Date of Award

1984

Document Type

Thesis

Department

Mechanical & Aerospace Engineering

Program/Concentration

Mechanical Engineering

Committee Director

Sushil K. Chaturvedi

Committee Member

John E. Lamar

Committee Member

John M. Kulman

Call Number for Print

Special Collections; LD4331.E56G44

Abstract

An analyt1cal des1gn procedure for Lead1ng-Edge Extensions (LEE) has been developed for thick delta wings. This LFE device is des1gned to be mounted to a w1ng along the pseudo-stagnation stream surface associated w1th the attached flow design lift coeff1cient of greater than zero. The intended purpose of the device is to improve the aerodynamic performance of high subsonic and low super son1c aircraft at incidences above that of attached flow design lift coefficient, by us1ng a vortex system emanating along the leading edges of the device. The low pressure assoc1ated with these vort1ces would act on the LEE upper surface and the forward facing area of the w1ng leading edges, providing an additional lift and effective leading edge thrust recovery.

The first application of this technique was to a thick, round-edged, twisted and cambered wing of approximately triangular planform having a sweep of 58'nd aspect rat1o of 2.3. The panel aerodynamics and vortex lattice method w1th suction analogy computer codes were employed to determine the pseudo-stagnation stream surface and an optim1zed LEE planform shape, respectively.

The aerodynamic effectiveness of th1rty six different LEE planform shapes were examined for the given w1ng by cons1der1ng the influence of geometrical parameters such as chord, sweep angle and span extent. This investigation showed that the outboard reduction of the LEE span-extent minimizes the lift-to-drag ratio, regardless of the LEEs' planform-shape and area. Also, with the same planform area, it was found that constant chord is relatively more effective than LEEs having sweep angles less than that of the wing. Further, relative to the wing root chord and span, a 3.2% constant chord LEE with 89% span extent was selected as being the best candidate for the final design planform.

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DOI

10.25777/wgpb-q668

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