A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Engineering
Johannesburg, September 2016 / The work in this dissertation presents the analysis of developing a novel means of flight trajectory alteration of a civil aircraft. Piezoelectric actuators have been advancing in the aerospace industry with uses in structural, vibrational and sensing applications. However, they have not been considered as a primary control method like an elevator, aileron and rudder. The analysis performed in this research involved developing an actuation model which is designed such that various changes in flight trajectory are brought about. The analysis began by building a base rigid aircraft model, where other analyses were appended to. The rigid aircraft model was developed using the aerodynamics of both Roskam (2001) and DATCOM. The DATCOM model was found to compensate for additional aircraft positions outside the flight envelope, whereas Roskam (2001) did not adequately provide the aerodynamics for when the aircraft would experience stall conditions, for example. The research then lead into developing the piezoelectric actuation model. This involved utilizing piezoelectric actuators on the wing of the aircraft, which was set to create vertical and twisting deformations, without altering the wing’s camber. Two novel methods of actuation are discussed. A wing - twist mode which consisted of three types of actuation, viz. linear twist, inverse linear twist, and linear twist symmetric. The second was the bending mode which altered the aircraft’s dihedral, and consisted of two types of actuation, viz. linear bending and linear bending symmetric. Effects of these two modes on the aerodynamics were depicted. Added to the overall model was the analysis of elastic aerodynamic effects. This was conducted by performing vibrational analysis on the individual components of the aircraft, viz. wing, horizontal tail and vertical tail. The results found that the elastic aerodynamic effects on the rigid model were significant only in lift. The rest were not significant because of the high frequency of the beams under consideration. Conclusively, the novel actuation methodology developed in this research yielded results demonstrating the viability of it being used above conventional methods such as elevator, rudder and ailerons. This was found by noting that various trajectory alterations were perceived without input from the conventional actuation methods. Increase in the rotational motions, as well as the translational motion was found, but did not cause any dynamic instabilities in the aircraft model. Thus, the actuation model was seen to operate well above the conventional methods, and situation specific uses were described for the actuation modes. These include uses in take-off and landing, cruise optimization and coordinated turns. / MT2017
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/22445 |
| Date | January 2016 |
| Creators | Keeka, Hemansu |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | Online resource (xiv, 116 leaves), application/pdf |
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