A cylinder of aspect ratio 1 experiences a rich mixture of phenomena when yawed through 360 degrees. Understanding this variation is crucial to aerodynamic load definition for objects of practical shape. This paper uses several diagnostics to explain the detailed airload map of cylinders with length to diameter ratios 0.25 to 4 in steady incompressible flow, at Reynolds numbers from 50,000 to 450,000. A sharp linear variation of side force coefficient with yaw is bounded by apparent stall. Drag and pitching moment depend more on the curved surfaces, while side force is dominated by flow over the end plates. Tuft visualization and stereo Particle Image Velocimetry complement 6-DOF loads. Pressure distributions are obtained from velocimetry as well as from computations. The flow over the suction side shows a curved leading edge vortex followed by reattachment and an aft separation. The lift at low yaw is largely due to suction from the zones near the front corner, while at higher yaw it comes from the pressure difference between the two sides. The presence of helical vortices differentiates the lift generation from models based purely on separation.

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