NOVAflier

My Feedback: (21)

I have never used these, and bought a package the other day. I had a failure with the CA hinges in my new Funtana 90 whereas they broke off at the hingeline. I had about 1/64" gap and sealed it with ultracote and the hinges just broke. They were the stock Hangar 9 hinges that came with the plane. So, I am replaceing them with the blue radio south ones. They look like thar are about 3/16 wide, which seems pretty narrow. My questions are:
Has anyone used these with success?
Is 5 on the aileron going to be enough?
should I double them up (width wise) because they seem so narrow?

SMALLFLY-

My Feedback: (19)

I have used the blue 1/4 scale ca hinges on many airplanes including my gas GP patty wagstaff with good success. Make sure you use the 1/4 scale hinge, I have had one tear in the lighter hinge on a 60 size 3d profile

joebob

My Feedback: (14)

I've used these for years and never had a problem with them. I would double them up widthwise since you got the standard size ones. They do make 1/4 scale ones that are about 5/8"- 3/4" wide. I like them because they're stiffer than the usual ones you get with kits, so it makes it a lot easier to get them to slide into the hinge slots. (I'm too cheap to but a slotter and use an Exacto knife...)

MinnFlyer

My Feedback: (4)

Nova,

First, if you're going to replace them with CA hinges, make sure you move them about 1/2" from the original locations. IF you're concerned about their size, space them so you can add an extra hinge.

Second, I would say that the 1/64" gap was the reason they failed.

I just finished building a FuntanaS 90 and when the hinges were properly installed (IE Aileron FULLY deflected when CA was applied) I got about a 3/32" gap. That's 6 times what you had.

It is CRUCIAL that the aileron be deflected AS MUCH OR MORE than it will deflect in flight when applying the CA. What probably happened in your case is that the aileron acted as a giant lever to pull the CA hinges apart.

NOVAflier

My Feedback: (21)

Minn, what you are telling me and what I had known are 2 different things. I was under the impression that the gap needed to be kept as minimal as possible (thus the 1/64"). I should also mention that the failure occured during flight on low rates. So, should I install the radio south hinges, delfect the surface fully and then ca it in? So, basically you are saying that the gap I had, when the aileron deflected, caused too much stress on the hinge joint, thus causing the failure. To remedy this, I need a larger gap (sealed of course) to allow greater deflection and less hinge stress.. Correct?

MinnFlyer

My Feedback: (4)

Absolutely correct.

If you've ever read my "How To" on CA hinges, you'd see that I addressed exactly this issue...

So many people put such a strong emphasis on that "All important GAP" that they tend to forget that the hinges need room to flex.

This is the case whether you're using CA hinges, - hinge points, or whatever else.

Here are the steps in a nutshell:

Insert hinges, Flex the surface AS MUCH OR MORE than it will move in flight. Add the CA.

If you wind up with a HUGE gap, that is because your plane NEEDS a huge gap to avoid stressing the hinges.

Now if that gap is too big, seal it up with covering/tape/etc.

Here's the Whole CA Hinge article:

http://www.rcuniverse.com/magazine/a...?article_id=55

NOVAflier

My Feedback: (21)

Well, I am now tempted to take off the other aileron and rehinge that just to be safe.
The 1/2" away from the originial location, this is to avoid the possibility of trying to attach the hinge to balsa that is already soaked with thin ca?

NOVAflier

My Feedback: (21)

I’ve decided to try the Robart Hinge Points. I ordered some from Tower and am going to give it a try. A little nervous, but I think they might be a better alternative to the CA at this point…Anyone had any luck with them?

MinnFlyer

My Feedback: (4)

Yes, the "1/2 inch away" is to avoid CA soaked areas.

And I think you're making a good choice with the hinge points. If I were building this plane for myself, instead of for a review, I would choose hinge points.

But the same rule applies...

Drill the holes, glue in the hinges (I like 30 minute epoxy, but melt some vaseline into the pivots first) Then flex the aileron to its fullest and let it sit there until the glue is fully set.

Think of it this way... Put in the hinges and push out any gap, then flex the control surface down, and return it to level (Without pushing it back in). If there is a gap, the movement of the control surface caused it. So if you didn't leave that much gap to begin with, the control surface would put that much strain on your hinges (Not to mention your servo).