40% Extra 260: Own-design build thread

[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.

[dmichael]

I fashioned my own rudder horn out of 1/8" and 1/4" aircraft ply. I had a little bit of apprehension that it would hold but it has proven to be solid and shows no signs of wear after 250+ flights.

First picture is of the rudder horn and second is the hole for the horn. I epoxied it in all around and later painted it after covering.

[dmichael]

On to the cowl.

I was able to get a cowl from the Radiocraft 40% Extra - this is the same cowl found on the Radiowave 40% Extra today.

I tacked it in place with CA after positioning and clamping the bottom half of the cowl ring in place. I did the same with the top piece and then tied the top and bottom cowl rings together with two small pieces of aircraft ply. After that I used fiberclass cloth strips and epoxy to finish gluing the cowl ring in place after roughing up the inside of the cowl with sandpaper and then cleaning with alchohol to remove the dust.

The cowl mounts with two screws on top that are accessible from the hatch area and two more on bottom from the front.

[sweetpea]

GS racing sells those blue washers. Car guys use em.