AbstractsTransportation

The development of unconventional aircraft designs complicates the conceptual design process of aircraft. To manage this increased complexity, it can be helpful to automatize part of this process. The further development of a tool for this automation, called the Initiator, is central to this thesis. The Initiator is a modular tool for preliminary sizing and design analysis, but the currently implemented design of the vertical tail in the Initiator is very basic. The goal of this thesis is to extend the design methodology for vertical tails in the Initiator and thus to develop a rapid aerodynamic analysis method for initial vertical tail design. To achieve this goal, vertical tail design methodology for both conventional and unconventional aircraft configurations was explored. Existing methods for the initial design of vertical tails for conventional aircraft were investigated and a rapid aerodynamic analysis method for vertical tail design for lateral-directional stability and control of conventional aircraft was developed and successfully implemented. This method was validated with existing windtunnel data, and four case studies were performed to analyze the design optimization. The validation of the implemented analysis method shows generally accurate results for most parameters. The main exception to this is the estimation of the tail-off rolling moment due to sideslip. The method is shown in the case studies to match up with the data for comparable reference aircraft. The method does have a trend towards an over-prediction for larger aircraft and an under-prediction for smaller aircraft. Windtunnel tests were performed to acquire validation data for blended wing bodies. No suitable rapid analysis method was however found for blended wing body aircraft configurations. The empirical method for vertical tail design in conventional aircraft does not work well on a blended wing body; the prediction of tail-off performance was especially inaccurate. A vortex lattice method comes up short when the angles of attack and sideslip become larger than 5-10 deg. These are present in some critical cases for vertical tail design, such as crosswind during landing and one engine out at take-off. The estimation of the tail-off yawing moment due to sideslip is inaccurate for the vortex-lattice method as well.