40% Extra 260: Own-design build thread

[atique]

Wow! That looks great

[dmichael]

Next I did the stabs.

First shot is of one of the foam stabs we cut. Since it is relatively small, it's not that difficult to do. I have some of the markings laid out for the hinge line and the phenolic and have the hole cut at the end of where the phenolic will be so that we can get the end of the cutting bow in to cut the phenolic hole.

[dmichael]

Next I lay in the templates for cutting the phenolic hole. I used a piece of counter-top material for the templates and laid them in place on both ends using small nails through holes that have been drilled into the templates.

I used bricks to weigh the stab down while I ran the wires to cut the foam. I found that this is a one man operation- using both hands to drop the wire down through the surface of the foam, around the hole and back out again. This wasn't all that hard to do.

[dmichael]

Here's what the hole looks like after cutting.

[dmichael]

Phenolic is installed with pro-bond and a plywood plate is constructed and sanded to fit the contour of the airfoil then installed at the end of the tube.

[dmichael]

Next, I used a dremel tool with a router attachment to make some cuts into the foam for the servo rails and servo pockets.

I elected to install additional reinforcement for the anti-rotation tube so that it would be supported on both ends. Using the bandsaw, I cut into the stabs, top to bottom, so that I could insert a small rib. The rib has a hole in it that accepts the end of the anti-rotation tube and is cut/sanded to match the contour of the stab airfoil. As you can see, I haven't finishes sanding this small rib as it sticks out a bit at the leading edge.

[dmichael]

Here's a shot with the servo rails installed, the root rib installed along with the stab mounting tabs, the small rib has been sanded flush and the anti-rotation pin has been installed and sleeved with some brass tubing and a small amount of epoxy over the end.

[dmichael]

Next, the stab is sheeted.

[dmichael]

After stabs are sheeeted and faced on the leading/trailing edges, the stab incidence is set at 0 degrees. Blind nuts are installed inside fuse after stab mounting tabs have been drilled for two 6-32 bolts on each stab.

The blue washers on the stab mounting tabs are from machined and anodized control horns usually found on pattern planes. I had won several packs of these at the now defunct Harrisburg, PA IMAC contest (lost field due to noise issues- get those mufflers on, guys!). Eddie Meyer from New York used to make these- maybe he still does but I don't know. I'd love to get some more of these washers as they work great and look nice.

[dmichael]

Once the stabs have been mounted and incidence is set I cut out the elevators.

I do this after setting incidence as this allows me to get a better reading from the incidence meter when I can use the whole stab/elevator in one straight piece. I don't think I get as good of a reading when setting incidence just from the fixed stab portion.

Counter balances are not scale but are IMAC legal. I will put together a list of things that I might do differently if I did another one and one of the things on that list would be to eliminate the counter balances. I wanted it to be 3D ready so I went with the counter balances.

[dmichael]

Finally, the stabs are faced, hinge bevels cut and sanded, hinges installed and sanded to be ready to cover.

[youngflyer]

nices, i cant wait to see the finished product. may have to take a trip to see it!

[dmichael]

Next is the vertical stab. First I cut the stabs cores from foam. The fellow in the picture may be recognizable to some- Marc Spicer. Marc used to be an IMAC regular in the NE and went to a few Nats but he is pretty much out of the hobby these days. He's building a Cobra kit car. Marc helped me cut the cores.

[dmichael]

Here's a couple of shots of the vertical stab after it has been sheeted and cut out so that it will fit on the tail. After this, I faced it on all sides- leading edge, trailing edge, top and botom tips, cut out the rudder and faced it at the hinge line and glued it fast. I put a dowel in the front to help secure it and used the hinge facing (stab side of the hinge line) to secure the rear by extending it all the way to the bottom of the plane.

[dmichael]

I filled in the area between the vertical and horizontal stabs with a sheeted foam block. The cut on the inside was cut at an angle that provided an extra measure of support for the vertical stab and it was very securey fastened.