Main Spar Preparation

The first step in construction of the wing is the preparation of the main spar.  The platenuts for the mounting of the fuel tank are flush riveted onto the spar flanges, 60 on each wing!IMG_5445IMG_5446

Then the tie-down anchor is mounted on the spar web.  This requires the addition of spacers  to compensate for the reinforcement plates on the spar.  The spacers had a tendency to slip and I had to make an extra set when the holes were misplaced.

Time:  8 hours

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Left Elevator

The difference with the left elevator is the incorporation of the trim tab.  The stiffeners are shortened on the inboard side and space is made for the trim tab solenoid motor.

The centering of the motor is important for the linkage to extend to the trim tab without interference.  Unfortunately the dimension shown on the plans is in error and must be carefully corrected.  A Z bracket supports the motor on the access door which is screwed to the elevator into nutplates.  These have to trimmed off to the borders of the access door after riveting to permit the installation of the motor.

The trim tab itself is a challenge as the end tabs need to be bent over each other.  A wedge shaped piece of hardwood is inserted in the trim tab skin and the tabs are bent over against the wood.  Mine came out pretty good, but not perfect.  After assembly the trim tab is mounted to the elevator with a piano hinge which needs to be aligned carefully to permit the trailing edge of the trim tab to coincide with that of the elevator.

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Time: 8 hours

Right Elevator

The next task is building the elevators.  The left and right elevators are different because the left elevator incorporates a trim tab.

I did the right elevator first.  The stiffeners are formed and back riveted to the skin.  This is difficult for the rivets closest to the crease, but the skin is just temporarily deflected back just enough to set the rivets.  The spar and end ribs and the counterbalance rib are assembled together with the counterbalance.

One caution to the wise:  The forward spars E-702 are not marked left and right, but they ARE different!  You must reserve the spar with the off-center hole towards the bottom for the left elevator.  This hole provides clearance for the tail screw of the trim servo, and of course I got it wrong and didn’t discover it until the skin was riveted onto the frame of the right elevator.  So I had to drill another hole and put in a reinforcing plate to cover the misplaced extra hole.  Vans really should mark the spars as left and right!

The skin now needs to be bent to the final shape.  This is done by making a homemade break out of two 2×4 boards united with several hinges.  The skin is put between the two boards and a 1/8″ rod is placed in the crease of the skin to provide a minimum diameter to the bend.  A lot of pressure is needed to make the bend and it has to be done in several steps.

The skin is then riveted to the spar and rib assembly to complete the elevator.

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Time:  6 hours.