Tuesday, June 30, 2015

The Eagle Grows Some Tail Feathers

The first order of business today was finishing the last cut on the F-1294B lower tailcone fairing. Was able to make the two necessary cuts outside with the Dremel outfitted with a cutting wheel just prior to the afternoon monsoons setting in.
Masking tape was used to mark the cut line where the slot will be extended.
The slot cut in the F-1294B lower tailcone fairing is now completed.

It is easy to see why Van’s has the builder hold off cutting the slot longer until last …. the fairing becomes VERY flexible after completing the cuts. At this point the upper and lower F-1294A&B fairings are to be screwed together and test fit with the rudder installed and clearances verified.

Being somewhat impatient and wanting to move things along, decided to permanently mount the RV-12’s vertical stabilizer and rudder at this point. I was hoping to finish off working on the tip fairings prior to mounting the vertical stabilizer and rudder, but the epoxy and fiberglass materials have not arrived yet … so will need to finish that task standing on a ladder.
Déjà vu … mounting the vertical stabilizer onto the tailcone, this time for good.

After the vertical stabilizer was installed and bolts torqued the rudder was installed. By utilizing the piece of vinyl tubing and wire tie trick to hold the bolt while inserting it into the tight area on the rudder, was able to control the bolt and get all the washers inserted.
Using the vinyl tube and wire tie to insert a bolt into the upper hinge bracket.
Close-up of the vinyl tube and wire tie used to grip the bolt as it is inserted into the upper hinge bracket … (taken before rearranging the washers.

However, after getting it all together, was not totally happy with the clearances on the upper mounting point of the WD-1205 rudder horn where it meets the lower hinge bracket. So removed the rudder and added an additional thin washer to the upper hinge bracket to effectively increase the clearance on the lower assembly by raising the rudder assembly by the thickness of one thin washer … which worked out perfectly.

During the final tightening of the rudder bolts, the lower hinge bracket bolt is easy to get to, however, the upper bracket is another story. Not wanting to only get a fraction of a turn on the bolt, decide to try putting a couple of extensions together and tighten the bolt from up above. This worked great for both tightening and using the torque wrench for final torquing. Of course, if the tip fairing were riveted on at this point in time, this would not have been an option.
Using a ratchet wrench and two extensions to snug down the bolt on the upper hinge bracket from above … this did work quite well.

Once the rudder was permanently installed, the tailcone fairing assembly was paced back onto the tailcone and positioned on the forward edge line on the masking tape. A check is to be made to insure that there is at least 1/8" of clearance between the bottom of the rudder and the F-1294 tailcone fairing assembly … which is exactly what there was.
Using a 1/8" piece of metal to measure the gap between the rudder and the F-1294 tailcone fairing assembly …. it is perfect.

The next step will be to drill the faring assembly to the tailcone and mount nutplates at the screw hole locations.

Monday, June 29, 2015

Work Continues On F-1294A&B Tailcone Fairings

Must say, the F-1294A&B tailcone fairings are beginning to turn into a time sucking abyss. This has become one of those tasks that, although not hard, has seemingly taken far longer than expected to accomplish.

The first task of the day was to enlarge the #40 holes drilled yesterday in the F-1294A upper fairing. The plans call for taking a #27 drill bit and purposely destroy the cutting edge by drilling a 1/8" hole into concrete to create a “modified” #27 drill bit.  Yes, you read that right … drill concrete with the drill bit before using it. Sounds easy enough right?  Well I’m here to tell you I could not get the drill bit to go much farther than 1/16", even tried a couple of spots … the hangar’s concrete floor is seemingly diamond hard. My best guess is that the whole point of using the “Modified” drill bit is so it does not shred the fiberglass or try to dig into the fiberglass to rapidly.

The modified #27 drill bit is to be used to enlarge the #40 holes in the F-1296A upper tailcone fairing and on into the F-1294C tabs. The reality of it is, I was able to easily drill through the fiberglass but the drill bit was so dull it just would not penetrate the F-1294C tab even with quite a bit of pressure applied. So I changed gears and just used the "modified" #27 drill bit to drill through the fiberglass and moved onto the next hole. After all the #40 holes in the fiberglass were drilled with the modified bit, the modified drill bit was exchanged for a normal #27 bit and the #40 holes in the F-1294C tabs were easily enlarged to #27.
Using the “modified” #27 drill bit to enlarge the #40 hole in the F-1294A upper tailcone fairing.

At this point, the instructions have the builder remove all the F-1294C tabs and rivet nutplates onto the tabs.
Using the pneumatic rivet squeezer to rivet a nutplate onto one of the F-1294C tabs.

After the nutplates are installed, the tabs are Clecoed back in position on the F-1294B fairing and the F-1294A upper fairing is now screwed in place. (A bunch of washers were placed on the screws so they could be tightened without needing to be screwed in a mile deep).  After the upper faring is screwed in place the plans have the builder mark and create a gap 1/32” to 1/16” between the F-1294A&B tailcone fairings. This became a little time consuming because I actually had the fairings sitting tightly together so had to slowly create the required gap by sanding , testing the fit then … repeat … repeat, etc.
The F-1294A&B tailcone fairings screwed together and the required gap has been established.

After the required gap is acceptable, the two rivet holes in the F-1294B lower fairing that secure the F-1294C tabs require countersinking for flush AN426AD3-3.5 rivets. When riveting the F-1294C tabs onto the F-1294B lower fairing it is preferable to not set the rivets fully so the fiberglass does not get crushed.
Using the machine countersink cage outfitted with a #40-100 degree bit to countersink the rivet holes in the F-1294B fiberglass fairing.
Riveting the F-1294C tabs onto the F-1294B lower fairing with AN426AD3-3.5 rivets.
All F-1294C tabs riveted in place. Note one can easily see the rivets my finger is pointing towards are not fully set when compared to the rivets above them securing the nutplate. This is OK when riveting fiberglass, as it helps keep the integrity of the fiberglass.

The next step (other than permanently mounting the fairings) is to enlarge the slot in the fairing. However, it was pouring outside and not wanting to make the necessary cuts inside the hangar, will complete this task during the next work session.

Sunday, June 28, 2015

F-1296A&B Tailcone Fairings Match Drilled

A very short work session yielded very good progress on the F-1296A&B tailcone fairings. After the initial trial fitting done during the last work session the plans instruct the builder to install the eight F-1294C tabs. Installing the eight tabs is a multi-step process beginning with temporarily clamping the F-1294C tabs onto the outside of the F-1296B lower tailcone fairing. Once the tab is clamped in position, the two rivet holes in the F-1296C tabs are matched drilled into the F-1296B lower tailcone fairing. There are no set locations given for positioning the tabs … other than placing two tabs adjacent to each of the mating surfaces. However, that said, there is a notch on each side of the tab and the notches need to be placed centered over the edge of the fiberglass. I chose to position the tabs 1/2" in from the edges and sides except for the two tabs on the top on either side of the slot … there I chose 1/8" in from the edges.
Using the two lower holes in the F-1296C tabs to match drill the F-1296B lower tailcone fairing with a #40 drill.
Finished match drilling the bottom holes of all eight F-1296C tabs into the F-1296B lower tailcone fairing. Note how the notches in each of the tabs are centered on the edge of the fiberglass.

Next the F-1296A upper tailcone fairing is set in place with the tabs still on the outside of the F-1296B lower tailcone fairing. The upper fairing is clamped to some of the tabs and the center hole in each tab is used to match drill the F-1296A upper tailcone fairing.
With the eight F-1294C tabs still on the outside of the lower tailcone fairing, the F-1296A upper tailcone fairing is clamped in position for drilling.
The center hole in the F-1294C tab is used to match drill the F-1296A upper tailcone fairing with a #40 drill . These holes  will be enlarged later and become holes for the mounting screws.

After all eight of the center holes in the F-1294C tabs are match drilled into the F-1296A upper tailcone fairing, the tabs are removed and the holes cleaned up. The tabs are installed again ... but this time they are secured with Clecos to the inside of the  F-1296B lower tailcone fairing.

All the holes have been cleaned up and the F-1294C tabs moved to the inside of the F-1296B lower tailcone fairing so the F-1296A upper tailcone fairing can be secured with Clecos. Note the tabs are now inside the fairing pieces.

This is where I stopped for the evening. Next the center holes just drilled are to be drilled out to #27 with a drill bit that has been purposely dulled by drilling into concrete. I have already countersunk the nutplate holes on the tabs prior to priming, so after the nutplates are installed the tabs can be riveted in place after the rivet holes in the F-1296B lower tailcone fairing have been countersunk ... something to look forward to during the next work session.

Saturday, June 27, 2015

Preparing F-1294A&B Tailcone Fairings For Drilling

The morning rains subsided during the afternoon which made it possible to cut and trim the F-1294A&B upper and lower tailcone fairings outside ... so as not to get fiberglass dust all over everything in the hangar. In addition, a little cutting was performed on the vertical stabilizer’s fairing as well.

Bolted up the rudder to the vertical stabilizer and checked the clearances between the VS-1213 stabilizer tip fairing and the R-1206 rudder tip fairing. Holding the upper bolt while inserting it into the bearing can be tough because there is not much room for fingers in the small opening on the rudder. A tactic I came up with that fellow builders can use to place bolts into tight places is to use a small piece of vinyl tubing with a long wire tie to grab and hold the bolt. When the bolt is inserted into the destination the wire tie can be pushed back through the tubing freeing the bolt.
A wire tie looped through a piece of vinyl tubing does a great job of allowing a bolt to be held while being inserted into a location too tight for fingers to easily maneuver.
Using the previously mentioned vinyl tubing & wire tie to hold a bolt so it can be inserted into the upper rudder bearing.

After the rudder was mated to the vertical stabilizer, the VS-1213 fairing was trimmed to the point that any tweaking will be done after the fairing is riveted in place to obtain a nice finished fit.

Moving on, the F-1294A&B upper and lower tail cone fairings needed to be cut and trimmed then sanded down to the scribe lines imbedded in the fiberglass. The Dremel outfitted with a cutoff wheel cut through the fiberglass like a hot knife through butter. Extra material was left beyond the scribe marks in the fiberglass and a Dremel with a sanding drum was used to get close to the line … hand sanding with a sanding block finished the process.

A time consuming error on my part …. typically, I make it a point to read ahead to obtain a better understanding of where things are headed.  Today was one of the rare times that I did not read ahead, and it cost me quite a bit if time. Basically, I left the upper and lower F-1294A&B fairings a little long with the exception of the forward edges that meet up with the tape lines on the tailcone. The thought was I would be able to make a fairly tight fit in the areas where the upper and lower fairings meet (and that was accomplished).

The F-1294A&B upper and lower tailcone fairings cut slightly beyond the lines so a tight fit could be (unnecessarily) achieved.

So the fairings were on and off, and on and off, quite a few times as the fit was slowly tweaked by hand sanding. After achieving, for the most part, tight fits all the way around with just a tiny gap in one area, I began reading ahead a little and came to realize all the time spent trying to achieve an O.J. Simpson glove fit was unnecessary. The plans instruct the builder to obtain a good fit, then drill the mounting tabs … after the mounting tabs are riveted in place, the areas where the two farings meet are to be filed to create a 1/32" to 1/16" uniform gap. Gee, I had that almost from the very beginning.
F-1294A&B upper and lower tailcone fairings were aligned to the red forward lines on the masking tape, then clamped and taped in place. The fairings are now ready for drilling of the mounting tabs that will secure the two halves together.