Speed brake glassing (outside)

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.