[Dave_ORCC]

With that done, I can see how much that wood weighs





The voids created by cutting this stuff out is replaced with lighter 1/8 balsa sheet.

[Dave_ORCC]

I also re-capped the ribs where the outboard servo mount was.



The wood that has been cut out will be replaced by the DDD boxes and control arms.



At first glance you might think that this is actually heavier than the conventional set up but, you’ll see as the install progresses that some of what is in the above pic also gets cut down a fair bit. There is also some more wood to be removed from the wing and aileron.

Here’s a pic of the box that will eventually hold the servo and where it will get installed into the trailing edge of the wing.

[Dave_ORCC]

The DDD stuff comes with cut templates to guide you as you cut big chunks out of the trailing edge. With the template aligned with the hing line you mark what needs to be cut out.





Now we use those lines and cut a big hole in the trailing edge! Yikes!! A bit scary, to be honest.

[TBrum]

Looks great Dave!!!

I`ve never seen a Durant Install done on a built-up wing before - should be really cool to see it come together!

That`s a little scary how much wood is left around the cut-out on a built-up wing (not nearly as scary when you have a couple pounds of foam and balsa sheeting around the cut-outs on a core/sheeted system.

Please keep us in the loop how this affects rigidity, etc!!!

Watching with interest!

Trev

[Dave_ORCC]

ok, not sure what's going on here. The pics that I'm trying to embed are getting all screwed up. Could be a little glitch with Picassa.

Stand by while I try to get this sorted out.

[Dave_ORCC]

Picassa seems to be working fine now....... on with the updates........



With this wood removed from the trailing edge, it’s a bit flimsy, to say the least. With the box installed and securely glued in place, the trailing edge is as rigid, if not more rigid than it was originally.



Repeat the process 3 more times and we’ve got all the servo boxes mounted.



With that done, we move on to the ailerons. Essentially the same procedure here except there is a bit more material removed to provide clearance for the boxes as the aileron deflects up and down. Here I’ve marked what needs to be removed.

[Dave_ORCC]

As you can see, the hole extends further into the aileron than in the trailing edge of the wing. Once that is all cut out, the hole that is revealed is capped with balsa. Doing this gives the covering material something to bond to and it also rebuilds the rigidity into the leading edge of the aileron. Think of this like a shear web connecting an upper and lower spar. I guess I didn’t really take any pics of this specifically but, in the next couple of pics you’ll see what I mean.

Now, we have to glue the control arms into the ailerons. First I take the supplied DDD control arm and mount an aluminum servo arm to it. Then I cut it down to the appropriate shape and size.



Initially, I cut them oversize then slowly sanded of material as needed to get them to the correct size. Eventually, I was happy with the fit.



Prior to shaping the control horns, I cut an appropriate slot in the aileron for the arm to fit into. Here you can see the DDD arm partially installed in the slot.

[Dave_ORCC]

Now we slide it in completely and align it with the already installed hinges and securely glue it in place.



Again, repeat 3 more times and the DDD system is complete.

With everything buttoned up it’s time to program some servos. Here’s a bit of a con with the DDD system. Programming is a bit trickier with this system because the servos aren’t easily accessible. It’s tough to disconnect one at a time for programming. I programmed the servos to match as closely as I could while they were out of the wing then installed them and fine tuned the system to work smoothly with no binding. To connect everything up, you need to mount the servos to the control horns.





With that done, slide the servos into the boxes and push them in until the hinges all line up.

[Dave_ORCC]

Now re-install the hing cotter pins and we’re done!! All in all, relatively painless. I’ve uploaded a short video to YouTube if you’re interested.


http://www.youtube.com/watch?v=aNFQoSlNj3M

You can hear a bit of servo buzzing which is just the weight of the aileron. I didn't show it in the little vid but, I had a watt meter hooked up and while the servos are moving there's about a .5amp draw but once you stop moving the stick, the current draw falls back to zero. I'm happy with the results. I'll let ya know in August how I like the DDD system

Next up, covering!

Cheers,
Dave

[Dave_ORCC]

Originally Posted by TBrum

That`s a little scary how much wood is left around the cut-out on a built-up wing (not nearly as scary when you have a couple pounds of foam and balsa sheeting around the cut-outs on a core/sheeted system.

Yep, when I had first cut it all out, it was a bit scary. After the install of the box itself, it stiffened right back up. ** insert joke here **

A while back I gave John Durant a call and asked a few questions. He assured me that it'd be just fine in the end. He also recommended aligning the boxes with a rib if possible and glue the box to the rib as well. Of course, in this wing, the ribs aren't perpendicular to the hinge line so I couldn't do that. I did, however, position the boxes so that the back corner met up with a rib. I then glued the box to the rib and reinforced it with a small 1/4" stick of balsa. Hopefully that holds up.