Foam hinge failure

[doctormike]

My Dynam Gee Bee Y crashed on it's second flight because of foam hinge sepration. I am strengthening all my foam hinges with a coat of E-6000, now. Any good contact cement will work. Doc

[fhhuber]

The molded foam hinges in EPO models are guaranteed to fail... eventually. It seems to be the thicker the hinge the fewer flexes before failure.
Might be a few flights... might be years.

When mine show signs of going bad, i cut the control surface free and re-hinge with CA hinges.

Adding thickness with some glue or tape trying to preserve the molded foam hinges just makes the hinge stiffer and in my experience makes them fail sooner.

[xviper]

My Dynam Gee Bee Y crashed on it's second flight because of foam hinge sepration. I am strengthening all my foam hinges with a coat of E-6000, now. Any good contact cement will work. Doc

Indeed. I've used regular contact cement from hardware store and also FoamTac, which I have lots of at all times. There is also the hot glue trick as well but not all types of control surfaces will take to that method well......
(Fold control surface away from the notched side till you get a flat surface between the control surface and the main wing, hinge in the middle. Then you squeeze a blob of hot glue on a scrap piece of foam board or stiff foam and run a thin film of hot glue all the way down the flat surface. Let cool before letting it go back to its normal position.)

[WintrSol]

Or, just use a sharp modeling knife before the first flight - cut the hinges straight and clean, insert DuBro hinges, and lock them in place with toothpicks. Your servos will love you for this, and you don't have to worry about control separation in flight.

[wrongroad]

G'day doctormike,
I do not subscribe to the theory of breaking in the hinges by flexing them by hand either. I did this with my first FMS [1400] Trojan and the rudder failed after twenty flights or so. Luckily I saw the failure on the ground. I used the supplied contact cement to refit the rudder and have had no problems since. I have never hand flexed the hinges on any model since and have experienced no servos problems because of not flexing or, for that matter, flexing them. I just hook up the servos work them a bit and go from there.
I think if I were to have any more dramas in that section, on any model, I would do some surgery and fit Dubro hinges. I have some ready for just such an emergency. Like with all spares or replacement parts, you never seem to need them:p
For a few dollars and a little bit of time, it would give much more peace of mind.
These models are getting far too exspensive here in Australia to risk crashing for a silly, preventable failure.:D
Regards and respect
Daryl

[doctormike]

Yes, Dubro pin hinges are the best way to go. Doc

[TiredIronGRB]

I've used clear Gorilla tape and it seems to work very good and it takes paint. I cut it the full length of the hinge.

[Pauly]

Just wondering if a strip of hinge tape would work on both side to strengthen it up a bit or help reduce a break?

[Lon]

Just wondering if a strip of hinge tape would work on both side to strengthen it up a bit or help reduce a break?

On the few hinges i've had fail. I've repaird them with Welder Professional industrial-Strength adhesive. Has worked great.

[xviper]

FoamTac, Welders glue and hardware store contact cement are all forms of contact cement. For foam control surface hinges that either completely or partially tear, any of these products make for a good repair. I had a Funjet (elapor foam) that ripped one entire elevon off that was fixed with contact cement. It survived high speed use on 4 cells. It was "dumb thumbs" that finally killed it not the hinge repair.
(There is a YouTube video that shows how it's done.)

[boomer108]

I've used Welders adhesive on completely torn hinges and it works great. I also use it to strengthen good hinges before there's a problem. I've never used Foam Tac on hinges, but I'm sure it works just as well.

Roy B.

[Pauly]

Thanks for all the info. I was just this week thinking if putting some hinge tape on all hinges just to strengthen them up before there's a problem, but after all the advice here I just may use some Foam Tac on all control surfaces instead of tape. One question though.....would I need to use a brush on the glue or just run a small bead down in the grove of the hinge?

[xviper]

Thanks for all the info. I was just this week thinking if putting some hinge tape on all hinges just to strengthen them up before there's a problem, but after all the advice here I just may use some Foam Tac on all control surfaces instead of tape. One question though.....would I need to use a brush on the glue or just run a small bead down in the grove of the hinge?

These types of cements don't work as well when there is no clean break or split. Just applying a thin layer on top of a hinge may not do much. You need 2 opposing, matched edges for this kind of "fix" to work.
If the hinge has not begun to tear yet, hinge tape as a reinforcement or "insurance" may be the way to go. The only problem is that if you have a hinge that lies at the end of a bevel, the tape has to follow the contour of that bevel. Hinge tape works best when the hinge is flat on one side where the main wing (or elevator) goes straight into the control surface. This is more prevalent in foamboard type planes or homemade depron planes where you bevel only one side so the control surface and move unimpeded in that direction.
Another way of doing a hinge re-inforcement also comes from foamboard or depron planes. After making one bevel, you apply a thin film of hot glue using a scrap piece of material. Load a glob of hot glue onto the scrap and squeegie it along the open control surface bevel. Let cook before releasing the control surface.

[Pauly]

Thanks Viper. I guess probably the best thing to do is just always do a good Pre-Flight of all hinges and any part of the plane before a flight and make a modification when needed. I don't have a large hanger full yet (only 3). My wife says that's enough for now. But us guys can never have to many "Right". I still haven't done anything to any of them in that department. Thanks for the advice.

[Pauly]

I've used clear Gorilla tape and it seems to work very good and it takes paint. I cut it the full length of the hinge.

Pretty good stuff. I just used some to repair my canopy when a friend of mine had his battery to die in his radio and lost control of his plane and guess where it landed at full throttle? Yep on top of my canopy and ripped a pretty good gash in it. Luckily there was no damage to anyone or the plane for that matter other then my canopy. I had to duck because I saw it coming and was just a couple of feet from my head when it struck the top and feel and we were able to grab it carefully and hold it down as I unplugged the battery since it was still full throttle.

[xviper]

In case some folks are a bit confused about what I mean when I'm talking about a single bevel and a double bevel hinged control surface, here are a couple of pictures. The first one is a "double bevel" foam hinge. Note the "hinge" is in the middle of the control surface and there's a dip on both sides. This type of hinge is best repaired with a new "slide in, CA hinge". You make a slit on both sides and slip the hinge in so that 1/2 the hinge is in each side, then wick in some foam safe CA. The other method is to make a contact cement hinge. Reinforcing with hinge tape may be "insurance" for an unbroken hinge but having the tape follow the contour of the bevel makes it a weak hold.


Next is the "single bevel" hinge. To make or reinforce or repair this type, the best is to use hinge tape along the flat side. You can use tape on the bevel side but again, this is a weak hold. This is also the type where you can leaved some of the foam intact along the flat side, fold the control surface such that the bevel side becomes a flat surface, then run a small film of hot glue along it to make what is basically a hot glue hinge. Reinforcing with hinge tape on the flat side makes for a fairly sturdy hinge.

[VOODOO]

I was concerned with the feedback on the 78" CarbonZ T28's foam flap hinges. When assembling mine last week, I decided to add CA hinges to the flaps, but did not want to cut the foam hinge apart, since it provides a perfect air seal. The hinge line is flush with the bottom flap surface, so I CA'd the flat hinges to the bottom surface after perforating the foam and hinge to improve grip for the CA. Then I ran Blenderm tape full length on the flap bottom. Works great, and I feel it solves the tear away problem without much trouble or disfigurement.

[VOODOO]

I applied hinge tape to my DYNAM PITTS after watching the flight video, where reinforcement was suggested. It now has well over 100 flights in over a years use. To apply, I fold the hinge tape sticky side out over a thin plastic ruler and then push the ruler down into the bevel, so that it adheres to the live hinge, then carefully lay out the edges onto the bevel and the control surface. I have used this procedure on all my foam hinged models, and never had a failure.

[bigdon1a1]

Pretty good stuff. I just used some to repair my canopy when a friend of mine had his battery to die in his radio and lost control of his plane and guess where it landed at full throttle? Yep on top of my canopy and ripped a pretty good gash in it. Luckily there was no damage to anyone or the plane for that matter other then my canopy. I had to duck because I saw it coming and was just a couple of feet from my head when it struck the top and feel and we were able to grab it carefully and hold it down as I unplugged the battery since it was still full throttle.

does not sound like battery died not running at full throttle

[Pauly]

Radio bigdon not the plane. Plane was fine.