Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.553294
Title: Dynamics and performance of flying discs
Author: Kamaruddin, Noorfazreena Mohammad
Awarding Body: University of Manchester
Current Institution: University of Manchester
Date of Award: 2011
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Abstract:
The study of dynamics and performance of flying discs is motivated by how variations in their design features influence the aerodynamic characteristics and flight performance, particularly range. Reviews in the literature focus on the development of fundamental research in flying discs and on the performance of sports projectiles. Theoretical background on disc dynamics, range and sensitivity are given. This work investigates disc aerodynamics by performing wind tunnel experiments to measure aerodynamic loads on a set of generic parametric discs and a set of commercial golf discs. The parametric discs isolate various geometrical features such as thicknesses, cavities, leading edge curvatures and cambers to study the influence of these parameters on aerodynamic characteristics. The commercial golf discs consist of three different categories known as putter, mid-range and driver: these discs are used for short, medium and long flight range, respectively. To study the performance, aerodynamic data of the golf discs are used as inputs in numerical simulations to predict their flight trajectories and range. Effects of launch attitude on range are assessed to study the optimal initial launch conditions to achieve maximum range. Further, the simulation provides a direct approach to analyse range sensitivity on launch parameters. Results from the experiments show a number of significant findings on disc geometry. First, a cavity is fundamentally important for a disc to have satisfactory flying qualities: the presence of the cavity produces a significant aft shift in the aerodynamic position to minimize the pitching moment about the centre of the disc. Hence, the disc will have a minimal tendency to roll about the flight axis. Second, the thickness of a disc has a significant effect on its profile drag: increasing the thickness increases the profile drag. Third, a disc with a positive camber produces a relatively higher lift-to-drag ratio (CL/CD) compared to one with no camber. Fourth, the effect of tapering a flat leading or trailing edge of a disc leads to a reduction in its lift (within the angles of attack tested in the study) with a significant reduction in its drag. Fifth, it is shown that peak lift-to-drag ratio of a free flying disc is not necessarily a good indicator of performance because the angle of attack (and hence, lift-to-drag ratio) varies widely through a typical flight. Furthermore, a disc with a significant pitching moment will roll significantly about the flight path direction, further reducing the achievable range for a given lift or drag characteristic. Finally, a novel method to quantify disc sensitivity with respect to changes in launch conditions has been developed. The simulations show that the range sensitivity of each disc with respect to launch pitch angle varies significantly, with discs design for long range being much more sensitive (and therefore harder to throw accurately) than discs designed for short range.
Supervisor: Crowther, William Sponsor: Universiti Sains Malaysia ; Ministry of Higher Education Malaysia
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.553294  DOI: Not available
Keywords: flying discs aerodynamics ; golf discs ; disc simulation ; disc range ; disc performance
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