Prepping and Priming Some Rear Spar Components

November 20, 2010

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Oh man, I’m furious. I just spent some time doing a huge writeup for this post, and when I clicked, “Post”, it deleted all of my text.

Grrr.

I’ll try to rewrite it, but it is going to have a little bit of an annoying tone.

Anyway, I managed to get out in the shop today for a little. I had previously gotten all of the doubler plates and reinforcement forks matchdrilled to the spar, so today was all about prepping and priming.

Here’s W-707F, which sits on the back side of the left spar. I’ve deburred and scuffed it; all I need to do now is dimpled the outboard holes in preparation for attaching it to the spar and outboardmost rib.

I love scuffed parts. They hide my fingerprints.

Here’s W-707E, which is the doubler plate that sits on the aft side of the rear spar, right in the middle. I’ve marked the cutout for the aileron push tube. Where’s that step drill?

Yup, here you can see my fingerprints.

I started looking around for my stepdrill. I spent good money on that stepdrill, but I couldn’t find it anywhere. On the workbench, under the workbench, on the floor, in some other shelves. I thought maybe I put it in some other tool’s case, so I got out the dremel tool, multifunction tool, jig saw, circular saw, etc. Nothing.

I even accused the girlfriend of selling it on the black market to fund an bottle of Opus One. She insisted that while she thought about it, she didn’t.

I remember putting it in this old small cabinet of drawers (that my dad gave me when I graduated college…thanks, dad!). I spent about 30 minutes just pulling out each one of these drawers, looking for my step-drill. Grrr.

After continuing to work on the airplane (angrily) for another 30 minutes, I finally found it when I came back to the drawers and opened them with my other hand. Apparently my sausage fingers (they’re not, I promise…I’m just mad) blocked my view of the stepdrill, which was right behind the lip of the VERY FIRST DRAWER.

Ugh.

Anyway. Back to the rear spar. This is the forward side of the left spar, outboard end. I’ve deburred the edges of the whole spar, and now I’m deburring all of the holes I drilled.

I always scuff the areas where there are holes I've drilled and deburred. Helps me keep the "did I do this already" time to a minimum.

Oh yeah, I managed to get a couple parts primed today. Like riveting, I always feel like it is a productive day if I can prime some things.

You can also see my primer of choice, Napa 7220.

Here’s the other side of those pieces (after plenty of drying time).

I like priming.

Back to the spar, more deburring holes and scuffing.

I'll finish scuffing the whole spar when I get closer to priming.

This is the middle of the rear spar, around the aileron pushtube hole. More deburring and scuffing.

Jeesh, there are fingerprints everywhere.

Finally, I brought the two primed parts back inside.

Primed parts on the workbench always means we're getting close to riveting. Wuhoo!

After this was about when I finally found my step-drill. I was too angry at myself to keep going, so I headed inside to some grilled chicken, jasmine rice, and creamed corn. Mmmm.

1.5 hours

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Drilled Wiring and Conduit Holes in Ribs

October 3, 2010

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Alright, a little off-topic, but I have to talk about food for a minute. Friday night, I got home from a very hard day at the office, and my wonderful girlfriend announced we are having steak (see? I told you she was wonderful). I also nailed the cooking times on the grill.

Also, that is stuffed squash and zucchini. Amazing.

Then on Saturday, she announced we were having “the best chili you will ever have” for our football date (see! amazing!).

Vandy lost, UNC won, but more importantly, the chili was amazing. Let me know if you want the recipe, but beware, it calls for a cup of strong coffee and a bottle of dark beer. Crazy good recipe, though.

Mmm. Chili.

Okay, back to the airplane.

After a big day on the house, I decided that tonight was all about the ribs.

I scoured a few build sites for ideas, but I basically need to come up with wire routing for the wings. I’m going to use tables to stay organized.

Wiring Requirements
Left Wing Pitot Total Pressure (the “pitot” part of the pitot tube)

AOA Total Pressure (…angled down)

Heated pitot leads

Landing Light (wingtip)

Taxi Light (wingtip)

Nav/strobe lights (probably AeroLeds)

Van’s Stall Warning (can’t decided between this and AOA for stall protection…also, is this left or right wing? Can’t remember)

Right Wing Landing Light (wingtip)

Taxi Light (wingtip)

Nav/strobe (probably AeroLeds)

Autopilot servo

Wingtip NAV antenna? (maybe)

So I clearly need more stuff in the left wing than the right wing, but I decided to drill everything the same way.

As far as the ribs are concerned, there are two flavors of ribs with respect to the tooling holes as provided in the ribs from the factory. (They talk about flavor of ribs in the manual, too, but they are talking about part numbers and flange orientations, I am talking just about the tooling hole arrangements.)

There are 14 total ribs.

The first 11 ribs (counting from inboard to outboard) have three tooling holes in the front part of the web (just behind the main spar). The top and bottom holes are small, and the middle one is 7/16″. I decided (based on a lot of other builder’s sites, and the guidance from the Construction FAQs from Van’s that I’ll enlarge the top and bottom holes to 3/8″. (I’ll get to the other flavor of ribs in a little.)

Here's a before (front) and after (aft).

By the way, I used my brand new #4 Unibit to drill these. I stared at the Unibit from harbor freight (~$15) for awhile, and then decided this is probably something I am going to use a lot and appreciate if it is higher quality. I sprung for the $42 one from Lowes-Aviation.

I think it goes from 3/16" to 7/8" in 1/16" increments.

So, after knocking all of the right wing ribs out, I gathered up the left wing ribs, labelled their positions and orientations, and did those 3/8″ holes, too.

Looking good so far.

The next flavor of ribs are the three outboard ribs (I’m missing one from the picture, look further down.)

They come with one hole in the forward part of the rib. I decided that I would just enlarge that hole to 3/8″ and not try to duplicate all three holes. (The construction FAQ sheet referenced earlier only talks about enlarging tooling holes in this location, not creating new holes.)

2 of the 3 outboard ribs done.

Here's the outboard most rib (upside down from the rest). Van's wants you to leave this one now for help in aileron alignment. I can deal with that.

Now, back to the construction FAQ. Van’s does let you drill a brand-spanking-new 3/4″ hole.

An additional hole may be drilled in the lower 1/3 of the rib between the large lightening hole and the next one aft. This hole may be up to 3/4” diameter to accommodate our wiring conduit (DUCT NT 5/8-50) or Bushing SB750-10 (5/8” I.D.). The conduit is light and flexible. It’s .810 “ outside diameter means that when snapped into place, the corrugations hold it from slipping out. If using the conduit, a dab of fuel tank sealant or RTV should be put on the conduit at each rib to prevent the conduit from being cut through over time from vibrations.

Sweet. I created a makeshift template. and started marking the center of the hole.

(Some people go crazy with this alignment. After reading a lot of other experiences, I reminded myself that this is a flexible conduit hole. They don’t have to be perfectly aligned. Although, after everything was all said and done, they were pretty darn aligned.) Don’t waste a lot of time here on a special tool. Cardboard worked great.

Fancy-schmancy hole alignment tool.

So, after punching 28 3/4″ size holes in both the left and right wing ribs, this is what I ended up with. (Really 3 flavors.)

11 inboard ribs each side with 3 holes and a conduit hole, 2 outboard-ish ribs each side with 1 hole and a conduit hole, and 1 outboard rib with 1 hole (that needs to be enlarged) and a conduit hole.

Of course, I had to lay out all the right wing ribs for this completely unnecessary picture.

Tada! (The left ribs are done, too, but they are stored back on the shelf.)

Okay, now that I’ve drilled the maximum amount of approved holes in each of the ribs, let’s figure out where this stuff should go.

Wiring/Conduit Plans in Ribs
Left Right
Rib # 3/8″ 7/16″ 3/8″ 3/4″ Conduit 3/8″ 7/16″ 3/8″ 3/4″ Conduit
1 Pitot Pitot Heat, Stall Warn AOA Taxi
Landing
Nav
Strobe
Servo VHF? Taxi
Landing
Nav
Strobe
2 Pitot Pitot Heat, Stall Warn AOA Taxi
Landing
Nav
Strobe
Servo VHF? Taxi
Landing
Nav
Strobe
3 Pitot Pitot Heat, Stall Warn AOA Taxi
Landing
Nav
Strobe
Servo VHF? Taxi
Landing
Nav
Strobe
4 Pitot Pitot Heat, Stall Warn AOA Taxi
Landing
Nav
Strobe
Servo VHF? Taxi
Landing
Nav
Strobe
5 Pitot Pitot Heat, Stall Warn AOA Taxi
Landing
Nav
Strobe
Servo VHF? Taxi
Landing
Nav
Strobe
6 Pitot Pitot Heat, Stall Warn AOA Taxi
Landing
Nav
Strobe
Servo VHF? Taxi
Landing
Nav
Strobe
7 Pitot Pitot Heat, Stall Warn AOA Taxi
Landing
Nav
Strobe
Servo VHF? Taxi
Landing
Nav
Strobe
8 Pitot Pitot Heat, Stall Warn AOA Taxi
Landing
Nav
Strobe
Servo VHF? Taxi
Landing
Nav
Strobe
9 Pitot Pitot Heat, Stall Warn AOA Taxi
Landing
Nav
Strobe
Servo VHF? Taxi
Landing
Nav
Strobe
10 Pitot* Pitot Heat*, Stall Warn AOA* Taxi
Landing
Nav
Strobe
VHF? Taxi
Landing
Nav
Strobe
11 Pitot* Pitot Heat* AOA* Taxi
Landing
Nav
Strobe
VHF? Taxi
Landing
Nav
Strobe
12 Taxi
Landing
Nav
Strobe
VHF? Taxi
Landing
Nav
Strobe
13 Taxi
Landing
Nav
Strobe
VHF? Taxi
Landing
Nav
Strobe
14 Taxi
Landing
Nav
Strobe
VHF? Taxi
Landing
Nav
Strobe

*The plans show Pitot tube installation after the 9th rib, or in the same place as the tiedown and aileron bellcrank. It’s going to be cramped in there, so I might move the installation one bay further out. Or maybe two bays further out…I have the holes for it. (Stall warning will go one bay outboard of tiedown.)

Anyway, those are my plans for now, but I’m sure things might change. For one, I need to look more at the tiedown/pitot tube geometry. I think it will be too cluttered in the bellcrank bay, but any further outboard, and the pitot tube might be in the way of the tiedowns (low wing short airplane means tiedowns will be at a small angle.) I don’t want the tiedowns getting hung up in my expensive pitot tube.

1 hour.

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