder showing orifice stations.
The local dynamic pressure q and the local Mach number
Atl used in evaluating the data were determined from free-
stream total pressure measured with the pitot tube mounted
ahead of the airplane wing and from local static pressure
measured with static-pressure tubes located on the right
wing at the same chordwise and spanwise positions-as those
at which the models were located on the left wing. These
pressure measurements were made simultaneously with

measurements of the drag of the models. In the pressure-
distribution tests of the cylinder the static-pressure measure-
ments on the right wing were made with a rake of six
static-pressure tubes, with each tube located at a distance
below the wing surface corresponding to an orifice location in
the cylinder (fig. 6). For the force tests of the cylinder and the
wake surveys, the static pressure on the right wing was meas-
ured with one static-pressure tube located 9 inches below the
wing surface (fig. 7), which corresponds to station 3 in figure 6.
The difference between local Mach number at various
distances below the wing surface and free-stream Machli num-
ber is presented in figure 8 for several flight Mach numbers.
S tatic-pressure tube        Thermometer.

FIGuR 7.-Static-pressure tube and thermometer mounted below right wing of
XP-51 airplane.

Disfo ce below wing surface, in.
FI RE 8.&-Variation of increment of local Mach number above flight Mach number with
distance below right wing surface as determined from static-pressure surveys.
In order to indicate the magnitude of the chordwise varia-
tion of static pressure in the test region, the .chordwise pres-
sure distributions, as determined from measurements of
static pressure on the lower surface of the wing of another
XP-51 airplane, are presented in figure 9 for an airplane lift
coefficient of about 0.15 and several flight Mach numbers.

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