On my current project I was intending to make the stabilizer and elevator 1/8 inch thick. For several reasons including stiffness I had decided to laminate two 1/16 thick pieces. Then the epifany, I hope, why not lay a piece of thin but strong cloth between the balsa sheets and let it serve as a hinge and an extra lamination. A little while ago I epoxied up a trial run. I intend to give it some bench tests tomorrow. Have any of you guys tried something like this? If it seems to work epoxy may not be the best glue. Any suggestions?

Sounds OK. Did the glue weep into the area that would act as a hinge? That might cause a problem since it would be brittle and break over time. The Pylon guys mold their hinges as part of the skin and it works quite well.

It's a good idea, but if you choose a wimpy fabric, the fibers can stretch, then the hinge gets shifty. the pros use 3mm kevlar cloth laid at a 45 degree bias. It kind of ruins the simpleness to your idea, though. If you make the gap really tight, with the flap side of the joint beveled, then maybe a continuous strip of Tyvek would be the way to go? I would use the thinnest amount of epoxy and lots of pressure to make this part. might even sand a faint relief in the wood to account for the thickness of the fabric strip.

What ever happened to sewn thread hinges?

Jerry Lewis used to have a 24 hour telethon to help stamp out sewn hinges in our lifetime. The last guy to win a Concourse d"Elegance award at a model show, using sewn hinges was Walt Goode back in 1939.

Jerry Lewis... LOL

I like the Tyvek idea tho

Thanks CP

The only part about the idea that I don't like is the resins' weight. That's why I would scrape it on real thin and use lots of pressure to clamps the lamination good. The thin resin centerline will give a natural hard point for an airfoiled stabs sides to converge at, for the most accurate shaping job possible. When you're building a 45 mph plane, you just can't be too carefull .

Heres the tail surfaces and hinge detail from one of my old plans, same idear.
Stewart

I used 'em on my last DNU and they work just fine. My stab balsa was thin and soft, and after failing with a conventional hinge slot I decided to give thread a try. My Wife thought I was nuts sitting on the couch with a needle and thread and my STABILIZER, but it was kinda cool actually. I sewed in the normal hinge places using 6 - 8 thread loops. Found that you have to keep good thread tension otherwise the elevator has too much slop and will fall below the stab. I doped them up when finshing the plane and they're perfect!

EG

combatpigg, I was at the VR/CS meet this past May where Dave Platt won the Concourse d'Elegance with his silk-covered Goldberg Falcon with sewn-on rudder and elevators.

After checking my test piece I see that way too much glue got into the cloth in the joint making it way stiffer than I like. I guess I'll try something else. Either the kind of glue or the amont of glue may be part of my problem.

I made a hinge like this years ago, it was for a Wheldon CL design. I used balsa cement to laminate and it worked fine. I had to brush lacquer thinners into the hinge line quite a few times to remove some residual glue that had oozed out.

Sewn hinges are great but crappy to look at. Well, my sewn hinges are crappy to look at.

How about trying/testing some epoxy Gel. I bought some 5 min. from an auto parts store in the twin tubes for about $4. I like it. No wicking.

Slowjohn

On the same idea only different, I laminate two 1/16!QUOT! sheets together with 1/64 X 1/4!QUOT! ply strips around the outside perimeter. You leave slots without the ply at the desired hinge locations. Then I use CA type hinges only cut down to 1/3 their normal width and insert them in the slots and install as usual. This also allows the sharpening of the leading & trailing edges of the tail surfaces down to the 64th ply, This is for speed applications of course.

I think I seen where you could also slice up some floppy disc material for laminating the hinge. Virtually no thickness, tough and flexible.

RaineDav, that event is run by guys who knew Walt Goode on a first name basis! Those guys still make wing fillets out of leather. Compared to just cutting a slit for an EZ hinge, then covering the entire prehinged assembly in one shot with iron on, all these other techniques represent to me are ways to slow down airplane production and take time away from flying. I like to seek out methods that are the lightest, simplest, quickest, and if at all possible, the neatest to look at. Most importantly, the end result has to be something that you can live with weekend after weekend at the field with the lowest maintenance. Laminating a fabric hinge in between two layers of 1/16 balsa can't gain you one iota of anything, really, except for the time it takes to build the model, and possibly a heavier tail VS using 1/8" balsa and EZ hinges, which has been tested [so far as we know] up to 150 mph on some 1/2A planes.

"then maybe a continuous strip of Tyvek would be the way to go? "


I've been using tyvek for hinges on most of my foamies for the past 1 to 2 years and none of them have ever broken at the hinge line. (everywhere else though [X(] ) Awesome stuff and free....usually, I use Post Office Priority mail envelopes and cut 3/4" strips. I slit the beveled edges of the control surface and slide the Tyvek into place for a continuous hinge. Add some thin CA on both sides and it actually reinforces the edges and well as being a continuous hinge. When dry, I flex the hinge a couple of times and its good to go.

It would be easy to laminate a piece of Tyvek between two 1/16 pieces using med CA. Try this out and see if you like it.

I like that Tyvek hinge!! I may have to steal that.

I've been building "live" hinges for years on small stuff and big stuff alike. While it is best to use a thin kevlar cloth, I've done many with regular fiberglass and they lived for a long time. On something like an elevator for a sport plane that doesn't use 3-D 45 degree throws, you end up flexing the glass within its limits and the hinge won't crack and break. I use 3/4oz glass, or two layers of .05 (1/2)oz glass at a 45 degree bias relative to the hinge line. This way you don't kink the fibers as much. If you use a light enough glass and light enough balsa, you can actually laminate the whole middle layer and the glass adds torsional strength to the tail. You want to use an epoxy that is thin so the hinge area doesn't have unnecessary epoxy build up and stiffen the hinge area. That'll cause excess stress and could lead to cracking. The actual hinge line needs to be opened up a little (I'd say 3/16" or 1/8" max) which allows a flex zone. Another glue that might work well in this application is polyurethane (gorilla glue) but test first. It squeegees like thin epoxy and soaks into glass fibers well. You just have to use it sparingly (like epoxy) because it foams; sometimes quite a bit. You could avoid the hing line with glue and let it naturally wick the rest of the way so it doesn't over stiffen the area.

Having said all of this, I am a big fan of monocoat hinges but if you want to add torsional rigidity to your tail, this is a great way to go and it kills two birds with one stone.

Yup. I've made surfaces like this several times with success. Tyvek doesn't really bond all that well, so don't use too wide a strip. To improve the adhesive bond, try running it through a sewing machine a few times with no thread, in other words perforating the surface in span-wise lines. If I was laminating a thicker surface like this stitch back and forth a few times with thread and leave it there, it does not hurt anything and will act as a "getter' for the adhesive.

Now as to sewn hinges.. hey CP I happen to highly approve of sewn hinges, for surface freedom of movement they are hard to beat. But, they only look right on certian types of models, I don't think SWR's are the right thing for antiquated hinge technology !

MJD

Yep, I've seen some very elaborate sewing jobs, and they do look good on the right planes. C/L ships and old timers. Some full scale planes have pretty fancy needle work, I would like to watch how one of those covering jobs gets done.

Finally got back to my elevator hinge. I ditched the idea of embedded cloth. I still think it can work and I may try it some time in the future. For now I decided to use a scrap of vinyl from a sign shop.

Wayne, when you do try it believe me, simple, dopey, cheap balsa cement to laminate works fine.

Luke

Take a look at this site. Scroll down to close sewn hinges.

http://www.iroquois.free-online.co.uk/knot.htm

I still have about 6 rolls of sewn hinges in several colors. Kind-of a pain, but they work really well!

Also on the Tyvec hinges, you can use a crayon to mark the centerline on top & bottom and that will keep the glue out of the flex line. Color matched to your scheme too!

Thanks for the comments guys. I wanted to show some pictures but I could never get them to load.