Chapter 6 - Step 2

Step 2 involves building the heat duct, the fuel valve mount, and the front seatback brace.

Foam Layed Out March 19, 2000. Here is foam for the heat duct and seatback brace all marked and partially cut. I cut some of the parts out before glassing for several reasons. The heat duct top was to be made of three pieces. I decided I didn't want to glass each part and then glue them together. Instead I cut the parts out and glued them first. I then cut out the two seatback triangles because one had to be flipped over before glassing so I was glassing the inside of both pieces.

One other thing I did different was to adjust all the dimensions of the heat duct and seatback brace. Before cutting I did a sanity check and found that the dimensions of my plane were slightly different. Nothing big but I decided to cut the foam to match my measurements. My seatback is not at 45° but about 42°. Not a big difference I know. But when you measure the triangle one edge needs to be a bit shorter. About 0.2". This meant the heat duct needed to be shorter too. I actually left the heat duct about the same figuring that it was easily shortened later.

Inside Faces Glassed March 20, 2000. The layups were straight forward enough. Two plies BID on the big triangles and two plies UNI on the straight pieces. Of course slurry was applied to all the foam first.

Fuel Valve Support March 20, 2000. Two exact birch plywood cutouts for the fuel valve support. The cutout for the fuel valve is slightly different than the plans show. The only difference is the exact shape of the cutout for the hexagonal part of the valve. I based my cutout on my valve. The plans drawing didn't quite match the valve I have.

Fuel Valve Bracket March 21, 2000. Bending the fuel valve bracket. I read all the stories of how easily the aluminum cracks trying to make these bends. I rounded an edge of a wood block, stuck it a vise, and slowly bent the bracket around the corner. It is hard to bend 2024 aluminum to such a small radius. After careful prodding I got the general shape I wanted. I have no signs of a crack but the radius is a bit more than ideal. No problem though.

Fuel Valve Bracket March 22, 2000. After getting the bends in place I proceeded to drill all the holes. The four 5/16" holes on the side were easy enough. The two 3/16" holes started out easy until I discovered they were out of place a bit. I guess the drill bit wandered when I started. To fix it I drilled two 3/16" holes of the proper spacing in a small block of wood. I them clamped the block to the bracket and used the new holes as a guide to redrill the aluminum. The net effect is two oval holes in the bracket.

To make the 3/32" holes for the nut plate I put the screw through the bracket hole and held the nut plate in place. I then drilled the 3/32" holes using the actual nut plate as a guide - perfect holes. When I ordered the chapter 6 parts I got two nut plates. One the right size, one the wrong size. I have a replacement coming.

Seatback Brace March 22, 2000. After rounding the plywood brace to accept the valve bracket I marked the location of the plywood on the foam seatback brace and then chiseled the foam away. I found the plywood to be a bit thicker than the foam so I sanded the edge of the plywood a bit to avoid a bump when this face is glassed.

Riveted Nut Plates March 24, 2000. I received the new nut plates from Wicks today. I also bought a 100° countersink so I could seat the rivets properly. I counter sunk for the rivet heads on the top of the bracket. I then put the rivet in place, put the nut plate in place, turned it over onto the top of the vise, got the hammer, set a metal rod in place on the rivet end and whack, whack, whack, woops! I creamed it. The rivets are softer than I expected. The other three I was much more careful about. You can easily see in the picture which one I did first.

Floxing Seatback Brace March 28, 2000. The seatback brace being floxed together. You can see lots of small nails holding the spacers in place.

Floxing Heat Duct March 29, 2000. Here the heat duct pieces are being floxed together. I grooved a board and set the two sides in the grooves to keep everything straight. A piece of foam was shaped and placed in the wider end to match the top.

Completed Seatback Brace April 23 2000. The seatback brace and heat duct are finally glued into place in the fuselage. All the joints were taped and peel plied.

Close-up of Fuel Valve Bracket April 23 2000. This close-up of the seatback cutouts for the fuel valve bracket shows where I needed to add back a little foam to the cutout. This will all get touched up later.