Wind-tunnel investigation of the NACA 654-421 airfoil section with a double slotted flap and boundary layer control by suction

Report presenting an investigation in the two-dimensional low-turbulence tunnel to find the effects of boundary-layer control on the aerodynamic characteristics of the NACA 65(sub 4)-421 airfoil section with a boundary-layer-control suction slot at 0.45 airfoil chord and a 0.32-airfoil-chord double slotted flap. The airfoil is designed primarily to obtain a high maximum lift coefficient. Results regarding lift and drag characteristics are provided.