Carden 260 Build Update #1

The first step in the Carden manual is to make sheeting for the various parts. I don’t want to stray too far from the manual but I was afraid that the sheeting might get damaged in the shop while I did the next few steps. I’ll do the sheeting at the last minute before its needed. I have a very generous offer to use some professional layup tables for skinning the flight surfaces on this project. So I’m going to work on getting them all skinned before I go any further.

The first big decision I had to make in the build was where to mount the servos in the wings. I really wanted to run 1 servo in each wing but I just couldn’t bring myself to do it. Saving 4oz and $300+ was really tempting. It probably would have worked just fine. I just don’t know enough to make that call so I went with the recommended 2 servos. My limited experience with model airplanes has been that servos are the worst place to be cheap.

I drew up the tapered ailerons to the dimension indicated on the plans and they looked fine to me. I just extended the aileron 1″ towards the wing root. I split the length into 4 and put the servos at the 1/4 marks, biased towards the root by 1″. Another big question was how far the servos should be from the hinge line. I looked at a bunch of build threads and came up with the magic number of 2 1/2 inches. I wouldn’t be surprised if they could be closer, there is enough thickness in the core for it.

I made up some servo boxes using the supplied servo rails (lengthened to 2 1/2 inches) and some 3/32″ ply. I made a little fixture to assemble the boxes so they where square. The main reason for the boxes it to make sure the servo rails go in square. The box internal dimensions are 21mm x 41mm. Standard servos are metric and about 20mmx40mm so the extra 1mm gives a little play. I used a paper template and the Dremel router to mark and cut pockets for the servo boxes. I just did the routing free hand and it worked out well. Just have the shop-vac handy to clean up the mess!

The tunnel for the servo wire is up next. I cut it with the Dremel to the same depth as the bottom of the servo cutouts. I did two passes guided by a straight edge to make it wider. The servo wire can wrap under the servo and into the tunnel and pass out of the servo box through the arch in the ply support. Study the plans and pick a spot on the side of the fuse clear of obstructions and run the channel out to that point. My exit was about 11cm behind the wing tube.
Finally I installed the servo boxes with Polyurethane glue. Once the first wing was finished the second one went much faster. I swear, the hardest part is just getting started!

On the the stabs. The plans call for a servo box up against the root of the surface. You don’t have much room to get creative here or the front of the servo box will come out of the bottom of the core. Also be careful not to put the servo over the tube socket, check the plans. I put the servo box 5mm in front of the stab, parallel with the tube (which is parallel to the hinge line) with one corner just touching the end of the foam.

I got my first scare after doing the first stab. I thought I had done it upside down! Then I checked everything over and it was alright. Unlike the wings, where there is an obvious left and right half and stabs are both identical cores. They both have the same side marked as “down” and that was what threw me off. If you follow that you will make two left stabs. You have to flip one over ad cut the ‘up’ side so you have both a right and a left. When you sheet them always put the side marked bottom on the table. One stab will be upside down in the shuck and the other upright. Confused yet? Good!

The whole ‘down’ side business is important. The bottom shuck has a perfectly flat surface but the top shuck is not flat. Sheet them upside down and you could warp the surface.

On to the wing tube sockets. I put the little dowel through the tube and added the 1/16″ balsa end cap, no problem there. Then I tried to fit the tube socket support plate and had my first real DOH! moment. At this point I had never picked the cores up out of the shucks for fear of causing damage to the foam. So I didn’t know that the hole the support plate goes in is cut clear through the wing core! I started jamming it into the slot and wondered why is was so far off center. I cut some material off one side. Luckily I realized my mistake before I cut too much for it to make contact with the wing skins on both sides of the wing.

Coat the tube and support plate up with lots of PU and do the push and twist ;-)



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