NACA-RM-A53J23

Abstract

INTRODUCTION <br>The potentialities of turbine-propeller propulsion systems are well recognized, particularly with regard to the take-off and range capabilities of multiengine airplanes. The combination of a turbine-propeller propulsion system and an airframe configuration utilizing a sweptback wing of high aspect ratio should make possible the achievement of long-range flight at relatively high subsonic speeds. This propulsive system could utilize supersonic propellers with high disc loadings. It is not believed that the effects of these propellers on the longitudinal characteristics of swept wings can be adequately predicted, either by existing theoretical methods or by available experimental data. <br>An investigation ha8 been made in the Ames 12-foot pressure wind tunnel to determine the longitudinal characteristics of a representative multiengine airplane configuration with sweptback wings of high aspect ratio. The investigation was made with and without operating supersonic propellers. The power-off longitudinal characteristics of several combinations of the components of this configuration have been presented in references 1 to 4. The characteristics of the propeller are reported in reference 5. The results of a low-speed investigation to determine the effects of operating propellers on the longitudinal characteristics are presented in reference 6. The present report is concerned with the effects of operating propellers on the longitudinal characteristics of the configuration at high subsonic speeds. Tests were conducted over a Mach number range of 0.60 to 0.90 at Reynolds numbers of 1,000,000 and 2,000,000. If the model is assumed to be 1/12 scale, the power conditions simulated at most test Mach numbers varied from windmilling to 5000 horsepower per engine at an altitude of 40,000 feet or to 20,000 horsepower per engine at sea level.