Fuselage 33 – Rudder & Elev Travel

Two projects for this evening. First, I wanted to check the travel of the rudder. The best way I could figure to do with was with a couple of plumb bobs and a protractor. I set a plumb bob at the hinge line and on the trailing edge. I then marked all points of the resulting triangle of movement on the floor.  

Using a straight edge, I connected the lines.

I used a protractor to measure the exact angles. 33 degrees in either direction. They need to be 30 – 35 degrees so this is right where it needs to be. I may file the stops slightly to get the full 35 degrees, and measure the distance to the elevators. Or I might not. We’ll see.

I removed the rudder and the vertical stabilizer. Next, I had two things to deal with on the elevator. First, alignment. There is a very slight mis-alignment.

With the elevator horn drilled, and bolted at both ends I clamped the right elevator at the counterweight. The result is a slightly high left counterweight arm. It only about 1/16th to 3/32″ max. It is most likely a slight misalignment in the elevator horn, but it could also be the counterweight arms, or the elevators themselves. Hard to say. I figured the trailing edge was more important, so I decided to examine that.

The best way I could figure to examine the trailing edge was to compare its level with one side clamped to the horizontal stab. I played around with multiple configurations. Using both a regular level, and a digital level.

Here’s the digital level on the horizontal stab. It reads 0.2 degrees high on the right.

On the elevator it reads 0.4 degrees high on the right. So thats a 0.2 degree difference. So the question then becomes, what to do about it? I checked the alignment of my buddies airplane. His isn’t perfect either, but better than mine. Although with the fiberglass done, its hard to tell. My instinct tells me to build on, but I’m trying to be as perfect as possible on the control surfaces and alignment. My options are either leave it as is, or repair, likely by welding and re-drilling the elevator horns. I could also possibly hide the slight disparity when I do the fiberglass work. I decided to email Van’s to see what they say.  

I also measured the up and down travel of the elevators. Both the fore and aft stops will need to be filed to match the offset horns, and to achieve full travel. Currently 23 degrees up (supposed to be 25 – 30) and 21.5 degrees down (supposed to be 20 – 25 degrees).

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