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Dave's RV-7A Builder's Log
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Date:  2-3-2018
Number of Hours:  6.00
Manual Reference:  
Brief Description:  Gear fairings

Today’s task was to get the gear leg fairings installed and a test flight completed. The addition of the wheel pants added about 6 knots to the top speed, so I was hopeful to get about that much more out of the gear fairings. Spoiler alert—I got about 7 more knots, at least for a bit…more on that in a second. The first part of the process is to install hinges along the trailing edges to provide a method of securing the fairings on the gear leg. The process is pretty standard with drilling, countersinking, riveting, etc., but care must be taken not to induce a twist while working along the edge. With the hinges installed, you then put the fairing on the gear leg and put the pin in to secure the trailing edge…works very well.

The primary challenge with installing the gear fairings is to get them aligned properly with the airflow to prevent them from generating lift in either direction (which translates to yaw based on their location) so after installing the hinges along the aft edge, the builder must avoid the temptation to eyeball them or use the TLAR method of alignment. This can involve the use of laser levels and other high tech methods, but in my case I resorted to the stone age technology of string. First measure a point on the forward edge of the fairing, move to a location exactly parallel to the centerline and level with the fairing, and run a string around the assembly. Once everything is set, adjust the trailing edge to be centered in the strings and clamp in place. This whole process is documented in a confusing page in the builder’s manual. Two quick pictures explain it much more effectively.

The test flight was promising, I attained 165 KTAS at 8,000’, but in a descent to try a speed run at 3,000’, the right fairing came loose from the clamp and there was a noticeable (and startling) change in the handling and speed. Erring on the side of caution, I elected to return to base and once on the ground found out what had happened. Shouldn’t be too much work to fix during the next session.
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Lining up the strings

Lining up the strings

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Centering the fairing

Centering the fairing

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Off to test

Off to test

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