time for conduit

[tmbg]

gonna get vans conduit, and put it in the recommended spot - bottom of the rib behind the first lightening hole.

So, a couple questions.... first of all, Vans recommends 3/4" holes for the conduit, but I think I've heard rumors of people using 13/16" for better fit. pros/cons? The only unibit I have only goes to 3/4" right now, so it'd mean buying a bigger bit

Next, obviously there's the hole already in place for pitot line, what other lines should I plan for? I'm probably going to be doing an AFS AOA kit, so should I plan for a left wing run for that? I think it's two tubes... anyone have any thoughts/suggestions for that?


Anything else that I need to drill holes for?

[Brantel]

I tried pulling the conduit thru the normal 3/4 hole with a test rib and it was almost impossible. I could not see ever getting it worked all the way thru the wing so I went with the larger hole.

I did add another smaller hole to match the pitot tube hole for the AOA tubing.

[bullojm1]

Ian,
I used a 3/4" hole for the Van's conduit. I had no issues installing the conduit. Just stretch the conduit while installing it and it will be somewhat easy to get through each hole. Once my conduit was installed, I put some proseal between the ribs and the conduit to keep the two from chaffing. Once dry, everything is solid.

You should locate the conduit hole in between the rib to skin rivet holes to make sure you can get a bucking bar in there later on.

I decided on the Dynon AOA system, so I went with two extra holes out to the pitot tube location - one for the AOA pressure line, the other for the pitot heat.

Here is a link to my builders log for the conduit:

http://rvplane.com/?categoryid=3&dayid=178
http://rvplane.com/?categoryid=3&dayid=181

[tmbg]

I just talked with AFS, and their AOA plumbing is two lines that are each 1/8" OD, so I think I'll drill a pair of 1/4" holes for 1/4" OD 1/8" ID snap bushings just north of the pitot hole. I'm assuming I can run the pitot heat wiring in the conduit, is this reasonable?

[Spike]

I have 3 sets of holes in the left wing. One for pito, one for electrical, and one for antenna coax. Im also not going to be using conduit. More weight, more pain, no real benefit as I can see as long as you are running aircraft grade cabling.

Im also going to be using the AFS AOA, but will be installing it into the right wing. Those tubes are pretty small so I don't envision having any problems.

John

[Womack2005]

I was orignally gonna go that way too Spike. However, when I did the math the conduit is lighter than all those clamps. It also allows you the option of easily adding wire runs later. To each his own Running the RF coax next to the other wiring is not an issue.

[Spike]

Running the RF coax next to the other wiring is not an issue.

Especially whey you don't do it Interesting information about the weight. I will probably still go with clamps as it just seems cleaner to me.

[tshort]

I pulled the conduit through 3/4" holes; it was a huge pain, even when I warmed and stretched the conduit. The only thing is, you only (hopefully!) have to do it once on each wing.
On the second wing I enlarged 75% of the holes a little to allow it to pass through better.

Thomas

[tmbg]

well I just went and bought a unibit that goes bigger than 3/4", and they only had it in a set of 3 (out of stock of the one by itself), and it was $65, so I guess you could say I'm pot committed to drilling those holes to 13/16

My only concern is that 13/16 is 0.8125, and vans lists the conduit as 0.810" OD. I guess 25 tenths is a pretty reasonable fit, but I hope it's not too sloppy. I'll use the prescribed dab of RTV at each junction.

[Brantel]

well I just went and bought a unibit that goes bigger than 3/4", and they only had it in a set of 3 (out of stock of the one by itself), and it was $65, so I guess you could say I'm pot committed to drilling those holes to 13/16

My only concern is that 13/16 is 0.8125, and vans lists the conduit as 0.810" OD. I guess 25 tenths is a pretty reasonable fit, but I hope it's not too sloppy. I'll use the prescribed dab of RTV at each junction.

It will not be sloppy and you will still need to tugg pretty good to pull it thru. There is no way it will ever come out on its own. Also the RTV will stop any rubbing but I can tell you that mine looked tight enough to make this a moot point.

Don't worry about having three sizes and paying out the nose for them, they will come in handy somewhere.

[JohnR]

Just another data point. I used the Van's conduit and put it in the 3/4 inch holes with not much trouble. It was snug but sure fits nice once it is there.

[svanarts]

I used the Van's conduit on the RV-4 and had the same results as John. I prosealed the ends of the conduit to the last inboard and outboard ribs just to be sure it didn't move.

[tmbg]

well, I just finished drilling them all to 13/16". I'm debating whether I want to drill a pair of holes for AOA lines near the pitot line or just run them in the conduit.

maybe I'll put the AOA in the right wing, and use the pitot holes and the 3/16" tooling holes for that plumbing. I can enlarge the 3/16" tooling holes to 1/4" for a 1/4OD 1/8ID snap bushing, and probably can find snap bushings that fit the pitot holes (what are they, 5/8"? I'll have to measure) that are 1/8" ID. That'll save a goodly bit of work.

Anyway, tomorrow I'll debur all the holes I match drilled for the rib to spar rivets and make a whole bunch of prime rib

[tmbg]

btw, thanks Mike for the link to your log, it planted the seed of using the tooling holes to replicate my pilot, and that worked great! I laid out the hole on my inboard left rib, and then used that clecoed face to face with the inboard right rib to transfer it, and then I used those two as master templates to drill the rest, assembly line style. I got it done super fast, and it was no hassle at all

I then enlarged them all with a unibit to 13/16. Unibits make such clean holes, it's amazing.