The purpose of this study was to extend the analysis methods in PACELAB APD 3.1, a recent commercially available aircraft preliminary design tool with potential for MDO applications, for higher fidelity with physics-based instead of empirical methods and to enable the analysis of nonconventional aircraft configurations. The implementation of these methods was first validated against both existing models and wind tunnel data. Then, the original and extended PACELAB APD versions were used to perform minimum-fuel optimizations for both a traditional cantilever and strut-braced wing aircraft for a medium-range regional transport mission similar to that of a 737-type aircraft, with a minimum range of 3,115 nm and a cruise Mach number of 0.78. The aerodynamics, engine size / weight estimation and structural modules were heavily modified and extended to accomplish this. Comparisons to results for the same mission generated with FLOPS and VT MDO are also discussed. For the strut-braced configuration, large fuel savings on the order of 37% over the baseline 737-800 aircraft are predicted, while for the cantilever aircraft savings of 10-30% are predicted depending on whether the default or VT methods are utilized in the PACELAB analysis. This demonstrates the potential of the strut-braced configuration for reducing fuel costs, as well as the benefit of MDO in the aircraft conceptual design process. For the cantilever aircraft, FLOPS and VT MDO predict fuel savings of 8% and 23%, respectively. VT MDO predicts a fuel savings of 28% for the strut-braced aircraft over the baseline. / Master of Science

This report focuses on the utilisation of flight mechanics in the context of aircraftconceptual design to assess stability, control, and motion characteristics. The pri-mary objective is to acquire the equations of motion and implement longitudinalstability and control criteria using Pacelab Aircraft Preliminary Design 8.1, a com-mercial software tool. The equations and criteria employed in this study are derivedfrom an extensive review of relevant literature.By incorporating a dedicated Flight Mechanics chapter within the software, it be-comes possible to evaluate aircraft concepts under varying conditions. To ensureaccuracy and validity, DATCOM+ and OpenVSP were employed for testing andverification purposes.The key aspects covered in this report include flight mechanics, its implementationin Pacelab APD 8.1, determination of aerodynamic derivatives, formulation of equa-tions of motion, and their application to the B747 aircraft model. The emphasis liesin assessing longitudinal stability and control, including specific characteristics suchas the phugoid and short period modes.This report provides valuable insights into the integration of flight mechanics withinthe Pacelab APD 8.1 software for aircraft conceptual design. The results contributeto a better understanding of stability and control parameters and their impact onaircraft performance.