26-11 Center Section Lower Doublers question

Okay I'm stumped on this one maybe I just don't get it:

Step 13 on 26-11 has you back rivet on the center section lower doublers which go like so:



Later step 7 in 28-02 has you dimple all of the #30 holes in the forward skins minus a few in the front. The picture doesn't show the #30 holes in the skins that coorespond to the same ones in the main skin you riveted the doublers to in 26-11 but they are there and are #30s. So I dimpled them.

Fast forward to step step two on 29-02. We connect the two half of the front of the fuselage by overlaying the front bottom skins on top of the main skin. When I do that all of the holes mentioned above have already been riveted to a doubler so there's no way to rivet those holes from the top skins through the main skin and then the doubler.

Was I not supposed to dimple the holes in the front skin? It's 40 rivet holes. I can't imagine, especially there where the wings attach that you wouldn't want those extra anchor points right?

My thought is (if I'm thinking correctly) to drill out all of the rivets from the doubler plate, cleco the doubler back onto the main skin with 5/32 clecos (the center of the doubler plate), slide the front and back half together again then pop rivet (when the time is right) the front skins, main skin and doublers. I say pop rivet because those holes lie underneath the bottom flanges of both wing box bulkheads and you can NOT get a bucking bar or backrivet plate in there. I've checked clearance of a pop rivet through the hole and it will fit.

- Kilroy

HA! NEVERMIND!

I WASN'T SUPPOSED TO MATCH DRILL THOSE HOLES!!!!

I misinterpretted Step 2 on 26-10:

(Tri-Gear Only) Match-Drill #30 the F-01483-L &
-R Forward Bottom Skins using the inside corners of
rectangular hole in the F-01484 Center Bottom Skin as
guides.

That was talking about drilling holes where you'll cut out the gear leg hole from the forward skins. I went ahead and drilled the holes around the 5/32 cleco holes. They're #30 right?! AIIGGHH!!!

Okay so a call to Vans in the morning. Best case scenario I 'undimple' the forward skin back to flat... ish and go about life. Or they could tell me to go ahead and pop rivet it all together if there is clearance... or... REDO THE ENTIRE FRONT SKINS! That option is going to suck. Let's hope it isn't THAT.

And I thank you kind moderator for posting my shame RIGHT ON UP on the front page.

Did you at least remember to "DO NOT RIVET" the middle two holes on the F-14140 stiffeners on page 26-11? I'm happy to report that I have emotionally recovered enough that I don't even remember how many pages later I discovered that mistake. The good news with cosmetic issues in that area is that nobody will ever see them. They're on the bottom of the fuselage in the area where you have to crawl under the wing to see. At least that's what I tell myself about some of my less prideful backriveting in section 26. The other good news is that you are rapidly approaching the step where you sit in the fuselage and make airplane noises.

kiljoy said:

And I thank you kind moderator for posting my shame RIGHT ON UP on the front page.

Click to expand...

It's good to get these things out in the open, cleanse your spirit and move on!!

Enjoy your YouTube channel FYI - rants included....

mturnerb said:

It's good to get these things out in the open, cleanse your spirit and move on!!

Enjoy your YouTube channel FYI - rants included....

Click to expand...

Thank you sir!

Heard back from Van's about this issue. Their best options for me are to drill out the main skin and doubler rivets and set them along with the forward skins all at once with cherrymax rivets. The other option is to de dimple the accidentally drilled holes and use filler to cover them up.

I'll be taking the drill out and pop rivet path. I don't trust my ability to get those holes flat enough to make the skins lay nicely. Plus the pop rivets will fit. I have a bag of them from Spruce ready to go and tomorrow we make history! No one else building a 14 has F'd up anything like this before

Okay maybe they did but I'm the first to admin it!

Okay so I've completed the 'fix' of this glorious accident.

Here is a picture of the area in question after the pop rivets had been put in:



You can see the hulking cherry max rivets holding the lower drag fitting in place with the 2 rows of pop rivets on either side.

Now... it was suggested that I use Cherrymax rivets on these locations. I bought a variety of pop rivets to try and fabricated a test setup of ~.114" (the approximate thickness of the pieces being riveted together) to see which one would work. The biggest problem was the space between the main fuselage skin doubler and the bulkhead. Unfortunately cherrymax rivets were too long. Other rivets were short enough, but lacked the grip length. In the end what wound up working best were cherry MSP-42 rivets.

The MSP-42 rivets were also SLIGHTLY too long... just short of 1/8". BUT... once you started to slightly pull these rivets they quickly shortened and allowed the rivet to push easily flush. Only the MSP model was just the right length that you could pull it somewhat, push the rivet in flush, and then on the subsequent pulling it'd tighten up strong and set correctly.

Now you might be saying, 'but those aren't countersunk rivets' and you'd be right. BSPQ-42 is the countersunk version of the same rivet. The problem is that when settled into the hole, the BSPQ rivet was far too long. Even when you started to pull them in an attempt to settle them in like the MSP rivets they'd tighten up in the hole too much before they'd be short enough to push them in the rest of the way.

In the end the rivets set very well and there was no rotation after setting. They're tight, they seat all the pieces together very well... and hopefully won't start shattering apart in 20 years.

I hope this doesn't affect the resale value?!

- Kilroy

I wish mine looked that good.

One good thing about building your own plane: The preflight inspection is really quick. If THAT RIVET (you know the one--it's different on my plane but you know which one it is on your plane) is still intact, then the rest of the plane is definitely fine.