Some Effects of Reynolds and Mach Numbers on the Lift of an NACA 0012 Rectangular Wing in the NACA 19-Foot Pressure Tunnel Page: 3 of 11

                                
certain phenomena observed  n f Iht. 'naimuch as the
information provided by the present tests is somewhat
scanty, further tests are contemplated when the pressure
of the present military testing program is relieved.
TESTS AND RESULTS
Figure 1 gives the details of the model.  The test
setup of the model mounted in the tunnel is shown in fig-
ure %7o.orce tests were made over an angle-of-attack
range from below zero lift through the stall nith the air
in the tunnel at two pressures, atmospheric (14.7 lb/.sq in.
abs.) and 35 pounds per square inch absolute. Tho tests
were made at values of dynamic pressure from 0Q to 200
pounds per sq-are foot, wVhich gave test Reynolds numbers
from 1,070.000 to 5_,250,000 at atmospheric pressure and
from 1,960,000 to 8,240,000 for 35 pounds per square inch
pro ssure
Tests were made to determine the effects of support
tare and interference, and corrections for these effects
mere made to tne coefficients presented herein. The
angles of attack are corrected for jet-boundary effects.
The variation of the lift coefficient 0L with angle
of attack  a  is given in figures 3 and 4 for the tests
at the different Reynolas numbers and the two tunnel air-
pressure c on4ditions. Examination of these curves reveals
some variation of lift-curve slope with Reynolds number.
Correcting the slopes to infinite aspect ratio  ao and
plotting  ao against test Reynolds number (fig. 5) gives
a separate curve for each of the two tunnel air pressures,
When  ao  is potted against Mach number, however, the
two curves show fair agreement in that the breaks occur
at approximately the same Mach number (fig. 5).
In figure 5$, the maximum lift coefficient 0    is
plotted against test Reynolds number for the two pressure
conditions. For atmospherto pressure, the value of   CLmax
increases up to a velociAty of approximately 1.50 miles per
hour after which it decreases at a rapid rate for the re-
maining portion of the range investigated.  Increasing
the pressure of the air in the tunnel extends the curve
.obtaned at atmospheric pressure to higher values of  CLmaa