Horizontal Tail

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Cutting the stabilizer spar doublers...
Believe it or not, I had to try several methods before I could efficiently cut those 1220mm bands of 0.040" 6061-T6.  I tried with aluminum snips.  It was difficult and the result was really not nice.   Then, I tried a couple of other methods (different saws)... did not work well.  Then, I tried with this saw with a 150 teeth plywood blade.  It worked well!

The setup displayed on the left includes a piece of wood that is clamped over the aluminum sheet (to serve as a guide for the saw).  I also put two bands of duck tape over the sheet to avoid scratches.

What is this extra piece?
When drilling the stabilizer attachment to the spar, the spar assembly moved... resulting in an elongated hole in the spar doubler.  I corrected this by making a doubler that fits over the existing spar doubler.  This new piece covers three holes, as it can be seen in the picture.
Completed spar assemblies!
These are the stabilizer front and rear spars.  Quite nice hey?  At the time I am writing these lines, I have the 6 middle ribs attached to the front spar.  I starts to look like an airplane part.
The stabilizer skeleton!
It's funny... one of my neighbor came by that evening and thought it was a full wing!  In fact, another neighbor thought the same thing about my rudder.   It is true that this assembly is about 7.5 foot wide... nearly the same as a wing.
Does it fit?
I am looking at how the skin will fit on the assembly (considering that a piano hinge has to be inserted in there).
My 8 foot hydraulic press!
This is the setup I used to bend my stabilizer skin.  What we do not see on the picture is the 2X4 suspended from the ceiling. 

To make the bend, I put the skin over the 2X4 assembly (center line between the 2 2X4) and I position a 3/4" (take note here!!!) plumbing steel pipe over the skin.  To make is stable, I duct taped the pipe on the skin.  Then, I put my "T" assembly (the 2X8 with 2X4 mounted at the center) over the pipe and the hydraulic jack between the two vertical 2X4s.  I then compress the skin until it is seated between the 2X4 in the jig.

We really need to be two people to do this... the whole thing is pretty unstable when we start operating the jack. It did fall one time on my skin, leaving permanent damage.

The first time I did this was with a 1/2" pipe... this is too small!  The radius was too small to fit on the end ribs (1/2" was the correct radius for the rudder nose skin).

I wanted this picture...
That is self explanatory... as you can see (by the straps), I nearly forgot to take the shot.

One important comment here.  When you strap the assembly on the work table, do not just do what is in the assembly manual!  I ended up with a skin not correctly positioned on the end ribs and as a result, my rivet line on top of the front spar is not correctly located (but it is acceptable).  The correct way would be to strap the assembly with a 2X4 on the rear spar in addition to strapping the assembly on the work table.  This is to make sure the skin follows the contour of the end rib.

Bottom riveted and top clecoed
Notice that the skin is oversize.  Since I don't work with pre-cut and pre-drilled skins, it is pretty hard to forecast how everything will fit.  For example, in this particular case, I did not make my bend exactly on the line.  So, there was a difference of about 20mm between planned and actual bend position on the skin.  This is OK since I made the whole thing several inches oversize both on the bottom and top sides of the skins (on the picture, bottom skin has been cut to correct size after clecoing).

 

Bending the elevator skin
I was pretty nervous about this step; especially after a correspondent told me he failed when he tried.  Before actually putting the skin in the bending brake, I practiced three times on scrap 0.016".  When I was satisfied with the result, I then made the real thing.

Surprise!  It is fine the first shot!  I can tell you I was very happy!

Note that I strongly believe that a 8 foot bending brake is required... if anyone reading this knows of another method, please tell me.  I will share this right here.

Bending the skin, part "deux"
The trailing edge bend was not complete when coming out of the bending brake (it is able to bend only to about 110 degrees).  To complete the bend, I inserted a 1/4" masonite in the skin and I pressed the top flange with a 2X4.  The result was still not satisfactory.  I took a friend to help me press the skin again, this time without the masonite.

On the right side, we can see one of my practice run with the skin bending.

Is this nice?  NOT!
I was so happy at this stage... I even attached the elevator to the stabilizer to see the effect.  This changed rapidly when I opened the elevator to deburr the holes and prime... I found that I scratched the front flange at every 40mm rivet location when drilling the piano hinge rivet line :(    Another important tip here:  NEVER inspect, open, look at any work you have done at midnight just before going to bed! (obviously, I did not say "to sleep" here).  The next morning, I called Zenith Aircraft and spoke with Roger who told me to redo the whole elevator.  It took me about 11 hours to get back to this point.
Cutting new rib blanks
My morale was not at its best, but I took my courage with both hands and cut new rib blanks out of my beautiful elevator skin.
Priming inside the skin?  Not difficult at all!
I read in someone else log that it is difficult to prime the inside of the skin... well, anticipating the difficulty, I decided to prime it before completing the bend of the top flange.
The cutout for the rudder
A friend showed me how he cuts aluminum with a knife.  Quite easy and makes straight cuts.  Thanks Angelo!
A great moment...
I like gadgets... and this trim servo is considered one.  After installing the servo and tab, I made a testing unit with the switch and indicator.  I used a dive light battery (12v 14ah).  It worked great!
Another look at the trim tab assembly
This is after I made the inspection plate (not shown) and primed it.
Finally...
I developed new skills while installing the fairings... I learned to apply fiberglass.  At first, I installed the fairings just ensuring that the back portion was quite square with the stabilizer.  I found that the elevator was almost touching the fairing on one side.  After showing this to André Létourneau, he told me to patch the holes, lay a stripe of fiberglass inside and redril the fairing in the proper position.  This was quite easily done and the result is very good.  I took the opportunity to correct some imperfections in the fairings.

 

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