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This study reports aerodynamic properties of two runback ice shapes molded from a mid-span full scale B737 aerofoil leading edge together with a series of simplistic ice shapes of the type sometimes used by aircraft manufacturers to mimic performance loss due to runback ice. The runback ice shapes were taken from a study of runback ice growth which had produced flexible silicone rubber moulds. These moulds were used to produce ice shapes without curvature which, together with the “simplistic” shapes were mounted on flat plates and installed into the Cranfield University 8 by 6 foot wind tunnel. A boundary layer suction system was used to match the wall conditions more closely to what would be anticipated on a real aerofoil. The icing conditions approximate to a hold case with the two shapes representing a 4 and a 10 mm thick runback shape. The aerodynamic tests have been performed with a tunnel speed of 45 m/s.

This paper describes a computer code for conceptual design of mission optimized twin-turboprop Commuter or Regional aircraft. Optimum configurations and flight profiles of such aircraft are determined by coupling this code to an optimization code based on Simulated Annealing. As an example, minimum DOC configurations were determined for 50-seat Regional aircraft for operation over three stage lengths. The DOC per seat-nm and DOC per trip of the optimum aircraft were found to be comparable or significantly (8 to 17 %) lower than the corresponding values for five contemporary 40 to 50 seater aircraft for short stage lengths.