New smoke tank
The new smoke tank from Smoking Airplanes showed up this week. I spent some time today working out the installation details. This will be one of the easier jobs to complete. There are more details here.
Hot Hangar
I got out to the hangar today after work to knock out a few things. It was over 100 degrees today and the hangar felt like it was more than that. After a couple hours of finishing up some welding, the breeze outside actually felt cool. Glad I have a mini fridge full of water there. The next couple months will be a battle with the heat. Hopefully, it won't slow down progress too much.
Monkey work
Now that I have the new belly sheet metal figured out, it's time to do the detail work. I spent tonight trimming, cleaning up edges and installing nut plates. Not exciting or fast work, but it will be done soon. After that I have a bunch of odds and ends to wrap up before diving into new stuff. There are a couple welds that need to be finished up on the fuselage and some work needed on the firewall. The battery mount needs to be installed as well.
Back in the garage, the next step is to install the leading edge ply on the new aileron so that I can shape the leading edge. Once that is done I can start working out the details for mounting the aileron cove. I also need to make a stack of nose ribs and start scarfing the spar extensions for the other bottom wing.
Sheet metal fit with tunnel and gear
I put most of the fuselage sheet metal back on the Pitts today. I wanted to check the fit of the tunnel and see what needed to be changed to clear the new gear legs. Everything worked fine with the tunnel and the next step will be to install all the nut plates. I didn't have time to get that started today.
The bottom of the cowl needed to be trimmed in the rear corner to keep from interfering with the gear legs. It looks like the bottom front corners of the panels behind the firewall might also need to be trimmed a bit. Otherwise, everything looks good. It really cleans up the bottom compared to the old stock landing gear.
I took a quick look at the landing gear leg fairings. I think that's going to be a tricky job, even with all the parts from Wolf. I'm going to have to think about that a bit before diving in.
Tunnel and smoke tank
Spent some time tonight cleaning up some details on the exhaust tunnel panel. I smoothed out most of the bumps and wrinkles on the 'wings' that overlap the side panels. It looks pretty good now. The rest of the mounting holes were drilled and everything is assembled with sheet metal screws. I got an order in from Aircraft Spruce today that has all the nut plates, rivets and machine screws needed to finish up the job. I should have a chance to get some of that done this Sunday.
I mounted up the gear with the firewall in place. This let me trim the lower flange on the firewall for the new gear legs and sockets. Once the fuselage was sitting on the gear again, I dropped in the fuel tank so that I could check the fit of the new smoke tank from Smoking Airplanes. I mocked up the tank out of cardboard and was able to verify the fit and location. The new tank will be 3.5 gallons, but I expect that there will be more useable oil than in the upper wing tank. This should give at least 5 or 6 minutes of smoke at the right settings. It could be stretched a little longer by turning the flow rate down and making a little less smoke.
I'm planning on using the external fill option on the new tank. The extended fill tube will run past the front of the fuel tank and behind the instrument panel. It would be a tight fit, but with the planned changes on the panel, the right side will have plenty of clearance for the new fill tube. This should make it much easier to fill than trying to fill the tank directly in the cockpit. It will also be easier to fill than the top wing tank.
Exhaust tunnel second attempt
I got to try out a second attempt at making the exhaust tunnel today. I tried a similar approach, but with some new tactics. This time, I made both of the bends needed to form the main flange and the secondary 'wings' to cover the gap with the side panels first. I didn't make any cuts this time other than the outline of the part. The main flanges were bent first on the brake. Then I fit the part with the side panels installed to mark the bend line for the overlap with the sides.
The secondary bend was made by clamping two lengths of one inch square tubing on each side and leaning into it. This was tricky, since the the two bends meet before the end of the part. I had to muscle it around a bit, but it came out as planned. With some additional work with a pair of seamers and a rubber mallet, it all came together pretty well.
I still have some smoothing to do on and near the wings, but the fit is nice and tight. The pictures make the ripples stand out more than they appear in person. With just a little more work, it should look pretty good with primer and paint. I got about half of the holes drilled and installed sheet metal screws to hold everything for now. I will replace them with nut plates and machine screws.
More pictures here.
Aileron hinge installation Part 2
While I was looking at the misplaced hinge on the center of the aileron spar, I realized that that wasn't the real problem. It was off center vertically a bit, but only because there was something else not quite right.
I got out the laser level to see where things got off track. It turns out the tip hinge on the rear wing spar was the culprit. It was low by about 3/32". I had it centered on the spar, but the spar isn't quite centered at the tip. This was caused by the spar extensions and scarfing them by hand. The ribs are in the right place, because I located them based on the other ribs. The tip of the extension is only off a tiny amount, but it was enough to throw off my hinge placement.
Once I figured out the real problem, the fix was easy. The tip hinge had to move up by about 3/32" to get everything lined up right and on center with reference to the ribs. I doweled the 1/4" holes since the new holes will overlap a bit. Since I didn't want to waste the extra epoxy, I glued the remaining ply wood strip on the trailing edge as well. I should be able to sheet the leading edge of the aileron next.
I will need to change up how I'm doing the spar extensions so that I can be more precise. I've got a couple ideas that should help. The extensions on the existing wing will work fine since the new ribs are in the right place, but I'd just like things to turn out a little better and with more control over the process. I should be ready to extend the spars for the other bottom wing in the next week or so. Sometimes building everything from new parts is easier than modifying old parts. This is one of those times.
Aileron hinge installation
I spent some time today getting the hinges installed on the first aileron. It went pretty well until I drilled the holes for the center hinge wrong on the aileron spar. I plugged the bad holes with epoxy and some 3/16" dowel. Now I can drill them in the right place. I'll go a little slower with the layout this time. Other than that mistake, it went well and the hinge placement came out correctly.
I also started prepping the other bottom wing for the spar extensions and catching up with the first wing. The second time always goes faster.
Aileron detail work
Put in a little time over the last couple nights taking care of some smaller details that need to be done on the aileron. I added the missing hinge doubler plywood that mistakenly got glued on the wrong end of the spar. Got the rest of the hinge doublers on the rear spar and a couple other odds and ends. Next step is to get the hinges and aileron bellcrank installed. Then I can finish up the aileron sheeting, capstrips and end ribs.
More exhaust tunnel work
Today I started working on the details of the rear of the exhaust tunnel. The goal was to close up the gaps in a nice way. I figured out how to do the second bends on the flanges of the tunnel part. Once that was done, I trimmed the flanges along the bend line until I got a few inches from the back edge. Here, I left a couple narrow tabs or wings that extend over the gap. It took some work to get the tabs to lay down correctly, but the first one came out pretty good. The second one didn't cooperate as well and got a little more chewed up from the shaping. By the time I had both tabs shaped correctly, the corners had cracked from work hardening. This is 6061 T6, so I think it will work better with T4. I'll get some in .032 and .025 so that I can try it both ways. I think the thinner sheet will be easier to make and might eliminate some of the extra work with the hammer.
I installed enough screws to keep everything in place. This let me see how well it all fit together. If you back up a couple steps it looks nice. I think the tabs could be a little wider and possibly enough to pick up the first screw on the side pieces. That would make it pretty secure and it looks fine as long as it is all snug.
I'll order some more sheet for next weekend's session and maybe try the welding on the current part just to see how it works out.
Here's one picture, but there are a lot more here.
