I am building my second Unicorn Wing, these things are great.

At any rate I have installed my Hitec 81MG servos potted in the wing itself and am running the Sullivan control rods mostly through the foam and just out of the wing before the trailing edge. It already looks very cool.

Before I seal the compartment where the servos are I notice that after I center them, and then readjust the horn, I get much more travel in one direction than the other. So the way I have them set now it looks as though I will get great response when bringing the elevon up than down.

Any rhyme or reason to this, and is there anything that I may have over looked?

I appreciate the help, this is going to be one bad little rocket when it is done.

Thanks,
Shawn

First of all, I'm not familiar with the plane. There may be some differential deflection already built in to the controls. This is unlikely though.

When you say there is more travel, do you mean the servo arm or the pushrod?

If it's the servo, be sure you don't have any subtrim in your radio. Also check your other computer settings just in case.

If the servo has the same amount of throw both directions, check to make sure the point where your pushrod connects with the control horn is exactly over the hinge line.

-Andrew

There seems to be more travel from the servo arm itself in one direction than the other....

A unicorn is a 48" foam wing, but the servo question is a universal one.
I will go through my radio again and see that there isn't some travel adjustment wrong...

Any other ideas?

I can't think of anything normal, this is just off the top of my head. If you can't find any radio settings incorrect, perhaps your potentiometer was misadjusted?

You may need to adjust the pot to get new center point. But before you try this, wait for a second opinion from someone else on RCU. I'm not even sure if that would fix your problem. But it seems that the servo is running into the normal travel stops that all servos have.

Also you might try plugging in a servo that's known to work in that slot in the receiver. Try swapping parts around and see if your results differ at all.

Mel try this. Set your transmitter trims to neutral. Then turn on the radio and reciever with the arms unhooked from the servo's. without the linkage hooked to the arm set the arms on the servo at 90 degrees to the case. you now set the control rods to the length to meet with the servo arms. Be sure your control surfaces are centered before adjusting the rods. After all is adjusted so the control surfaces are neutral with the trims neutral. And with 90 degrees on the horns you should have the same up as down.

Having said that if you want differential (more down than up or vise versa) you only have to move the horns during set-up. If when everything is set at neutral instead of having the horns at 90 degrees you set the horn slightly ahead of the shaft of the sevo and then set the control rods and surfaces at neutral you will have differential. It is used mostly for ailerons which work more effectivly with differential. When you see a control throw that says say 1/2" down and 3/4" up or something similar you will know how to set that up. You can also get the same results by bending the control horns (or toque rods in strip ailerons) forwards and backwards to achieve the same result.

Good luck with your project.

Mark Shuman