Ball joints on comp-arf surfaces?

[FastnLow]

On my comp-arf 2.6 330L I used 4/40 clevises on the elevators and ailerons because the manufacture said ball joints create a dangerous side load on the phenolics or something along those lines. Yet I have seen many planes of that style on the net with nothing but ball joints. What's right/wrong? I'd love to get rid of the clevises they get sloppy quick in the phenolics. Plus get rid of the phenolic servo arms they supply and replace them with aluminum.

[Flyinhigh]

I'm not going to say the phenolic arms can't be used succesfully, but I never gave them a chance. I went straight to metal servo arms, and I use ball-joints with great success and accuracy. Intuitively, those phenolic arms seemed to me like they would be the achilles heal of the linkage.

[Cookie]

Hi Stacy, over here in Australia our C-ARF dealer sells heavy duty replacement horns that you can run ball links on without fear of them throwing in the towl.

You can also use double links, that is one rod on each side of the horn with ball links, that stops the horn twisting.

Dealer is Desert Aircraft Australia.

	Quote: Originally Posted by FastnLow
	On my comp-arf 2.6 330L I used 4/40 clevises on the elevators and ailerons because the manufacture said ball joints create a dangerous side load on the phenolics or something along those lines. Yet I have seen many planes of that style on the net with nothing but ball joints. What's right/wrong? I'd love to get rid of the clevises they get sloppy quick in the phenolics. Plus get rid of the phenolic servo arms they supply and replace them with aluminum.

[forgues research]

	Quote: Originally Posted by FastnLow
	On my comp-arf 2.6 330L I used 4/40 clevises on the elevators and ailerons because the manufacture said ball joints create a dangerous side load on the phenolics or something along those lines. Yet I have seen many planes of that style on the net with nothing but ball joints. What's right/wrong? I'd love to get rid of the clevises they get sloppy quick in the phenolics. Plus get rid of the phenolic servo arms they supply and replace them with aluminum.

Phenolic is a very strong material, are we really talking about phenolic or another material.

Roger

[Tired Old Man]

On the single leg or wheel shaped phenolics you cannot safely use a ball link. It has to be a clevis or eventually the side loads imposed by the ball link on the phenolic will break it. With the single wheel horns (ala rudder servos) a clevis is quite limiting in travels and movement. However, there's nothing to prevent using a ball link on the servo side when using a metal servo arm. You do need to make certain that the phenolic horns are installed in a manner that permits a fairly straight shot from the servo side to prevent binding of the clevis though.

On the larger Comps using the double phenolic horns you simply install the ball link between the horn legs. That's what they are designed for.

[PatrickP]

If you want some carbon fiber control horns.
email me. I use the double ball links both sides.
1/16 thick carbon fiber.
I have a waterjet to cut them out with.