Aerodynamic properties of an arrow: Influence of point shape on the boundary layer transition

Using two high-speed video cameras, we recorded the trajectory of an arrow (archery and crossbow) and analyzed its velocity decay rate, from which we determined the drag coefficient. In order to investigate Re number dependence of the drag coefficient, we developed a new arrow-shooting system using compressed air as a power source, which enabled us to launch an arrow at an arbitrary velocity (up to 60m/sec). We attached three points of different type (streamlined, bullet and bluff bodied) to the arrow-nose. The boundary layer is laminar for the streamlined point and turbulent for other points, in the measured Re-range (0.78 × 106 < Re < 1.65 × 106). These results are consistent with those from support-free wind tunnel measurements using JAXA's 60 cm Magnetic Suspension and Balance System (MSBS), confirming that the point-shape has a crucial effect on the laminar-turbulent transition of the boundary layer.