Computer methods for the preliminary design and operational optimisation of twin engine propeller driven aircraft

Twin engined propeller driven commuter aircraft pose particular challenges in their design as well as in their operation. This thesis examines both aspects through computer techniques geared specifically towards such aircraft. A program (GATEP, General Aviation Twin Engine Propeller driven) is developed to assist in the preliminary design phase. It is utilised to compare the characteristics of individual designs, conduct parametric studies around a baseline design, and estimate potential improvements. The mass, aerodynamics, and vital performance items are calculated, with particular attention focused on characteristics critical to this type of aircraft, such as the Balanced Field Length and Second Segment Climb Gradient. Studies are presented showing the applicability of GATEP to a typical commuter design. The operational optimisation of propeller driven commuters is addressed through SCOPE (Short haul Commuter Optimum Profile Evaluation), a program designed to determine optimum flight profiles for the short stage routes along which these aircraft operate. Multivariate Optimisation (M.V.O.) techniques are used to analyse the entire flight. The climb and descent segments are shown to be particularly important, and the methods used are applicable to common flying techniques (without requiring an autopilot). Flight profile optimisation has been previously treated as a mathematical exercise in relation to large jet aircraft. SCOPE uniquely offers a method for studying propeller driven types, and places emphasis on realistic operating techniques including Air Traffic Control constraints.