A research report submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science in Engineering by course work and research project. Johannesburg, May 2016 / The design of a conceptual aircraft was required to fulfil the recreational and commercial flight training roles as part of a rural development initiative. The regulations regarding the airworthiness of aircraft and the South African microlight and ultralight aircraft market were investigated to determine the niche performance requirements. The large sales enjoyed by the new Light Sport Aircraft (LSA) category created an opportunity to design an aircraft conforming to both the non-prescriptive ultralight and prescriptive LSA consensus standards. This would allow the aircraft be used in several countries. The best practices regarding design for manufacture used in industry were investigated to create a framework of consideration for the detailed design of the aircraft. The performance of the market leading ultralight and LSA was analysed. The Cessna C-162 Skycatcher and Tecnam P-92 were investigated as the main competitors. Flight speed, payload, structural efficiency and aerodynamic efficiency were analysed to set target performance requirements. The aircraft was required to have a minimum power utilisation of 1.05kt/hp, minimum useful load of 250kg and a minimum cruise speed of 110kts. The aircraft was constrained to a 100hp engine. These performance user requirements were used with cost, environmental and operational requirements to design a high-level concept. The concept was developed so that each major system on the aircraft had been designed to create a complete concept. The method used to develop several concepts for several systems and assess them against the user requirements was developed from the dialectic engine principle of destruction and creation. This process was performed simultaneously. The systems were broken into basic principles and components before being creatively integrated into improved systems. Three design features were generated and patented. The designs included a propeller spinner that assisted with air induction for better cooling, a winglet to assist with breakdown of wake vortices and an excrescence free flap system for a light aircraft. The only design used on this aircraft was the flap system. The aircraft concept was further refined using the same destruction and creation synthesis technique. The concept aircraft was the subject of a detailed business plan and launch strategy that would use the aircraft to leverage funding to start a new industry in the Eastern Cape province. The performance of the aircraft concept was calculated using standard performance techniques that were modified for use, based on experience with other light aircraft. The major emphasis was on the energy available to accelerate, climb and turn. The method developed to analyse a descending turn without power was used to demonstrate that the aircraft could manoeuvre better than the competitors at low power settings. The energy levels needed to surpass the competition were used to design an aircraft with a significant energy margin at speeds of 65-85KCAS, making the aircraft ideal for flight training. The aircraft was designed with a higher aspect ratio and lower wing loading than the competitors to achieve better energy levels and better performance in hot and high conditions. The reduction in maximum speed was not significant when compared to the turn and manoeuvre performance. The structure of the aircraft was then designed to withstand the loads prescribed by the consensus standards. The aircraft was shown to comply with the standards. The completion of the structural design of the major components allowed for the design to be costed. The business plan was revised to include the cost of the manufacturing facility and total investment cost required to realise the project. The proposer of the project funded a full-size mock-up of the aircraft that was launched at a major airshow. The regulatory framework of regulations and technical standards was extensively revised, making the process of obtaining production-built type approval for a design less onerous. Recommendations for structural testing and transient energy analysis were made. / MT2016

Advances in computational power have produced great strides in the later design and production portions of an aircraft s life cycle, and these advances have included the internal layout component of the design and manufacturing process. However, conceptual and preliminary design tools for internal layout remain primarily based on historical regressions and estimations a situation that becomes untenable when considering revolutionary designs or component technologies. Bringing internal layout information forward in the design process can encourage the same level of benefits enjoyed by other disciplines as advances in aerodynamics, structures and other fields propagate forward in the design of complex systems. Accurate prediction of the volume required to contain all of an aircraft s internal components results in a more accurate prediction of aircraft specifications, mission effectiveness, and costs, helping determine if an aircraft is the best choice for continued development. This is not a computationally simple problem, however, and great care must be taken to ensure the efficiency of any proposed solution. Any solution must also address the uncertainty inherent in describing internal components early in the design process. Implementing a methodology that applies notions of an intelligent search for a solution, as well as deals robustly with component sizing, produces a high chance of success. Development of a robust, rapid method for assessing the volumetric characteristics of an aircraft in the context of the conceptual and preliminary design processes can offer many of the benefits of a complete internal layout without the immense assignment of resources typical in the detail phase of the design process. A simplified methodology for volumetrically sizing an aircraft is presented here as well as an assessment of the state-of-the-art techniques for volumetric considerations used in current aircraft design literature. A prototype tool using a combination of original code and publicly available libraries is developed and explored. A sample aircraft design is undertaken with the prototype tool to demonstrate the effectiveness of the methodology.

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The purpose of this paper is to describe the mechanization of the basic equations of motion for the performance and maneuver characteristics of an airplane with some simplifications which render solutions more practicable. The results of a study made to program these equations for calculation by the IBM MODEL 650 digital computer are presented as well as the steps to be taken in using this method of calculation.

Time-averaged properties of a wing-body-junction flow surrounding a cylindrical wing with a 1.5:1 elliptical nose and a NACA 0020 tail have been compared to those for the above wing with a 1.5 inch radius fillet normal to the wing's surface. An attempt was made to determine the effectiveness of the fillet in improving the uniformity of the wing-body junction flow downstream of the wing, and in attenuating the junction vortex. Measurements included oil-flow visualizations and surface-static-pressure measurements of the flattest floor surrounding the wings, and hot-wire anemometer measurements made in the flow downstream of the wing. Calculations of the drag and the volumetric entrainment of free-stream fluid due to the presence of the baseline wing and wing with fillet were performed. The results of these calculations are important criteria used to determine the effectiveness of the fillet as a flow control device. Results show that the vortex is present in each case, and its size is slightly larger for the wing with fillet as compared to the baseline wing. For each test case, the drag and volumetric entrainment of free-stream fluid were the nearly same for the wing with fillet as compared to the baseline wing. It was also found that increases in the boundary-layer thickness cause only small increases in the size of the junction vortex. The 1.5 inch radius fillet does not appear to be a viable flow control device. / Master of Science