Carlson Skunk Works

April 11th, 2014

AMF 14H MARANDA SN:1026 Making Sawdust April 11, 2014

Posted by Roger in AMF 14H Maranda SN1026, news

Well, it is spring and, even though I did install the engine on the fuselage a couple of weeks ago, you are probably wondering what I have been doing all winter. I have been working on the ailerons and elevator. All of them are nearly done, but the ailerons are the farthest along. That is probably because I had some help with them.

A group of young men from church spent a couple of Sunday evenings working on the spars for the ailerons and on the skins for the elevator. Then my son, Nathan, came from California for my birthday and we installed the aileron ribs. The rest of the process I did by myself. Oh, and I did take some pictures.

This shows the aileron spars with the ribs sort of attached. The locations for the nose ribs are being marked.

The trailing edge of the ailerons is being made the same way that I made the trailing edge of the wings and elevator, rather than the way the plans call for. The plans call for the trailing edge to be cut at the appropriate angle with a notch cut lengthwise to accept the gussets. What I have done is to cut a piece of 2mm plywood to run the full length of the aileron, then I marked the desired location of the aileron ribs and glued them in place. Once that much was assembled I cut fir strips to be glued on each side of the plywood. Later I shape the trailing edge with a planer and sander.

All of the aileron nose ribs are identical. I rough cut the ribs, then stacked them together and sanded them to make them identical. I used my little pull saw to cut the notch for the leading edge stringer.

The locations of the nose ribs were marked. These are not all placed directly on the other side of the spar from the rear ribs.

To make gluing the nose ribs into place a bit easier, I clamped a couple of boards across my bench to allow me to hang the ailerons with the front of the spars up. I could mix up some T88 and glue the nose ribs pretty easily. Of course, I stapled the nose ribs as I glued them and pulled the staples once the glue had cured.

Before I glued the trailing edge strips I marked where I wanted to cut out the plywood. This results in some weight savings and makes everything look like the plans. However, I think it makes things a bit more durable and secure.

After the first trailing edge strip is glued to one side of the plywood, I used my pull saw to cut out the area ahead of the trailing edge strip. The areas of the plywood that I left correspond to the gussets that the plans call for. I cut the angles to 45 degrees because it was easier to mark that angle with my combination square, than to mark the 30 degree angle called for in the plans.

The center rib for each aileron was built just a bit differently than the plans as well. The plans call for two ribs to be positioned in the center. These ribs needed to have a gap between them for the aileron horn. Since I plan to use push-pull cable to activate the ailerons, the aileron horns will only protrude above the ailerons. Therefore, the horns can be inserted from one side. Therefore, I used 3/4″ fir in place of the two ribs. Then I cut a notch in the rib to accept the horn.

Partial plywood skins are glued on the top and bottom of the ailerons. Holes needed to be made in the skins to allow the horns to be inserted and bolted into place.

The bottom skin is flat, but the top skin is curved. There is a solid fir strip on the leading edge to hold the top skin while the rest of it is bent to the contour of the aileron top surface.

The way that I did this was to glue the fir strip to the plywood first, then I smeared glue on the top of the ribs and spar. As I positioned the skin assembly in place I glued and stapled the gussets in place to hold things securely. Once all the gussets were in place I could staple the skin to the nose ribs, spar and aileron ribs. I had to carefully work things to fit the required curve. I used enough staples to hold things securely.

When the glue cures things should look nice. Then the trailing edge strips were planed and sanded to the proper shape.

The next step will be to cut the piano hinge to make the hinges for the ailerons.