summerwind

what are you guys using on your speed stuff?

i've been using CA hinges, and until today i have had a lot of confidence in them.
now the failure i just had may be due to several things, but i want to play it say with the new stuff i'm building.
the plane i currently tool around with is a GP's Super Skybolt, and it is powered with a YS 110s, APC 15x8 on 20/20.
it's obviously grossly overpowered, but it is fun!
the upper right aileron parted company with the wing this A.M. and i was lucky to see it flickering in time to chop throttle and land.
all 3 CA hinges were sheared off at the point where they are into the wood.
now i have not ever sealed the surfaces and there is just over a 1/32" gap.

i'm going to replace these upper wing hinges with Dubro pinned as i will probably have to big of a slot once i dig the hinges out.

my newest projects are GP Patriots, 1 with a Jett BSE 50, and the other with the new SJ 56LX..................don't have the luxury of extra ailerons like i did with the skybolt, so i need to use the best hinge.

combatpigg

My Feedback: (3)

I've had to replace worn out CA hinges on 160+ MPH planes after just a handfull of flights. Don't know which brand, probably SIG. Anyway, I use the Large HD real hinges now and dowel them with round toothpicks. I don't bother gluing the hinges in, just make the toothpicks a tight fit through the pilot holes and they won't go anywhere.

MJD

My Feedback: (1)

I think the demands on many speed airplane hinges may be less than those on aerobatic biplanes.

Are you positive there was no flutter involved? What is the control throw? How much flex is there when you grab the aileron TE's and wiggle them?

Over a 1/32" gap, no sealing, overpowered, with the control throws one would use for aerobatics = potential recipe for flutter. In order for them to tear like that along the hinge line, they either have to be lacking in tensile strength for the job - not likely, the materials used are generally pretty darn tough and normally would rip the adhesive and substrate out - or they have fatigued from the angle of deflection they flex every full control cycle, and/or continuous oscillations due to incipient flutter. The latter is what I suspect.

I and others have dozens and dozens of flights on CA hinged Demons with sealed gaps, and nothing has sheared yet that I've heard. Doesn't mean they won't shear on the next flight of course, but my point is there sure seem to be mitigating factors here. The maximum throw on my delta elevons for example is about 3/16" (launch, low speed antics), 1/8" at low rate (95% of the time), meaning they only flex 7-8 degrees maximum and normally only 3-4. That will fatigue the material far more slowly than 15,20, or more degrees per cycle as on aero birds.

What I am saying is that I would be far more concerned bout CA hinges on your Skybolt than I would be on a fast plane with sealed hinge gaps and tight control linkages and small control throws. But now that you've had that scare, I bet CA hinges are not on top of your LHS shopping list.

MJD

summerwind

Mike,

all of what you just said makes mucho sense, and ye they are moving quite a bit deflection wise.
the airplane was really designed with a lower powered engine in place too.
amazingly i have done some downward dives at 25* angles and we've not heard any flutter.
i'm now checking the other hinges, and wow, they move like pinned hinges now.

yes i'm a bit concerned about CA in the new planes, but as you say, the deflection is nil compared to the bipe.
have to give this some more thought.

Iflyglow

My Feedback: (79)

I have no faithe in any of the CA hinges except for the RADIO SOUTH CA hinges. I have done quite a few test samples, and the GP's were the worst. The fiberpaper would stay in the wood, and the mylar would pull out. The sig are a little tougher, but the Blue Hinges from Radio south are the hardest out there to destroy. You have to grab tghem with a visegrips, and twist them, and twist them to break the hinge. My RV-4 that was also YS 1.10S that was also fed on 20/20 with a 15-8. It shredded the tail on a high speed flyby from flutter, and the hinges are totally intact. Here is a picture showing the the 3/8" thick stab that sheared off, and the mangled 4-40 pushrods. The fun part was gettng it on the ground, which I did with flaps and power.[X(] Here are the hinges that I am talking about. You can also by the material in rolls and cut your own size. You will not break these. Here is a video of what flutter looks like in real life.[X(]

http://www.youtube.com/watch?v=iTFZNrTYp3k&feature=fvw

http://www.youtube.com/watch?v=DU7c0...eature=related

MJD

My Feedback: (1)

Ouch! Now if you only had that on video.. like the one wing landing of an RC model (versus the fake commercial).

MM - I'm with you on the delamination thing. On my CA hinges I dremel a hole and pin them with bits of bamboo skewer. My comment on the tensile strength is talking about the intact, new hinge. I don't even know what hinge material I own (I should pay more attention), I pick it out of the hinge drawer, play with it and if it seems up to the job I use it, but I do pin them - so the core is doing the work even if the fuzzy bits aren't well bonded to the core or the airframe. Except on parkies, that's too much work for those. Definitely on the deltas.

This situation sounds like there wasn't a bonding problem but a fatigue/tearing thing going on.

MJD

summerwind

i think vibration played a big part in these hinges crumbling.
replacing them with pinned.

any reason not to use pinned hinges on the Patriots?

daven

My Feedback: (1)

Outside of skinned hinges, I've used CA hinges on tons of 165mph+ quickies.

I like the Sonic Tronics hinges that have the slot that helps glue wick into the surface.

mk1spitfire

I've found C/A hinges great, its just the thin cyno putting them in that can run everywhere!
However, I've had to replace the hinges after a few hundred flights, usually its the hinges next to the horn or root side of elevator that break.
To much elevator travel for flairing the model puts strain on the hinge but for flight, hardly any elevator is used to save drag.!

airraptor

My Feedback: (66)

i always replace mine even on light wieght small 3d planes.
I agree with motorman. i did have the GP ones in a revolver and the plastic pulled out of the fiber stuff. this was on both elevators at 130 30 feet above ground during a split S lol not much left of the plane. lol

smoknrv4

My Feedback: (11)

I've always used ca hinges, but yes the Radio South ones seem to be the most robust, for my liking.

combatpigg

My Feedback: (3)

I think some of the trouble with CA hinges is forcing them into less than perfect slots. If the slots aren't totally parallel with each other, there will be a tearing action as the hinge is flexed.

An old style, thick plastic hinge can't be forced into crappy, misalligned slots as easily.

The hinges I can't bring myself to use are those Robart hinge points.

Ever notice that ALL the "ARE THESE THINGS ANY GOOD" type threads are about CA hinges instead of the old style?

petec

My Feedback: (58)

I stopped using CA hinges for a while and went the Robart route until I got a bag of Radio South CA hinges. I use them in my pattern planes, giant scale planes and speed planes.

summerwind

quite the concensous here in regards to R South hinges......glad i asked. i did not know they had hinges, so i'm a listener, and ordered a bunch to try out.

question though, do these get stiffer than GP or Sig CA's?

smoknrv4

My Feedback: (11)

They don't seem too get any stiffer at all, I also drill a 1/16 hole down the middle of the slot so CA can wick.

vicman

My Feedback: (10)

I'm not a big fan of CA hinges since I'm never sure I'm getting enough glue down into the slot. I use the plastic ones from DuBro and glue them in with Gorrila glue. No pinning required. I have a pic where the hinge pulled the back rail out of the wing in a mid air.

C_Roundy

Obviously there is more than one way to skin the cat as far as outright shear strength and longevity, But now that the focus is on the issue, I will say something.

1) I have seen every imaginable mistake regarding the installation of C.A. hinges; with that said, in my experience, most of those gross mistakes are committed by ARF builders who simply have not put enough time into the game to get their head into what an adhesive joint really means.

I.E.) putting ANY CA on them before complete alignment and assembling them ruins the "first good bite advanage" of whatever the underlying mylar is,

I would actually be interested to know what anybody who has studied these things has ro offer.

summerwind

C_Roundy,

i'd be interested in hearing your description of "every imagieable mistake" for installing CA hinges is. not to challenge you, but to hear how many different ways there are to do it wrong.
personally i never have had a CA hinge break, or come undone. since 69' i have always installed pinned hinges. wasn't til i came back to RC after a 15 year layoff did i use CA hinges and all that i've installed have not yet failed with the exception of the bird mentioned above. i contribute the failure to overpowering and excessive vibration (and yes the prop is balanced) as the previous underpowered Skybolt (OS 91SurpassII) flew many more flights and no hinge failure.

so for me, i'd like to hear your experience Mr Roundy, as it would help others to understand what not to do.

combatpigg

My Feedback: (3)

It's best to use 1 drop of fresh THIN CA per side [meaning only 2 drops total per hinge tab].

The kind of hinge that has the fuzzy stuff bonded to an inner smooth plastic layer is inferior to the single layer style. That's what I read in an advertisement...it could even have been a Rocket City or Radio South ad?

Mike Connor

My Feedback: (5)

CA hinges are great if done right. Here is a RCU "how to" article. Good article except I think they use more CA then necessary.
http://www.rcuniverse.com/magazine/a...rticle_id=1180

mk1spitfire

Isn't the fuzzy stuff the capilary wick and sticks better than smooth.

combatpigg

My Feedback: (3)

Using CA hinges VS pin style reminds me of using OSB VS plywood for roof decking and house siding. If installed properly, OSB works well....to a point. Nobody can dispute that exterior grade plywood is better, but the argument is that OSB is good enough.

summerwind

OSB you say......

i had a customer who used it on his deck.........when i was there installing he told me to be careful of a few spots as the material being 3 years old was just falling apart......i found a couple new spots for him as well

i agree with you 100%

combatpigg

My Feedback: (3)

SW, you might remember when Louisiana Pacific came out with the fake cedar OSB siding? Millions of homes had it installed...by carpenters and painters in too big a hurry to do it right and LP had to pay out a big class action law suit. It takes too much attention to detail for the average carpenter, but if it's installed right and well painted it works adequately.
Better than real cedar though?
Not with the carpenters I see walking around nowadays.

Iflyglow

My Feedback: (79)

They work awesome don't they.