Aerodynamic performance measurements at moderate Re

There has been renewed interest in the aerodynamics of lifting wings at Reynolds numbers from 10^4 to 10^5, partly due to engineering requirements of small-scale, remotely piloted aircraft, and partly because birds and bats operate in this regime. Even when the wings do not flap or pitch or plunge, the flow over the small aspect ratio wings is likely to be three-dimensional and unsteady. Wind tunnel test results are described where force measurements are combined with DPIV studies. Some problems and principles of such measurement programs will also be discussed.