Aircraft High Bypass Fan Engine Performance

The purpose of this Technical Note is to discuss the performance characteristics of high bypass fan engines. The performance of a CF6-6 type fan engine is compared to two types of modified engines based on the CF6-6 type design. The fully modified engine has an increased bypass ratio 5.81 to 9.01 and a variable fan pressure ratio. At takeoff power the modified engine produces the rated takeoff thrust of the standard CF6-6 engine with a 32 percent improvement in thrust specific fuel consumption TSFC and a turbine inlet temperature 460 deg F lower than the standard. At maximum continuous cruise power at 35000 feet and Mn 0.8 the improvement in TSFC would be 18.8 percent and the turbine inlet temperature would be 270 deg F lower than the standard CF6-6 engine. The advantage in performance obtained by the increased bypass ratio and variable geometry fan more than offset the increase in the engine weight that would result from these changes. Fan engine performance, Variable geometry fans, High bypass engines.