Spar Party

[Chris In Milwaukee]

Started laying out the main spar tonight, and dug out the bar stock I got some time ago. I forgot how much I bought, so wanted to make sure I had enough.



I had the spar blanks end-to-end and got the tape measure out. Starting from the tip end, I laid out the spreader locations and lightening holes.



I put the the splice plate in place, then started thinking ahead as to how all the pieces fit together. Something felt a little off, though, so I went upstairs to the computer and gave the CAD measurements another glance. Glad I did because I had the spar blanks reversed!

So I got my can of Sharpie eraser out, cleaned things up, flipped the spar blanks, and then remeasured. All came out perfect afterward.



Next task was to match drill all the end plates. I was snapping drill bits left and right. So I slowed down the drill a bit, and also found the deck was about a half degree out of square. I squared everything up, and chucked the drill bit up so it was shorter, with a lot less flex. I didn't break any after that.














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[Chris In Milwaukee]

Got the rest of the attach plates deburred and started laying out the spar caps, spacer bar locations, and spar cap splice locations. Started by drilling a clecoing the attach plates in place so I had a starting point from which to measure.





Then I measured from the tip end, and measured back to get the spacer bar and lightening hole distances correct.



Knowing where the rivet holes are helped to determine where the spar cap splices are. The spar caps are full-length on this wing, not stepped. There is a two-foot overlap between the inner and outer spar caps, creating a wide splice area.



Now that I know how long each layer of the inside spar caps will be, I can get them trimmed and make the outer strips. Then time to match drill the caps


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[BTAZ]

I can't see it in your photo, but make sure the spar web goes all the way to the tip of the attach fitting. The spar is then contoured to fit the outline of the fitting. I know that has "bitten" people before.

[Chris In Milwaukee]

Yes, that one completely *did* bite me, as a matter of fact. I cut the spar webs a bit short, to the back edge of the plate instead of all the way out, having the exact problem you described. I was going to redo the spar webs, but I decided to call Bob first instead of wasting and expensive piece of .032 material. He said it was no problem putting a filler plate in there, although he did give me a fair amount of crap for forgetting to do so.

[Chewie]

Knowing where the rivet holes are helped to determine where the spar cap splices are. The spar caps are full-length on this wing, not stepped.

Out of curiosity, what is your rib spacing? The Patrol uses 12.25/12 spacing, I ended up creating a special 1.021x ruler to simplify some of the measuring.

[Chris In Milwaukee]

It's the same. I may come up with a similar jig, however since I know the spacers are 6.125" apart, it becomes easy to set a rivet fan for the necessary distance between them. I suspect it's comparable to your device.

[Chris In Milwaukee]

Don and I set up and drilled a couple of reference holes on the main spar cap strips to get them lined up. We then set them up and match drilled the top and bottom pair on the front of the main spar. I'll be using them as templates to match drill the back set. The #30 holes you see right now are just where the dividers and wing ribs will go. Still need to drill the other holes between them ~1 inch apart, and then opened up to #21. The spacers are 6-1/8" apart, and then I set the rivet fan to fill in the middle at equal distance.








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[Olm]

Hi there. How do you call this device?

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[Chris In Milwaukee]

It is called a "Rivet Fan" or an "Adjustable Rivet Spacer".

http://www.aircraftspruce.com/catalo...clickkey=23991

It's a great tool! It spaces the rivets equally from one another between two points.

[Olm]

Thank you! I also find it very useful, especially after marking ribs and rivet holes on my first cap strips. Thinking of buying it.



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[Chris In Milwaukee]

135 holes going once... Three more sets to go, using this one and the next set as templates for the two to follow (top and bottom). And these are just pre drilled to #30. I'll open them up to #21 in place when ready to fasten them to the web.




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[Chris In Milwaukee]

I finished drilling the long parts of the cap strips last night, front and back, for the main spar. Now to cut the short ones and get them marked and drilled. You may recall that the caps run all the way to the end on my wing.





Group shot of the long pieces.



Short end to go.



I've had a work project that has slowed me down a bit, but hopefully I'll gain more momentum shortly.


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[DRLPatrol]

....

After hauling up the sheet of 4' x 12' x .125" from the basement, I covered the one uncovered side with some plastic sticky sheet from Menards that one would buy to stick on carpet and other floors. You might find these on stairs or high-traffic areas when you're visiting a home for sale or similar. It was a good way to protect the sheet from the saw as I was cutting. (Note to self: when buying metal, be sure to ask the supplier to cover *both* sides). Don is getting the air bubbles out....

Word of warning.
When I first read this I thought it was a great idea. I had just got a good deal on a couple 4'x12' sheets of .025 that were not covered so I went to Home Depot and got 2 rolls of Surface Shield brand film. I even tried a small section first and I could get it right off. Today, 3 months later, I spent half an hour getting it off a little scrap about 2"x4". I'm guessing different brands use different adhesives.
Still think it is a good idea but we need to figure what brand to use.

Doug

[Chris In Milwaukee]

Thanks for the warning . So far, so good, but we'll see in a few months!

[Chris In Milwaukee]

After a couple months off due to work, I found some inspiration to get myself back down in the shop today. Had to get things cleaned up and organized so I could get started again.

Today I cut and match drilled the spar caps that go to the end of the spars. Note that the Expedition spar caps go all the way to the end, and have a two-foot overlap/lamination 10-12 feet from the root.





After positioning to allow for the kerf, I placed a sacrificial piece of wood on top to keep the the blade from grabbing the piece and bending it. I haven't bought a blade meant for aluminum yet, but the carbide will do just fine. This just holds everything still.









Getting the guide marks set up and aligned:



Getting the hole spacing right:



Drilled a few hundred holes in everything:



Everything lines up nicely:



You can't really see the splice in the photo, but it's there, and looks great:



Next step is to cut the dividers.

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