Empennage tips 5

This post covers two evening work sessions. First up – completing the vertical stabilizer tip. The tip is going to be removable, but I still wanted to fully enclose the rear. I used some foam and fiberglass. Neither are secured to the rib or skin.

I also completed the remaining sides of the rudder.

And flipped the horizontal stabilizer to do the bottoms.

Here is the completed vertical stab tip. I will clean up the edges and then use some body filler to complete the job. 

I sanded the completed areas and trimmed excess fiberglass.

Empennage Tips 4

Here is a good photo of the work from the previous session after a little sanding. I started off the work session by cleaning up the previous fiberglass work with a sanding block. I also did some filing on the elevator counterweights and associated intersections, and verified that all the clearances will be appropriate after the work is completed.

If there is one thing I learned in the first fiberglass session it’s planning. If you use fast hardener, you really need to plan your session appropriately. You’ll also want to plan carefully if you want to avoid wasting epoxy. With this in mind I decided to prepare the rudder tip and vertical stab tip. (I am not going to complete the rudder bottom until I purchase my strobe light and I have verified clearance with the tail wheel springs. Some builders have reported interference on landing)

I needed to countersink the fiberglass and dimple the rudder for the tip. First I torqued and applied loctite to the counterweight.

I don’t have a great picture, but for both the rudder and the elevator tips you are likely to have clearance issues with the pop rivets closest to the trailing edge. There are two techniques that can work here. First you can set the most visible rivet first, and then using a hand puller, slowly squeeze and apply pressure to get the rivet to set. Alternatively, you can use a different size pop rivet in this location. For the elevators I used the first method. For the rudder, it was clear that there was no way a CS4-4 rivet was going to work. I opted for a smaller rivet.

Next it was time to turn my attention to the vertical stab tip. Here is where I plan to deviate. I do not intend to fiberglass the tip of the vertical stab. I’d like to mount a camera here in the future, and as a result I want the tip to be removable. I haven’t decided how to mount the camera, or even what camera I will use, so that decision can wait.

The first step in the installation of the vertical stab tip was to measure, and trim to size.

Then it was time to drill. I drilled #30 and set the dimples for #6 screws. These are slightly smaller and I think more aesthetically appealing. Plus they use smaller holes through the fiberglass.

After dimpling, and countersinking, you can see the intended result.

Sometimes I think about taking a picture, and my mind remembers that as having actually taken a picture. I could have sworn I took a photo of the tip with the nut plates installed. But, apparently I did not. Suffice it to say, I used the appropriate nut plates and AN426AD3-3.5 rivets. You can use soft rivets or you can slightly under squeeze the hard rivets. I did the later. I’m quite happy with the results.

At this point, I turned my attention back to the fiberglass work. I was ready to do multiple fiberglass sections in one section. I would cut all of the fiberglass and prepare all of the surfaces before mixing any epoxy. While I was cutting the fiberglass the wind picked up. I looked out at the airport to realize a thunderstorm was imminent. Really imminent. No sooner then the realization dawned on me, then I saw sheets of rain at the far end of the runway. Crap! My truck window are cracked. I sprinted 25 feet to the truck and wound the windows up. In that 10 seconds the rain was upon me. In the next 10 seconds that it took me to race to close the hangar doors the wind and the rain became so torrential that more than half of the hangar as soaking wet! The wind was so strong that several unlatch end hangars were blown open, and I struggled to close and latch both doors!

Well, so much for fiberglass work. All my fiberglass was soaked, and so was much of the hangar. I did my best to dry everything up and clean up. I turned the fans on and decided to return to fiberglass in the next session.

Here you can see some of my fiberglass strips after drying for quite awhile. The back ones are still wet.

I still need to bend my custom instrument panel. To do this, I need a good, highly accurate bend line. I put the panel in place with screws and clamps and made a new bend line. I will try to get this bent courtesy of my buddy Chad this week.

Empennage Tips 3

My buddy Mike was nice enough to give me his fiberglass 101 class tonight. We walked through working with the epoxy and fiber glass to glass in the tips of the elevators and horizontal stab. I riveted the tips in place and then we got started.

The first step was preparation. Tape off, scuff with 80 grit, and clean with acetone.

Then we mixed up some flox for the counterweights. We should have done this prior to riveting the tip in place, but we were able to get plenty of flox into the area. Flox is a mixture of ground cotton and epoxy. You can mix it to different consistencies based upon the use. Because of its high epoxy content, it’s generally pretty heavy. The cotton adds structural strength. The flox we mixed for this purpose was pretty thick. It would flow but only just.

Next we measured and cut the fiberglass cloth for placement. Here you can see the dry strips at the top and a strip that has had epoxy applied at the bottom. The secret here is to fully saturate the cloth with epoxy and remove all excess epoxy. You want the absolute minimum amount of epoxy required to saturate the cloth. The general mistake made by rookies is too much epoxy.

After setting up the left elevator we got to work on the left horizontal stab. This was a two part process. We needed to bond the intersection of the fiberglass tip and the horizontal stab, and we also needed to enclose the end of the tip. To enclose the end, I used balsa wood and flox. I recommend making your balsa or foam insert go all the way to the rib. Additionally, you should consider covering the intersection of the two with fiberglass.

For the tip to horizontal stab skin intersection we used three layers of fiberglass.

We repeated the process for the right tip. In this photo you can clearly see the 90 degree fiberglass intersection of the balsa wood and end rib.

We did the right elevator as well (one side).

Here are a few photos from the next day.