Fuselage Frame 605, 606

May 11th – 6 hours;  May 18 – 2 hours Don and Jay;  May 19th – 2 hours Don and Jay

It’s been some time since I last worked on the plane.  I blame work.  With the semester nearing an end, I needed to spend more time helping the students and less time being absorbed in my project.  But today was the last day of school, and I hope to kick butt over break.  The first step was to dig out the fuselage crate, and unpack those beautiful parts.

The firewall was factory drilled and partially assembled.  Frame 204 was factory jig drilled.  Frame 205 is the first part fuselage part that I get to do all by myself!  Frame 205 forms the back of the cockpit.  It consists of 6 large pieces and several smaller ones.  It also contains the aft “carry-through spar” (my term, not RV’s).

The first step to completing the frame is to join the two bottom bulkheads 605A R and L.  These are joined by a splice plate.  The rivet holes are spaced a bit weirdly, because there will be a hole in the center to allow the elevator controls to pass through.

Next order of business is to add 605B – the pre-curved 1/8 thick by 1.5 tall structural bar.  This sticks out on both sides of the frame, and will mount to the aft spar of the wings.  After this is measured and clecoed in place, the edge 605C bars are added.  These have a joggle and form a fork around the wing attach brackets.  They do have to be contoured pretty aggressively.  Thankfully, this can be done with a bandsaw and a power sander.  One per side, and we are ready to move on.  The edges of the spar forks that are formed should be 1/8 inch above the edges of the frame.

The 605D’s form the sides.  The 605A’s have to have part of the flange cut away to fit them.  Also, these have to have part of their flanges cut away in the top outside corners to clear the 3/4 by 3/4 stringer that will form the top of the fuselage boat.  No good picture of this.

I chose to go a bit out of order, and install 605F next.  This forms the seat rest along the top of the frame, and it is quite hefty.  At this point, a lot of very careful measurement had to be made to ensure the frame was true.  The top of the frame is 42.5 inches wide, and the bottom 42 inches wide.  Once I established all the proper dimensions for the four legs of the rectangle, I put a single rivet hole and cleco into each corner.  I then added C-clamps, and adjusted my diagonals until they were equal.  After that, I never released more than 1 corner at a time to maintain shape.

The plans note that the 605E’s and the spacer strips H and I are not needed if you are going to use a sliding canopy.  Since I don’t have a canopy yet, there is a chance that I will need them – so I am putting them in.  They are a little narrower than the 605D that they double up and reinforce, and the gap is to be filled with two strips (605H and 605I) that are made from .032 and .063 aluminum.  I just grabbed some scrap for spacing purposes.  Look carefully in the two photos, and you see one shot with the spacers in place, and the other after they have been removed post drilling.  I’ll add them back in when its time to drill and rivet the skin.

Also visible in the above photo, you can see the reinforcement extrusion 605G.  This is a 1.5 by 2.5 angle, 1/8 thick.  Any time you add a piece like this, tight fit is essential.  Both faces were clamped against their respective surfaces before drilling and clecoing.

At this point, the frame is assembled, and ready for zinc chromate and rivets.  I couldn’t help but lay out the frames in order, and photograph them.

That’s where I’ll be sitting – right in there!  Still not ready for any airplane noises.

Here are all the parts disassembled and zinc chromated.

Reassembly, with Jason as the master of the cleco pliers.

Riveting – a refreshing change to be installing universal head rivets.  Riveting went pretty smoothly with Jason placing the rivets, and me knocking them in.  I didn’t have to set down my tools between rivets, so things went pretty fast.

While Zinc Chromating frame 605, I went ahead and zinc chromated the next 3 frames.

These frames are much less work to assemble, as the tooling marks are also alignment marks.

Frame 606 is 3 pieces, and has to be measured diagonally to ensure proper shape.  Then the three parts are riveted together.  This frame is really, really thin.  There are 14 rivets to this frame, so it didn’t take long to finish this one out.

Frames 607 and 608 are two part, and are just temporarily set in place with two bolts each.  Here they are set on top of the fuselage jig, which I’ve just started setting up…

 

 

 

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