A study was conducted of the effects of using variable-sweep wings on the ride-quality and mission-performance characteristics of commuter-type aircraft. A fixed-wing baseline vehicle and a variable-sweep version of the baseline were designed and evaluated. Both vehicles were twin-turboprop, pressurized-cabln, 30-passenger commuter aircraft with identical misslon requirements. Mission performance was calculated with and wlthout various rlde-quality constraints for several combinations of cruise altitude and stage lengths.
The variable-sweep aircraft had a gross weight of almost four percent greater than the fixed-wing baseline in order to meet the design-mission requirements. In smooth air, the variable sweep configuration flying with low sweep had a two to three percent fuel-use penalty. However, the imposition of ride-quality constraints in rough air can result in advantages ln both fuel economy and flight time for the varlable-sweep vehlcle flying wlth high sweep. (...)
The fixed-wing and variable-sweep configurations of the study were designed to meet the same mission requirements. Both vehicles carry thirty passengers, two pilots and a flight attendant. The deslgn mission is shown in figure 1. It is unrestricted except that the selected cabin-pressurization system limits the aircraft to an altltude of 25,000 ft and aircraft velocity is limited to 250 knots equivalent airspeed at altltudes of 10,000 ft or less. Required is a range of 500 n.mi., a missed-approach allowance, a subsequent climb to 5,000 ft altitude, a 50 n.mi cruise to alternate, and an allowance equivalent to a 20 minute hold thereafter.
The two configurations were constrained to have as many identical components as practically posslble in an attempt to isolate the effects of wing selection. Further, the levels of technology in the underlying disciplines were assumed to be identical.
