Hi, I'm a newbie to gas.

Locally many gassers are using similar linkages to their 60 sized glow planes with z bends being pretty common. However, most build threads I've seen online use a ball link of some sort on at least one end. This applies not just to the control surfaces but also to the throttle/choke linkages.

Is there any reason why z bends may not be suitable for a gas plane? I understand that over time, a z bend will develop a little slop, but then again, wouldn't a normal clevis do the same?

Is that why ball links are so prevalent?

Thanks.

These larger planes have larger / heavier surfaces. You want your surface gap sealed and your linkages tight. This will help prevent flutter which will destroy your plane.

Ball links by far are the prefered choice here for best performance and overall safety reasons.

Let's consider this a moment. Most, if not all, Z bends are in a metal rod, right? Now using a metal rod direct to the throttle lever on the carb of a gasser usually ends up a metal to metal connection since all the carbs have metal throttle levers. A metal to metal connection that fits loose, as in almost all Z bends, creates RF noise right next to the ignition system. Now what's the one thing you don't want more than anything else in a radio installation? RF noise of any type.

So one answer is because a Z bend creates RF interference due to engine induced vibration between two metal components. The ball link is used for three reasons. One is that it is encased in a plastic or nylon housing, breaking the electrical chain. Two is because it's a solid and secure connection that prevents vibration, and three, because it permits less restricted movement between the throttle arm and the control linkage.

As for the control surfaces, Synergy has it right. You do not want loose linkage connections anywhere, and Z bends are usually a loose fit. A Z bend will permit a lot of excess and inaccurate control movement whenever the engine is running or the plane is moving. Flutter is your enemy and a Z bend promotes it. For many planes a simple clevis still works at the control surfaces, but larger planes often require the security of a ball link.

Thanks Sinergy, I'm already sealing all the hinge lines on my glow planes, not so much to prevent flutter but because I find that the surfaces become more effective and the trim settings are more consistent.

Silversurfer - thanks for the instructive discourse! I figured out the metal to metal issue for the throttle linkage but could only guess at the rest. Your post definitely clears up the issue for me! Was rather foolishly hemming and hawing on whether to save a few bucks and just put in Z bends as almost everyone I know has been suggesting. Sorry, I guess its a silly question from a newbie; thanks for your time and perhaps you've just saved my plane from a crash!

There really are no silly questions. You are the one being silly if you don't know and don't ask a question []

Karol