Tuesday, October 27, 2015

Stabilator and Rudder Fairings Finished

Builders building their RV-12 as E-LSA can disregard this post. Yesterday, tackled one of the unfinished tasks on the tail feathers which was to install the vertical stabilizer and rudder with fairings.  Back when bonding the foam block onto the canopy arm, some of the left over flox mixture was used to bond thin strips of aluminum onto the inside of the rudder and vertical stabilizer fairings. This was done because the DOG Aviation RV-12 is being built with flush rivets on the external surfaces and to keep a consistent look, the rivet holes will need to be machine countersunk to accommodate the flush rivets. Countersinking the fairings will leave the fiberglass thin so the thin strips of metal will allow the rivet to set on metal without the fear of crushing the thin fiberglass resulting from the machine countersinking.
The two thin strips of aluminum were bonded onto the inside of the rudder fairing so the rivets can set onto metal instead of thin countersunk fiberglass. Two aluminum strips were also added onto the vertical stabilizer fairing as well.

The fairings were placed onto the tail feathers and match drilled. Care was used not to push in too hard on the drill bit so the thin metal strips would remain bonded onto the fiberglass.
Match drilling the rudder fairing - carefully not pushing hard so the metal strip inside stayed bonded to the fiberglass.

After the rivet holes were drilled into the vertical stabilizer and rudder fairings, the rivet holes were machine countersunk. Because the joggle built into the fairings prevented the countersink cage from sitting flat on the fairings, the cage needed to be removed and the countersinking was done by hand. (The joggle can be seen in the first photo if looking closely). A little scary, but care was taken not to get carried away by using short spurts of the drill and low RPM’s.
Machine countersinking the rivet holes in the rudder’s fairing using a #30 120 degree countersink bit. Note the countersink cage is removed so the countersink bit could be placed square to the rivet hole.

The last remaining item prior to final assembly was to dimple the rivet holes for the vertical stabilizer fairing (the rudder was dimpled during assembly long ago). The small step stool I was using would not cut it … I did not feel comfortable holding the pneumatic rivet squeezer high above my head so searched around and Ed, a gentleman on the field who buys and restores airplanes, was kind enough to loan me his step ladder. Thanks Ed.
Standing on Ed’s step ladder while making the 120 degree dimples with the pneumatic squeezer held at eye level felt a lot more comfortable than holding it high over my head.

While dimpling the vertical stabilizer, I could not easily get square to the aft hole on each side (because the rudder was installed) so used the dimple dies that have a nail hole through the center of them that Bob Avery at Avery Tools made for me long ago. A hand rivet puller is used with these dimple dies to draw up on the nail which compresses the dies into the metal.
The custom made 1/8" 120 degree dimple dies Bob Avery made special for the DOG Aviation RV-12 project.

Although the dimple dies above have not been used regularly, they have been used successfully quite a few times to create dimples in tight places during the construction of the DOG Aviation RV-12 … they work great. Builders doing flush rivets on their RV-12 will want these dimple dies.

After the rivet holes for the vertical stabilizer’s fairing were dimpled, the fairing was secured on the stabilizer with Clecos. The fairing was sanded down until there was clearance between the rudder’s fairing and the vertical stabilizer’s fairing throughout the rudder’s full range of motion. Once happy with the clearances the vertical stabilizer’s fairing was riveted in place.
Riveting the vertical stabilizer's fairing in place using flush rivets in the place of LP4-3 rivets.
Completed instillation of the vertical stabilizer fairing and rudder fairing.