One of the most important tasks to do with any giant scale airplane is to install your hinges correctly. I recently completed construction of my Balsa USA Fokker Triplane, and with this giant scale 33% WW1 fighter, I wanted everything just right. Lets check out those Hinges and how to install them.
Hinging Made Easy.
I think the easiest hinges to install in a built up airplane like the Triplane is Robart HingePoints. All you need is the Robart drill guide and a 3/16-inch drill bit. (for the big hinges.) Also to give something for the glue to stick to, you need to install some hinge pocket blocks. I make these thinner that the thickness of the control surface so they do not show through the covering.
I mark the hinge locations with the surfaces held together so they line up properly. You place the self-centering guide over the mark and drill with the 3/16 inch drill keeping thebit square to the contro; surface edge. Once all the hinge holes are drilled, I fit the hingePoints into place and check the alignement. if all is OK I then use a round file or a round bit in a Moto-Tool to form half-round pockets to clear the hinge knuckles. This keeps the hinge line gap to a minimum
As you can see, the elevator edge has been rounded and the HingePoint sets nicely in the half-round space.
Here you see the pocket blocks added to capture the HingePoints. I used 1/4-inch thick balsa and they are all installed so the hinges go into the end-grain. This increases the wood’s grip when it swells as the glue dries.
Once the HingPoints are all in place, you can check the movement and make sure there is no binding and the surface moves smoothly.
When the hinge is too long for the surface, you can easily cut it to length. Here I have not yet cut the hinge to length. The covering will seal the hole in the elevator trailing edge.
For Flat Hinges like those from DuBro I use the Hinging Slot cutting tools from DuBro. They are easy to use and they make the job quick to complete.
Here is the inner end of the aileron with the DuBro flat hinge installed. I like to install all the hinges in the movable control surface and then transfer their locations to the trailing edge of the wing.
You can use the brass cotter pins that come with the hinges (quarter scale) or you can replace them with a length of music wire that is long enough to go through all the hinges.
It is important to keep the clearances between the wingtip and the aileron counter-balances. 3/32-inch is about right for cloth covering.
Depending on the thickness of your trailiong edge, you can simply glue the hinges in place after covering, or you can glue in pocket blocks like was done on the elevators.
You should also have your control horns and servo ready so you can establish the linkage location to position the control horns. (to keep the linkages straight.)
I added a plywood internal brace for the aileron control horns to add regidity and minimize flex of the control surface.
Here are the control horns screwed into place.
Shop Tip: For years I used Pacer’s Hinge Glue for all my model airplanes. The glue is no longer available but a great substitute is Formula 560 Canopy Glue. It is basically the same formula but it is not wood colored and it dries clear. Just like with Canopies, the glue sticks very well to the plastic the hinges are made and being water based, it swells the wood around the hinges while it cures. Excellent results and a lot better than epoxy! If you get any glue in the hinge pilot pin, just wipe with some water to clean!