Standard Pilot Blog: tail feathers

Monday, March 18, 2013

Tail Feather Construction, Part 2

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The construction of the horizontal stabilizer is very similar to the elevator construction, which we just finished in the last post.

Let's get going. The ribs are glued to the main spar using 2216 adhesive; the "X" cross sections are glued to the ribs using high quality wood glue. The front spar (from 1/2" aluminum tubing) has been given a mild bend to match the sweep angle. The middle ribs have been glued together, along with a small wooden spacer.

Gluing up the horizontal stabilizer for a Belite ultralight airplane.

View from the front of the glue up process.

The bushing tubes are glued into the wooden support washers, which in turn are glued to the "X" brace using high quality wood glue. (Some of our early production used a welded bushing tube on the spar; compensate accordingly.)

View of bushing tube with wooden washer on top and bottom of "X" brace.

Wooden washer and bushing near leading edge.

Now glue the leading edge on using 2216 adhesive epoxy.

Gluing on the leading edge.

Detail of leading edge glue process.

Using fiberglass cloth and epoxy, glue the leading and trailing edge in place over the "X" brace.

Fiberglassing the "X" brace in position.

After finishing this step, the strips of wood are glued over the trailing edge, and the wood balsa blocks are trimmed and glued on the ends. Smooth and sand; finish with two coats of varnish to protect the wood.

That's it. You're done.

Construction of Tail Feathers

We'll cover both pieces of our horizontal tail assembly in this document: the elevator, and the horizontal stabilizer.

Construction of both pieces is very similar. Please refer to the blue prints for layout dimensional information.

Prior to assembly, all wood pieces are sanded and deburred. Steel and aluminum pieces are cleaned. Steel pieces are also painted, except where glue joints will be. (We cover the steel pieces with strategically placed masking tape, then spray paint is applied.)

Let's start with the elevator. We use 3M 2216 glue to attach the wood ribs to the elevator spar. We also glue tail end gussets to the end of each rib using high quality wood glue.

Elevator Assembly already under way.

The trailing edge is fitted into place. It will fit snugly over the wood ribs and gussets. The trailing edge usually has a plastic film both inside and outside; remove the film.

Trailing edge being fitted over elevator.

Still checking fit of trailing edge.

Trailing edge cut to length.

Now it is time to install the four bolts, one on each torque arm.

Bolts added.

Use rivets to hold the trailing edge in place. Rivet washers are also used on the underside.

Trailing edge riveted in place.

The wood strips are prepared by gluing in spacer blocks.

Wood strips and spacer blocks, glued together.

The wood strips are then glued to the wood ribs.

Wood strips glued to wood ribs.

Closeup of clamping detail.

Two pieces of trailing edge material are cut to fit in the center section.

Preparing the center section trailing edge.

More preparation.

Glue the balsa block on each end. Make room for the top of the bolt. Also, unlike shown below, it may be helpful to pretrim the outline of the rib in the balsa.