Having a Rib Party

[Chris In Milwaukee]

Finished the aft ribs and started pre-drilling the center ribs for routing.

New band saw blade made for easy trimming of the excess aluminum. Although using a narrow blade is a stinker because it tends to wander. Perhaps some more tension is in order.



Got them in the router table, and life is good.



Had some more helpers in the shop tonight, doing a fine job with the drill press, as well as general supervision of events (guess which ones are the supervisors).





Now all the centers are drilled and ready for routing:





Have to be mindful, though. The .032" ribs have different aft lightening holes than the .025" ones. There's a separate jig/pattern for that hole. Don't screw up!


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[Chris In Milwaukee]

Finished routing the .025" center ribs today, and got about half of the .032" ribs preliminarily routed. The aft hole is different, so when I finish the forward ones, I'll have to jig up for the aft one.





First half of the .032" ribs:




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[Chris In Milwaukee]

With the exception of the two full-length ribs (I ran out of MDF for the routing forms), the rib cutting adventure has concluded! I jigged up the aft holes in the .032" center ribs and got them all cut out.



And then I drilled the flap torque tube holes and aileron cable holes one at a time with the Unibit.



I went back and drilled the same two holes for the false ribs behind the fuel tanks as well.



Now, they're all stacked up and ready for deburring. My Scothbrite wheels should be arriving from ACS any day now.












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[Chris In Milwaukee]

An evening of final deburring of the skinny stuff with the new Scothbrite wheels that came in this week. I've never used the skinny ones before. I like them. Although they don't last very long.








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[Chris In Milwaukee]

Deburrathon 2016 continues. 200 ribs, 4000+ holes big and small.












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[Chris In Milwaukee]

Deburrmageddon 2016 has finished!










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[Peter Bishton]

Chris impressive production Line for the rib construction. They look very uniform.
Peter
4 place plans # 1134

[Chris In Milwaukee]

Routers and solid patterns are the key to everything!

[N3UW]

Very nice work. Moving along quite well. It is a nice feeling when you do not have to pick out metal shavings from your hair every night.

For deburring the drilled holes I ended up investing in a small cordless screwdriver and an adapter bit from Avery. Really speeds up the process and saves the hand for the thousands and thousands of holes you will have. The cordless screwdrivers turns slow enough to not be aggressive like a drill. Mine was something like 60 rpm. Got mine for $9 from ikea.

[Chris In Milwaukee]

It's been a while since I've checked your progress on YouTube. Your wings are assembled now? Now that's progress! I wish I had the luxury of a hangar, but I don't have a need for it just yet. Soon enough, I'm sure!

[N3UW]

Chris,
The Patrol has been paused since last June. Last summer we moved from Colorado to north of Seattle, I had to spend all summer preparing the house to sell and move. We had a LOT of crap and I needed to organize and get rid of a lot of stuff. in the fall we hired movers to fill up 4 15' storage pods (that was after reducing stuff). I packed up the patrol wing and ribs in wooden crates in the pods. We also had to move my mother-n-law out of her place because she was moving in with us. We then bought a 1910 house and a hanger and a business for my wife (she is a dentist). I have built an office in the hanger and a large storage loft suspended from the ceiling. the nice thing is I go to the hanger every day to work out of the office there. My company is back in Colorado but I work remotely. It is a dream to work out of my hanger. On nice days I pull the plane out and go flying for lunch. The enclosed office was a necessity once I got the first gas bill to heat the hanger to 68deg in the day ($300....ouch). I have started now setting up the wood and aircraft shop. I have to build all new benches because they are cheaper to build than ship. I hope to get back to the patrol this summer. The wing is still in the crate. I will post some photos of the hanger soon. Things are starting to slow down just a bit,

[Chris In Milwaukee]

Busy life, to be sure! Sounds like a dream working out of your hangar, as you said. I'm a telecommuter myself, so understand that scenario. Just walking out to your plane and taking a ride when you feel the urge is an awesome thing. What are you flying while you're building?

[Chris In Milwaukee]

The only thing left to do is trim the ribs to account for the spar depth. These ribs were all cut "to the line". The spar calculations are nearly done, so I'll know how much material I need to remove.

[Chewie]

So Chris these are Expedition wing ribs, yes? Would you mind putting a tape measure next to your ribs?

[Chris In Milwaukee]

Sure thing. Happy to. For reference, this is the same airfoil as the Patrol. It's 15% longer than the stock one, and about 10% taller (that's how the math worked out for the size change).







If you need bigger pics, let me know. Hopefully they're readable.


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[Chris In Milwaukee]

I trimmed the ribs to length today, which required a bit of massaging of the routing jigs. The nose, center, false, and long aft ribs were all shortened by 1/4". The centers on both ends.









When I first started going down this path, I knew how big the wing cross section was going to be, but I hadn't yet calculated the spar sizes. So to avoid analysis paralysis (you techie types know what I'm talking about), I created the forms "to the line" where the spar web line was on the master wing panel. I finished the spar calculations this week, and trimmed the ribs back to accommodate.

Interestingly, the spars for the Expedition, aside from being longer, use the same size and collection of spar caps that the regular 4-place Bearhawk does (.125" x 1.25"). References tell me that the stiffness of an I-beam increases with the cube of its height. And the Expedition spar is 2" taller than the regular 4-place spar. So it all makes sense. The aft spar caps will be double-stacked, unlike the 4-place which has only one layer. Because there is an extra 10 inches of chord to deal with, the chord-wise moments are going to increase substantially, especially with larger flaps and ailerons.

Because the shear on the main spar is greater at this height and weight, there will be more spreader bars and more frequently, running from the root to the tip, breaking up the shear "boxes" into smaller chunks. More to come on this.


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[Chris In Milwaukee]

Routed out the rib routing jigs for flanging the lightening holes today. Getting ready to start bending ribs. My favorite thing!







Also created the hardwood bending form for the edge flanges. Made from solid oak, they'll last a long, long time. I bent a lot of ribs on the last set I created.







The circles you see traced into the top will be routed out on both sides so the lightening hole flanges will have a place to go since they'll be done first. If you remember the last set of ribs I built a while back for the 4-place, I routed notches in the edge of the bending form for the flutes, which I'll pound in with a hammer and the edge of a screwdriver. More to come there.


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[Chris In Milwaukee]

Gave the first rib a press today to see how the routing went. Had to go a little wider to make sure the flange was wide enough. 12-ton press did an admirable job, but just not enough oomph. Going to replace it with a 20-ton unit tomorrow and hope for better.



I'm lucky to have a friend who's a dairy farmer and he gave me a couple of chunks of cow mat that he uses for his critters' comfort. The price was right (free) and is the perfect density and durability for pressing these ribs. Coupled with a couple sheets of steel and we're in business.




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[N3UW]

very nice write up. Glad you are going with the rubber press method. As long as t rubber is dense enough and the press is strong enough, you will love it. Your first ribs look great. The air assist 20ton jack from harbor freight was also a great upgrade for me. makes it go really fast. Keep us updated.

[Bcone1381]

The Rubber Press Method is an Industry Best Practice for scratch builders. It would have saved me at least a month, and the results I sense are flawless.

[Chris In Milwaukee]

Got all the aft and nose rib lightening holes flanged today with the press. Looking good!





Don "Pressmaster" Holloran at the controls.



Apparently it's a precision operation, with everyone keeping a very close eye on things.




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