AIRCRAFT FUEL ECONOMY -- THE PROPULSION SYSTEM CONTRIBUTION

This paper examines the possible contribution of the propulsion system to the fuel economy of executive/computer type aircraft. A review of engine and component performance as currently demonstrated in North American production aircraft was made to establish a base line 1977 technology. Using these data four 1977 engines were synthesized, large and small turboprops (2000 SHP & 1000 SHP) and large and small turbofans (4500 lb & 2000 lb thrust). Using projections of technology improvements, equivalent 1987 production engines were synthesized. This showed that a 1%-19% reduction in cruise specific fuel consumption could be expected for this class of engine over the next 10 years. To examine the effect of engine performance on aircraft mission capabilities, two pairs of aircraft were designed -- turboprop and turbofan powered, using 1977 and 1987 engines, but constant 1977 airframe technology. Reduction in specific fuel consumption and specific weight results in reduction aircraft weight for the same mission with further reduction in fuel flow, from 17% for the larger turbofan aircraft to 21% for the larger turboprop.