After exchanging a couple of emails with Joe Blank at Van’s, they determined that my lower cowl doesn’t have a long enough side flange.  They’re going to send me a new lower cowl, so I’m going to work on a few other things until then.

Since I marked the cut points on the exhaust pipes last night, I pulled the lower half of each pipe and cut the three longest pipes to match the shortest.  I then cleaned up the ends so that there were no burrs and reinstalled the pipes.

I then fabricated the exhaust hangers.  These are each comprised of two pieces of stainless steel tubing connected by a piece of rubber tubing.  I flared the ends of the stainless tubes so that they couldn’t slip out of the rubber tube.

Now that the exhaust is installed for good, I installed the heat muff around the #1 and #3 pipes.  This was a bitch to get on since the fit is really tight.  I moved it almost as far forward as possible so that I can get maximum heat transfer as well as provide the most room for the aft SCAT tube.  I could have moved it forward another 1/4″ or so, but I wanted to be able to inspect the weld on the #3 pipe during annuals.

Despite moving the heat muff forward, the right exhaust hanger is still going to interfere with the aft SCAT tube.  I’m going to have to shorten the exhaust hangers which will have the effect of moving the upper attach points farther out.  Hopefully that will give me enough clearance that the SCAT tube won’t rub on the exhaust hanger.

In order to make sure the cowl returns to the same position each time, I drilled a piece of scrap aluminum angle to the top cowl so that it aligned with the spinner.  The clecos didn’t really hold in the fiberglass, so I ended up putting some scrap aluminum on the other side and using some wing-nut draw clecos to anchor this firmly.

I also made a series of marks around the spinner to serve as reference points.

With the cowl in its final location, I put a light inside the cowl and put some masking tape along the cut line.

I did the rough cut with the cutoff wheel to within about 1/16″ of the line. After putting the cowl on and off a few more times, I was able to iteratively trim the line with a vixen file so that these edges align with the firewall flange.  I’ll trim the exit once I’m happy with how everything is fitting.

While I had the cowl in its final position, I took the time to position all of the exhaust pipes so there was an even gap all around them.  Each pair of pipes will be clamped together and then everything is loosely anchored to the engine mount.  I also made some marks on the pipes that are even with the shortest pipe.  I’ll cut all of these so that all of the ends are even.

Here’s a shot showing how much clearance I have all around.  I have about an inch of clearance top and bottom and about two inches on each side.  The pipes look like they aren’t vertically aligned here, but that’s just because the lengths vary.

I drilled and installed the pipe clamps.  The bottom steel straps needed to be bent to conform to the pipes.

I finished adjusting the flange on the front to be perfectly round and then drilled a hole on each side to lock in the position.

The plans specify that you mark a line 2″ aft of the firewall flange as a reference point for trimming.  As I’ve seen several other builders do, I used some 2″ wide painters tape.

I laid a straightedge across the top cowl to see how the four flanges lined up.  Three were nicely in line…

However, one of the flanges sits about 1/8″ shy of the line.

After doing a bunch of research on cowl fitting, I decided to fit the bottom cowl first.  I started by making a paper template for the gear let cutouts.

I transferred this to the cowl and then cut it out with the angle grinder.

After loosely fitting the cowl halves, I just had to take a picture.  This is looking pretty damn sweet!

The flanges around the inlets needed a little trimming to get the joint tight.  This is pretty close.

After a little further trimming of the gear leg holes, the cowl halves fit together reasonably well.  There’s still a small gap down the side, but that should disappear after making the trims along the aft edges.

This is a problem though.  Even if the gap pulls tight, the joint along the right side isn’t remotely straight.  I can’t cut a straight line here because that would just make the gap even wider.  The instructions (as well as other builder’s websites) indicate that the sides should overlap during the trial fitting.  I’m starting to wonder if these pieces weren’t trimmed incorrectly at the factory.

The joint on the left side is pretty close to straight though.  I’m going to email Van’s tech support and see why these flanges aren’t overlapping and what they suggest I do about it.

I’ve been laid up on the couch for the last day and a half with the flu, but I’m starting to feel better, so I’ll push myself as usual :-).  I started by clecoing the forward top skin to the fuselage so that I could file the firewall flange back flush with the skin.  This is because the cowl flange butts up against this skin, but it’s quite a bit thicker.

I also taped together some pieces of popsicle sticks to hold of the front of the cowl.  This will allow me to adjust the height if necessary.  This is roughly 3/4″ thick.

I cut a 44″ long piece of the 1/8″ hinge material.  I sandwiched a strip of 0.020″ aluminum between the hinge and the firewall flange and then drilled the hinge to the flange.  This was slow going since I couldn’t use clecos to keep the holes in the skin and the holes in the flange aligned.

I biased the hinge forward slightly so that you wouldn’t see the eyelets between the forward top skin and the cowl.

I was getting tired of having to squeeze under the engine to get from one side of the plane to the other, so I took the tailwheel spring off and tucked the tail up tight against the wall.

This gives me almost two feet between the spinner and the garage door; perfect.

While I had the tail spring off, I took the opportunity to get a bunch of the parts ready for powder coating.  Since I’m using the JD Air Parts tailwheel link which only attaches on one side, I sliced off the other arm from the tailwheel linkage and ground the part smooth.

I also stripped the primer from the Bell tailwheel fork so that it can be powder coated.  Afterward, I wrapped silicone tape around all surfaces of the tailwheel parts that I don’t want to be powder coated and set them aside.  The tailwheel spring is too big to fit in my little powder coating oven, so I’m going to see if I can drop by a friend’s place who has a pretty big powder coating oven and do them there.

I needed to get the joint at the front of the spinner adjusted so that the opening is circular.  Instead of measuring, I just put the spinner on the front of the cowl and adjusted the fit until everything lined up nicely.

I’m using 1/8″ spacers between the cowl and the spinner.  The gap is surprisingly good along the top.

However, the joint between the top and bottom leaves a lot to be desired.

The left side is a little better, but there’s still a noticeable step.  I spent a little time working on the fit, but there is still a lot to do before this will look good.  I’ll probably end up making the gap between the cowl and spinner a little larger to start with and I can tighten it up with some fiberglass layups at the same time I’m fixing the fit between the top and bottom halves.

I spent the rest of the night digesting the instructions and plans for the cowl.  This is likely going to be one of the tricker parts of the build.