Conduit and Wire Routing in Wing Ribs??

Before I drill and prime all 28 ribs with these hole locations I would like some feedback on the conduit locations and wire routing.
Do you guys see any hidden problems with my layout?

The pictures show the left wing just outboard of the bell crank. Your suggestions will be appreciated.

Chuck

I don’t think I would put that conduit next to the rear spar. You may have access problems going into the plane. I have dual conduit cross from each other where your electrical conduit is. I asked Vans about it and they said it has not been tested (dual) so, I pressed Ken and he said “ I don’t think it will fall out of the sky!” 1 other thing.. I would stay with the 3/4 Inch holes and RTV the conduit if you think it needs it. You will find it's pretty tight if its the Van's conduit

Hey Chuck-
I'm in the same exact place as you & just finished drilling mine. I like your runs alot! Here are a couple more options to noodle over & things I did was run my pitot & AOA lines higher "up" in the rib(s) to run above the bellcrank to prevent moisture condensing in the sag or low point(s). I made a bracket that supports the lines above the bell crank. For the NAV / COM coax runs, what are your thoughts on using gromets rather than a honking 3/4" hole for conduit? The RG400 coax is pretty well insulated & heavy walled stuff. (if you are using that). Also, did you double check that the rear conduit doesn't interfere with aileron / flap controls / connections? it looks like looks like it may be a little close if you are running that to the tip. All looks awesome from my point of view though... But I don't know much, Im just bouncing ideas and thoughts over morning coffee / VAF fix.

Conduit and Wire Routing in Wing Ribs

Guys thanks for your comments!

To randyintejas--

The rear wing access to the fuse was a concern of mine but I wanted to make sure I did not get noise in the radio. I probably will move the conduit up in line with the electrical run to match your design. It only makes sense. I just had a pilot hole in the rear to start with.

To Daniel S--

That's a good suggestion to run the pitot and AOA as high as possible. My thinking was to provide a stiff run behind the bell crank to attach the other loose wires to. I failed to consider moisture build up.

The coax in the gromets would work fine. The conduit does allow a smooth pull of the coax after the wings are completed. It is a little big. But, there's room for future creature features.

Thanks Again,
Chuck

Ray-
This is not my site but here is my inspertation and an example of the AOA / pitot runs. ( I haven't updated my site all week).

http://www.mykitlog.com/users/displ...a&project=711&category=4889&log=124325&row=40

Also, One other question after looking at this again (the coffee is kicking in) Are you using rubber gromits around the conduit? Those holes must be huge (1"+?). I think protocal is just a 3/4" hole & conduit and then adding a dab of RTV / silicone to the conduit at each rib. Keep in mind most production planes have all exposed wire & very little conduit (if any). At least that's what I saw while back in college, hammering on flight school planes. I stuggled with drilling holes for my own conduit based on this premise

Hope this helps & I'd love to see pics of the finished product!

Conduit and Wire Routing in Wing Ribs

Yes that is a 7/8" mill spec grommet. The drill hole diameter is just over 1". Usually the drill hole is 1/8" over the grommet ID. I was attempting to create a larger surface area to eliminate the knife edge of the rib. The conduit seemed very soft to me. (My OCD kicking in)

As far as the coax goes... (experience with sensative industrial equipment), if the outer jacket becomes scratched for some reason and rests on a metal structure, all the electrical noise in the aircraft ground will travel down the coax sheild. This is my reasoning for placing the coax in the conduit. I do think the grommet suggestion will work in place of the conduit though for the coax.

Thanks for the input.

Chuck

Conduit Routing

On mine I made a small hat section bracket with the length aligned with the wing span which fastened to the bolts that hold the tie down AEX. I'm using this bracket to ty-rap the wires etc. that go through the aileron belcrank bay to ensure they don't foul the aileron bracket.

Conduit and Wire Routing in the Wing Ribs

Terrye--

Would you happen to have a picture?

Chuck

Flame suit on: Swiss Cheese!

There are four very large, rib lightening holes within each rib. Consider installing your runs through these holes maintaining
structural integrity of the whole wing. Vans has a suggested drill location for conduit placement. Just one guy's POV.....you asked.

Conduit and Wire Routing in Wing Ribs

Thanks for all of your feedback. Attached are pictures of the final outcome. Also included is a picture of the rib template. I believe I have incorporated suggestions from everyone. However, I did opt to keep the grommets and conduit.

By placing the conduit just under the top skin there was room to reach in through the access holes with no obstructions into the wing. Moving the Nav/Com conduit forward in the rib eliminates potential interference with the aft push rod through the rear spar and possible problems with fuse attachment. Moving the electrical run to just behind the spar helped to eliminate the extra wire pull for the stall and pitot heat. The stall horn and pitot heat will be run through the electrical conduit and broke out in the bell crank area.

I did elect to move the AOA runs higher in the wing due to moisture concerns. The pitot run will be aluminum tubing instead of flex to prevent sags and moisture build up.

Thanks Again!

Chuck

Left wing looking outboard toward the bell crank.

Whenever I wires and hoses in the wings routed this way it tells me you guys aren't thinking about long term maintainability. In 20 years when the AOA tubing dries out and needs to be replaced how easy will it be for someone to reach in the wing to run new tubing?

I dislike corrugated tubing. Its a pain to retrofit wiring because all those square corners tend to catch on the end of a wire being shoved thru.

In my rocket I have one 3/4" run of PEX plumbing that extends thru a hole in the fuselage with the wings on. I can run a new wire, hose, whatever in seconds from inside the fuselage all the way out to the tip. No opening of panels, cussing, requiring assistance, etc. Along the way I cut "windows" out of the tube so that wire could exit at that point (ie, pitot heat wiring). There's no reason you can't bundle everything going out to the wing with one conduit.

In a lot of certified aircraft they simply ran the wires thru the lighnening holes and just let it lay there. It makes you cringe but its amazing that wire could hold up to that for 50+ years.

My #1 rule is make it easy to work on because some day you would rather fly than work on your airplane!

Aileron belcrank bay wiring bracket

Here's a drawing of the bracket

http://i50.tinypic.com/nv4ldt.jpg

wow - holes

I used two 1/2 inch dia holes with plastic grommets for everything, Nav, Strobe, Servo, AoA and pitot heat, archer antenna and marker, no conduit, enough room to pull wires.

Swiss Cheese

lorne green said:

There are four very large, rib lightening holes within each rib. Consider installing your runs through these holes maintaining
structural integrity of the hole wing. Vans has a suggested drill location for conduit placement. Just one guy's POV.....you asked.

Click to expand...

Agree! A simple 'L' bracket and adel clamp makes a great way to use the existing holes for running conduit, etc.
See AC 43-13 1b, figure 11-14 for examples.

PEX Tubing

Hey Bob-
Is this what you are refering to using rather than the corrigated conduit? Do you have any idea what the weight diff is? This tubing comes out to be 1.65 OZ per foot or 1 lb per wing.

http://www.homedepot.com/h_d1/N-5yc...gId=10053&langId=-1&keyword=pex&storeId=10051

PEX tubing

I like Bob's PEX tubing idea. If I wanted to run navs/strobes (LED's I hope) wouldn't 1/2" be big enough? If I were to run VOR/COMM coax, I would run those seperately most likely.

Right?

G

Like Walth, I see swiss cheese too!

I don't mean to sound too discouraging, and I see that this is an older thread, but if I were inspecting a plane or looking to purchase a plane, ribs with more holes than are necessary, ribs with holes bigger than necessary, and ribs with holes that are bigger, more numerous, and in locations other than that which Van's specifically recommends, I'd probably look elsewhere. It seems like one of those instances where a builder is overthinking (which I've been guilty of more than once) and is looking for a solution in search of a problem instead of going an already-proven route.

I agree. In reading through the thread, I got the feeling those ribs were a bit Swiss Cheesed. I try to keep these sort of possible structural divergences (from plans) to a minimum.

Steve Melton said:

I used two 1/2 inch dia holes with plastic grommets for everything, Nav, Strobe, Servo, AoA and pitot heat, archer antenna and marker, no conduit, enough room to pull wires.

Click to expand...

I just pulled two wires through grommets from just inboard of the aileron bellcrank to the fuselage, with a bushing in every rib. Took about two hours and lots of straining. I would never build one without conduit after that experience. Not looking forward to the coax I have to add all the way out the other wing....