Preferred Elevator Hinge Method?
 

I'm finishing my first .35 sized plane. The kit came with CA hinges. I'm tempted to use the "stitched" style string hinges to make the hinge more flexible. Any experienced suggestions?

Dubro makes hinges that are ideal for your application. Dan.

Well, CA hinges work very well. I have them on airplanes up to 50cc and have never had a problem. Dubro, Robart, and Great Planes all make good hinges, just beware that the trade off is that you may have to do some adjusting of the control surface and the trailing edge if you decide not to go CA. This is not a simple drop-in operation. For example if you use a hinge (Great Planes/Dubro) with that little metal rod in it, you will need to trim each surface to recess the hinge joint. Otherwise you will have a large hinge gap along the length of the elevator that may need to be sealed. But none of these are complex operations. But all of these work better before you cover or paint your airplane. One thought is to just go with the CA hinges and work the joint back-forth gently a couple of dozen times. This will loosen up the surface. You don't need to have complete 100% friction free "flopping" for things to work right. Just make sure you use the appropriate slotting tool for the replacement high you purchase. Makes life much easier.

I like the fabric hinges, and use a nylon/polyester shirt like material. I glue it on criss cross with Sigment usually. It is a bit hard to use shrink films that way because it goes directly on to the balsa. Monocote hinges are ok too, but not as strong. I criss cross those too, overlapping 3/16" in the middle. They both give a nice free action.and look better than sewn hinges which I find that they always shift.

CA hinges can be stiff, decreasing the smoothness of control inputs. I like either the pinned hinged flat nylon or the Robart hinges.

Thread hinges can be the freest and have absolute minimum gap between fixed and moving surfaces. They are not particularly 'pretty,' tho.
The kind I refer are actually thread, sewn through holes punched by the sewing needle. These are also called 'figure-eight' hinges. because the thread travel forms a Figure-8.

Example: stab to elevator, wood sheet surfaces: thread the needle with heavy button thread. Between 1/4" and 1/2" from the hinge gap, push the needle through, say, the stabilizer, from bottom to top. Pull enough thread through so you can lead the needle over to the hinge gap and pass the needle down through it. Go about the same distance from the hinge gap onto the elevator and push it up and through. Continue this pattern of over-and-under "stitching" separated about 1/8" until you have say 6 or so passes through the wood. The surfaces should be in contact at the gap line and the thread pulled firmly taut. NOT too tight, but snug so the surfaces stay in line. Snip off the thread where it comes out. A drop of CyA, or even model cement on the pierced holes and the end will keep things honest. Button thread shouldn't become brittle even after doping over it. These do last. They strengthen the surfaces they're on.

Sew another sequence a few inches away. You don't need more than two or three such hinges on each side from center.

Plain ol' cloth hinges have worked great since I was a kid and I'm 70 now. That's what I'll use on my current Nobler build, anyway.

I have used every common type of hinge or hinging method out there and each has its place. I would never suggest one size or method fits all. However sewn hinges have one advantage over all other types that the others cannot even touch. And that is ease of rapid field repair. This is a huge asset when one travel hundreds of miles to an event and you suffer a broken hinge of any kind.

It takes only perhaps fifteen minutes to do a sewn hinge repair to get you going agine and it makes no difference controlline, RC or whatever the other hinges on that surface may be. All you need is some heavy thread a small drill bit in a pin vice and some CA. Doing a sewn hinge does not require complete removal of the surface like most other methods do.

As all other types the sewn hinges do have some disadvantages as well. First depending on the type thread, cord used they are subject to rot over time. Use of fishing line helps in this regard but make the assembly and sewing process much more difficult. Also they are most usefull on two surfaces that are relatively flat in nature, for instance use on ailerons is not practical where the wing is very thick at the hingeline.
Here are pictures of my very elderly little Ringmaster Jr where the cloth/doped hinges have failed and it was very simple to sew the surface back on and the freedom of movement is just as good or better than the cloth/doped hinges.

As far as the uglies go, well to each his own, I love the look of sewn hinges that are not painted over in an attempt to hide them. Even have used them unpainted over new surfaces that are monocoated.


John

I’ve given up on CA hinges, too many failures.. I usually catch the broken hinge while cleaning my plane, but did lose a very nice Ringmaster due to a CA hinge failure at the bottom of a wing over. Never again.

RC or CL, CA hinges are not reliable enough for me.

JohnBuckner should like this.

Yes indeed grotto I do enjoy the look of sewn hinges. In the vernacular of kids these days, a 'Steampunk' look:cool:

John

I taught my grandson to use sewn hinges on his 1/2A control line models. I use em on all my single channel stuff....Gene

I bought a Flite Streak from a friend back in 1980's. Sewn elevator hinges. I still have it and the elevator still moves freely. Sewn hinges rock. They may look archaic, but they work just fine. Would use the method again.

I use hinges that I can REMOVE the metal pin somehow. Or a piece of THIN plastic material.
I have vise that clamps a Moto drill with a THIN cutoff wheel in it. I clamp a guide piece of wood so I can cut a CONTINUOS slot in all hinge slotted pieces. I use a 36" long piece of wire thru all the 1/2 hinges in 1 surface piece. Slow epoxy is used to get total floppy action. That rod ....IS THE SAME DIAMETER AS the original pins in the hinges. I do all surfaces that way. A slight 90 degreed bend on all of the....Brass..... rod ends. Done You can put bevels on the wood edges to help air flow over them. I see no difference in control response.

good thread for sewn hinges is spectra or dynema fishing line or a few threads from an old bow string.

Interesting to see this thread. <-Pun???

I, too am an oldie, in my 70s, and have been flying on and off nearly that long.
When I started building control line as a young kid I thought the string hinges were the neatest thing. I had seen pictures and thought that was what all the pro’s used. Of course, there was no internet to research, but just looking at a picture it wasn’t hard to figure out how to do it. I don’t remember using it often in my building, but I had used it some.

It has been years since I used string. Reading an article today made me remember the string hinges and I began to wonder if anyone still used it as I haven’t heard of it in years. It’s nice to know it is still in use.

I agree with John,
I, too love the look, it brings back my early days of model flying.

I have a GP Ultra Sport 60 kit (one of two I bought when they came back a few years ago. The other died a result of an elevator servo failure) ((Really. For once it wasn’t pilot error.)) and it hit me that it would be fun to make it “retro” and use thread hinges when I build it, along with a unique covering scheme. When I do get around to building it I am going to do some experimenting on reinforcing the hinge area and different type threads so it won’t pull through, or break easily. It should be a fun project.

CA Hinge Method is NOT good for CL A/C
 

1. PLEASE do NOT use CA hinges in your CL A/C. They are too stiff for our mission.
2. Just when you get into trouble overhead in windy conditions and you have very little line tension to give you control, the CA hinges will not move freely enough to give you the control you desperately need to avoid disaster. This factor applies equally to the beginner CL pilot and the seasoned contest flyer.
3. Contest Precision CL flying requires small light "feel" corrections and inputs from the pilot with the entire control system working as smoothly and effortlessly as possible. The beginner CL pilot needs to learn the "touch" required to fly CL planes, a stiff control system will prevent this learning to take place.
4. ALL the other methods mentioned in this thread are good for CL planes, as long as the result is a smooth movement of the control surface and a hinge that allows the control surface to drop down from its own weight with little to no resistance to its movement.
5. I flew my 1st CL in 1952, and my 1st RC in 1970. I think I have used every type of hinge along the way, my favorite by far is the Robart style hinge, they make them in every size we need. I use them in small foamy park flyers up to my 36 lb. IMAC planes, and in all my CL planes. They are the smoothest and strongest hinge I have found. They are also very easy to install accurately if you use their wonderful hole guide system and use epoxy AND read/see their install instructions on their web site. I have thousands of flights using them on all types of planes with ZERO failures. Even the individual planes that have more than 1,000 flights on them still have the controls move smoothly and as effortlessly as the day they were born. :-)

PS: CA hinges are Ok for sport flying RC planes. The servo is always there to push them past their stiff resistance when needed, but they are fighting the servo to do this. From a production standpoint, they are a brilliant creation for ARF manufacturers. They are very cheap and easy to produce, and they work OK for most sport RC flyers.

Geez imacone, 15 years a member here and this is your 3rd post? That was well written. I pretty much agree with you but have yet to try the Robart style hinge. 66 here and my first CL flying/building was in the late '60s. I've installed the DuBro nylon hinge on many planes, but they're really a pita to get them right. Don't know why I haven't tried the Robart style hinge yet except for ignorance and I'm usually very open to new products and techniques. I will have to try them on the next build. Thanks and looking forward to your next post in 8 years. Chime in more often.

" they are a brilliant creation for ARF manufacturers". The discovery and application of DMD (Dacron, Mylar, Dacron) came from Gail Helms, Steve Helm's dad. I like them for RC applications, but not so much for control line.The control line application produces many thousands of more cycles. I've had them fatigue, and break on control line models.

So I've just searched for a method for hinging. I've got a.35 Buster and the elevator thickness is really too thin for a Dubro or a Robart type hinge. Sewn is really the best method. OH, I originally searched this in 2019. Don't make it more difficult that it has to be.

Monokote hinges
 

If the model is to be covered with Monokote or UltraCote, then consider making film hinges. I have used these hinges on CL and RC planes with great success. Some are now over 30 years old with the original hinges still working fine. These hinges are as nearly frictionless as you can get. Cut a 1" strip of film and cover the leading edge of the elevator and the trailing edge of the stabilizer. Now cut a 2" strip of film and cut it in half to make two equal length 2" wide strips. Lay one strip down adhesive side up. Flip the other strip adhesive side down and lay it along side of the first strip and overlay 1/4" of adhesive. Use a sealing iron at 220 degrees F to seal the 1/4" glue area. Now cut off 1/2" wide strips to produce hinge straps with half the adhesive facing up and half down. Iron on these hinge strips with the same spacing as you would have used with old cloth crisscross hinges. Once the hinges are in place, then cover the surface with film as usual, which also seals in the hinge straps. These hinges will be incredibly strong, very durable, extremely light, super smooth, nearly gapless, almost invisible, highly flexible, require no holes or slots, are inexpensive, extremely cheap and and don't cost much either. I know you won't believe how strong these hinges are, so try hinging a couple of scrap pieces of balsa together and then try to pull them apart. Then you will know just how tough these can be.

Now, that is a very good writeup on a most excellent hinge! Thinking back, this method came to mind, but I couldn't recall the particulars. I do recall how incredibly wonderfully they worked, though.

When I go to cover the GB Ultimate that I am building, I plan to try this method. I know that if I do the job right, that it will work great.

Monokote hinges
 

Monokote hinges will work just fine on the Ultimate. I used them on all the flight surfaces of my Balsa USA Phaeton 90 powered with an Enya R120-4C. I built it in 1988 and it still has the original hinges after countless gallons of fuel flown through it..

I have complete confidence in the ailerons and elevators with film hinges, but I do wonder about the rudder, since it will be pull-pull with a really strong servo for the huge rudder. Lots of strong forces in various directions on the hinge back there. I wonder how film hinges would hold up to that over time. When the forces are in some directions, it may tend to peel off the film hinges from the attached surfaces.

edited: or maybe I am just over-thinking this, as I tend to do.

Film hinges for rudder
 

Film hinges for the rudder should work just fine so long as the hinges are not supporting vertical shock loads from the tail wheel which would put shear stress on the hinges instead of the tensile loads for which they excel. Monokote and UntraCote bond to themselves really well. By covering the rudder leading edge and vertical stab trailing edge prior to applying the hinges, the hinges now have a better surface on which to adhere. The surface covering also helps lock the hinge straps in place. In addition, when applying the surface covering after the hinges are ironed in place, cut one piece of film covering large enough to cover one side of both the vertical stab and the rudder in one piece. Cover the vertical stab and then fully deflect the rudder and continue applying the film down into and back up out of the stab/rudder hinge valley and then continue covering the rest of the rudder. This does two things. It 1) totally seals the rudder hinge gap to increase aerodynamic effectiveness and 2) it helps ensure the rudder will stay attached even if the hinges were to fail. I do not do this for control line models because it will cause the control surface to try to deflect slightly and is a little stiffer, but for RC use with a strong servo, it won't be noticeable. To ease your mind, just install more hinges in a solid line of hinges instead of staggering them, i.e. XXXXXXXXXXXXXXXXX instead of XX XX XX XX XX. If you still have any doubts, just make a sample and then try to pull it apart. Bet you can't do it.

I have a variety of hinge styles that were intended to to be used on this plane, but they will now all go into my hardware supply boxes. I now plan to use these film hinges on everything on this Ultimate. Lots of advantages to this method.

Thanks!

Pull-Pull hinges
 

The hinge loads on a pull-pull system are not all that different than that of a single push rod system. When a pull-pull system is activated, there is a pull on essentially one side only, the same as when a single push rod system is pulled. The only difference is that the pull-pull system will have some forward pull on the rudder all the time. With film hinges, this thrust load (tension) is absorbed by the leading edge of the rudder pressing against the back of the vertical stab. For this, I recommend leaving the trailing edge of the vertical stabilizer somewhat flat and rounding the leading edge of the rudder so it has a surface on which to "roll" as the rudder is deflected.

So I get a little lost in your explanation of the hinge straps. Are those straps once sealed/adhered together (one up, one down, 1/4" overlap) a 1/2" wide by 3 3/4" long? Once applied it would go past the initial leading and trailing edge pieces that were applied. Is that right? Then I should cover the elevator and stab right up to the hinge line capturing the hinge strap. If so, I think I got it. Thanks.

Hinge straps
 

Hi Tom, Yes you have it right. The main reason for covering the leading and trailing edges prior to attaching the hinges is because once the hinges are finished, the leading and trailing edges are no longer accessible to be covered. Not a problem with dope but it is with film. The top layer of film will also help anchor the hinge straps in place. If the hinge were to be highly stressed, then yes, covering more of the leading and trailing edges would provide for a more secure hinge strap attachment because the UltraCote sticks better to itself than it does to raw balsa wood. Also the hinges can be cut wider than 1/2" if desired for extra strength. Attached are some photos of the flap assembly for a Sig Twister I am building. Since the flap has to slide through the wing hole before inserting the wing, it is not possible to hinge the flap to the wing prior to installing the wing. The hinge straps will be ironed onto the wing after the wing is glued to the fuselage. As you can see, it was possible to entirely cover the flap after ironing the hinge straps onto the flap.

Assuming you are going to cover your .35 Buster with UltraCote or Monokote, then film hinges would be perfect for hinging the thin elevator to the stabilizer... no holes, no slots. Hope this helps. Let me know if you have any questions.

David

https://cimg7.ibsrv.net/gimg/www.rcu...62f851e56f.jpg
Leading edge of flap was covered prior to installing hinge straps. then the entire flap was covered.
https://cimg9.ibsrv.net/gimg/www.rcu...0b08a5654e.jpg
Flap hinge is almost invisible once the top layer of film is applied over the hinge straps.
https://cimg0.ibsrv.net/gimg/www.rcu...9ec0f5bf00.jpg
hinges ready to be ironed on after wing is glued to fuselage
https://cimg2.ibsrv.net/gimg/www.rcu...29275d6ce9.jpg
Wing trailing edge covered prior to hinging. Flap has hinge straps installed and then covered to seal in the hinge straps.

This makes so much sense that I'm daffy with excitement. My Brodak Buster has been sitting on a table in the basement unfinished because I got stuck on how I was going to do the hinges. I think properly installed MonoKote hinges like you describe is a really neat procedure. I've known about MonoKote hinges but never thought that they would hold up to the rigors of a Controline model. I will do as you suggest and just take some scrap balsa and test it. Thanks for sharing that man. Tom.

Tom,

Here are some photos of the finished Twister. As you can see, the hinges are nearly invisible. It flies fine and the hinges are still perfect. It balanced perfectly with an OS Max .35S without any balancing weights. How is your Buster coming along?

David

https://cimg3.ibsrv.net/gimg/www.rcu...664d1a5d90.jpg
https://cimg5.ibsrv.net/gimg/www.rcu...11be6407cd.jpg
https://cimg8.ibsrv.net/gimg/www.rcu...350e617c1b.jpg

posted twice, deleted second post

Dave, that's a beautiful looking Twister. I don't see it in your photos but you may want to add a fairlead (some have even just used a cotter pin) to prevent the pushrod from the flap to the elevator from bending when its pushing. But that is a very good looking Twister. Did you MonoKote the fuselage as well? My Buster project got shelved once again. The GF and I moved 1700 miles from Carol Stream Illinois to Queen Creek Arizona. So I had to pack all my models, built, half built, kit or ARF. I'm pretty sure it made it, I should unpack the wing and see how it did. Moving is the worst thing for a modeler. Imagine deciding which planes go and which planes get junked or given away. Also the work shop has to be disassembled. But I really like your MonoKote hinges and when I can get back to it I will certainly use your suggestion. Keep those lines tight. Tom.

Tom,

The Twister is covered in orange and white UltraCote, including the fuselage. I did apply some Cover Grip (by Deluxe) to the forward fuselage plywood doublers, wing tips, and to the wing/fuselage joints to help ensure the Ultra Cote will not loosen in these areas. I thought about adding a fairlead. However, I built it completely stock (except for the landing gear) and did not lengthen the fuselage like a Francherized Twister. The supplied elevator push rod is quite stiff and is so thick that I had to seriously drill out the control horn holes to get it to fit. So far, it has not shown any signs of flexing, even in the tightest loops.

I hope you enjoy the Arizona weather. Definitely better for winter flying. Post some photos of your Buster when you get it finished. I remember when I had to move, I ended up giving away several airplanes and some nice kits rather than move them and have to pay storage costs. I wish now that I would have been able to keep several of them ... R/C Nobler, CG 1/2A Skylane, CG Ranger 42, CG .35 Cosmic Wind, Sig Super Chipmunk, Astron .40 (Bill Evans) etc. oh well...

David

I’ve got a problem way too many kits and they will never get built. Hindge,! I use Aircraft grade A Fabric and Stits polyfibre D-103 still have some Ambroade glue the hot summers here keep the cloth hindge tight and they don’t deteriorate.

Hindges
 

I do old school and it's cheaper than buying the newer style. I've got some grade A fabric tapes that you use to cover to cover wing rib stitching. Pinked edge and I cut a two inch tape twice gives me about a3/4,inch wide hindge. Its been years sense Ive seen fabric hindges in a hobby shop. I use to fly RC and used the fabric method never had an issue.AJ

Don't they get fuel saturated or brittle? I used cloth hinges on my first 1/2'As back in the '60. But those planes didn't last long. The hinge material supplied in Carl Goldberg kits I believe was nylon..

Hinges
 

Well I don't know the fuel I use has lots of caster. And when I finish I use Silver xcide mixed with Butirate dope. Never had one fail. A few Of my planes are 45 years old. My most recient build is the Brodak Bi Slob. I used the same material its old Aircraft cotton with pinked edges I coat the balsa with 3 coats of nitrate. To fill the balsa for a smoth finish I mix talc with BUTIRATE dope. Then finish in silver. I tried using stits polyfibre finish but I went back to randolph. They supply to Sig And Brodak. Those just 9 dollar bottles. If I used color I would buy a Quart. Did buy a quart of yellow. For my wings. Just use the silver I know I am going to crash so why do a nice finish. Also much easier to repair. My planes are not pretty but I sure enjoy getting dizzy. AJ.