Framing the Fuselage

5-23-18, 1.5 hours Jay and Don.  5-24-18 2 hours Jay, 3.5 hours Don

So after the frames comes the framing.  We have already set out the fuselage jig, and laid out the frames in their rough locations.

Seems like you can never just go to town.  There are always so many more things to do.  Today (5/23), it was zinc chromate the seat ribs.

Not much to say about this.  The ribs are attached to frame 604 and 605 on either end, and form the floor of the seat area.  After transferring the measurements over, it was time to set them in position.

Here is the rearward end of a central rib jutting forward from 605.  It proved to be rather difficult to place them exactly in position vertically.

In the end, I clamped a sheet metal “ledge” to the upper edge of 605.  This allowed easy placement.

Here is the rib, set on the ledge and clamped in place.  One hole was already predrilled when building frame 605, so location of the first cleco was easy.

Moving outward from the center, clamping, drilling, and clecoing.

And here are all of our seat ribs in place on 605, and set against 604.

Clamping the ribs into position on 604.  Here, they fit into the lips on the rear of the bulkhead, so location is much simpler.

Drilling all the rivet holes in the bulkhead.  These will be riveted in place with AN426-3 rivets, so there are a lot of them.

Notice the two center ribs do not have the same drill pattern.  On of them (the left one) gets three screw instead of some 8 rivets.  This is so that the rib can be disassembled to allow the control yoke to be installed or removed later on.  More on this in a few pictures.

Jason drawing straight lines in to drill the remaining rivets on frame 605.

Drawing in.

And here are pilot holes all drilled.  We will enlarge the 3/32 inch holes as we rivet.  This side gets 470-4 rivets, and does not fit against anything flat.  This makes it easier.

Remember the disassembleable rib?  Here is the drawing showing where it is cut and bolted back together.  I have drawn in my line mostly as per plans.

The plans didn’t specify what to make the scarf piece with.  I went with .032 2024-t3 because I had a scrap the right size.  Here you see it being laid out.

Here the scarf is cut as per plans, drilled and clecoed for rivets, and drilled for the AN3 bolts on the other side.  The rib isn’t cut yet.

Drilling holes co form radiused corners

Cutting out the edges up front.  Here you can see the one change I made to this part – I left the tab on the bottom that will hold when the skin is riveted on later.  This will make this rib consistent with all the rest.  You can also see all the drilled holes.  Only now are we ready to cut.

And there is the cut.  Since we fit the rivets and bolt holes perfectly before the cut, it will still be the exact same shape when bolted back together.

While I was at it, I had to make a couple of small clearance notches in the next pair of ribs.  This is to allow the wing spar bolts to be installed without interference.

Once again, I start the cut by drilling hte corners.

Here you can see one of those ribs in place.  You should be able to see where the wing bolts will fit, and why the clearance was necessary here.

Here is the back side of the completed sectioned rib.

I set the section up on the fuselage jig.  It reminded me of a tugboat or an airtractor, so I decided to make airplane noises.

Actually, this was just an excuse to use the self timer and take my own picture!

I decided to set the firewall loosely into place on the wing jig.  Bad idea.  I slipped and drew my first significant blood on the project.  No stitches, but that end’s today’s (5-24) work.

One more view of the progress on the frame before calling it a day.


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…