Vertical Stabilizer, Epoxy On Vacation

Looking forward to giving my epoxy skills a rest. I'll be focusing next on the center wing sections, so it will be awhile before I'll need to indulge again.

Now that I've completed the rudder and horizontal stabilizer, the vertical stabilizer should be a breeze, right? Well, yes, it was getting easier.

Garage tech indeed.

Fitting the cross braces amounted to aligning the foam with small pencil marks and using my thumbnail to score a line. Cutting with a bare hacksaw blade, a hair oversize, then bringing down to size with a 100 grit garnet paper sanding block.

As learned previously, I layed-up the short brace pieces of fiberglass tape first, then glued the longer pieces over them. I also made use of the microballoon filler after the initial gluing. Also, paste waxing the melamine work surface worked like a charm in resisting any stray epoxy.

The top and bottom are coated with epoxy to resist the eventual melting effects of the Dacron covering chemicals.

High tech, it ain't.

Holding off on drilling holes until ready to assemble.

Hanging from ceiling makes placing fiberglass tape much easier.

Horizontal Stab and Always Time to Do It Over

Remember that expression, "Never time to do it right, but always time to do it over?"  Fits my experience with the horizontal stabilizer. After days of cutting ribs, gluing, installing and fiberglass-epoxy layup, I was not thrilled to learn that I'd oriented the rear tube 90° out of position:

That bolt in the foreground should be 90° clockwise. Doh!

One thought was to re-drill the tube, but that meant having 'extra' holes, and I didn't want to chance compromising the strength of the part. I decided to cut the foam at each rib about 1 inch from the tube, then drill out the four rivets on one end. That way I could separate the tube, clean it up, re-orient it properly and Bob's your uncle, fiberglass it back almost as good as new. As long as I had it apart, I added vinyl tape to the sleeves for a better fit, too.

Surgery complete, where are those sutures?

Post-op, patient recovering nicely.

Lessons learned:

1. Fiberglass tape sequence matters. Take overlapping into account.
2. My epoxy usage comes out to about .275 grams per lineal inch of fiberglass tape.
3. Gravity is not your friend. When doing a vertical layup like this, be sure the tape overlaps some to help hold it in place. I found that blue painters tape can be helpful.
4. Use a red rag like in the image above to keep your head from being drawn like a magnet to the aluminum (even though both are theoretically non-ferrous).

Uninvited Flying Friend

While in the garage, working on the horizontal stabilizer, I caught something out of the corner of my eye that was out of place. What I assume was an escaped pet parakeet.

Unexpected volunteer.

He didn't mind handling, and didn't try to fly away when gently encouraged, so I placed a Facebook post in the local neighborhood group looking for anyone with a lost pet matching his description.

Pretty lethargic and probably hungry.

There were a few replies, some having checked with other bird owners, but no luck. In the meantime, I picked up an inexpensive cage and some bird food for his expected day or two sleepover.

Turns out she had quite an appetite.

In the end, we had a local bird person that was willing the give her a home. Last we heard, she had a much bigger cage, a new name (Sapphire), some other bird friends and quite a talkative streak!

Pining for the fjords, no doubt.

Parts, Rudder and Guard Dog

Temporary bolt aligns parts for drilling.

Never succumb to the temptation of removing drill shavings by hand from the spindle while it's moving! Something I learned the hard way about forty years ago.

The component parts collection is growing (below), so I decided marking each and every part with a drawing page number and ID, would help later on.

Marking parts will help later, right?

While weather still permits, my unheated, one-car garage makes an excellent place to do epoxy work. Especially since my wife prefers not to have the house at a temperature that curing epoxy likes - 80° F. 

Guard Chihuahua keeps unauthorized insects out of the garage workshop!

Clear shipping tape keeps epoxy from sticking to the work surface. In the image below you can see my solution to the problem of needing a small, light-weight clamp for the foam: a couple of pieces of sawed off hardwood shim and a random carriage bolt with two nuts.

I later discovered that paste wax applied to the melamine work table surface works well for keeping epoxy at bay.

Gluing rudder braces and ribs with 'shim' clamps.

Fiberglass tape and epoxy layup complete. Some lessons learned:

1. Rough up aluminum-to-glue surface with 100 grit sandpaper all the way around the tube before gluing the ribs and braces.
2. Let the continuous fiberglass band overlap by about an inch. This keeps gravity from attempting to detach it from the foam.
3. Wear breathing protection and gloves if you're sensitive to epoxy. I discovered that I am, probably from working with it over the years.
4. Use microballoon filler mixed into the epoxy to approximate a peanut butter consistency. Works nicely to fill gaps that are inevitable when making non-precision cuts with a handheld knife or hacksaw blade. Only regular epoxy for the fiberglass tape.

Rudder almost ready for covering.

 

Rudder Rib and Brace Assembly

 

The aluminum rudder frame has been acetone-cleaned, 80 grit sanded and re-cleaned in preparation for Aeropoxy attachment of ribs and braces. Clear shipping tape was used on the table to prevent sticking, though I've read that two coats of paste wax on the melamine surface will yield the same effect.

Dry fit prior to cleaning

The foam is easily sanded by wrapping sandpaper around a tube to create the groove needed to mate with the rudder torque tube and trailing edge tube.

Making Multiple Parts

To increase efficiency (and decrease boredom), some changes are needed when making lots of copies of the same part. In this example, the Strut Fixture (reference B4W5) requires thirty-four copies.

The normal procedure for one or two-off parts is to individually measure and mark each part, center-punch all holes, manually set the x/y coordinates on the drill press table once the part has been clamped in the vise and drill. Follow that by grinding, hole deburring, hand-filing and hand polishing with a ScotchBrite pad. However, that all gets a bit tedious after the first five, twenty or more parts.

My solution involved setting up a simple backstop guide on a wooden table that I clamped into my drill press vise. A chunk of walnut and oak that were laying around were clamped in place and a toggle clamp screwed down to hold the work in place.

With the 6061 aluminum being a relatively soft metal, the lack of a center-punched hole did not prove to be a problem. It doesn't hurt either that the designer allows for a generous 1/16" tolerance. Also, close examination of drilled holes shows a slightly triangular shape - evidence of a drill chuck taper/quill runout problem that I need to fix some day. Anyway, this method made pretty quick work of the drilling of the 104 holes (left)

The next step required making a 3/8" radius on the four corners. I started by clipping off a small amount of each corner with the band saw (one part in each hand, alternating and flipping), then grinding a smooth curve on the grinder.




















I forget to mention, I used a small flat file after the hole drilling operation to knock off any burrs, allowing the part to sit flat on the grinder table.

The next step was to hand-file the burr created by the radius grinding, knock off the burr around the radius and smooth the grind marks a bit.

The final smoothing and polishing was carried out on the drill press using a ScotchBrite aluminum oxide wheel at about 1,500 rpm.

There, 34 pieces. Almost time to go over the pre-flight checklist.

Parts Fabrication - Tail and Wing

That virus that's going around has slowed things down a tad - that and helping my wife survive after she shattered her right arm/elbow in a fall. When I'm not making meals, doing laundry, cleaning, dressing or bathing my wife, doing the finances or working my regular job, I'm darn sure working on the Bloop!

The primary focus the past two months has been small part fabrication for the tail and wing: