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Front stick wire exit

Blain

Well Known Member
At the risk of another primer war, have we ever determined the acceptable exit for the front stick wiring? And yes, I've read the 8 page thread a while back. But it never solved or exposed an answer. But there are some entertaining opinions......:eek:
 
My spot.

Most of the front sticks I have seen, pick a spot just above the collar of the pass-throu bushing. That is about as little flex as you will put into the wires as you push the stick around. Also make it as small as you need. You can get the little grommets at you local ACE store. Yep that's were mine is.
Hope this helps. Yours as always. R.E.A.III #80888
 
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I'd have to look at my log for sure but I think I came outjust below the mounting bolt pass through, in the front. I only have put on my stick so it is a small hole with a small grommet. I also installed a connector there to make it easy to remove stick if need be. May be a pic in my log link below


Bird
 
Co Pilot Stick

If this is what you are talking about, I did it this way. The stick boots that I ordered from Classic Aero covers the exit and tape.
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I later installed a 9 pin plug to make the stick removable. I ran the wire out of the bottom on the pilot stick as it was not removable and I didn't want to jeopardize the strength of the stick.
 
I did my front stick the way MikeyDale did his rear stick. Exit up high and secured it to exterior of stick with tie wraps. The wires never get in the way, minimal flexing, and most importantly, if it ever develops a crack, I still have enough stick left to fly the plane. It has worked well for me for 260 hours. My Tosten grip is wired for two axis trim, flaps up/down, and PTT.
 
If this is what you are talking about, I did it this way. The stick boots that I ordered from Classic Aero covers the exit and tape.
otkaqx.jpg
[/IMG]
I later installed a 9 pin plug to make the stick removable. I ran the wire out of the bottom on the pilot stick as it was not removable and I didn't want to jeopardize the strength of the stick.

"Stick boot". I never liked the idea of wire exit up high because they are exposed and, frankly, doesn't look clean. But the boot covers them. I like that idea.
 
Blain, I can get a picture if you want it, but here is what I have done and why.

Background: There are two forces on the stick. Elevator, and aileron. Both of these can act on the stick above the bolted pivot joint. This means any hole there can be in a stressed area due to some combination of the two.

Below the bolted pivot, only the aileron forces act on the stick, the load always go side to side. This means there is a "neutral axis" where a hole can be placed with confidence.

The hole should be small, and only what is needed for the wire bundle, maybe a snake skin sheath, maybe 5/16?

The hole should be carefully deburred and basically polished around the perimeter.

Hole Location:

If the hole is put in the lower part of the stick, drilled along the axis of the aircraft, (perpendicular to the aileron rods), and just above the lower weldment, then it is in the neutral axis and in the lowest bending moment portion of the stick. To keep flexure of the wires to a minimum, and keep wires from moving around in the hole, tape the bundle back to the stick so it tracks back up to the bolted elevator pivot point and then loop to fuse so in full motion the wire moves the least.

firesuit on - YMMV

PS - the principles work for the 8 as well, but I don't know if the geometry allows this like the 7.
 
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Blain, I can get a picture if you want it, but here is what I have done and why.

Background: There are two forces on the stick. Elevator, and aileron. Both of these can act on the stick above the bolted pivot joint. This means any hole there can be in a stressed area due to some combination of the two.

Below the bolted pivot, only the aileron forces act on the stick, the load always go side to side. This means there is a "neutral axis" where a hole can be placed with confidence.

The hole should be small, and only what is needed for the wire bundle, maybe a snake skin sheath, maybe 5/16?

The hole should be carefully deburred and basically polished around the perimeter.

Hole Location:

If the hole is put in the lower part of the stick, drilled along the axis of the aircraft, (perpendicular to the aileron rods), and just above the lower weldment, then it is in the neutral axis and in the lowest bending moment portion of the stick. To keep flexure of the wires to a minimum, and keep wires from moving around in the hole, tape the bundle back to the stick so it tracks back up to the bolted elevator pivot point and then loop to fuse so in full motion the wire moves the least.

firesuit on - YMMV

PS - the principles work for the 8 as well, but I don't know if the geometry allows this like the 7.

Seems like we are rehashing an old thread but here is my thought on your suggestion; Any failure below the pivot will render the control system useless. And pre flight inspection difficult. However, above the pivot leaves the system intact with whatever is left of the stick. And inspection much easier. Questioned Vans via email. Didn't get a response.
 
Below the bolted pivot, only the aileron forces act on the stick, the load always go side to side. This means there is a "neutral axis" where a hole can be placed with confidence...
.
With the -8, the forces acting below the pivot are the elevator only (fore/aft). To your point, a hole in the side of the stick would be of minimal impact there. (But then again, I would worry more about the stick failing in fore/aft loading, just due to the higher fore/aft stick loading, versus lateral, in an RV).

In either instance, drilling as far from the pivot as possible is always the best choice. Not opinion. It's physics.
 
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I drilled the stick just under the grip and ran the wire down the front of the stick.
Can't see the wire. As stated in other posts, the further from the pivot point the better.
 
Not sure how different the 7 is from the 8, but I was surprised to see how well it worked running the wires out the bottom of the stick. I used dsub pins in heat shrink as a disconnect point, doubled up the heatshrink and it fit nicely between the 2rod end bearings. I doubled it back onto the lower control stick, wrapped it with silicone tape and secured it to a "node" on the other wiring behind the spar.
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993B0E11-B5FF-4615-BBED-BA2CB5BAEED8-7663-0000043AFCA3FA6C_zpsa019992c.jpg


Since my copilot stick was removable I did like previous posters and ran the wires out if the stick but under the stick boot

F95A5EE8-18D1-4EB1-87D8-96FFBD862BBD-7663-0000043B078E3BF2_zps8ab5160a.jpg
 
I drilled the stick just under the grip and ran the wire down the front of the stick.
Can't see the wire. As stated in other posts, the further from the pivot point the better.

If this is done, it will interfere with the Anti-Splat Aero gust lock mechanism (probably not an issue for taildraggers, but for us nosegear guys...different story).

Just an FYI.
 
The OP has an RV8 stick, which nothing like the stick from a side-by-side model. Can't run the wires out the bottom.

Weld on a reinforcement patch above the pivot and drill as desired.

 
The OP has an RV8 stick, which nothing like the stick from a side-by-side model. Can't run the wires out the bottom.

Weld on a reinforcement patch above the pivot and drill as desired.


Perfect!!!
 
The OP has an RV8 stick, which nothing like the stick from a side-by-side model. Can't run the wires out the bottom.

Weld on a reinforcement patch above the pivot and drill as desired.


Would you Tig that, Dan?
 
Vans response

Questioned Vans and got a response. Too late for me, I had already made my decision. But as a conclusion to this thread I thought I would pass it on.

Copy of email;
Sorry for the delayed response, I finally got word back on this from the engineers. They will
allow a 1/4 inch hole (no larger, smaller is preferred) on the forward side of the stick just
above the cross tube. I have take pictures of what we have on our RV-8, this hole is 3 3/4 up
form the bottom of the stick. See attached picture.

Sterling



BTW, I put a 1/4" hole on the aft side about the same height as suggested. Will probably plate it per Dan H. diagram. Seems that there would be less tensle stress on the aft side but I'm no engineer......and they probably wouldn't endorse a bent stick either.

 
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The OP has an RV8 stick, which nothing like the stick from a side-by-side model. Can't run the wires out the bottom.

Weld on a reinforcement patch above the pivot and drill as desired.


The Infinity grip cable is fat, so something has to be done. I was thinking about welding some bar stock or possibly even a sleeve to "double" the area where the cabling exits the stick, but the patch seems to me to be the most elegant solution.
 
Questioned Vans and got a response. Too late for me, I had already made my decision. But as a conclusion to this thread I thought I would pass it on.

Copy of email;
Sorry for the delayed response, I finally got word back on this from the engineers. They will
allow a 1/4 inch hole (no larger, smaller is preferred) on the forward side of the stick just
above the cross tube. I have take pictures of what we have on our RV-8, this hole is 3 3/4 up
form the bottom of the stick. See attached picture.

Sterling



BTW, I put a 1/4" hole on the aft side about the same height as suggested. Will probably plate it per Dan H. diagram. Seems that there would be less tensle stress on the aft side but I'm no engineer......and they probably wouldn't endorse a bent stick either.


Ok, this is what I have used over the years and seen no problems with. If you are concerned with a stress crack starting from the edges of this small hole. I offer an old trick that works to make this area of a tube much stronger without welding. Take two strips of .040 or .050, 4130 about 3 inches long. form them into a sleeve that will fit around half of the stick tube.
notch out for the through bushing weld, drill a hole to match the place you drilled the hole in the stick. Leave a little slack between the two along the edges wear they come together, maybe 1/8" or so. Make sure you round and be-burr everything, prime it all as you wish. Put your two fish plate you just made onto each side. Then take some .032-.021 safety wire and spool it around the stack-up with a good pull on the wire while you rap it around. You could cut a peace say 4 foot and put one end into a vice, then spool and rap to make a nice looking wind. This method has been used for thousands of years and there is no telling who came up with it so, if you like it as I have at times and you get concerned about a stress riser in this little hole, you may wish to give it a try. Hope this helps. R.E.A. III # 80888
 
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The reinforcement sleeve or patch as Dan suggested seems to be the obvious solution. If only a Vans would do it we could stop all of this debate and get back to building. I'll probably do as Dan proposed.
 
I drilled a 3/8 inch hole just above the pivot point in the pilots stick for the very fat Infinity stick grip wire bundle. When I cut nearly 3 inches off the top of the stick I kept the excess material, sliced it in half vertically, cut it to shape and had it tig welded in place. One less thing to worry about.
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That is such a better idea than a washer! I stressed about this very thing after reading threads about sticks breaking in half and toxic fumes from welding cad plated washers. I ended up just drilling the hole just below the grip itself and running the wire along the front of the stick. That way bending loads in the area it was drilled are minimal. I like your way better.
 
47490138441_a5def67f7c_o.jpg" width="256" height="192" alt="Infinity Stick Wire Hole1"

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I made 1/2" hole under the pivot, on the outboard side, and TIG welded a doubler made from the material trimmed from the top of the stick.

Wire routing in progress...
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