I have two types of control horns for my servo. One has 4 arms and i have 4 others that have 6 arms. Does it matter which control horns i use? Which would be better? the instructions for this thing really sucks but i guess its not meant to be built by someone who has no idea what they're doing either. LOL.

Use whichever servo horns provide the movement you need. Many modelers cut off the extra arms once they have fitted it properly - especially if there are two servos turning right next to each other to prevent them from hitting.

I used the smaller horns so I would have more room for the receiver and fuel tank. Now I have to figure out where to put that . Thanks for the advice. It is greatly appreciated.

The purpose of the round or star shaped output arms is in one case the aileron pushrods can attach to the wheel not directly even with the the rotation center. This will provide something called differential aileron throw without the need for a computer radio or dual aileron servos. The purpose is to minimise 'adverse yaw' which is just the tendency for the nose of the airplane to try to point away from the direction you are turning when using only ailerons (the down moving aileron is more draggy than the upward moving one making the nose want to point the wrong way).

It makes for a much prettier flight and is done with a highwing trainer just by using a round or star servo wheels and making the Aileron pushrod just slightly longer so they attach to the wheel just beyond the servo pivot points.


John

There shouldn't be too many choices on where to put the fuel tank.

maybe I need to put the round ones back on lol.

What John is referring to is that the splines on the servo don't have the same ratio of degrees as the arms, so that if you line up the #1 arm (look closely, each arm is numbered) and it is not centered, you can try the #2-6 arm.

nope already installed the tank.

<<What John is referring to is that the splines on the servo don't have the same ratio of degrees as the arms, so that if you line up the #1 arm (look closely, each arm is numbered) and it is not centered, you can try the #2-6 arm.>>

MY GOD! I never realized this! I never even considered the possibility! This explains why some of my semi-careful alignments seem to be slightly off after I snip the unused arms. I figured I was just misaligned when I replaced the horn - not that they were designed that way. Like most thngs - it do make sence once it's been 'splained.

MikeB for President!

Thanks Charlie, but there are WAY too many things in my past (and present for that matter) that I wouldn't want anybody digging up and making public!

I never knew that about the servo arms either. And how do you make those great drawings?

Yeah, please do tell. You seem to have a great graphic for every answer (or question).
By the way, I've been flying for 8 years, and I never knew this either. Does explain a couple things.
Dennis-

I'm a graphic artist by trade. Most of what you see here I created with Photoshop, Illustrator, and Dimensions (All by Adobe).

I will often draw something to better illustrate a point, then I save them all for future posts since the same question gets asked every now and then.

And while I copyright them in RCU's name, anyone may use them, (or for that matter anything seen here on RCU) for their club newsletters, etc. as long as you add the statement: "reprinted with the permission of rcuniverse.com"

And IMHO a damned fine job you do of it!

:taking bow:

Thank you, thank you.

I take PayPal

and being a mod for RCU is just one of them

Not to MENTION that night in Tijuana!

MinnFlyer: your post #7 is great Thanks.
Another thing that does not get explained much is just where to put the brass grommets when installing servos. No instructions on order of assembly comes with the servos. What I saw at field was grommet visiable. 9CAF manual shows how to do per Futaba, grommet next to the wood.