Drag of 5 and 4 Fineness Ratio Cylinders Parallel to Flow

Drag coefficients of axial cylinders of 5 and 4.1 fineness ratios were measured in support interference free by the NAL 60cm MSBS(Magnetic Suspension and Balance System) at speeds from 10m/s to 35m/s. The drag coefficient of the cylinder of 5 fineness ratio is 0.891 at Reynolds number of 1.0×105 based on model diameter. It hardly varies with Reynolds number in range from 8×104 to 1.4×105. The drag coefficient of the cylinder of 4.1 fineness ratio is 0.867 at Reynolds number of 1.0×105. Contrary to the former case, it increases a little with Reynolds number in range from 5.0×104 to 1.1×105. Wake of the cylinder of 5 fineness ratio was measured with a pitot tube at 4.2 model diameters downstream at several flow speeds. The wake diameter (99% dynamic pressure ratio) is about 3 times as much as the model one in the Reynolds number range.