tailwheel cable clevis?

13brv3 · #1 09-27-2006, 09:38 AM

Greetings,

Has anyone else had problems with the tailwheel cable interfering with the rudder stop bracket? If I install the cable as designed, it hits dead on the rudder stop, which is not a good thing. If I install it as shown in this pic- http://www.radrotary.com/tailwheelcable.jpg it clears fine.

My question is whether this is OK to do. I think it probably is, but figured I'd get a few more opinions.

Thanks,
Rusty

n5lp · #2 09-27-2006, 09:47 AM

Quote:

Originally Posted by 13brv3

Greetings,

Has anyone else had problems with the tailwheel cable interfering with the rudder stop bracket? If I install the cable as designed, it hits dead on the rudder stop, which is not a good thing. If I install it as shown in this pic- http://www.radrotary.com/tailwheelcable.jpg it clears fine.

My question is whether this is OK to do. I think it probably is, but figured I'd get a few more opinions.

Thanks,
Rusty

I've noticed a lot of RVs have this interference. I think it would be better to not go off center like that, just because it puts a little bind and extra friction in the system. Looks like it wouldn't be quite as strong either.

I just modified the rudder stop a little bit to avoid the interference.

TerryWighs · #3 09-27-2006, 10:02 AM

HI Rusty,
I am not even close to this point in my RV-8, and don't have the building experience you do, but feel compelled to comment. I am curious about whether the rudder stop angles are upside down??? Also, seems the clevis from the cable would be more stable if centered on the rudder angle/bracket rather than attached below???

Ironflight · #4 09-27-2006, 10:59 AM

I have seen other's write about this intereference before Rusty - enough times so that I was surprised that I didn't have it. My rudder stops are shaped differently however - I had to extend them aft somewhat to give the right travel limits for the rudder. It is possible that makes the difference. I'd be a bit nervous (as you seem to be by asking the question) of that installation, but I can't back that nervousness up with any facts - just looks odd.

Paul

bsacks05 · #5 09-27-2006, 11:13 AM

I had the same problem with my -9 that was noticed by a EAA TC. He suggested that I file the end of the stop so that, if the clevis does hit, it won't hang up, but just slide past. I would not mount the clevis under the bracket. In the very unlikely event that you loose the cotter pin and the nut backs off, the clevis and cable drops off also. If you install it the correct way and have the same bad luck with the cotter pin, then the bolt and cable tension should still hold the clevis on.

13brv3 · #6 09-27-2006, 11:45 AM

Thanks for the comments. The rudder stop is in the correct position relative to the rudder horn, so it can't be moved. I could round the bottom corner off, which would allow the cable to slide down below the stop, but it would soon wear away the aluminum stop from the constant rubbing, so I don't think that's a good option.

I think the current arrangement of the clevis probably looks worse than it really is. My bet is that the bolt and clevis is still stronger than the thin section of aluminum between the hole and the edge of the horn. Still, I'm not sure I want to leave it like this. I've thought of a few options to strengthen it up beyond question, but I'm still deciding if it's worth the hassle.

FWIW, I think this problem is a result of the vertical placement of the vertical stab on the fuselage. There's actually a conflict between where it supposed to be, and the location for the lower bolts. Those bolts have to go through the tailwheel spring weldment, and the lower hinge weldment. Too high, or too low, and you don't get good edge distance on one or the other bolt.

I set the vertical height to make the edge distance correct for the bolts, because I figured that was more important than anything else. As a result, the vertical stab, and rudder are lower than they should. If they were higher, the stop would be higher, and the cable would come up at it from a better angle to clear the stop.

The other problem is that the chain for the tailwheel rubs the bottom of the rudder tip. Basically, the whole rudder horn could stand to be lowered where the cable, and chains attach. I've thought of a way to effectively do that, but again, not sure it's worth the hassle, though it will almost certainly bug me until I do it

Thanks,
Rusty

sf3543 · #7 09-27-2006, 11:56 AM

I would not mount the rudder cable to the rudder horn in that manner.
Instead, I would install the cable correctly and mount the stop so that the contacting part of the stop is slightly above the cable. Make sure you rivet the stop to the longeron instead of to the skin. Looking at your picture, I would make the part so that the mounting side of the stop is down, rather than up, so that you can rivet it to the longeron. You can drill out a rivet or two in the longeron and rerivet the stop on, utilizing the same holes. You may need to get a new piece of angle with a wider side to make it work or look nicer. I had to do that with mine to get the clearance I wanted.

dan · #8 09-27-2006, 12:24 PM

Quote:

Originally Posted by TerryWighs

I am curious about whether the rudder stop angles are upside down???

Terry you hit the nail on the head. The rudder stop angle is upside down.

13brv3 · #9 09-27-2006, 03:55 PM

Quote:

Originally Posted by dan

Terry you hit the nail on the head. The rudder stop angle is upside down.

Sorry, but thank you both for playing

Unless the plans are wrong

the rudder stop is installed correctly.
http://www.radrotary.com/installed_correctly.jpg

Even if I wanted to change it so that the vertical flange points down, it would not change a thing, because it's the horizontal part of the stop that hits the cable. The horizontal part has to be vertically aligned with the horizontal part of the rudder horn for the stop to work, so it's going to have to be right where its at, regardless of which direction the vertical flange points.

I have thought of a fairly simple mod I can make to the rudder horn that will allow the clevis to be lowered, but also end up much stronger than the stock attachment. I should even be able to lower the attachment point of the tailwheel chain to help keep the chain from rubbing on the bottom of the rudder tip. I'm still deciding whether it's worth doing or not, so I may just go on to something else and keep thinking about it.

Thank you for your comments.

Cheers,
Rusty

Bill Dicus · #10 09-27-2006, 04:00 PM

Quote:

Originally Posted by 13brv3

Greetings,

Has anyone else had problems with the tailwheel cable interfering with the rudder stop bracket? If I install the cable as designed, it hits dead on the rudder stop, which is not a good thing. If I install it as shown in this pic- http://www.radrotary.com/tailwheelcable.jpg it clears fine.

My question is whether this is OK to do. I think it probably is, but figured I'd get a few more opinions.

Thanks,
Rusty

May not be pertinent but the throttle cable yoke to servo arm on our Pitts S-2A is mounted on one side as in the pic. Loads are less but this has worked fine for 25 years. Bill