FIX: Putting a hole in your control stick for wiring

[rvmills]

Originally Posted by L.Adamson

I have my secondary & redundant control system all worked out...........


In case of joystick failure. I'll just leave the wireless passenger stick, firmly bolted in................no matter how fat the passenger is!

L.Adamson --- RV6A

Gotta agree with ya there Larry...mine's staying put too. My kiddos and friends would scream foul!

But mine's not wireless...that's pretty hi tech...what'd ya use, 803.b or .g?

Cheers,
Bob

[L.Adamson]

Originally Posted by rvmills

Gotta agree with ya there Larry...mine's staying put too. My kiddos and friends would scream foul!

But mine's not wireless...that's pretty hi tech...what'd ya use, 803.b or .g?

Cheers,
Bob

Actually, in my case,...............being "wireless", means the passenger PTT is on the panel!

L.Adamson --- RV6A

[Bevan]

Why not put the wire exit hole BELOW the pivot point? This way there are NO elevator loads, only aileron loads which are, I would think, considerably less.

Bevan

[Bill Wightman]

A few of you have asked about putting the hole in a better place in the stick. The analysis I did had the hole in just about the worst possible location, and it was 1/2" diameter to boot.

I have a couple comments about alternate locations: First, consider putting the hole in the side of the stick rather than the front or back. This is simply because the roll forces on the stick are less than the pitch forces. I'd guess off-hand that the roll forces are maybe 2/3 or even 1/2 the pitch forces. That would result in a corresponding decrease in stress around the hole.

Second, placing the hole further UP the stick is better than closer to the pivot. The controlling distance is what's measured from the hole to the application of load, ie the stick grip. Locating the hole higher up on the stick does give us some other problems to deal with and those have already been discussed.

Finally, there's no substitute for an actual test of this part. The FEM analysis is pretty and it has merit for showing how stress is distributed. BUT its hard sometimes to draw the correct conclustions from this type of analysis.

I'll try and get a few tests in for y'all.

[PJSeipel]

Originally Posted by chaskuss

Mat,
Another solution would be to run the wiring harness externally along the outside of the control stick. McMaster-Carr and MSC sell nice spring steel clips for this purpose. The clips are shaped like a C, with a bulge (for the harness) in the middle of the C. Two or three clips (or other securing methods) will keep the harness in place.
Charlie Kuss

Charlie,

Do you have a part number or a better idea of what these are called? I'm interested in something like this, but I've searched all over McMaster and MSC's websites and I can't find them. Obviously I'm not using the right search terms.

Thanks,
PJ Seipel
RV-10 #40032

[derLuigi]

Hi all,

Originally Posted by Bevan

Why not put the wire exit hole BELOW the pivot point? This way there are NO elevator loads, only aileron loads which are, I would think, considerably less.

Bevan

The elevator loads aren't gone below the pivot point (we are still talking about the RV-8, right?). There's a steady rise of moment from the point you apply force to the stick to the pivot point, then a steady decrease to the attatchement point of the elevator pushrod. The shearing loads change direction and increase at the pivot point. The aileron forces however should be gone below the pivot point (the point where the stick is bolted to the welded construction, see rick's pics).

Still, drilling holes in this area of the stick scares me a lot, I'll have a close look at mine (side by side) when I come to that task.

Kind regards,

Mario

[clam]

Originally Posted by sprucemoose

Another interesting idea, except I don't find this in AC43-13. Do you have a page number?

try fig 4-38, p 4-172

[sprucemoose]

Originally Posted by clam

try fig 4-38, p 4-172

This figure deals with using a split sleeve to repair a damaged tube section. I was thinking about this as a way to reinforce the area in the stick where the hole would be, but it seems like an awfully heavy, overkill way to do it.

I think I have a better idea now after re-reading the post. What you are talking about is making a T-joint right over the hole in the stick (similar to putting holes within a cluster joint for line oil to penetrate) then cutting off the vertical leg of the T after welding, so that only 1/8 inch or so remains. This seems like a good alternative to welding on a washer. My next question is- does the vertical have to be the same diameter of the stick? If the hole is 1/4, why not use 5/8 or so tubing for this?

[Bevan]

Mario,

On my stick (RV7A), the lower portion of the stick (below the pivot) is aileron loads only.

Bevan

[LynolA]

I added a hole to my control sticks for the Infinity Grip under the pivot and on the side. Under the pivot for reduced stresses on elevator loads. On the side to reduce moment caused by lighter aileron loads. TIG welded doubler made from trimmed portion of stick.

https://drive.google.com/file/d/1v79...ew?usp=sharing
https://drive.google.com/file/d/1TVZ...ew?usp=sharing

Installed cable at hole interface with silicon tape wrapped and cable tied to stick to reduce any movement at cable exit through hole. Cable routes to bottom with a loop on inner skin, wrapped in snake skin to prevent wear or chafing.

https://drive.google.com/file/d/13zQ...ew?usp=sharing
https://drive.google.com/file/d/1Gph...ew?usp=sharing