Spar Party

[Chris In Milwaukee]

Cut all the spacer bars this evening. What you see is actually double-stacked, with both the front and back parts all together on the front side.

I measured the distance between spar caps, then set a stop block so each is the same length. They are mainly 0.25" x 0.5" 6061 bar stock. I did use some 0.125" x 0.5" where I needed to layer them for special cuts.





The spacer bars in place and trimmed where necessary for angles.


















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[Chris In Milwaukee]

Got the lightening holes cut in the main spar web. Low and slow is the way to go with the fly cutter.










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[Chewie]

Did you happen to weigh all the blanks?

[Chris In Milwaukee]

I did weigh the ribs some time ago. I'll see what I can dig up. You talking about the ribs? Or all parts?

[Chewie]

No, I meant the lightening hole discs.

[Chris In Milwaukee]

Oh sure, sorry about that. I misunderstood!

447g, 15.75oz. Almost a pound

[SpainCub]

Congrats Chris, and a big thank you for taking the time to share with such great level of details.

Quick question If I ma, I know your building with greater GW... what did you change in your spar from the original plan? I might be following your steps in making some changes, but for a different reason... build time...

[Chris In Milwaukee]

My pleasure

There's more than just a bigger spar with this wing. The whole thing is bigger. It's about two feet longer, about 10 inches wider in chord, and about 10% thicker.

Conceptually, though, the biggest difference in the spar is that the caps go all the way to the end instead of being "stepped". Bob suggested it would make it a heck of a lot easier to manufacture (he was right). But it does add weight.

The limit to most aluminum is 12 feet in length. Because my wing is over 16.5 feet long, I had to take some cues from AC43.13-1B for spar cap splicing. So I have a two-foot overlap in the spar caps between the 10-foot and 12-foot mark (essentially a mechanical lamination) to ensure I have adequate strength at that location.

I don't "need" all that metal out there toward the tip, but from a manufacturing standpoint, it means that every rib, attach angle, spacer bar, etc., can be the exactly same.