Sunday, September 29, 2013

Trim Servo Needs Polarity Change

When I was looking at the PAP to verify the trim tab is doing the right thing, the measurements that I was supposed to get were completely off. In what I thought was full up trim, I measured more than 3" of distance between the AST trailing edge and the TE of the stabilator when the stick was full aft.
A check on the forum confirmed that my trim tab is moving the opposite way: Forum Thread

So, the trim tab TE should go UP when you trim all the way down and the TE should go DOWN when you trim the nose all the way up. Mine is following the trim direction and so I will have to change the polarity.
As the spade connectors were hooked up in a way that this would not be possible by accident, I will swap the wires at the control box.
One possibility to swap them is at the Fuselage connector and swap pins 31 and 32 which provide the pulsed power with changing polarity for the direction.

Trim Servo Is Working

The servo was stuck in the full down position because the trim potentiometer on the black box had been set to such a slow value that it had not enough torque to drive it out.
I adjusted the potentiometer, after removing the main and ignition switch panel for gaining access, to 25/27s for full travel. It is always slower in one direction (down, I believe) and that must have been the reason why the torque was not enough to get it out of the full down position with the factory setting.
So, now, it needs about 25 seconds to get from full up to full down and 27 seconds to go the opposite way.

This is how the Anti Servo Tab looks like when trimmed to full up and the stabilator being in full down and full up position respectively. CAREFUL! The servo is moving in the wrong direction in these photos!

Once the servo was working I worked on the calibration of the trim tab position. To get a first idea if the SV display is reading your tab position you can check the sensor debug data. Search for the ELEV sensor and watch it change from almost 0V to almost 5V over the range of the full travel of the tab.

If you see that, you are ready for calibration. Go to EMS Calibration and select "trim calibration" to start the process. A good, safe take off trim position is at 1.75" of trim tab deflection when the stabilator is in full up position. This reflects on my plane to 2.55V. I know that Van's suggest 1 7/8" but I rather pull the plane off the run way than have it jump in the air.

1 7/8" reflects to be 2.927V on my servo.

I also installed the Cotter pins now that I did not have to take off the servo assembly and I also installed them on the control linkages.
Then I washed off all the red ink on the aluminum skins that was still on in some places and forgot to take a picture of the washed down bird.

Oh, well, next time....

Saturday, September 28, 2013

Anti-Servo Tabs Installed

Let's start with the good news for some positive thinking: The Anti-Servo Tabs were installed today.

This shows the deflection of the tabs in full down and full up position of the stabilator.
I had run the trim servo to full down position before I took those pictures, after I had hooked up the servo to the electrical system.

Unfortunately, these connection will have to come off again as I was not able to drive the servo out of the full down position. The trim up button had no response on the servo.

I had no tools at the hangar to track down such a problem and so I will have to bring everything I need for this tomorrow and go out there again.

To be efficient despite this setback, I checked the electrical connections of the wings and found all systems to be working correctly. Stall warner, landing light, and strobes and position lights all work as designed.

I put the N-numbers on the vertical stab and removed the vinyl from all surfaces.

On the left wing a lot of the vinyl did not come off and flaked. It is all on the belly side, so the scratches that I will inevitably put on there won't be easily visible.

Thursday, September 26, 2013

Vertical Stabilizer Installed

The assembly is progressing. Today I installed the horizontal stabilizer and the rudder.

I also hooked up the control cables to the feathers and installed the trim servo.

Next step here should be to install all the cotter pins and lock them.

Wednesday, September 25, 2013

Wings Are On

With the help of German friends that were visiting me in Tucson, I was able to put the wings on and remove all the blue tape I had put to keep bugs out.

They did not quite get in all the way and after a while of head-scratching and continued wiggling, the problem was found on the left side.

The additional aluminum sheets from the landing gear reinforcement have eliminated the clearance between the skin of the wing and the fuselage. I will have to trim this off a bit.

I also attached the stabilator later in the day.

Tuesday, September 24, 2013

Cowling Built Up

To strengthen the thin layer of flox and micro balloons that are holding onto the thin edge of the cowl, I laid up two strips of cloth on the inside. To smoothen it out and get it as thin as possible, I clamped the backplate on with clecos again.

The next day I removed the backplate and saw that the layup had cured perfectly and with a smooth surface.

Now the holes will have to be filled and the outer and inner surfaces smoothened and I will cut it roughly to shape.

Monday, September 23, 2013

Fixing Cowling

Here's my bird's new home:

I also took more photos of the gap between the cowl halves on the left side.

The maximum is around the size of the hinge loops. After a long debate with myself I decided that it will be easier and doable to fix this my modifying the top cowl. Here is the way I am trying to fix this.

I cut a piece of scrap aluminum and match-drilled it to be used as a backing plate. I had removed the piano hinge before that step. The plate was then slightly wiped with Carnauba wax and clecoed back in place while the in- and outside of the cowl was roughened up with 100-grit sandpaper.

I mixed epoxy and flox with a bit of micro balloons and filled up the edge. To smoothen the surface and get an even transition, I taped a strip of packing tape over the setup and pushed it down with a straightedge.

This is how the front looked like.

The plan is to glue a strip of fiberglass over the backside of the edge and then cleco the backplate on again and let it cure. That should help to keep the extension in place.

Tuesday, September 17, 2013

Fuselage Moved

In the morning by Flight Instructor and good friend H.L. Cooper showed up with his trailer and we loaded the fuselage onto it. Tied it down and go everything ready for the ride to the airport within 40 minutes.

I had to go into work, so I could just send him and Dawn onto their way to drop the fuselage off for me. This time I did take some photos!

And a very empty looking carport...

If anybody needs 3 16' ramps, they are free for pick-up!

Monday, September 16, 2013

A Little Setback

While I was readying the plane for its trailer tour tomorrow, I tried to close up the cowling to make it streamlined. Obviously I did this for the first time ever as it turned out to not fit.

This gap showed after I put all the other hinge pins in. No matter how much I tried, I could not even get the pin in the first two eyes of the left side.

My guess is that when I glued the channel in for the air supply to the radiator I must have distorted the shape of the lower left cowl just enough to bulge it out a bit and "pull" the fiberglass down and away for the top cowl.
I will try to fix this by "filling" the edge up with resin, remove the piano hinge and then rematch and redrill this side and rivet a fresh piano hinge in. This will show until it is painted but I think it will work and save me from completely redoing the upper cowl.

It's a pity but just more work and nothing serious at least.

The rest was easy. Just putting the canopy on and taping up the loose side of the cowling.

Ready to go. Let's see how it works out in the morning ...

Sunday, September 15, 2013

Partial Move Successful

We picked up the truck in the morning and drove it back to the carport to load it. The first step was find a way to safely get the wings inside. We tried quite some approaches and none of them succeeded - at first. The wings were still sitting in their cradle, a cradle built for RV-6 wings which are much shorter. So my RV-12 wings were extending quite a bit beyond the length of the cradle. Pushing the cradle up the built-in truck ramp did not succeed because of the wings extending too far and touching the ramp before the casters reaching the ramp.
We ended up unloading the cradle and storing one wing on a table and the other on saw horses and then carrying the cradle into the truck. We then loaded the cradle again and tied down the wings and the cradle.

We also loaded a work bench, the stabilator and the rudder/stabilizer assembly and some small stuff before heading out to the airport.

And no one was even thinking about taking pictures. Sorry!

We safely unloaded the truck which took about 1/3 of the time we had needed to figure out what to do when we were loading it.

Everything but the fuselage is in the hangar now. And again no photos.

Finally on the way back we realized that there was no evidence of this great milestone and we took some "Mission accomplished" photos.

This is my brother-in-law Mark, obviously still quite hot. And a very relieved and happy builder:

The fuselage had to wait that day as we were way too tired and overheated and Mark had to attend some other work as well.

While I did not take any photos of the parts being delivered to a new home, I at least took some photos of the relieved space.

This is where the coasting workbench was that carried the canopy for quite some time and on which the fuselage was built.

And this was the wing storage corner.

To be continued ...

Ramps Built

As I am waiting to pick up the moving truck, I can report about about the previous long workday. I was out in the heat for 10 hours building the 3 loading ramps for the move.
The idea I have is to Use a 20' U-Haul truck (about 16' usable length on the main floor) and stuff the whole fuselage in there and let two feet of the tail stick out.
To get the fuselage in, I need long ramps and three of them for all three wheels. Long, because I want to have only a small incline to push up and because the tail might actually hit the ground before the mains reach the ramp.
I used the spar box that I kept from the build and modified it to allow for an easy roll-on/roll-off experience. See the line for the cut. I used a water level to transfer the ground line onto the side of the ramp while the ramp was propped up to 3' on the opposite side (a tad more than the loading deck height of the truck).

Before I got all rallied up in the build, I decided to also start the battery test - now that I knew it would pass easily.

I was able to manage a really nice cut on the first ramp.

The opposite side was marked as well, using the cut off piece as a template.

The battery test had finally completed.

Both cut back ends of the ramp received some reinforcements.

That concluded the work on the first ramp. My wife and I out a stress test on it by both sitting in the center of the ramp while it was propped up and it did not even flex.
The second ramp was a bit tougher as I had to build something from 2x4s. The layout I used was 2 8' long 2x4 on each side building the frame of the ramp. To enhance the 8' long ones to become 16' long, I used a 4' long 2x4 on each side to support it. Here you see it with 2 additional 2x4 in the center to keep a 9.5-10" width. This photo was taken right before I put the plywood surface on.

The third ramp is for the nose wheel and a little bit less sturdy. It only used one 4' piece to extend the main side. Everything else is identical though.

It was late when I finished a very long and exhausting 10-hour workday.