POWERPLANTS FOR VTOL AIRCRAFT:PERFORMANCE CALCULATIONS FOR SEVERAL HYPOTHETICAL TURBOFAN ENGINES

摘要

Calculated performance data are presented in tabular form for a wide range of altitudes, forward speeds, and engine speeds, for four hypothetical aft-turbofan engines, of bypass ratios 0, 1.39, 3.13, and 8.24. These performance data are used along with weight estimates to illustrate the application of turbofan engines to a typical VTOL mission. It is shown that on the basis of powerplant system weight (engine plus fuel), the highest bypass cycle Is clearly superior. The high bypass cycles suffer from a tendency of the fan to over speed at high forward speeds, so that the gas generator must be throttled back considerably. The high level of installed thrust means that the thrust reduction accompanying throttling is no problem, except insofar as it adversely affects the specific fuel consumption.