Apr 27, 2024     Firewall grommet shields - (6.5 hours)       Category: Firewall

While thinking about what to do next and where to mount stuff on the firewall, I realized not everything going through the firewall will have or need some trick fitting. Some stuff can get by with a simple grommet and a stainless steel protective shield over it. (typically wires). I used a few of these shields on my RV build. They're simple and light and do the job on Cessnas and Pipers for decades. Probably good enough for me too.

They're about $12.50 a throw from Acft Spruce (plus shipping), but anybody can do that. I recalled reading an article by Tony Bingelis in an EAA publication about how to make your own shields (for less).

Tony used a socket and a larger piece of steel tubing to telescope the socket into with the stainless sheet pinched between, squashed in a giant bench vise. I did about the same, except I used a pair of big and little sockets squashed in an arbor press. The bigger socket is twelve-point, allowing a slightly larger small socket to fit into it.
I had a bunch of leftover SS scrap from the firewall fabrication, so I cut some generously sized pieces to stamp the shields from.
First step just squishes the smaller socket into the SS sitting on top of a scrap pine 2X4, making a round dent. Next, the dented SS is carefully centered on top of the larger socket and the smaller socket replaced in the dent it formed in step one. Placed in the arbor press, time to squash again. Pressed about an eighth of an inch into the larger socket forms about the size dimple required to cover half a firewall grommet.
It's pretty wrinkled up after step two, but plenty of malletizing with a small ball-peen hammer makes them mostly flat again. Sanded the edges back to get them in more of a pleasing and eye-catching shape before punching out the attach holes and a center hole.
The center holes will be widened as necessary depending what is going through it's respective grommet.
Oh yeah, Tony calls for a small disc of baffle material to be placed under the shield on top of the grommet when it's screwed in place as well as some sealant if the grommet doesn't tightly fit the wires (or whatever) going through it.

  Apr 18, 2024     Cockpit floor update - (8.0 hours)       Category: Interior Finish

Was monkeying around trying to figure out assembly sequence for the cockpit area prior to covering, so I got the cockpit floors out to see where in the sequence they would need to be installed. Turns out it's pretty early in the scheme of things.

The finish on the floors is pretty nice, so I'd hate to scuff it up too badly and planned to cover them in masking paper prior to install. Got me to thinking about heel scuff plates for the rudder pedal areas. It will be easier to install now than anytime later, so I did.

Forward ones are stainless steel and bonded in place. The rears are screwed down as there is one floor install screw that needs access underneath the rear plates.

  Apr 13, 2024     Javelins - (9.5 hours)       Category: Wings

Taking a mental break from adjusting aileron travails, decided to move in another direction for awhile. these needed to done anyway.

I had a ready supply of 1-1/2" X 1-1/2" clear straight-grained oak left over from a home remodeling project. I trimmed them down to about 7/8" square on the table saw and went about borrowing my neighbor's wood lathe, and tools.

Having never operated a wood lathe, I spent an evening at YouTube University and watched a lot of video...

Started out slow to kinda get the feel of it, then just kept chipping away at it. Made three oak broomsticks. Tapered the ends of each, probably okay.

Next questions involve: Do I just simply lace them in place? Do I relieve a groove in them at each wire contact point? Install a removable insert for each? TBD

I like the idea of a groove cut in the javelins to positively nest the wires in position and then lace them fixed. I think I have an idea for a jig/sled to hold the round javelins so I can then push them thru the table saw using a dado blade. The crossing wires are not perpendicular to one another nor are the landing wires perpendicular to the javelins, so some angle setups will be necessary to cut these properly.

  Apr 11, 2024     Aileron setup (cont'd) - (11.5 hours)       Category: Controls

Continuing to fiddle around getting the ailerons to move to the plans limits of 25 degrees up and 20 degrees down.

Between the control arm at the base of the control stick to the aileron control tabs on each wing there are three linkages, an idler and a bellcrank as well as six rod end bearings (for a total of twelve). This doesn't include the fourth set of linkages to the upper ailerons also utilizing a pair of rod-end bearings each.

Given all the aforementioned bespoke components, each of which are connected by a pair of adjustable rod ends, some differences can be expected between the left and right systems due to "building tolerances". So setting both sides to match one another's movements has been an iterative process.
They're pretty close now, and probably good enough. To reach the full 25/20 degree throws shown on the plans, requires a full 30 degree throw of the control stick to each side to achieve same.

I don't think that much control stick throw is going to be available once everything is connected up. The aft end of the control torque tube at the base of the stick connects to the elevator pushrod assembly via a rod-end bearing. There is a total of two such bearings until reaching the elevator idler. Each of those rod ends would need to allow 15 degrees of rotational travel to reach the above limits. I'm thinking these rod ends will bind up at less travel than that and so will have to check that out with further assembly. Wherever the travel limits are, I'll need to set the aileron stops in the cockpit accordingly so things don't get bent.

Edit 4/19/24: Turns out the Aurora bearing co. publishes a 13.0 degree divergence angle for their bearings. In a perfect world that would give me a 26 degree control stick swing each direction prior to reaching a binding point on the elevator pushrods.

  Mar 19, 2024     Wing rack - (8.5 hours)       Category: Tools

Had to rework the old wing rack. Previous version had a pair of padded arms that I hung the wings on, hanging by their respective upper or lower spars on the padded arms. Once I cover the wings in fabric, that option won't be available.

Moved the old center structure over to one side and added padded arms to accept four panels horizontally placed on them. Also added a pair of short arms to the bottom of the back side to hold the center section in a pair of carpet straps similar to the originally designed wing rack.

This thing started out as the old classic Tony Bingelis' wing rack utilizing a pair of straps to hold a wing on either side.

  Mar 15, 2024     Center section drain fairings-- Revisited       Category: Fuselage

So this has been another "educational" moment for me. As a review, the first four pictures below outline the fabrication process for the fiberglass fairings to fit the fuel drains under the center section, done in Feb and Mar 2022.
A few days ago while searching the loft for something else I had squirreled away, I blundered across these fairings I had stuffed up there last year. Nope. It was two years ago! Anyway, they're all warped now!? WTF? They are proper fiberglass/epoxy layups and not supposed to act this way, as far as I know.

Pretty sure the culprit is the high-build primer I had sprayed on them to fill the fabric finish on the outside of the layups. It was a two-part, catalyzed PPG primer, so I figured it was going to be pretty stable. Guess I should have read the fine print, or the FULL instructions.
Everything was fine spraying and wet-sanding them out, but over time, the primer layer must have shrunk some as some polyester layups will. The fiberglass was thin enough and the primer thick enough, that the one overpowered the other.

Anyway, what to do about it? A simple fix would be to blob a bed of flox around the inside of the flanges, then press them onto a flat release surface... and wait.
Following their release, wait again for nice enough weather (non-life threatening) to take them outside and grind off all the unwanted bumps and lumps. (very, very dusty).
Losing my enthusiasms for making chemistry play nice with others, I instead made a shout-out to my son to see if he may be interested in a 3-D printing project.
I sent him some basic dimensions, and he launched back the two "Fairing" images below in about an hour. Pretty much exactly what I'm looking for. Since it apparently wasn't much of a challenge for him, I suggested he work up a teardrop shaped set... No, these are fine. Really. He said something about PLA, carbon fiber mix should paint well.... k?
I told him I wasn't in any hurry and could pick them up the next time we meet up. He's in the UK, so I should update this when we get back from his house in Sept.

The beautiful red Hatz pictures below show these in situ under the center section fuel tank. Pictures are of John Hanson's Hatz Classic.

  Mar 05, 2024     Aileron setup - (12.5 hours)       Category: Controls

I've been busy completing the connections for the ailerons setup. The project to this point has been mostly a part-task, bit at a time affair. Now, the disparate components are coming together for the first time looking a little more like the finished product. This leads to the next challenges. While the wings are on and generally rigged in position, time to finish the aileron connections and get them working properly.

Interference problems tend to pop up unexpectedly. So far, just a bit of sanding and filing which will require some touch-up paint and varnish once disassembled again. Each one takes time to resolve and make sure I'm not creating more problems. The most concerning interference problems haven't developed - yet anyway.

I was concerned the aileron pushrods crossing the lower longerons may bump at the neutral (centered) stick position. Was prepared to splice in smaller diameter tube to the pushrods, but unnecessary. I think the 2.5 dihedral on the lower wings caused the miss.
The same pushrods cross under the #1 inboard compression tube under the wingwalks as well. At a full 30 degree control stick roll input, the math looked as if they would collide as well. So far, it's a clean miss. Still making measurements, but I think I'm reaching other travel limits before getting to 30 degrees of stick input.
Have been monkeying around trying to adjust aileron travel and differential. There's no information on this in the plans, so it's been a bit of trial and error to see what the next thing does.

  Feb 14, 2024     Groundhog day - Part Duh! - (15.5 hours)       Category: Rigging

Okay, finished up the remake of the ten flying and landing wire attach tabs that I screwed up on the first go-round. Once the new parts were cut out, fabrication involved the welding, heating forming, drilling, reaming and powdercoating. Once complete, I installed same, replacing the aforementioned problematic tabs.

The first pic below shows the lower left wing landing wires attach tab in position. On the black pad are the first tabs that I drilled the holes too close together resulting in the terminal ends interfering with one another. D'Oh!

The middle pic shows the new rear flying wire tab installation. All four were remade, the first ones were too short by 1/4", pictured beside it on the black pad.

The third pic below shows the forward flying wire attach tab. All four of these were too short and remade about 3/8" longer each. An original is pictured beside it on the black pad.

  Feb 02, 2024     Groundhog Day - (22.5 hours)       Category: Rigging

So it is Groundhog day today, but it's felt like it all week. Got the Forward flying wires attach tabs re-made to a longer dimension. After a careful re-measuring, I discovered the aft flying wires (all four) were long enough, but only about one and a half threads were past the witness holes in the terminals. Not comfortably enough to allow any future adjustments. Better to build longer attach tabs for these too.

Lastly, the lower landing wire attach tabs on each side where both wires attach are the proper length, but I drilled the holes too close together. The end terminals interfere with one another. I contemplated welding them shut and then re-drilling. Abandoned that idea since I wasn't confident it would be as strong as a re-made new one. Are you keeping count? Yeah, it comes to re-making another ten attach tabs. The parts are pictured below in the first picture, less the bushing stock which I needed to order more of.

The second picture below shows the terminal ends coming up a bit short. The top one is the forward flying wire, the check nut is located where it was against the terminal when installed. The witness holes in the terminals are also visible just beyond the threaded ends of the rods. The lower wire is an aft flying wire, where the threads made it to the witness holes, but only just.
The powdercoated tabs pictured also displays my sloppy drilling on the right one. Thought I'd just drill it full size (5/16") in one step, but it wandered off before I noticed it was happening. Had I drilled a smaller pilot hole first, likely wouldn't have had the problem.

I've got four more tabs to go in the welding process. After that,. Drilling, fitting, reaming and powdercoating to go to finish things up and get back to where I was.

  Jan 20, 2024     Forward flying wire issues - (1.5 hours) Category: Rigging

It's been miserably cold and windy around here the last week or so and not so fun to go warm up the hangar as it takes forever.
Did however remove the forward flying wires which are coming up a bit short. Yup, I need to make new attach tabs a bit longer. The threads were just short of the witness holes in the end terminals. Comparing the bolt-to-bolt dimensions of the tab attach bolts to the pin-to-pin dimensions of the forward flying wires (103.75" vs. 100.5") leaves a difference of 3.25". Divided in half for each end means each tab should require 1.625" or 1-5/8" from the C/L of the attach bolt to the C/L of the terminal attach pin hole. Further working that out, the center insert tab needs to be 1-15/16" long and the outer wrapper length is calculated from Murray's analysis (2 X Tab length + 1.33" to wrap around a 7/16" tube) comes out to be just a smidge over 5.2".
So, I'll re-make the attach tabs to the new lengths, but I don't think they'll be noticeably longer to the eye. Unless compared side by side with the originals.
These should result in a pin-to-pin dimension of the installed wire at 100.5" which leaves plenty of length for adjustments in either direction.