PERFORMANCE AND LOAD-RANGE CHARACTERISTICS OF TU1780JEl

In order to determine the optimum combination of compressor pressure ratio and turbine-inlet temperature on the basis of load range for flight speeds in the transonic range, an analysis was made of the performance and the load-range characteristics of the turbojet engine for flight speeds from 500 to 800 miles per hour,,altitudes from 10,000 to 70,000 feet, compressor pressure ratios from 2 to 30, and turbine-inlet temperatures of 1700°, 2000°, and 2300 ° R. The values of the lift-drag and structure- to-gross-weight ratios of the aircraft and the efficiencies of the engine components assumed for this analysis are representative of the _bestvalues obtained either in practice or in laboratory investigations. The variation, with flight conditions and engine operating variables, of the thrustper square foot of engine frontal area, specific weight, thrust specific fuel consumption,ultimate range, and range with pay load are discussed. The following results were obtained for the case of a sub-merged engine installation: Maximum, or near maximum, ultimate range was attained at any of the flight conditions investigated with a compressor pressure ratio of about 8 to 10. For all ‘speedsinvestigated at altitudes of 10,000 and 30,000 feet, and for speeds up to 700 miles per hour at 50,000 feet, the variation of ultimate range with turbine-inlet temperature within the temperature range investigatedwas about 5 percent or less, with a temperature of 1700 ° R giving the longest range at the lower speeds and altitudes. At an altitude of 50,000 feet and a speed of 800 miles per hour, and at all,speeds investigated at 70,000 feet, a turbine-inlet temperature of 2300 ° R gave a 10 to 30 percent longer range than the temperature of 1700 ° R and a 4 to 10 percent longer range than the temperature of 2000 ° R.