Abstract:
Tests on NACA 0020 sections of 1.2 and 2.0-in. chord completely spanning the tunnel showed that there was no appreciable difference in compressibility drag rise due to wind-tunnel interference. This was the case both with the aerofoil yawed (40 deg) and straight across the tunnel. The results, and further measurements on a Piercy aerofoil previously tested, showed also that the gain in Mach number has been increased from 65 to about 80 per cent of the theoretical value that assumes infinite span and no boundary-layer effects, now that the air is dried to a large extent by use of return ducts. Some explorations of the flow behind the aerofoil are considered to justify these conclusions at Mach numbers up to at least 0.92.
