Rudder trim

Rudder trim

4/19/2016

It has been over a month since I caught up on my blog.  Too much time building, gone fishing, and also was sick for a couple of weeks.  Sheesh, time to get it together again!

So, I am almost done with the rudder trim mod.  Last I left off I had the trim tab cut out, the brace made and the inspection opening complete.  So I began fitting some hinge material to the opening.




Here is one side of the hinge, drilled and clecoed into place onto the rudder body.

I then dimpled and used nutplates to screw on the hinge.  Added the mating hinge piece to the trim tab and after lining everything up drilled and clecoed.  As is shown here, I found a new use for the neodymium magnets.  They are strong enough to hold the steel rulers to the sides of the rudder trailing edge.  Very helpful.

I forgot to take pictures of the rudder horn fabrication, but I basically just cut it out of a piece of aluminum angle and made a slot in the tab for it.  I also glassed in the sides of the hole, and the sides of the tab.  A little cleaner, prettier and stronger.

This view shows the slot cut for the actuator arm.  It took some futzing around to find the right position and length of the slot and arm.  Eventually found the winning combination.

This view shows the cutout better, and the servo ready to mount.  I used mounting bolts that are made by Click-Bond.  These are basically metal discs, and can be attached to bolts, tie downs and all kinds of devices.  They are bonded with a special epoxy.  Some have had trouble with them, but if the instructions are followed to a "T", they are suppposed to be bulletproof.  This is the major type of connector that is used on current military aircraft.  Good enough for me.

You can see the aluminum/primer needed to be scuffed up for a proper bond.  The epoxy set up really fast, but I got them all down before it set up.

Here the servo has the Click-Bond studs held in position, and the epoxy is setting up.  (New use for a bucking bar).

Also shown is the final riveting and placement of the rudder horn which will connect to the servo arm.  Almost done!

It is also a lot of fun to connect to a 9V battery and run.  It is a DC motor, so reversing the leads runs it in or out.  I have about an inch of deflection each way, so it seems to be adequate for the job.






Am making a fiberglass fairing to cover the slot and aerodynamically cover the arm/horn.  When I get it ready to install I will take final pics.


3/7/2016

I am almost done with the fiberglass and epoxy on the wingtips.  So while I wait for my QB wings and fuselage (which are coming any day), I decided to work on a rudder trim mod.

Here is a picture of the trailing edge of the rudder, and the starboard side.  I laid out with a Sharpie where I wanted everything to sit, based on three or four well documented posts of other builders.  Most were very happy they did the mod, and it is way easier than adding later.

I made a cardstock cutout of the tab, and flipped it to the other side to make sure the layout would match well.  I used a standard Van's inspection plate doubler and cover for the access hole.




  This is the scary part.....cutting up your rudder after months of careful construction.  A dremel tool and a carborundum cutoff wheel worked great, it was not as scary as I thought.  (although I was extremely careful).














And now I am deburring and smoothing down all the edges.  Everything looking good so far.













And now making sure the inspection plate fits well.....








Here is the final cutout of the trim tab, and the inspection plate cutout.  I made a tapered and bent aluminum brace for the leading edge of the cutout.  After much tweaking it fit great.  Then I remembered I have to put a hinge in there, which will change the dimension of the space.  Oh well, I have lots of aluminum.  Maybe tomorrow.