Category: Forward Fuselage

April 1, 2015 – Well, I made the shims for the brackets correctly…

I roughly shaped the angles to the dimensions on the drawings. I found them too big, so instead of going exactly with the drawings, I trimmed each one to fit to the airplane.

I drilled the angles through the skin, then used a reamer to enlarge the lower (which is really the upper) hole to .189″, then clecoed that.

The other hole is a new hole, meaning it does not exist in the skin, so it has to be located and drilled. I drew a line connecting the rivet holes above and below it, so I had a reference centerline to place the bracket hole. I used a drill bushing to drill a smaller hole through the bracket.

I made sure the hole was centered, then took the hole up to size with a reamer.

…and here’s the bracket, inside and out…

Repeated the process for the other side.

Time: 2:20

March 24, 2015 – I’ve done quite a bit in the last few days and had to get this log caught up.

I put the left side F684 gusset in place along with the lower longeron.

Backtracking just a little bit, I needed to figure out where to drill the four bolt holes that go through the longerons and the lower engine mount brackets on the firewall. I’ve read many times that the location called for in the drawings will not give enough edge distance for the bolts going through the mount brackets.

I used a scrap piece of the longeron angle, and drew a line where the plans called for it: 1/2″ from the outer edge of the flange. I transferred that line to the mount bracket. Yup, I agree, the edge distance is not good. So I drew a line 1/2″ from the apex of the angle on the flange and transferred that line to the mount brackets. I can live with this edge distance.

So here’s the sequence. The red line is the dimension called for in the plans; the black line is where I placed the line:

I drilled #30 (1/8″) holes in the scrap angle on the black line:

I put the angle in place and poked a Sharpie through the holes to get the hole locations. I like it.

I drilled the holes with a #30 through the longeron:

Then I clamped the longeron in place and drilled through the mount bracket:

Here’s the final result from underneath:

I took the holes up to .189″ using a reamer.

The next job was to drill the F684 gussets.

I pulled the side skins back to drill the holes through the firewall angle. Made sure the gussets were well-clamped and in place, then drilled using an angle drill.

I then drilled the holes through the auxiliary longeron and the engine mount bracket. The aft hole is a little close, but that seems to be part of the design… Here’s what the gussets look like in place:

I made sure the F902 side bulkheads were fitted well to the lower longerons, and I fitted the F7101 gear attach webs. These webs nest nicely in side the skin between the lower and auxiliary longerons, and the F704 and F7101 bulkheads. I drilled the F902 bulkheads to the skin, then drilled the holes between the web and the F902s.

I went ahead and drilled the rest of the holes for the lower longerons through the side skins. The plans and instructions are silent on when to do this. I’ve read that some people wait until clecoing the lower skin in place, but this doesn’t make a lot of sense to me. The holes will line up with the side skins.

The next step is to fabricate parts for the tank attach bracket, where the fuel tanks will attach to the fuselage. I misread the plans and made two shims when there should be four, then I mis-identified them. So I have to make new ones, and I’ve learned some tricks about making and drilling these anyway, so it’s OK. So in the interest of full disclosure, here’s my mislabeled shims:

Time: 4:10

March 11, 2015 – I continued with the work in the forward part of the fuselage.

I drilled the longerons where they attach to the upper engine mount weldments. Pretty straightforward; the edge distance might be a little tight, but the mounts were firmly clamped in position with the longerons.

I started on the F713 auxiliary longerons by marking the centerline on the outboard face so they could be lined up with the existing holes.

The aft end of the angles are to be trimmed to fit flush against the flange of the F704 bulkhead. Here’s a before and after:

The forward end is clamped in place:

Here’s the right longeron drilled in place:

The F719 stiffeners get done next. These have a joggle on the aft end that is pretty rough. I straightened it out as well as I could, then fit it in place. I had to trim the forward and aft edges to an angle so it would all fit properly. The joggle fits over the flange of the F704 bulkhead.

I also had to make the attach angles that secure these stiffeners on the forward end. Once the stiffeners got drilled to the skin, the angles get drilled in place. I had drilled the two holes in the angles where they attach to the stiffeners; I did not drill the hole to attach the angles to the firewall until they were in place.

Here’s the product of today’s work (on both sides, of course):

Time: 4:10