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Stick Grip Wire Routing

My RV-6 has been flying 11.5 years and 2,198 hours. When I built it, I ran the wires for the PTT right out the bottom of the stick past the rod end bearings.


IF you are using one of the fancy grips with all kinds of buttons, you will need more conductors but should still be able to route the wires straight down to a connector then out to the panel or what ever accessory that your stick gip button operates.

This is where the models differ a little bit Gary - the 8's forward stick doesn't pull off like others, and the cross-stick weldment blocks the bottom, so you can't run anything straight down. Just thought I'd mention that so folks weren't confused...

Paul
 
You may draw your own conclusions from here. I would advise against the hole. If you have a hole and must keep it, a washer of about .050" thick welded around the hole would help to distribute stress.

Note: There is probably a very sensitive relationship between the hole size and placement, and the max stress in the tube wall. If any of you have concerns about YOUR airplane, email me and I'll take a look at your specific situation.

wouldn't it be fairly easy to shape a gusset (is that the proper term) that could strengthen the tube more than an undrilled tube and keep the hole? i'm thinking of more of a diamond shape than a washer, along the lines of bicycle frame reinforcements.

kind of like the lugs on this bike frame http://www.bikethink.com/joint_stress.htm


From a rag and tube biplane fuselage builder, here is my 2 cents. Hey, pick the spot where you want drill your hole, grab a piece of 063 or 049 chrome moly plate, cut out a shape that when heated you can wrap around the hole area lengthwise(not the whole circumference of the stick, maybe half.) The piece my be 3” by 1” in maybe a diamond shape. Adapt it well with heat , and weld it to the stick. Clean up and paint. DONE! If you can’t tig weld, find someone that can.

Mark Wyss
RV4 fuselage
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yeah, this is exactly what i was thinking of.
 
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To Pat Tuckey:
RE: The issue of accomdating the "cable" the comes with the infinity stick grips.

Pat,
I would be interested to know if your stick was drilled for the Infinity or any type wiring. You obvioulsy put a very agressive force in gaining/maintiainig control of you aircraft when the auto pile servo screw went awol on you. Will you enlighten us?
thanks,
Don

Don,

I drilled the hole in my stick on the side of the stick about an inch above the pivot point. In my case there were only 2 - 22 gage wires to accomodate, so the hole is only about 3/32" with a rubber grommet to protect the wires. There is no apparent deformation after my "incident."

Pat
 
So how does Van's get their wire(s) up to the stick grip on all of their demo planes?
THAT is a very good question yet to be answered with any degree of certainty. In any case,
we know that Van's has installed electric trim on the RV-8 joystick:
The elevator trim is actuated by an electric servo which the pilot controls with a 4-way
switch that was mounted on the top of the front seat control stick.
The above quote is drawn from the NTSB report describing the factory built
demonstrator RV-8 crash some years ago.
http://www.ntsb.gov/ntsb/GenPDF.asp?id=LAX98FA171&rpt=fa

Was the joystick assembly on the accident aircraft essentially the same design as today? If so, I am
more than mildly interested in knowing how the factory dealt with routing wires from the joystick grip.
It is interesting to note the calculated loads generated on the elevator that are also included in the report.
 
So how does Van's get their wire(s) up to the stick grip on all of their demo planes?

THAT is a very good question yet to be answered with any degree of certainty.
I asked the question originally because I am almost certain that I have seen approval from Van's for small holes in the control sticks for wiring. I'm not sure where and whether it was model specific, but this is the first time I've heard anything to the contrary. Anyone else remember such approvals and where I might have seen them?
 
Van's RV-8A stick wires

So how does Van's get their wire(s) up to the stick grip on all of their demo planes?


I was searching this post trying to see how guys looped the wire coming out of the front stick to keep it from putting force on the controls when I saw this question.

It so happens at a show I took pictures of the under side of the Van's RV-8A, I wanted to see how they made the fuel line under there. It shows the exit hole for the stick just above the pivot point at the forward side of the stick. So I am not sure about the statement from them in this thread about "not putting holes in the stick", this hole does not seem large but it is very close to the pivot point.

I put my hole like many others on the aft side of the stick. Oddly enough I put the hole in the rear stick on the side, and this works better for not inducing any resistance in the controls. I am still experimenting with loops int eh wire from the front stick to prevent inducing resistance in the controls, I now wish I had but the hole on the side there as well, the only movement of the wire is in pitch, in roll the whole control column moves so you don't have to worry about wire movement.

245wx3m.jpg
 
Mike,

I've since had a patch welded over the hole I'd drilled in the rear of the stick, and put a new hole in the side, and further up the stick from the pivot.

It was an easy fix and now I just don't have to worry about it anymore.:)
 
.......I took pictures of the under side of the Van's RV-8A.....It shows the exit hole for the stick just above the pivot point at the forward side of the stick. So I am not sure about the statement from them in this thread about "not putting holes in the stick"...

2rognrp.jpg

Copied from Doug's post #9, here is the statement issued from Van's:

"Any hole anywhere in the control stick will reduce its strength. The nearer this hole is to the pivot point of the stick (where the bending forces are higher), the greater will be the severity of the strength loss. Van's recommends that builders do not drill holes anwhere in the control stick, particularly near the pivot point. Generally, the accepted routing for electrical signal wires is through the opening on the bottom of the control stick."


Lucy, you got some splaining to do!
 
Does anyone have any pictures of how they secured their wires coming out from the bottom of the stick on a 6/7/9? I've only got a PTT and ground to run, and don't want to drill a hole, given the contradictory advice from Van's noted above. Obviously, however, I want them secured in such a way that they can't interfere with full control movement.
 
Does this show what you're looking for? I cut no holes in my sticks, but cable management is a bit of an issue with the infinity grips. Allowing for a large service loop which doesn't contact anything or rub anywhere is the key.


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Secret next phase...?

My objective is to develop a redundant control architecture with error checking and automatic cut-over. Might be overkill for a simple aircraft but then it allows the next stage of integration (triple super secret).

Remote control? :)
 
Infinity Stick Grip



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Infinity Wire Routing

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I have installed four of these Infinity grips in RV-8s including the Doll.

I found the blue Infinity cable to be too large, and I feared the cable would put a load on the stick causing control input to a responsive RV. I decided that each switch did not need its own ground wire. I disassembled the grip and removed the outer blue cover and shielding from the cable. I cut the ground wires from each switch, and grouped them together in the open area in the middle of the grip. A single ground wire exits the grip to handle the ground function. The remaining wires from the original cable are now down to a manageable size, and can exit the stick through a small hole just above the pivot bolt. I then ran them along the top of the control quadrant through the center section to a small 12 contact strip connector mounted to the floor rib on the right side of the control quadrant just aft of the aileron push tubes.

The Doll has over 1200 hours and I have not experienced any problems with this set up. The Infinity grip provides the following functions in the Doll:

Trigger- Push to Talk
Left switch- Flaps
Coolie Hat Switch- Aileron and Elevator Trim
Right top button- Engine Starter (when enabled)
Middle left button- Auto pilot disconnect
Lower button- Boost pump
 
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Here's what I finally came up with. Routed through the bottom of the stick and then back up the stick (secured by a couple zip ties) to the pivot point and then over to the rib. Allows full movement and no apparent chance to bind up the controls if something came unsecured.

 
Noah,Mark,Steve and Danny. Thanks, all points well taken as well as the NOTICE from Vans on DO NOT DRILL STICK! OK then its out the bottom! Much appreciated as always. Merry Christmas to ALL!
Ron in oregon
 
The AeroElectric Bob idea of using individual D-Sub pins and sockets as connectors is a good fit here. Just slide a piece of heat shrink over each mated pair.

Using this technique it is then still possible to pull the stick grip off without removing a connector (or large terminals) from the cable end.

It's also possible to test your system before the stick grip is installed.
 
OK and a thanks to all with all the help and ideas. Now I'm at this point on my 8A and without disturbing the powder coating and not drilling a hole what is the general consensus on how to plumb your stick since 09 original post. I'm going with an RC Allen grip if that matters. Opinions please?:confused:
 
Drill up high

I did not find enough clearance to run the wire bundle out the bottom of the stick. After following this thread, I drilled the stick on the front side just an inch or two below the grip and ran the wire bundle down the front outside the stick. If the stick fails because I drilled it, there is enough of it left, albeit shorter, to still be able to fly the plane. I never notice the wire bundle, it does not interfere, and it flexes over a greater length which reduces the concentration of repetitive bending stress.
 
Howdy Rick,

Got a note from the engineering side of Van's about your control stick hole and thought I'd pass it along.
b,
dr

Any hole anywhere in the control stick will reduce its strength. The nearer this hole is to the pivot point of the stick (where the bending forces are higher), the greater will be the severity of the strength loss. Van's recommends that builders do not drill holes anwhere in the control stick, particularly near the pivot point. Generally, the accepted routing for electrical signal wires is through the opening on the bottom of the control stick.

I've seen it done both ways in certified aircraft. The Hueys have wire bundles in thick poly sheaths exiting through holes very close to the pivot points on both cyclic and collective control sticks. There's some very specific instructions on removing, replacing and repairing these stick grips and associated wiring. The control sticks are also VERY beefy. Not anything like the light weight sticks on an RV.
 
This whole thread seems a bit strange to me. It appears it would be preferred to drill a hole near the pivot point but it also appears that this weakens the stick. Some have decided it was fine others have not. Vans reccomends against it. My question is why not use a thicker or stronger material so a hole can be drilled where most people want to put it? That would eliminate all of this discussion and potential risk for those who have decided its strong enough. I'm not a mechanical engineer but it seems like it might be as simple as using thicker tubing or welding a reinforcement plate. How expensive could that be in production volumes. Maybe even one of the many little RV related product companies could offer one.
 
First off I like Brads idea of putting a hole just south of the grip so if it bends or breaks you still have something to hold on. Second after reading all the threads I can find I can see why you really don't want to drill a hole down by the pivot point. Third I was looking at my buddy's 9A today and see that his is so much different than my 8A. I suspect that that is the way the 6,7 and 9 are built? My stick doesn't have a hole down low. Fourth what about that picture of Vans plane with the hole in theirs? What about the hundreds of you guys that drilled yours at the pivot point?:eek: Still looking for comments and ideas without reinventing the wheel. Thanks again in advance.
 
I am a mechanical engineer, and I drilled a hole in my stick. I don't have a photo for the exact location, but it's near the pivot. Hole needed is only about 3/16" or 5/32" for the Tosten wire bundle... Maybe another point in favour for Tosten?
 
Haven't seen this YET. Get the same metal tube, drill a 5/32" hole 1" below the pivot hole. Stick the tube in a VISE,stand,yank,pull,hit it with a hammer,and when you are done and all you have is a beat up pipe. NOW would you ever do this to your control stick in the plane. Doubt it. Its going to be your 22 gauge wire that will break first. Want to minimise the wire breakage at the pivot point,curl it. I am sure at some point in your life your have wrapped a piece of wire around a pencil and made a make believe spring. Do the same here,just a few, and you'll sell the plane first before the wire breaks.

Ron in Oregon
 
I think I ran my wire down and out the bottom of the stick and then up front toward the firewall. It works fine.
Dave
 
Here is mine -RV7

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I researched VAF and found that Vans said a 3/8" hole was max. I considered for a while then it struck me, the stick below the pivot point only has bending moment for lateral loads of ailerons. Than means a hole in the middle (neutral axis) would be minimal, to no risk. I did take a while with fine grit trimite to smooth the hole for fatigue resistance.

The hole is right at the red tyrap location and parallel to the line of flight. I covered the 26g a wires with expandable covering and wrapped it with fuseable silicone tape for the pivot strain relief.

Sorry for no picture in the post, I have not re-learned how to do that from picasa yet.

OK, here we go - -

IMG_0699.JPG


BTW - I have a Ray Allen Grip - there are 10 wires in that sheath. gnd,+12v,trm L, R, up, dwn, PTT, CWS, flap-up,dwn.
 
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I'm about to start my Infinity Grip installation, on my front stick, in my -8. I've read the various pages on the topic of how to handle the cable. I've decided to run the cable out the top and down the exterior of the stick.

I need some form of cable keeper to keep the cable from rotating around the stick and also keeping the cable close to the stick. Something like what's in the thumbnail, Problem is I can't find those things in different sizes (or any size actually) online.

In one thread, someone mentioned "steel spring clips" with a bulge for the cable , from McMaster-Carr but I couldn't find those.

I'd like something professional looking and acting so cable ties are out.

Any suggestions/ideas here would be appreciated.
 

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Similar solution on my RV8. The hole at the top of the stick makes cable routing a lot easier than the hole drilled at the bottom. I put a couple of silicone tape wraps to secure the wire loom to the shift, and avoiding the tie wrap entirely
 
I was thinking about adding a doubler down low at the exit point. Russ M. said he could weld them on for me although its been a while since we chatted. I like that option myself. I used the piece that I cutoff from the top, cut it in half and with a little work I had my doublers. I'm still waiting until I get my panel installed to determine the stick length before I take the next step.
 
Similar solution on my RV8. The hole at the top of the stick makes cable routing a lot easier than the hole drilled at the bottom. I put a couple of silicone tape wraps to secure the wire loom to the shift, and avoiding the tie wrap entirely

I'll be rotating the grip counter-clockwise as you look down on it for a natural grip at the wrist. The plus is that now the cable will not get pinched between the seat pan corner and the stick. And I think that also avoids pinching with the anti-splat elevator and rudder lock but I have to actually try that.
 
Maybe something like this could be made to work. They are microphone cable clips for clipping the cable to the boom.
 

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just me

I looked carefully at the spacing between the ball joints at the bottom of the stick. There seems to be enough space to run the wires out between the gap with no need for holes in the stick.

You all think this is a good idea?
 
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I am looked carefully at the spacing between the ball joints at the bottom of the stick. There seems to be enough space to run the wires out between the gap with no need for holes in the stick.

You all think this is a good idea?

That's what I'm doing.

Out the bottom, make a U-turn, back up the stick to the pivot point and then to a seat rib...no holes needed.
 
Took a look at the bottom of my replacement stick. I'd have to drill a hole in the bottom which I don't think is a good idea:
 

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Maybe something like this could be made to work. They are microphone cable clips for clipping the cable to the boom.

These clips work pretty well. They grip the stick tightly and don't crush the cable. Might be a touch too much looseness in gripping the cable but some heat shrink tubing will fix that.

My next chore is to figure out where to cut the tubing so that the overall length - when the grip is installed, does not exceed 15". Not sure how to do that given that the grip is canted

And after that figure out a way to determine the angle the grip should be rotated on the stick for a natural grip.
 

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Drawing 79 question

n the plans it has a note on the Flight Control page DWG 79:

"Maximum stick length is 15 inches from the pivot bushing."

What is meant by "from the pivot bushing"?

The center of the pivot?

Or the top of the pivot?

I assume the center but I thought I'd ask.

Thanks.
 
Mine is still a work in progress. I'm working on the pilot stick right now. I made a doubler out of the cutoff portion of the stick. Now I need to get the doubler welded on. Then I'll drill the hole to the final size.
 

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Gregg,

I would suggest getting the stick length figured out first. Its a little difficult to get it exactly where you want it. I put the cable down the center of the stick and did a test fit, then cut more off of the stick and repeated that process until I got it where I wanted. The tricky part is you can't actually slide the stick grip into position since there is that mounting boss in the grip. I set the length based upon clearing all of my panel switches. If you don't have your panel at least temporarily installed (like I do) then I suggest you wait until you do.

Once you have the length. Then you can set the rotation. I climbed in the plane, sat on a pillow, held the grip on the stick with the cable running down the tube, and then rotated it so my wrist was straight. Then I marked the position of the rear grip joint on the stick. After you have the position you have to figure out the 90 degree location for the 29/64" hole. I used a circle template with 90 degree tick marks to mark the top of the tube and then extended the lines down the tube.

I hope this helps it was a pain and a little tricky to get it right.
 
I got my sticks back from the welder. They were kinda a mess with some of the powder coating melting a little, but I got them cleaned up. I opened up the wiring hole to 1/2". Now they are ready for priming.
 

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I’m not an engineer but has anyone considered that a grip that attaches this way may be the weaker than a stick with a hole in it?
 

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