The micro on the bottom trailing edge was well cured by Tuesday when I began removing the excess Styrofoam from the top trailing edge. Removing the foam exposed the peel ply (Dacron fabric that is used to create a good bonding surface on fiberglass once it is peeled off, hence the name “peel ply”). With lots of elbow grease, I was able to pull off the peel ply from the trailing edge. Next I used a large sanding block to remove and shape the top foam surface. The trick is to make sure that the airfoil is very flat with no dips or bumps. The two elevators looked terrific
Edge-on view of one elevator showing the trailing edge on the the right. The blue
Styrofoam on top will be removed, see next image.
This is the elevator after the excess Styrofoam and peelply have been removed.
This elevator needs a bit more sanding of the foam in order to be ready for the
next fiberglass layer.
Chuck was over on Wednesday. Before he arrived, I put both elevators under black plastic and set them out under the sun to cure for 2 hours. The temperature reached 113.4 degrees F. This really helps cure and stiffen the fiberglass.
Heat curing the parts using black polyethylene plastic and the sun. We call this our
“black bag cure” technique.
We used a combination of 5-minute epoxy and Bondo to glue the two elevators to the side of our worktable. This allowed us to have access to 3 sides of the parts. We cut out all the glass cloth we would need for surfacing the top surfaces and followed the same “prepreg sandwich technique” that we used last week on the lower surfaces. We began mixing resin 5:30 PM and finished the lay-up two hours later.
Thursday morning we attached the leading edges to the two elevators. These had been cut out from the original foam cores back on May 10th. We used a thick micro slurry to bond the leading edge onto the flat forward surface of the elevators. This area is technically a spar web, the “backbone” of the elevator, and very strong. We used cotton/resin flox to bond the inboard torque tube tunnel to the spar web in the same bonding operation.
Applying micro to elevator where leading edge will be attached.
Leading edge in place with weights to get good contact.
We let the resin cure for 3 hours, during which Chuck prepared fiberglass for the leading edge. Next Chuck began applying one and one half layers of fiberglass over the leading edges. The elevators were now fully covered and had their final shape. We were very pleased with the results. Chuck headed home.
Leading edges with fiberglass.
Friday, Darryl removed the elevators from the worktable. He spent nearly an hour removing duct tape and excess fiberglass from the two parts. The tailing edges were also smoothed using sandpaper. Once again the parts were put outside under black polyethylene sheeting and allowed to cure for 4 hours. This time the temperature reached 136.9 degrees! We got a really great cure on the parts.
Chief assisting in black bag curing the two elevators.
Later in the afternoon, Darryl cut out the first of three cutouts on the leading edge where one hinge bracket will go.