Rear Fuselage Construction, continued

Let’s continue our work on the rear fuselage.

You will have two top rear fuselage plates; they have a notch in them which goes around the rudder post.  They are laminated together as we’ve done for other pieces.

After laminating the top rear fuselage plates together using a high quality wood glue, the resultant piece is sanded and then glued to the foam using gorilla glue or 2216 glue.  The edge is also routed round; this is easily done either before or after gluing to the foam.

Rudder Test Failure-9

Top rudder reinforcement plate. Note that the edges have been routed round.

The rear rudder post receives a 4″ strip of 2 oz glass on each side.  After sanding, we apply some lightweight spackle over the glass to smooth the joint.

Carbon fiber cloth is cut to fit over the top and the bottom plate.  Each piece is, in turn, epoxied in place.  The overlap area should be at least 4″.  Cut around the exit point for the rudder cable.

There are two pieces of vertical stabilizer foam:  the main and the front piece.  They are glued to the rear rudder post and to the front rudder post using gorilla glue.  The front piece is also ‘pinned’ into the rear fuselage foam using scrap pieces of 1/4″ aluminum tubing:  a 12″ piece and a 6″ piece.  Drill a quarter inch hole, clean the scrap pieces of tubing; and insert into the holes using water mist and gorilla glue.

Rudder Test Failure-10

Orientation of 1/4″ aluminum pins in front rudder piece.

The above photo shows the carbon fiber cloth reinforcement which was epoxied over the wood and fuselage.  A bottom piece is also epoxied over the bottom wood piece; the overlap area should be at least four inches.

Carbon Fiber over bottom wood

Carbon fiber cloth epoxied over bottom wood. Note cloth overlaps with carbon fiber cloth which was epoxied on the top wood. Make cut in cloth for rudder control cable tube as necessary. Overlap area is at least 4″.

After the glue sets, we route a round edge to the top and front edges of the vertical stabilizer, and then apply a 4″ fiberglass reinforcement over all edges, and also over all tube / foam glue joint areas.  The front foam piece is also glassed to the fuselage using 4″ pieces on each side and around the front.

There are three more pieces of wood to be installed in the rear fuselage.  The first is the lower front fuselage reinforcement.  The pieces are laminated together as shown:

Lower front fuse wood reinforcement

Lower front fuselage wood reinforcement laminated together.

This piece fits on the lower bottom of the fuselage, where it butts to the cabin.  The notch allows proper operation of the elevator bellcrank.  In order to install it, the foam is cut out exactly 1/2″ (the thickness of the piece), and the part is Gorilla glued in place.

lower front wood with gorilla glue

Lower front wood with generous Gorilla glue.  Note use of peel ply below to ease cleanup.

In order to make it easy to glue, and in order to ensure that the Gorilla glue didn’t get over the fuselage, the fuselage is lifted into place.

lower front wood gluing with weights

The fuselage is carefully squared to the wood piece, and held in position with same added weight.

The view on the floor:

lower front wood gluing with weights 2

The view of the gluing process. Note that the Gorilla glue is expanding outward and down, making cleanup easy.

Next we laminate the lower front load spanner.

Lower front load spanner being laminated using high quality wood glue.

Lower front load spanner being laminated using high quality wood glue.

And we place it over the bottom of fuselage, using a sharpie pen to mark areas to be cutout.

lower front wood load spanner_-2

Cutout areas marked.

lower front wood load spanner_-3

1/2″ depth waste areas routed out.

lower front wood load spanner_-4

Test fit. This example wasn’t cut as exactly as it could have been. You can do better.

lower front wood load spanner_-5

Use only 2216 glue to attach this piece.

24 hours later, after the 2216 glue has set, sand the entire surface smooth.  Large gaps must be filled with additional 2216 glue.  Small gaps (less than 3/16″ depth) may be filled with spackle.  There was a slight warpage in the wood piece, it was also sanded out.  Note that the front piece has also been sanded to uniform fit perfection.

Sanding.

After sanding.  Small gaps may be filled with spackle.  Large gaps must be filled with additional 2216 glue.

The next piece of wood to be installed is the trim ring around the cargo area.

The two pieces are laminated together.  Here they are, before lamination:

Cargo trim rings, before lamination.

Cargo trim rings, before lamination.

The location of the foam cutout is marked with a Sharpie.

cargo trim rings-2

Cargo trim ring shown in place with sharpie marking the route line.

cargo trim rings-3

A router bit set to a depth of 1/2″ (the depth of the trim ring) helps make a clean cutout.

cargo trim rings-4

The trim ring is glued in place with Gorilla glue.

After the glue is set, excess glue is cutout and removed.

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