Continuing to Level Right Wing Skeleton

January 30, 2011

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Well, I keep chugging along on this right wing skeleton.

Except by “chugging,” I really mean “don’t seem to be making any progress.”

First thing, I wanted to free up one of my clamps, so I drilled and bolted the outboard rib’s special angle to the support of my wing stands.

Here’s my first mistake. I was really careful to line everything up the first time so I wouldn’t have to notch the support angle to accomodate the skins (which overhang the spar end). I didn’t remember this on this go around, so now that they are bolted in, I’m going to have to notch the supports.

No big deal, but just annoying that I forgot.

A couple of 1/4" bolts will do just fine here.

Unlike everyone’s very pretty lower outboard support, I made an ugly one.

See? More ugly. (Functional, though).

After getting it clamped to the rear spar, I used my air drill and a 3/8″ bit to drill a hole for a 3/8″ bolt.

I'm not sure why I took this picture.

Here’s the inboard rear spar support.

Inboard rear spar support.

And the outboard rear spar support.

I'm using the clever clamping trick that many builders before me have used.

Then I spent some time leveling the spar to 0.0°. After that, I dropped some plumb bob’s and carefully measured from the plumb bob string to the top of the rear spar. The outboard side showed 2 1/4″, and the inboard side showed 2 3/4″. A half inch of twist doesn’t sound like a lot, but of course I wanted this to be perfect.

I chose to split the difference. I pulled the outboard edge of the rear spar down (aircraft axes) and clamped, then pushed the inboard side up and clamped.

Here’s my problem. It seemed like I really had to push the spar to get it exactly where I wanted it, and there was plenty of (what I’ll call) springback force.

After clamping the rear spar in place, I remeasured the spar, and it was now no longer square. (Of course, moving the spar edges moves the ribs, which twists the main spar.)

I releveled the main spar and really tightened up the clamps. I’m now level with the main spar and within 1/32″ on the rear spar.

I’m sure I can get it even closer, but I’m worried about how much force I’m holding with the clamps.

Here's a picture of just the skeleton, squared up within 1/32" (I want to improve this).

To see if I was close with the skins, I clecoed them on. They fit great.

Another picture with the skins clecoed on.

Anyone have any thoughts? Have any other builders seen a lot of force required to straighten the wings?

Jan 31st update:

Oh man, I love the forums. bkthomps had the following to say:

did you put skins on yet? you’re on the prepunched kit like i am, the twist thing is a null issue- once you cleco both sets of skins on, it will be dead on, other than the slant of your stands/garage floor.

and

I followed jamie painter’s blog and decided not to spend countless hours with the lasers/bobs/etc that I had and I just built the wings doing only the basic level checks and a string down the spar length to get rid of the droop, after finishing them, they are dead level in every dimension, if that helps w/ encouragement.

1.5 frustrating hours. (After talking with bkthomps, I am much happier. I’ll push on now and verify straightness after clecoing both sets of skins on. Wuhoo!)

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Drill Press!!!

April 26, 2010

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After the other day’s sucesess with fixing my dimpling errors, I need to run to the aviation department of my local big box store and grab a 6′ long 2×8 to cut in half and some hinges to make my homemade bending brake.

Instead of making it there, I had to stop by Harbor Freight to grab this drill press. Normally $90, I got a coupon in my email for $49.99. I can’t pass that up.

The box is a little damaged, but everything inside was okay.

A blurry shot of me starting to assemble.

Another in-process shot. This is surprisingly nice quality.

I had to install the little yellow knob to help open the lid. After this shot, I moved the belt down to the lowest speed (650 RPM, which is still pretty high).

I also bought these cool long pliers. I didn’t need them for the airplane specifically, but rather my girlfriend needed them to help clean out a hair clog in her sink in the bathroom. Good excuse to buy tools, and they don’t get accounted for on the airplane budget. Wuhoo!

Pretty nice pliers. I have a feeling I'll be using these often.

In the same email for the drill press, they wanted to sell me a (normally $15?) drill press vice for $7.99. Who am I to say no. I was a little disappointed that this one was only 2.5″. There were 4 sizes above it that looked nicer, but they exceeded my value-for-the-money threshold.

Drill press vise, also had via sale.

The allen wrench the drill press provided to help with assembly got filed away with my other extra allen wrenches.

You can see I am a little short on allen wrenches.

Back to the drill press vice. After a little cleaning, this thing doesn’t look half bad.

I'll have to find some bolts to mount this. Except I'll have to move it for different pieces. Maybe I'll just use clamps.

After a few minutes of trying to figure out where to put the drill press. This is what I settled on for now.

Notice I'm drinking sunset wheat tonight. Mmmm.

No hours tonight on the airplane, just tool assembly. Maybe I’ll grab some wood in the next few days to continue on the right elevator.

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