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The utility of airplane flow-field measurements for wind-tunnel testing is reviewed. The methods and equipment developed at Boeing for these measurements are also described. The details of the latest system are presented along with typical results from recent wind-tunnel tests. Using the latest system, flow-field surveys of airplane configurations in industrial low-speed and transonic wind tunnels provide spatial distributions of lift and drag (profile and induced) with good repeatability. In addition, the probe speed and survey region is optimized so that typical full-wake surveys take 20-30 minutes to complete. Final data, displayed as total pressure, velocity vectors, vorticity contours, and distributions of lift and drag (profile and induced) are available approximately 10 minutes after survey completion.

The wake imaging system (WIS) for rapid mappings of wind tunnel model flowfields is described and a summary of recent results is presented. Three different types of systems are discussed. These are: Photographic WIS in low-speed wind tunnels. Computer graphics WIS in transonic wind tunnels. Flying strut traverser for large low-speed wind tunnels. In addition, progress toward developing a low intrusive WIS for high-pressure transonic wind tunnels and for flight test applications is described.

An initial wind-tunnel test was conducted to investigate the aerodynamic interactions between a propeller slipstream and a supercritical wing at transonic Mach numbers. The primary independent variables examined included Mach number, wing lift coefficient, and slipstream Mach number and swirl. The interference effects were found to be weak functions of free-stream Mach number, wing lift coefficient, and slipstream Mach number; swirl was found to have a significant effect. At a free-stream Mach number of 0.8 and a lift coefficient of 0.5, incremental drag results for 7° of swirl (upwash inboard) and a slipstream Mach number of 0.87 indicate a penalty equivalent to a 0.024 loss in propeller efficiency. However, at 11° the drag increment was favorable and was equivalent to a 0.032 increase in propeller efficiency. Wing pressure data indicated the effects of the slipstream were essentially restricted to that section washed by the slipstream.