Enhancing aerodynamic performance estimation in small aircraft development using object-oriented technique

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Air transportation is expected to play a major role in global transportation systems in the future. A third world country like Ghana needs to prepare to leapfrog into the era of small aircraft in air transportation. As such, small aircraft design has to be approached in such a way as to derive optimum performance for any configuration that may be developed for given mission. Estimation of the aerodynamic forces developed by aircraft configuration forms a significant and challenging part of the design process. In practice, the aerodynamic performance is estimated from the coefficients obtained from the chosen wing profile. However, it can be envisioned that every section of the configuration could contribute to the aerodynamic forces. The goal of this work is to develop a technique or method that takes into account the contribution of all sections of the configuration with the aim of improving the accuracy of the evaluation of the aircraft performance. The concept of the research is built on object oriented technique such that an object is defined as a function that accepts an input and results in an output. The input parameters comprise of two components, namely, fixed and design parameters. The output gives the geometry and performance characteristics of the aircraft. The performance is modelled as integral function over the surface and results in determination of Lift and Drag forces. The design parameters are used in creating the geometry such that with given set of parameters, unique and specific class of aircraft would be developed. The developed system and tools were validated and found to be satisfactory. The lift performance of models with same wing profile indicated that fuselage components also contributed toward the overall lift force. The total lift and drag estimates of an aircraft using the developed system is more accurate than using estimates from the wing alone. Further, results of the research show that for design of small aircraft, drag performance is optimum at angle of attack between 2o and 4o. Also, performance study shows that luggage cabin object significantly influences the drag performance such that, shorter portions perform better. It is recommended that the influence of the luggage cabin as observed be validated experimentally.
A thesis submitted to the Department of Mechanical Engineering, Kwame Nkrumah University of Science and Technology, Kumasi in partial fulfillment of the requirements for the Degree of DOCTOR OF PHILOSOPHY