Some results of preliminary investigations of N.A.L. transonic wind-tunnel test-section were described. Tests have been carried out with the use of a 9 percent scale model of the tunnel. Mach number distributions along the axis and on the walls of the nozzles were shown. Using the combinatons of a convergent divergent nozzle and a perforated wall test-section, acceptably uniform Mach number distribution over the Mach number range from 1.0 to 1.4 were obtained. Gurves for mass-flow removal of air-vs. Macn number were presented. Pressure ratios of the main copressor required for starting the tunnel at various Mach numbers were also invetigated.