Ideal Lift Distributions and Flap Settings for Adaptive Tailless Aircraft

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Title: Ideal Lift Distributions and Flap Settings for Adaptive Tailless Aircraft
Author: Cusher, Aaron Anthony
Advisors: Dr. Ashok Gopalarathnam, Committee Chair
Dr. Robert T. Nagel, Committee Member
Dr. Larry M. Silverberg, Committee Member
Abstract: With ever increasing maturity in the field of subsonic aircraft design, there exists the desire to tailor the performance of an aircraft to suit specific flight conditions. This has led to several adaptive-wing approaches which seek to improve aircraft performance by changing the wing shape in flight, resulting in drag reduction. One such adaptive-wing approach that has gained considerable popularity is the use of multiple spanwise trailing-edge flaps which are used to optimally distribute the lift of the wing such that drag is minimized. Recent research has been conducted utilizing such a technique applied to an aircraft with a wing-tail configuration and discussed the need to extend these methods to tailless, or all-wing, aircraft, thereby improving design possibilities to include unconventional configurations. The current work explores tailless aircraft configurations which utilize multiple trailing-edge flaps for the purpose of wing adaptation and drag reduction. As with all tailless aircraft design, the trailing-edge flap settings, and thus wing lift distribution, must be solved while satisfying a longitudinal-pitching-moment constraint in order to ensure longitudinal stability and trim. This is due to the lack of a secondary horizontal surface, such as a tail or canard, which is typically used for stability and trim purposes. The current work implements a numerical approach which was developed to solve for the optimal flap scheduling of a wing with multiple trailing-edge flaps for various flight conditions. Theory presented by R.T. Jones was used as a starting point to solve for the target lift distribution resulting in minimized induced drag with a pitching moment constraint. Also utilized were the ideas of basic and additional lift, as well as thin airfoil theory relations in order to reduce both induced and profile drag by the redistribution of wing lift along its span. The cases were solved with longitudinal trim and lift constraints. The results were presented for planar, tapered wings with multiple quarter-chord sweep angles as well as multiple airfoil sections in order to verify the theory and gain insight into design capabilities and trends. It has been shown by these results that such adaptive wing methods are applicable and beneficial to tailless aircraft configurations, as reductions in both induced and profile drag have been achieved. In addition, the method is successful for achieving longitudinal trim, and was explored successfully for multiple static margins in order to test the consequence of different longitudinal stability considerations.
Date: 2006-01-11
Degree: MS
Discipline: Aerospace Engineering
URI: http://www.lib.ncsu.edu/resolver/1840.16/1803


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