Control horn problems on 73" Yak.
 

Ok, having problems with the aileron servo horns:

First of all they two horns I got are not the same shape. One has the hole about 1/8" farther out than the other. I took a picture of it, but it's hard to see. They are stacked on each other:

http://schu.net/gallery/main.php?g2_...serialNumber=1

One horn is longer than the other by almost an 1/8".

I put them next to each other then ran a ruler though the holes so you can see how different they are:

http://schu.net/gallery/main.php?g2_...serialNumber=1

Obviously one of them is off, but when I go to put them in the ailerons the smaller one is off about an 1/8" and the other is off almost a 1/4" if I put them where QQ recommends (1/8" behind the hinge.)

http://schu.net/gallery/main.php?g2_...serialNumber=1

http://schu.net/gallery/main.php?g2_...serialNumber=2

The servo arms fight pretty tight in the slot so either the slots are in the wrong place or the arms are way too long. I could fix it by lengthening the slot but on one side that is going to leave a 1/4" gap. Also since the hole on one side is higher than the other I'll need to bury the horn deeper into the balsa.

Any ideas on how to fix this?

RE: Control horn problems on 73" Yak.
 

Hi There,

I would move the one doesn't line up with Ail hinge line further back so it does line up. If you can make the slot a little bigger and move it, it would be fine. I would try moving it, shouldn't be hard to do, this way you will be compensating for the 1/8" difference. You can fill the gap with glue, epoxy. This won't cause you any problems. If you just lengthen it with xacto knife, you will be just fine.

Let me know if I could help you any further,
Reza
Quique's Aircraft Support

RE: Control horn problems on 73" Yak.
 

Reza,

The directions call for the hole to be 1/8" behind the hingle line, so if I do that both of them will be off 1/8". I got your message suggesting that I fix this in sub-trim, which is fine, but there is still one problem. The longer horn not only has the hole .085" father forward, but it is about the same amount taller. So the geometery of the linkage won't be the same on both wings because the servo horns are different.

I'm thinking about drilling a new hole in both horns. This would allow them to both be 1/8" behind the centerline of the hinge but also puts the holes in exactly the same place. Here is a diagram that shows the different shapes of the different horns and where I would drill the new hole.

http://schu.net/gallery/main.php?g2_...serialNumber=1

Does that look like a good way to fix that to you, or does it put the new hole too close to the existing hole on the small horn? Also, Do you have any extra horns laying around? Perhaps sending out another one would be better, as I would feel much more comfortable with this if the horns where the same.

Hopefully I'm not asking dumb questions, but I'm not an expert on linkage geometery, all I know is you want everything exactly the same so that one wing doesn't act differently than the other.

Thanks,
schu

RE: Control horn problems on 73" Yak.
 

Hi schu,

I understand you but that won't make that much of difference, especially if you do the subtrim trick that Quique mentioned. Drilling a new hole is also OK as long as you don't hit the other hole. If you want, call the company tomorrow and see if they have extra horns that they can send you, otherwise, any of those fixes are fine.

Reza

RE: Control horn problems on 73" Yak.
 

Ok, I'm going to modify the horns so that the hole is in the same place on both horns. I'll make sure it's a good 1/8" away from the other holes. If it comes up a little short then I'll move the subtrim the other way, at least it will be a bit closer and both sides will be the same.

schu

RE: Control horn problems on 73" Yak.
 

It's a good idea. Keep me posted. Thanks for the pics.

Reza

RE: Control horn problems on 73" Yak.
 

That fix worked well, the hole is about 1/8" behind the hinge where QQ says to put it and both horns are exactly the same now:

http://schu.net/gallery/main.php?g2_...serialNumber=1

This PC board stuff is great!! It's very light, strong, and easy to work with.

schu

RE: Control horn problems on 73" Yak.
 

Thank you for sharing and being cool about it. Thanks again and sorry for the extra step that this caused you.

Reza
Quique's Aircraft Support

RE: Control horn problems on 73" Yak.
 

Nevermind, I thought I had a problem, but was able to work it out.....