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Old Oct 29, 2008, 05:11 PM
No substitute for aspect ratio
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Norwalk, CT aka the Nutmeg State -- I just can't seem to find any %$#@! nutmeg here?
Joined Nov 2003
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Full length rudder hinge - Osiris Mk2 Discus Launch Glider (DLG)

A couple pals asked me to post these photos from my recent review in Fly RC Magazine. I think they'll be giving this treatment to a Sky Sergio and original Osiris. Here's how I modified my rudder with great success....

I learned that some modelers have had mixed results on the original Osiris using a tape hinge on the rudder. This is likely due to the force of the pull-pull cables acting on the tape adhesive over time. I chose instead to make my own modification by installing a full length CA hinge made from a strip of Coverite Micafilm covering material (reinforced with mica, rip-proof).

I first made up a small jig that placed a single edge razor blade in the center of layers of balsa forming a channel such that the surface to be hinged fit into the jig with the blade positioned at the exact center (see photographs). This made the task of cutting a full length slot in the center of both surfaces very easy. I went ľ inch deep in each half, then carefully beveled the rudder face to facilitate surface travel, and next inserted a full length piece of the Micafilm that was Ĺ inch wide.

Once the hinge was in place and I was confident with the surface travel, I carefully applied thin CA to the entire length. The stabilizer and the rudder are now mated forever, travel beautifully, and the hinge is rock-solid.

Installing the full flying horizontal stabilizer was relatively simple. The center pivot of the stab is installed in the pylon with epoxy, making certain it is perfectly level to the wing and square left to right. Next, two tiny holes are drilled in the top of the boom both fore and aft of the pylon so that they align with the front and rear carbon alignment rods that join the two-piece, removable stabilizer. These holes are lined with small sections of tubing and make up the pull-pull exits for the elevator. The pull-pull cables loop over the alignment rods to actuate the elevator. Again, all of this is detailed in the instructions.

Actuating tail surfaces via pull-pull may be new to some modelers. My personal preference is to do this step not with typical wire or cable (very nice thin cable is provided in the Osiris kit -- some modelers have reported this cable has too much friction to really be a viable choice) but rather with Spectra braided composite fishing line. My preference is Spiderwire Stealth which has Teflon in the weave. Itís incredibly strong, thin, lightweight, and knots may be secured with CA instead of using connectors. And, a lifetime supply is around $11! I chose 50 pound test knowing 20 pound would have been sufficient.

I think long-term an elevator mod will be necessary -- over time I'm not loving the centering.
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Last edited by SPasierb; Oct 29, 2008 at 05:21 PM.
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Old Oct 31, 2011, 09:26 PM
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Joined Oct 2011
1 Posts
I just purchased the mk2 and started construction last night. I see you posted a picture of where the control horn mounts on the aileron. I was using your pictures as a reference, but found there was a carbon fiber spar in the way so it looks like my aileron horn will mount about 1/8" behind yours. Did you run into the same issue? Where in relation to that spar did you mount your control horn. Any help is much appreciated. Thanks

mrbrownmoos
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