What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Rudder stop: any reason not to trim?

A

alpinelakespilot2000

Well Known Member
Is there any reason NOT to trim the red-shaded portion of the rudder stop shown below? I saw a couple of RVs at Oskhosh that had trimmed them and it seemed pretty logical not to carry around a portion of the stop that seems to do nothing. (I'm building a tailwheel version, so I don't think there'd be a need to drill a hole in the stop for a gust lock.) Thanks.
 
Last edited:
Leave it the way the plans show.

The farther you trim it back, the more the loads will be at the contact points when your rudder does hit the stop. Eventually, you could damage or break something.
 
Kyle Boatright said:
Leave it the way the plans show.
The farther you trim it back, the more the loads will be at the contact points when your rudder does hit the stop. Eventually, you could damage or break something.
Click to expand...
How would trimming the excess increase the load at the contact points (fuse or rudder)?
 
It is a leverage thing.

If you cut the stop to 1/2 length, the contact point on the rudder will experience twice the force at the contact point as would have been experienced with a full sized stop.

Compare it to a door stop in your house. You know, the little thing that screws into the baseboard and has a rubber bumper on the end.

You install those as far away from the hinge point as possible, because that gives you the most leverage and results in the lowest force necessary to stop the swinging door.
 
Kyle Boatright said:
It is a leverage thing.

If you cut the stop to 1/2 length, the contact point on the rudder will experience twice the force at the contact point as would have been experienced with a full sized stop.

Compare it to a door stop in your house. You know, the little thing that screws into the baseboard and has a rubber bumper on the end.

You install those as far away from the hinge point as possible, because that gives you the most leverage and results in the lowest force necessary to stop the swinging door.
Click to expand...

Not quite sure what you're saying here Kyle. The point is that the rudder does not touch any part of the rudder stop that I've colored red. How does leaving the red part on provide more leverage to stop the rudder from moving if the rudder cannot possible touch it?
 
If that portion of your rudder stop doesn't contact the rudder horn, the geometry on your rudder stop is different than mine.

For the reasons I've mentioned earlier, the outboard end of the stop should hit the rudder horn, and if it doesn't, I think you should adjust things (or make a new stop) until it does.

By the way, a gust lock is a good idea on the tailwheel version. The rudder chains and springs have a fair amount of slack and a gusty wind can cause the rudder to slam around pretty badly.
 
alpinelakespilot2000 said:
Not quite sure what you're saying here Kyle. The point is that the rudder does not touch any part of the rudder stop that I've colored red. How does leaving the red part on provide more leverage to stop the rudder from moving if the rudder cannot possible touch it?
Click to expand...
The red is unnecessary. (edit: assuming correct construction geometry) I'd leave ~ 1/8" excess for extra support to resist rounding over forces and trim the rest. No problem.

-Mike
 
Last edited:
Steve, I have no knowledge of the -9, but could the piece you shaded red be cleco'd up-side-down (can't really tell from the picture)? Or could the horizontal green line be mis-drawn too high? If you were able to flip it around, or move it down; then the stop would contact rudder horn over a larger area. Just a thought. -Jim
 
I agree with "cut it off"

It's just limit for goodness sake not a normal operation load bearing structure.

Bob Axsom
 
Thanks for the replies all. I posted it on the -9 forum because from what i've read, the geometry of the stop IS different on the other models. It's not upside down, sideways, or anthing like that from what I can tell and there's no way to make more of the stop engage the rudder horn because if the stop were any lower, the rudder cable would rub against the top of the stop when the rudder was deflected in the opposite direction. IF I've read the plans right, it's pretty close to the specified dimensions and in the proper orientation, and the appropriate distance measured down from the longeron.

If any other -9 builders can confirm that mine does, in fact, look about right, I'd appreciate it.

All that said, leaving the excess on to keep the possibility of having a gust lock in there (even for the TW version) is also a good idea, Kyle.

Thanks again.
 
Last edited:
if it doesnt touch

then trim it after double checking all your rod end bearings are correct and you have the correct amt of swing. ive seen people make templates and not account for the angle of the side of the fuse from centerline. dont fall in that hole, go with the clearance from the elevator to rudder as the plans show. and rod bearings installe to correct depth and then trim if there is excess as shown in the pic. however its only a gram i bet
 
I had to remake my rudder stops because -- like so many others -- the dimensions on the instructions weren't working for me. I ended up making the forward end per the instructions and then left the aft part uncut -- you know, just a piece of angle, basically.

With the rudder mounted and everything adjusted properly. I began filing the aft end...checked it with the rudder...filed...checked...filed...checked...filed checked.... until I had the proper degree of deflection.

It ended up looking like this:

18_rudder_stop.jpg


Which, oddly enough, is how the original post's target in this thread is going to look when he hacks off the artwork. (btw, yes, I know the bolt in the bottom hinge is upside down, it was just for fitting purposes)
 
Rudder cable attach hardware

Hi all:

Since we're back here in the general area I have a question about the hardware callout which is used to attach the rudder cables to the -9A rudder horns. I can't find where they hit this hardware in the drawings. Can somebody point me in the right direction?

Thanks

Kelly Johnson
San Jose, CA
 
Not sure what the # is, but it's the same drawing as the rudder stops are on. You can look that # up in the index if necessary. If I remember, they use AN3-5 or 6 with castle nuts. Hope this helps.
 
Found it

Thanks. It's on drawing 27A...the one that I didn't have in the binder or out on the workbench.
 
You must log in or register to reply here.
Back
Top