Tuesday, April 23, 2013

Tail Surface Welding is Finished

 The last parts to weld to the stabilizer are the fittings which hold the front spar of the fin to the front spar (or as WACO called it, the Front Beam) of the stabilizer.  The rear spar goes into the tail post of the fuselage.  The bolt which holds that together also holds the rear of the stabilizer.  When it's done there is no adjustment to the fin for rudder trim or to the stabilizer for elevator trim.  They solved those short comings on the Model TEN (GXE).
A fitting is welded to the stabilizer spar 7/8" apart  on each side of the fin and a bolt passes though it all to hold it together.  The fittings are 3/4" wide made from .0125" steel.  The 1/4" bolt hole is 15/16" above the top of the stabilizer spar.  It's taken some research and the help of Frank and Rich to find all these dimensions since most are missing from the factory drawing of the tail surfaces.
 To carry the loads better and to prevent distortion to the fin front spar I welded a piece of 5/16" x .028" tube into the bolt hole.  The rear spar mounts in a way that a bushing would not help and welding it in would just cause more problems than it's worth.
The rear bolt was installed and some string used to hold the fin in positions to tack weld the fittings.  I tacked them at each end, and in the middle.  With the fittings tacked I bolted a 7/8" spacer tube between them to help assure the spacing didn't change during welding.  It worked great.

 Welding was easier with the stabilizer tipped by setting it on some bricks.  Welding these on warped the spar a little.  It shrunk on the fitting side.  The trick of heating the back side of the spar and letting it cool took out the warp.
It all fits perfect.  With the bolts in the fin is square to the stabilizer.

My first tail surface is sand blasted, ready for priming.  This is so cool to finally have the tail surfaces made.

I've go some modifications to make to my blast cabinet to do the other parts and the prime them.

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