So now that the air brake recess on the fuselage was complete, it was time to build the actual speed brake flap itself.
The plans say to use urethane, but since I had extra H-45 Divinycell (same foam that the front seat and passenger seat is made out of), I used that instead. Here I am epoxying two sections together to give me the 17.5"x17.5" dimensions that were required.
I let it cure overnight and then used the band saw to cut a 45 degree bevel around the entire perimeter.
Test fitting the flap... looking good!
Following the plans, I used dabs of 5-min epoxy to temporarily bond the foam to the fuselage. This lets me sand the flap flush with the fuselage's belly waterline.
I placed a heavy box on top while it cured...
Just when I thought I would never have to use this tool again... here I am sanding the speed brake flap flush with the fuselage...
Ooooooo... looking goooooood!
Sanding the beveled edges causes about a 1/4" gap around the perimeter of the flap and the fuselage. Here I am using clay to fill the void to keep the glass from sagging during cure. I should also note that I put packing tape all around underneath the clay and around the borders. This is to prevent the glass that will be laid on from bonding with the fuselage.
I then used more duct tape to keep the glass from bonding to the fuselage... surface is ready for glass!
I had my 3 plies of 45 degree BID cut to size and started glassing the outside.
After the 3 plies were applied and wetted out... I let it cure overnight...
The next day, I made a little jig out of 2x4's and 1x2's and used Bondo to adhere the jig to the flap. This is the same procedure as was done with the fuselage floor - so that the foam will keep its form when it is removed from the fuselage and allow me to glass the inside.
After the Bondo cured, I pried the flap open. The damage from the 5-min epoxy will be easily fixed later.
I now have the speed brake sitting on my bench and ready to be prepped for inside glassing.