First step was to trim the foam panel to match the fuselage side contour. Here is Sara (one of my USF mechanical engineering protégés) helping me align the strake top foam panel...
I drilled a hole through a mixing stick...
And used it as a guide along the fuselage wall to draw the contour onto the foam panel...
Took the panel to the bandsaw and trimmed away...
Perfect match!!
I then focused on sanding the top ribs to be flush with the spar's bevel...
This will allow the top foam panel to be perfectly flush with the top face of the spar...
Here I am using a small scrap piece of foam to test the flushness... perfect!!
Trimming the aft edge of the panel was difficult, since I couldn't stick my hand inside the fuel tank to mark the foam...
So I started out by making a reference mark on the fuselage and foam to be able to realign it (fore and aft)...
I then drew a line on the spar where I wanted to cut the foam (the top of the bevel) and then made another line 3" aft of it.
This allowed me to mesure 3" forward of the aft line and mark it onto the foam...
I aligned the panel's edge with my worktable edge and weighed it down...
Using a belt sander, I sanded the 1" bevel along the trailing edge...
Fine tuning by hand...
Looking good!!
I then test fitted the foam panel on... Per CP#32 builder hints... Smooth transition... NO JOGGLE!!! Looking good!
With the side edge butted up against the fuselage wall and the aft edge aligned with the spar, it was time to focus on the leading edges... I started by marking the ribs onto the foam...
I tried to bend the foam to follow the ribs' forward top contour, but the inboard leading edge has a very tight radius. The plans say to use a hair drier or heat gun to apply this bend. CP #34 under "builder hints" suggests to put 2 layers of bath towels that have been soaked with 4-6 quarts of boiling water! (Seriously?! You want me to pour boiling hot water onto towels and my foam panel?! I don't think so buddy!) So I had to come up with a better solution!
I drew 1" marks starting at the rib's leading edge... extending 10" aft...
I then drew 1" marks along the inboard edge... starting at the leading edge...
And then connected the dots... drawing out an accordion...
I used a few clamps to hold a scrap piece of foam to the top of the fuselage wall cutout...
This acted like a shelf and allowed me to place the accordion onto the leading edge...
Notice I put duct tape on the rib... this was so I could use hot glue gun to temporarily hold the accordion in place...
The accordion trick did a great job at following the proper contour!
I then placed the remaining foam panel back on and weighed it down to keep it from moving...
The outboard leading edge was a bit more forgiving... so I used a heat gun to help me bend it into place...
With a little bit of patience, I was finally able to get the outboard leading edge to bend and follow the ribs' top contour... however, it didn't want to bend permanently..
So I put a strip of tape to the leading edge... and used hot glue gun to temporarily tack the foam panel in place...
With the top foam panel holding its proper contour, it was now time to build the "lumber assembly". This will allow me to remove the foam panel, place it upside-down on my workbench and fiberglass the inside of the top skin - all the while holding its proper shape.
The plans show a sketch of the lumber assembly using 6 planks.. there was no way the foam was going to hold its contour with just 6 planks! So I went a little overkill... I purchased two bundles of 12 stakes (2"x1"x1.5') from Home Depot and used Liquid Nails instead of bondo - its just as strong and much easier to apply with a calking gun rather than having to mix bondo. Also, notice I used pour foam over the accordion to help beef it up - this will get sanded later. I let the liquid nails cure overnight.
I wanted to make sure the leading edge had plenty of support and maintain its proper contour...
With the Liquid Nails dried, I used a blade to cut most of the hot glue gun blobs and then I pulled on the lumber assembly and yanked the top foam skin off...
...and placed it upside-down on my workbench...
The lumber assembly did a great job at keeping the foam in its proper contour...
I glassed the inside surface with 1 ply BID... making it extra wet to prevent any fuel leaks... also, I installed peel ply along all surfaces that were later going to get bonded to the ribs and bulkheads...
The next day, I removed all the peel ply...
...and sanded the entire surface to do an epoxy wipe.. I wanted to make sure this skin would never leak fuel!
While we were at it, I also sanded all fuel tank surfaces, and did an epoxy wipe there as well...
After the epoxy cured, I re-opened the drain valve hole and test fitted the drain valve...
Turkey is ready!!! hehe
Happy with the drain valve... I removed it and replaced it with an NPT plug...
Since the inboard edge fiberglass overlaps onto the fuselage, I had to prep the surface for glass. First I had to fill the t-nut holes that hold the rollover structure. I clamped a few pieces of cardboard to act like shelves...
...and used pour foam to fill the holes...
After cure, I sanded everything smooth and prepped the side rail for a good glass-to-glass bond...
After the top foam gets installed, a few BID tapes are applied to help seal the tank.. so I also prepped all areas that will get BID tapes installed...
..including the R45 outboard top surface...
This picture was taken after glassing the 1-ply BID....
After cure, I sanded the entire surface to do an epoxy wipe to prevent any fuel leaks..
I also sanded and prepped the spar's bevel surface where it will bond with the top skin's beveled edge...
With all fuel tank surfaces epoxy wiped, and all other surfaces sanded/prepped... it was time to install the top foam panel on! I made sure to remember to remove the tape on the end of the vent lines and the tiny holes behind the fuel sight gauge... once the top panel gets installed, there's no going back!
So I mixed epoxy, and epoxy wiped the entire inside surface...
I installed a 9" BID tape to the aft inboard edge... this piece will overlap onto the fuselage wall 1"... I'll explain why only 9" in a bit....
While waiting for the 9" BID tape to become tacky... we prepped all other surfaces by painted plain epoxy.. on the spar's bevel lip... on all rib and bulkhead top surfaces... all areas that were going to get BID tape, etc...
Also applied plain epoxy to the fuselage side wall...
Remember how I only applied a 9" BID tape to the aft inboard edge of the panel? That's because I figured it would be much easier to have gravity on my side! So I added the remaining BID tape to the fuselage wall.. and let it hang... after installing the top panel, I can reach from the inside and brush the skirt onto the panel...
I kept a portion of the skirt dry so it wouldn't stick to the fuselage wall... the 9" BID tape on the aft end was for the aft inboard portion of the fuel tank - where I won't have access to...
I then mixed up a bunch of flox and applied it to all rib and bulkhead top surfaces...
Including the spar's bevel lip...
With plenty of flox in place, I brought the top panel over and set it in place... being careful to lift the 9" BID tape on the aft inboard edge over onto the fuselage side. I then placed a bunch of bricks to weigh everything down.
I then installed BID tapes on all edges...
I used clamps to get a good seal on all leading edges...
Per plans, I also installed BID tape from the inside of the cubby...
The passenger cubby also got BID tapes....
Passenger cubby looking forward... (so from left to right, this is showing my modified BAB bulkhead, R23 rib, and the forward BAB bulkhead I added to separate the cubby between the pilot and passenger).
Here is a good pic showing how I brushed the skirt that was hanging from the fuselage wall onto the underside of the top strake panel...
Perfect fit!!
I made sure the aft bevel was weighted down to create a perfect seal...
With everything weighted down, all BID tapes in place... it was time to step away and let cure...
Everything was repeated for the other side and both strake top panels are installed! Next up, I will flip the airplane over and prep the bottom outside skin for glassing!
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