Drag coefficients of cylinders of trapezoidal cross-section were obtained from the subsonic wind tunnel experiment. Four cylindrical models having different side angle(5, 10, 15, 20 degree) were tested. To determine the drag of these trapezoidal cylinders, both the balance method and the wake survey method were used. It was found that the drag coefficient of the trapezoidal cross-sectioned cylinders increases as the side angle increases in the range of $1.0×10^5＜ Re ＜ 3.0× 10^5$. It was also found that the critical Reynolds number, at which the drag starts to decrease substantially, was about $2.0×10^5~ 2.4×10^5$.
