Alieron cove ribs

[geraldmorrissey]

Finishing up my rear spars and have come across an issue regarding the placement of the cove rib aft of center rib #14. I'm confident I've located the outboard aileron hinge centerline on the spar web correctly. I'm also confident that I have center rib #14 located correctly. However the distance from the outboard edge of the center rib #14's flange to the aileron hinge centerline should be 1.375. I measure 1.75. Ref sheet #2, the wing assembly drawing shows center rib #14 and the cove rib aft of it. The webs of the center rib and the cove rib are planer. I don't know where I've gone wrong. Checked everything over and over, still come up with the same answer. All the other measurements on the spar have checked out so I'm missing something. I have center rib #14's flange pointing outboard, the center rib attach angle flange common to the spar web is pointing outboard. Doesn't matter much if I install the rib on the inboard or outboard side of the attach angle, I'm still to far inboard of the hinge center line. Has anybody here had this issue.
Thanks
Gerry
Patrol #30 wings

[Chewie]

I'll take a look next opportunity Gerry.

[geraldmorrissey]

I should have said "the webs of the center rib and the cove rib are coplaner"
Gerry
Patrol#30

[geraldmorrissey]

Make that "coplanar". Now I'm done.
Gerry

[Chewie]

Ok Gerry I think we're both engineers so let's do this: I believe your measurement of 1.75 is correct, or more precisely 2R-0.25 = 1.792 in from the centerline to the edge of the attach angle flange. I made up the unit R to represent one rivet space on the spar = 12.25/12, and the .25 is half your flange width if using 1/2" flanges.

Basically I believe the callout of 1-3/8 from the hinge centerline refers only to the aileron rib web, not the features on the rear spar. So while the cove rib and center rib are coplanar, I do not believe they are also flush with the aileron rib despite the appearance on drawing 2. That aileron rib has flanges pointing inboard anyway, whereas the center & cove rib flanges are oriented outboard at that location, so right off the bat those rib webs will be offset. So the center and cove ribs are riveted 2R inboard of the hinge as shown on Sheet 6, detail for Sta. E, and the flange extends outboard from that rivet 0.25 in.

Incidentally I put the next outboard cove rib only one rivet space outboard of the hinge with the flange inboard, but I don't see any reason why the exact placement of those ribs is critical. My interpretation of the asymmetric hinge pocket on the ailerons and flaps is to provide enough clearance to get the hinge bolts in. There is one exception where I scrutinized the cove rib attach angle, and that's on the first one (most inboard). I oriented the flange inboard to force the rib web to be flush with the beginning of the aileron, which is located at 104.625 from my datum reference of the inboard edge of the cap strips.

Whew!

[geraldmorrissey]

Thanks for responding Mark. I appreciate your detailed explanation. My 1.75 measurment was done with a 6" scale, combined with tolerance and senior eyes. I'll be in the shop today to digest all this. It's really useful to have a second set of eyes on these issues. I'm confident I can move forward.
Cheers
Gerry
Patrol #30

[geraldmorrissey]

One more thing, does the most inboard cove rib plus the cove ribs on either side of the inboard aileron hinge get a spacer bar? Not shown on the dwg. If so, a spacer bar on the fwd side of the rear spar as well?
Thanks
Gerry
Patrol #30

[Chewie]

I did not use a spacer on spans over a lightening hole. The hinge ones I was just off the lightening hole so I added spacers there, just the back side of the spar.
I made sure to orient my inboard attach angle such that the pocket rib would be flush with the inboard end of the aileron.