Apr 06, 2024     Spars       Category: Wings

All four spars are substantially done except for some touch up painting. But there are a few rivets I'm only let's say 85% confident of. I have drilled and replaced quite a few already. Sometimes the 2nd attempt is not much better than the first. Although I think these structures are very strong, I don't want someone to say "you really ought to replace those rivets" at some later stage.

So while I wait for a visit from at least one persnickety EAA technical counselor, I'm marking everything which could conceivably be a problem and then get expert advice. I am improving but the main problem is deformation of the factory head. You really have to keep your eye on the ball.

The main goal is to get a thumbs up on airworthiness of the spars. Only then will I tear down my elevated spar bench.

In the meantime, I can do some more rivet replacing, touch up painting, organizing and clean up. The plan for reconfiguring the shop for initial wing assembly is starting to take shape.

  Sep 05, 2023     Left wing spars       Category: Wings

Main and rear spars for the left wing are now substantially done. An EAA Technical Counselor visited and he went over every rivet with a flashlight and magnifying glass. He said my work was good but still found about twenty rivets to drill and replace. Having done that, I feel more confident about both the riveting and replacing rivets. Most of my problems were with the factory head. I learned that short rivets require less pressure than long rivets of the same diameter. And one long burst is better than three short bursts.

When bending the spar flanges on the brake, it's important to pay attention to maximum bend radius as well as minimum. I exceeded the maximum and thus impacted internal parts dimensions. But Bob approved my fix and so I pressed on.

Basic sequence after the spar flanges were bent as follows:

Layout and mark front and rear spars together. Stack and clamp the cap strips together in position. Triple and quadruple check all marks and measurements.

Drill cap strips undersized using drill guides for plum holes. Cut and stack spacer bars at rib locations, lock into place and drill undersize holes with drill guide.

Spar attach and splice plates were difficult to cut using MDF template and flush router technique. Mostly cut these pieces with table-mount jig saw, hand saw and files.

Remake pieces as necessary to get good fit.

Cut lightening holes in main spar on drill press with fly-cutter.

Assemble the spars vertically mounted to bench, now with all pieces in their correct locations, front and back.

Cut rib attach angle blanks. Drill the rib attach holes only. Then bend the attach angles.

Using tape, square and clamps, drill the attach angles to match the spacer bars and cap strips.

Now that all pieces are in place (excluding wing strut attach fitting and its rib attach angles) , go through and drill to final size holes.

Disassemble, deburr and prep all pieces. Treat with Stewarts Eko Etch and paint with Stewarts Eko Prime.

Reassemble and rivet.

Flush rivet spacer to accommodate wing strut attach fittings.

Mark wing strut attach fittings and cut slot in spar flange.

Drill pilot holes for wing strut attach fittings. Hold in place with temporary screws.

Notch rib attach angles to fit over wing strut attach fittings.

This is where I will stop with the left main spar. When the time comes I will drill and ream the wing strut attach fitting holes for the AN3 bolts.

I'll also remake at least one of the rib attach angles over the wing strut attach fittings to get better edge distance for the ribs at that location.

Here's a short video of some highlights:

https://youtu.be/ibsnJjDfwvQ

  Sep 07, 2022     Ailerons 2       Category: Wings

Ailerons are complete at this stage. Upcoming will be the addition of steel hinge parts, alignment of trailing edge to the wing trailing edge, and fabric covering.

With more bucking experience and customized bucking bar, I will go back and replace or upsize a few rivets. So far I replaced/upsized maybe four rivets.

Pop rivets feel tight. Dimpling for the flush rivets enlarges the hole. Some of the shop head of solid rivets don't look exactly like the textbook diagrams.

There is a small pile of rejected pieces. Mistakes were made, even though the plans clearly state "Don't screw up".

Here is a five minute video:
https://youtu.be/88XLh21KJmg

  Apr 06, 2022     Aillerons 1       Category: Wings

  Mar 18, 2022     Reality check       Category: Wings

Approximately 20 months into the project and total expenses are close to 4500.00.
Not captured in the pie chart is 262.00 for Stewart Systems. But there are a few non-project household expenses included.
The total does include the 12 foot cap strip material and its expensive shipping.
But still a few hundred dollars yet to spend on wing materials and tools.
Time spent on the project so far is roughly 1440 hours, based on 18 good months (72 weeks) of 20 hours per week.
I'm 68 years old and in good health. Colleen and I live on Social Security and retirement savings.
The expenses so far have been pretty well covered by our monthly budget.
Looks like the entire airframe can be constructed at this slow pace and rate of expense.

  Feb 27, 2022     Rib joggles - bending brake       Category: Wings

Milestone achieved with the bending of the spar C-channels and joggling the ribs. I should have followed Dave Clay's plan (google: dave clay bending brake) more closely in some respects. Immediately discovered two four-foot nickel steel hinges were inadequate. Replaced with one six-foot stainless steel hinge (with two one-foot pieces of the nickel steel cut for the ends). Need that single solid piece across the middle. The straightest of the 3x3 steel angles was used for the bending edge (there was some bowing of all the pieces). Though the apparatus flexes a bit under pressure, it has held up well. The results look good to me.

The aluminum sheets from Aircraft Spruce had some pretty heavy wrinkles and folds in the plastic film. A couple of edges weren't covered at all. Rather than deal with the annoyance, I replaced a lot of it with protective film from the art store.

Though the 032 wing parts could fit on two 4x8 sheets, I bought three sheets and glad of it. I had a couple of sad results before establishing a ‘method'.

The joggling was easy after the joggle blocks were made. Paint on the inside of the joggle tended to come loose. Will take care of that and touch up the paint after the ribs are trimmed to length.

My EAA Technical Counselor gave me a good report and encouragement.

A short video covers the highlights:
https://youtu.be/PUgFZ8DvDVg

  Dec 12, 2021     Rib stiffeners       Category: Wings

Finished riveting the rib stiffeners. The ribs are now ready for assembly, except most if not all ribs will be trimmed for length (depending on location) and the nose ribs leading edges will be trimmed after fitting the skin. Also there will be some paint touch-up to do, mainly on cut edges.

Riveting the rib stiffeners is likely the easiest riveting for the entire project. The bench-mount squeezer makes it a breeze. I fabricated a bracket mount for the narrow yoke which came with the squeezer kit, in order to fit inside the smaller lightening holes.

The rivets themselves are pretty consistent. Important to keep the work square to the dies. I have marked just a few to possibly drill out. I will try to get my EAA Technical advisor in soon to check my work and talk about tolerances.

Here's a link to a short video which hits the highlights:
https://youtu.be/BjzkMHSgAf4

  Nov 16, 2021     prep/paint/rivet       Category: Wings

Prepared the ribs and stiffeners for paint by first removing ink and residue with acetone, then washing with dish soap, and then scrubbed with Ekoetch 2:1 using medium Scotchbrite pads.

The paint is Ekoprime diluted 10% with distilled water and applied using a HVLP electric sprayer. Ekoprime settles in the can quickly and needs to be stirred often. A solid sludge will form in the can after just a day or so.

The weight of the paint adds an additional 4.35% or so. This was calculated by weighing the nose ribs before and after painting. I'll repeat this on other wing parts to see if this holds true.

Practiced riveting using the bench-mount squeezer from aircraft-tool.com. Made some practice pieces which were riveted, drilled out, then riveted again.

Riveted rib stiffeners to nose ribs. The bench-mount squeezer gives consistent results.

Here are a couple of short videos which highlight the steps:

https://youtu.be/MGYRM3ycstU
https://youtu.be/h5hzgzNQvxM

  Sep 23, 2021     Deburring       Category: Wings

It takes time to deburr the ribs and stiffeners. Partly it's learning techniques, going over the pieces several times until they are consistent. Partly it's summer. But this marks about a year on the project. Maybe pick up the pace a little?

Before deburring I needed to form some new pieces to replace defectives. Mostly cracks created when pressing the lightening hole flanges. Now I realize I should have deburred/smoothed the lightening holes before pressing the flanges. The fly cutter did leave some roughness. Smoothing before pressing the flanges would have stopped the cracks.

Probably a point in favor of the router method of cutting lightening holes, since the router cuts more smoothly. But the fly-cutter method has certain advantages. At any rate, other builders would be wise to smooth their lightening hole edges before flanging since the metal gets stretched when pressing the flange.

Also, part of the process of prepping these pieces was to check and fine-tune the flanges to 90 degrees and tweaking for maximum flatness/straightness. It occurred to me that if I have to bend things to make them fit upon assembly, then I might be inducing or storing stresses in the structure. Better to minimize that sort of thing by making the pieces as straight as possible to begin with.

Not satisfied with deburring tools. They create a beveled edge on drilled holes if enough pressure is applied to remove the burr. That amount of pressure would also cause the tool to sometimes catch and create a little nick. So I adopted the strategy of going over the pieces lightly, with just enough pressure to remove some of the burr bot not enough to cause a bevel or a nick.

The real deburring was done by Scotchbrite wheel, a few different grades of Scotchbrite pads and 320 grit sandpaper. The Scotchbrite wheel works fast with little effort. Even some of the lightening hole edges are reachable by the wheel. But the bench grinder needs to be respected since it can grab your piece from you and throw it across the shop. Getting close to edges and into tight areas I used a small rotary tool and Dremel wheels, and also cut Scotchbrite pads to fit onto a hand-drilll mandrel.

My EAA Technical Counselor paid a visit and said it was good, though he found a few tiny lips and curls to be smoothed. A fingernail will find the burr where a fingertip will not. The noses of the nose ribs will be removed, and the fore/aft edges of ribs will be cut to length upon assembly, so those edges are not smoothed.

After this, the next steps will be: clean with soap to degrease - etch with Ekoetch - light coat with Ekoprime.

Youtube video to show progress:
https://www.youtube.com/watch?v=uFzPv1zLK2A

  Jul 11, 2021     Rib stiffeners       Category: Wings

These are the steps I took to make the rib stiffeners:

1. Cut the 1 inch blanks on the table saw using a sled and stacked rough cut pieces of aluminum.

2. Trim the blanks on paper cutter. There are five separate lengths and as many as 36 each.

3. Make five drill guides from 1/2 inch aluminum bar stock from hardware store. Cut the bar with jig saw and refine the ends with disk sander. Make a jig to hold the piece and drill the holes. Add nails as jig pins and insurance. Add a slight chamfer to each hole to aid the drill guide.

4. Stack six or eight blanks with the drill guide in the jig and clamp together. The jig rides freely on the drill press table and the drill guide does the work of alignment. Add the nails again as jig pins as insurance.

5. Use the disk sander to cut the angles into the stack of blanks.

6. Use a simple bender to form the angles. Made from MDF and 1/8 masonite. A 10 degree angle is cut into the fence/shoe/ clamp. The 1/8 material brings the bend to the center of rotation. A piece of aluminum under the shoe serves as a 1/2 inch stop. Three nuts and washers are torqued down to clamp it together.

7. Using the drill guide and cleco-clamps, measuring from the spar-ends of the ribs, drill the holes in the ribs. “Left” and “right” ribs use the same drill guide, just rotated 180 degrees.

8. Randomly cleco ribs and stiffeners together to check the fit.

See Youtube video for all steps in detail.
https://youtu.be/QVNxnR8ypY8