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KDaniels
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Date: 3-7-2015
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Number of Hours: 6.50
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Manual Reference: None
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Brief Description: Trim Tab Control Fairings
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First Modification.
The plans call for the trim tab control push/pull cable to extend through an opening in the bottom elevator skin and connect to the trim tab control horn via a clevis. The result is functional, easily inspected (both good), draggy and ugly, So I decided to try constructing a pair of fairings that would at least partially enclose the exosted portions of the trim controls.
A layout of the controll system showed that a fairing that stays outside of a line extending from the front of the elevator skin opening at an angle of 17.5 degrees, and then curving into streamline would provide clearance for the control mechanism. A line extending at an angle of 60 degrees from the trailing edge of the elevator intersects the clevis when the trim tab is in its neutral position, and this establishes the rear extenr of the fairing.
With the geometry established, I made up a couple of wood forms to help maintain control over the shape, and made up a paper form to use as a pattern for cutting the alluminium. I included an allowance of 3/4 inch for a flange.
The fairing is constructed using 0.032" 5052-H2 aluminium alloy.
I used one wood form to establish the radius and width of the fairing, and a second form to work down the flange and make a 1/4 radius between the fairong and the flange.
The most difficult part prooved to be establishing the curvature of the rear of the flange. In order to curve the faring to stream-line, the metal must be shrunk . My efforts were only partially successful - but I did get some curvature - without mauling the mettal. The result of the day's work is shown in Image 3 - two fairings roughly shaped, and ready for final fitting.
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Right Fairing - test fit
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Right Fairing - flange trimmed to 5/8"
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Left and Right Fairings -- ready for final fitting
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