ORIGINAL: doxilia
ORIGINAL: jarvis johnson
I wanted to use CA hings, do you do them the same way?
Jarvis,
I don't recommend CA hinges on foam core surfaces (wing & stab), CA will eat the foam. There is foam safe CA but personally, I find it doesn't work that well. I also find that the design of the surfaces doesn't lend itself well to CA hinges but it could be done if you really want to. I just don't know how well the foam safe CA stuff holds on to the hinge material. One is supposed to use thin CA and foam safe ain't thin!
David
Jarvis,
I knew a Jarvis Johnson who used to fly in the Kansas, Oklahoma, Texas area in the 90s. Any chance that's you?
David,
I've never worked on a Saphir II so I can't speak to that model in particular. However, I guess we're going to have to agree to disagree again on CA hinges. I've used CA hinges - I prefer
Radio South 1/4 Scale hinges - on every pattern plane I built since the LA-1 in the mid-90s. I have found them to be the fastest, cleanest installation, and easiest to use hinges that provide the tightest hinge line gap when done correctly. They are also the easiest to repair when needed in my experience. Here's the technique I use.
- Mark the hinge lline on both fixed and movable surfaces.
- Cutslot with a #11 XActo blade just slightly longer than the width of the hinge itself but <span style="color: rgb(255, 0, 0);"><span style="font-size: larger;">
NO WIDER THAT THE THICKNESS OF THE BLADE</span></span>. This will provide a SNUGfit for the hinges without excess gap. Do this on both fixed and movable surfaces.
- Position the hinges in one surface - I prefer the control surface itself.
- Run just a very small bead of thin CA right along the line where the hinge and surface meet. Do this on both sides and no more.
- After all hinges are glued into the control surface, assemble it to the adjoining surface. Start all hinges one at a time, then press the surfaces together as tightly as possible.
- Deflect and
hold your control surface a bit farther than the maximum throw for the surface. If throw is supposed to be 1/4", deflect it 5/16" or so.
- Tack the outer two hinges with 1 drop of thin CA on the inner and out hinges. Another tack may be needed on long surfaces like ailerons.
- Run just a very small bead of thin CA right along the line where the hinge and surface meet. Do this on both sides and no more. Deflect the surface while doing this.
- Wait a minute or so and give the surface a good tug to be sure it's secure.
- Done.
This works for me and I have never had a hinge failure. Your mileage may vary.
Jim