I started out by tracing the rib templates from the full-scale drawings found on A14 and drew the bulkheads from page 21-1. I butted R23 and B23 to make it one long rib. The plans purposely separates them so one could do the inside layups of the fuel tank without having B23 in the way.. but I decided to do them as one piece.
My parents came to visit for the weekend, so I put them to work! There is no question I wouldn't be where I am today without their love and support! Thank you guys for everything! ::wipe tear::
The plans say to build a jig table under the spar, and to bond the bottom skin and ribs with micro. I had such a difficult time wrapping my mind around how one is supposed to do that while making sure the ribs were properly positioned and level?! Obviously it is possible, since hundreds of builders before me have done it in the past, and are flying very well... but I decided to do the 1-ply BID layups on the ribs first, install them onto the spar and fuselage, and then install the bottom skin - knowing the ribs are exactly where they need to be!
Here are my parents helping me cut the 1-ply BID that goes on the ribs...
Wetting the 1-ply BID out...
The next day, we flipped the foam sheets over, and put 1-ply BID on the other side...
I left an overhang on all edges to trim later..
After cure, I cut all ribs and bulkheads out with the bandsaw...
To get a nice flush edge with the foam, I took my router table out...
Notice the bearing wheel rides along the foam edge, while the blade cuts the fiberglass perfectly flush with the foam...
One quick pass sanding it by hand to straighten out any imperfections... I purposely left the edges of all bulkheads extra long to account for beveling... I'll show that in more detail later...
Ooooooooo... nice flush edges!
Of course, this had to be repeated for all the ribs and bulkheads... the pic below shows the "rough cut" to separate all the pieces.. I then took each individual piece back to the bandsaw for a more accurate cut...
To cut the fuel passages, I put a thin straight bit in the router...
Here I am testing to see how well it worked as a manual CNC... worked perfect!
So I drilled a hole through the view outlet as a starting point...
And used the router to mill the outlet out...
Also cut the vent and fuel passages...
Taaaaa-daaaaa!
But these cutouts need a flox corner so the foam won't soak up fuel... so I put a rabbet router bit and milled out a 0.5" deep channel...
I then used a dremel cone bit to remove the little bit of foam/micro that was left to get a nice glass-to-flox bond...
Looking good!
For the B23 cutout, I had to use a flat surface grinding wheel to remove the extra foam/micro for a good glass-to-flox bond...
With all the cutouts prepped, it was time to mix up some flox!
I first painted all interiors with plain epoxy...
And then applied flox to all cutouts... I mixed it on the dry side so it wouldn't ooze out...
After cure, I took it back to the router and smoothed all edges...
With the flox corners complete, I sanded ALL surfaces for a good glass-to-glass bond...
Time to install the ribs and bulkheads to the spar! I placed supports under the spar and built foam jigs that held the ribs and bulkheads in position, allowing me to shim each one individually - giving me full control over each pieces' position.
I started out by measuring the B23 and R45 rib locations. The middle part of the spar is straight (no sweep).. so it was easy to locate buttline 23. It also helps that BL23 is where the spar begins its sweep.
I placed the outboard face of B23 on buttline 23 (page 21-7 looks to show this).
R45 is trickier to measure... since the spar has a sweep, BL45 is actually 22.25" outboard of BL23 measured lengthwise along the spar... I placed the inboard face of R45 on BL45 (page 21-7 looks to show this).
Showing the inboard face is at 22.25" along the spar from BL23...
With B23 and R45 locations marked, I butted them up against the spar... I made sure B23 was square with the middle section of the spar...
I also verified that the front end of R23 was square with the right strake R23..
46" (23" left and 23" right)... perfect! I trimmed the fwd BAB bulkhead until I obtained the perfect measurement. (Remember that this fwd bulkhead is not per plans and was added for extra top skin support due to the passenger elbowroom mod of shifting the original BAB bulkhead further aft - this was explained in the previous post - fuselage cutouts).
Can't use a square on R45 since the spar has a sweep. R45 needs to be parallel to R23... so simply measuring from B23 works...
So I shifted the front end of R45 until it was 22" outboard of R23...
With B23/R23 and R45 in position, I then focused on cutting the bevels on DB ends... the templates show where DB intersects with R45.. and pg 21-7 shows the inboard end of DB intersects where B23 and R23 butt up...
So I positioned DB in place and drew the bevel underneath...
Bevel line marked under DB...
I took DB to the bandsaw and cut the bevel... after dry test fitting it and happy with all ribs and bulkheads, I glued all pieces in place with 5-min...
Detail showing TLE (fuel tank leading edge) and BLE (baggage leading edge) connected to R23...
Detail showing DB and TLE connected to R45....
Notice the shims... gave me full control to position each piece exactly where I wanted...
Before using 5-min to bond everything, I made sure everything was perfectly level...
And vertical...
Waterlines all perfectly leveled...
Leading edges leveled....
All pieces bonded with 5-min... perfectly leveled and exactly where they need to be!
I then painted plain epoxy on all mating edges...
Applied a flox fillet to all edges...
I then applied 1-ply BID tape (3" wide) at 45 to all mating edges...
Finally, I peel plied them for a nice transition...
After cure, I trimmed and cleaned all edges...
The strakes are now ready for their bottom skins! This might have added a bit of extra work (having to apply BID tape to all mating edges), but at least I know all ribs and bulkheads are perfectly aligned and all edges are properly bonded to each other. Very happy with the result!
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