First off, I would like to take a moment to thank everyone who stopped by the MAN booth at the recent WRAM show to say hello and check out my project airplane. Our exclusive Build-along has been one of the most popular posts on the MAN site. Here’s a basic technique that every RC builder should know.
Making control surfaces move requires the installation of hinges. Many ARF and several basic kits today use the convenient and easy to install CA cloth hinges. But for this project being a fun fly plane and having a larger than stock engine, we want something more sturdy to stand up to the wear and tear and vibration, especailly in the tail. For this I rely on the pinned hinges from Du-Bro.
To install them you have to cut hinge slots in the edges of the control and flight surfaces and the easiest way to do this is with Du-Bro’s Hinge slot cutter tools. These are very easy to use and you can cut all the slots and insert all the hinges in an entire plane in less than 30 minutes. Here’s some of the details for the process.
You need few tools and supplies. The Du-Br hinges and Hing Slot Cutting tools are available at most hobby shops. The glue I like the best to secure plastic pinned hinges is the product “Hinge Glue” from Pacer Zap Glue. The long skinny applicator tip makes getting the adhesive deep into the slots a piece of cake. But this is done of course, after the model has been covered. (Note: The Pacer Hinge Glue has been discontinued.) Pacer Formula 560 Canopy Glue is the same adhesive as Hinge Glue and makes a perfect substatute. It dries clear instead of yellow, but it works just as good…
First things first, use a marking pen or pencil and find the centerline of the control surfaces and determine the locations of the hinges. Use your finger tips and strike a centerline along the edge of the surface and then flip the surface around and check to make sure your line is centered. For a glow powered sport plane, I always uses at least 3 hinges per surface and most often 4. Two hinges is not enough as if one fails, you will lose the entire surface in flight.
Use the forked tool that’s the width for the hinges you are using (here the 1/2-inch hinge tool) and insert into the edge of the surface at your marked location. Use a rocking motion and slowly push the tool into the surface about 3/4 inch deep. Make sure to center the tool and keep it parallel to the surface. If it is angles, the ends will protrude out the side of the surface.
Clean out the waste material from the middle of the hinge slot with the clean out tool. This picks the material cleanly out with a sweeping motion and the width of the tool blade makes the slot perfect for the hinge to be glued into it.
Here you see the freshly cut slot and the leading edge slightly recessed (about 1/16 inch) with a hobby knife. This helps minimize the hinge gap between the mating surfaces.
Here you see the difference between the recessed hinge slots in the rudder (left) and the yet to be recessed hinge slots in the elevator (right). Having neat, tight fitting hingelines and slots both looks better and helps minimizes the chances of control surface flutter during high speed flight. The same tools are used for the ailerons.
Shown here is the hinge inserted and you can see that it protrudes through the leading edge strip. This is fine as there’s plenty of gluing surface covered to properly support the hinge. In larger planes where less than half of the hinge leaf is covered with balsa, you have to glue in additional material to form a deeper hinge slot pocket.
For hinges to operate sloothly and not bind, it is important to install all the hinges so they all fall in line with each other. This hinge alignment is especially important for longer surfaces like the ailerons on this fun fly airplane. That’s it for today. Thanks for stopping by my workshop. Next time I will be assembling the control linkages and installing the control horns, then it will be time to prep the airframe for covering and finishing. Until then…. Build Something!!!
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