Installing Bearings in Composite Arf Phenolic Hinges (Rudder/Elevator Hinges)...

[Paul Cataldo]

Guys, WHERE have I seen this procedure done on the net? I swear a while back, I saw someone who had actually installed little round roller bearings? (I think) in the hinges of the rudder, and POSSIBLY the elevator TOO.? Not sure about the elevator, but I KNOW I saw them in the rudder hinges. I cannot for the life of me, remember WHERE I saw this, and on WHICH Composite Arf plane it was on. However, I DO remember seeing this somewhere, and I'm 90% sure it was on a Composite Arf brand plane, at least 2.6m, or maybe even a larger one. Can anyone help here?Has ANYONE here EVER done this mod to their plane? HOW do you drill out the phenolic hinges for the bearings? Do you possibly have to use a 90 degree angle drilling attachment for a Dremel tool? More importantly, I would like to know HOW the bearings are held/fastened in the phenolic hinges???? Is Aeropoxy/Hysol 9462 used???? Finally, has anyone EVER experienced significant wear between the aluminum hinge pin and the phenolic hinge points???? I would think that someone, somewhere has, otherwise no one would have ever decided to start putting bearings in their hinge points. I wonder how bad the wear can be, and how long (after how many flights?) does it take to get this much wear in your hinge points????? Now for those who just cannot handle seeing guys perform cool modifications to their planes, and for those who are absolutely dying to jump in here and say that this mod is unnecessary, then let me lay out a disclaimer and say YES, I KNOW that bearings in phenolic hinge points are not necessarily needed, but I think it's an interesting mod, and if nothing more, I'd like to obtain more info on this procedure. Thanks so much for any help guys....

[Kiwi]

Paul.

That thread is is on this site but I cannot remember where. If you do a search for McMaster Carr I'm sure you will find it.

You drill the phenolics out with a step drill bit. Just twist it it in your fingers as the phenolic drills very easy.

You can fit ball bearings to the upper and lower rudder hinge and you use nylon panel bearings for everything else including elevators. Its a must do modification and makes a huge difference.

[reyn3545]

I just finished an Extreme Composites Edge 540, and felt there was too much slop in the elevators (the rudder is held pretty tight by the cables). The manual suggests an option to install bearings on the ends of each elevator.

I went to bocabearings.com and bought 2mm inside / 5mm outside bearings, and some 2mm carbon fiber rod to replace the metal rod. I haven't installed them yet, waiting on the carbon rods to arrive.

They say to just CA glue them in place, but I plan to use just a dab of Hysol. I guess the critical part will be drilling out the phenolic for the bearings.

By the way.. where can I find a step drill bit?

[Kiwi]

They are are an off the shelf item at most big home improvement stores and SEARS has them for sure.

[reyn3545]

OK... thanks. I just haven't looked yet.

[japan3d]

I used these bearings from McMaster Carr for y 3m Extra elevators. Part Number 7817K33 I used a metric step drill to enlarge the holes in the inner,middle and outboard phenolic hinges.

[Paul Cataldo]

	Quote: Originally Posted by Kiwi
	Paul. That thread is is on this site but I cannot remember where. If you do a search for McMaster Carr I'm sure you will find it. You drill the phenolics out with a step drill bit. Just twist it it in your fingers as the phenolic drills very easy. You can fit ball bearings to the upper and lower rudder hinge and you use nylon panel bearings for everything else including elevators. Its a must do modification and makes a huge difference.

Kiwi,Thanks for the info bro. You seem to know a bit about this procedure. I would like to ask you WHY would it be recommended to only use two bearings (one on each end rudder hinge), and then change to nylon panel bearings in the middle hinges of the rudder? Why also, would you not use the regular bearings in the elevator hinge? I'm just wondering WHY you would not use the regular bearings throughout, and WHY would you not do the elevator the same as the rudder? It sounds like you are saying this mod is recommended for ANY size Comp Arf plane, eh?I have NEVER once heard of this procedure until just recently-(even from the diehard modification guys like me, who are ALWAYS looking to upgrade their planes). I suppose that the only worry I would have with this procedure, is IF the bearings ever wore out, you would not really have an easy time (if even possible) of removing/replacing the bearings. I suppose that sealed bearings requiring no lubrication for the life of the bearing, are what is recommended, yes? Thanks so much for your help. I look forward to finding that thread and reading more about this procedure. I also look forward to hearing from others, who have done this procedure, and hearing what they have to say about the results/etc.

[pfact]

I've modified all of my C-ARFs including a new 3.3M Yak.

You can use bearings but the outer width is such that you need to remove a lot of the phenolic horn leaving only a thin rim of material around the bearing - I am concerned that more support is needed. The plastic bushings require removal of only a small amount of material.

I bought a 5.2 mm drill from McMaster Carr and used a regular drill for the outer horns, for the inner one I twisted the bit by hand. I did see a post where someone used a dremel with a right angle attachment and a cone shaped grinding bit to enlarge the holes in the phenolic horns.

The other issue you will have to deal with is that the height of the bushing is greater than the openings for the horns in the rudder and elevators. A flat file to the balsa and brass tube and a few minutes of elbow grease enlarged the opening enough to get the bearings through.

When done you will see a huge difference - no more wobbling of the elevator or rudder!

Phil

[Kiwi]

What Phil said,

You will never have any trouble with the bearings wearing out unless you plan on flying the plane for 20 years or more. They dont wear.

Also you junk that aluminum tube and buy the correct size brass tube. It is a little heavier and it DOES effect the CofG minimally.
You can also use a carbon fiber tube but there have been serious incidents with RF noise generation and loss of a clean signal to the Rx. I personally have used the carbon and with no problems but be aware it can happen and a lot of guys stick to the brass tube for that reason alone.

As for never seeing it I suppose a lot of people just fly their C-ARFS as they arrive out of the box but this mod has been around for years, at least 5 that I know of and it makes an enormous difference to the fit and slop on the rudder and elevators.

As pfact said above the only really PITA is opening out the outer and inner phenoloics so the bearings are a neat fit between the two hinge points but it takes you 30 minutes to do the whole plane once you have done it once before.

The panel bearings clip in and can be removed in a second if need be,

The ball bearings I use a low strength loctite (242) as its a non hardening retaining compound. You can remove the bearing (carefully) if desired.

[DesertHucker]

I done the bearing mod on a 2.6m YAK with all the hinge points, I too was worried about how much material was left. I used flanged ball bearings 4mmID 7mmOD
But after a bad crash, the rudder post was pulled out, one of the hing pin tube int the elevator surface broke, but not one phenolic broke.

I found a stepping bit metric, works better than a drill. A drill can bite hard and brake the phenolic.

Also make sure all the phenolics line up. They can be out 3-4mm. Once the bearing mod is done the tolerance is to close to get the tube back in. The old phenolics have that much play in them that it does not matter too much.

[JagerBomb]

I have just recently installed the panel bushings in both my 3.3 Yak and a new Pitts Python also from Composite-Arf. I ordered a 12 inch long #7 drill bit and was able to drill the phenolics easily and this also insured that everything lined up perfectly. McMaster Carr also has those bushings in 2 different thicknesses. The wider one worked perfect on the outer hinge posts without having to thin the phenolic.

Mark

[Hammbone]

	Quote: Originally Posted by JagerBomb
	I have just recently installed the panel bushings in both my 3.3 Yak and a new Pitts Python also from Composite-Arf. I ordered a 12 inch long #7 drill bit and was able to drill the phenolics easily and this also insured that everything lined up perfectly. McMaster Carr also has those bushings in 2 different thicknesses. The wider one worked perfect on the outer hinge posts without having to thin the phenolic. Mark

Do you have part #'s for us?

Thanks, Jim