brian

brian

Well Known Member
How are people dealing with handling the moving wires in the case of a plane with control stick grip switches?

It seems the least amount of wiring movement would be had if I drill a hole in the side of the stick (this is RV-7A, but presumably same situation for all RV models) right near the weld, closest to the pivot point. But it would be extremely difficult to feed wires down the tube, then get them to make a 90 degree turn out the side of the stick. In the case of Infinity Aerospace grips with the wire bundle having about a dozen wires in it and being ??-5/16? in diameter, this would be even more difficult.

If the wires are run out the bottom of the stick, it looks like the wires will have to be moving around quite a bit with the stick. I can see leaving enough slack to allow for the full range of stick movement, but I am concerned about causing fatigue in the wires with so much constant wire movement. It will also have to be carefully laid out so it can?t catch on anything.

I know lots of people have RVs with stick grip switches. How are others handling this?

Thanks,
brian
 
brian,
I have not started any wiring yet, but after reading your post and looking at mine - can the wires be ran thru the bottom then back around on the outside and secured close to the pivot point? Maybe notch the bottom to clear the pushrods

jim 7a fuse
 
I installed 2 infinity grips. I drilled the holes below the weld on the pilot side and above the joint on the c/p side. I used rubber grommets versus snap bushings for 2 reasons, the hole could be smaller and I could feed the grommet down around the cable after working them out through the holes. Far less difficult than I had expected. If you have a multi strand cable such as with the infinity grips (17 wires) strip back about 1.5 inches of the jacket so as to allow pulling the wires through individually. You need to hook under them and pull them out, I used a small jewelers file.

I then wired up a 21 pin circular connector to each cable so as to allow easy stick removal. The connectors are from Mouser, P/N 571-2061521 and 571-2058393.

http://www.mouser.com/index.cfm?handler=home,

The ship side of the connector is wired to a terminal board under the seats. Why the connector and not simply go to a terminal board? To keep the c/p stick removeable and both sticks wired the same. The cable exits the stick just above the joint and continues down under the floor to the connector. A tab of velcro underneath the floor allows the wiring to be secured when the stick is removed.

Jekyll
7A
 
Just a comment/question for the engineer qualified group. If a hole was put in the vertical stick portion....but not a round hole...lets say an longitudinal oval shape... would this be structurally sound. Seems it would be a way to reduce the 90 degree bend in the wires. If sound structurally, then lining the edges would be the only challenge...or do they make oval shaped grommets???
 
Probably OK

You could mill or drill and file a reasonably sized slot, I would think. Then use a small rattail file at an angle to knock off the top inside and bottom outside edges to further taper it.

Rather than a grommet, you could just use thickwall internal-glue heatshrink (the tough stuff) on the wires where it exits. Use a couple of cable ties inside the stick right at the slot for a bit of strain relief.

Metal guys may disagree but I think if you are pulling hard enough on that steel stick to make a small slot a stick-structural issue, its probably good-bye tailfeathers anyway.

And thanks for the heads-up, Rene (sorry, don't know how to do the fancy accent for your name). Guess its time to get in on the Hooker order..
 
FWIW. Don't drill a hole in your stick. Just run the wires out the bottom and cover the wires with 2 layers of shrink wrap before the wires exit and all the way to the first support. The stick doesn't move that much and these little wires are very flexible. Just leave enough hanging out so you can make complete control deflections without pulling the wires out of the stick.


Img_4918.jpg
 
Going through the bottom of the stick depends on the number of wires and diameter of the harness. The Infinity harness was too large to go through the bottom on my 7.

I think the bottom exit is best if possible.

Jekyll
 
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