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prkaye

Well Known Member
I'm preparing the wing ribs now... the plans say to "make provisions for wiring if you want to install wingtip lights" (which I do). Questions:

1) I'm thinking the aft tooling holes are a good position for these, since the forward holes are used for the pitot line. Good plan?

2) How big do I drill these holes?

3) Grommets or conduit? I'm really trying to keep weight down, so I'm guessing grommets is a better choice? Where do I get the grommets, and what do i look for?

4) What sort of wiring do I need to get, where to I get it, and how much do I install? I want to have wingtip position lights. Will probably put strobe on the tail, and would like landing lights somewhere. Landing lights best on wingtips, or leading-edge? Suggestions??

I wish the plans gave you suggested configurations for installing lighting.... oh well, that's what VAF forums are for :)

Thansk!

Phil
 
Go with Vans

Hi Phil,

Vans have a PDF on their 'Construction FAQs' page with recommendations on how to run wiring in the wings.

http://www.vansaircraft.com/pdf/Wing_Wiring.pdf

I went with the Vans conduit in the recommended location. Once installed, just run several draw strings through until you know for certain what wiring you will need. I preferred to use conduit rather than grommets as I felt it would be easier in future if I had to run additional wires (I'll leave a drawstring in place for that very purpose). The conduit supplied by Vans is pretty light weight, and easy to install. Use a unibit to make a 3/4" hole in the recommended location; I made myself a little jig to drill a small pilot hole to ensure I got all the holes in the same place. See the links below for my kitlog; that's how I did it.

http://www.mykitlog.com/users/display_log.php?user=jpreou&project=45&category=1382&log=12276&row=229


http://www.mykitlog.com/users/display_log.php?user=jpreou&project=45&category=1382&log=12293&row=228


http://www.mykitlog.com/users/display_log.php?user=jpreou&project=45&category=1382&log=15116&row=164


Cheers,
 
thanks!

Thanks antigravity,

After just looking at your website, and seeing that conduit (flexible!), I think that's probably the way to go. I like your idea for the jig.

What about landing lights? What's the most common way to do these?
 
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Grommets or bushes

If you're going to run wires through holes, then use grommets or bushes.
Not sure about running the wires through the lightening hole itself. Personally, I think I would maybe cut a short length of soft walled silicon or PVC tubing or something like that, run the wires through that, and then cable tie it in place. Otherwise, a amount of tape, perhaps that self-amalagamating stuff, would probably suffice. I'm sure someone else can confirm. I went with the conduit because it was easy, and I don't think the weight increase is much. We're removing 3/4" of metal from each rib and the conduit itself is very light weight. Makes life much easier in the future. I can't imagine trying to run wires through individual grommets, bushes or whatever later on when the wing has been closed up...

Cheers,
 
Hi, Phil,

Don't run wires near the aft spar even if opening the tooling hole tempts you. It's hard to reach back in there and even inaccessible from the inspection openings, and you're likely to foul the aileron pushrod.

Poke holes near the top forward end of the main ribs; I use two centered 1" apart on the top side because it's easy to look in and see what's going on when you're on your back beneath the airplane. Pay attention to clearance from aileron bellcranks. Not to worry if you keep the holes within 1 1/2" of the spar flange. Consider also alignment of the holes in the root rib with where the wires will depart the fuse for the wing. You'll probably have to introduce a bit of joggle in the wiring, so don't make it too acute. Be sure and keep the pitot line in your planning. The biggest challenge is figuring how to route the mess from the panel to aft of the center section.

I don't believe conduit adds anything except weight. Pop in snap bushings and string the wires by reaching in or use a fish wire. Tie wrap as desired, if at all, between ribs.

Van's tip landing lights are awful. I reviewed on this forum. Duckworks are very effective and you have your choice of lamps. Steinair is a good source for electrical supplies.

Do a real good job of smoothing those rib lightening holes that you'll be reaching through.

John Siebold
The second -7 flies Tuesday
 
conduit

Thanks for all your replies. I think I've decided to go with Vans conduit. I drilled the 3/4" holes as per Vans suggestion... two concerns:

1) I used a jig, but was careless about aligning the left and right ribs (all the lefts are aligned and all the rights are aligned, but the lefts aren't perfectly aligned with the rights). Is the corrugated conduit flexible enough that bending it slightly between mis-aligned holes will be non-problematic?

2) Vans catalog says their conduit is . 0.810" OD. How is this going to fit into the 3/4" holes they called-for in their drawing??

Thanks!

Phil
 
Phil,
As I understand, the Van's tubing outer diameter is 0.810" on the outside, and where the corregations are is 0.750" This makes it snap into place and stay. The stuff is very flexible also, so you can probably be up to 1" off on the root ribs (the close ones) and much more on the others. I wouldn't worry.
 
Flexible friend

Hi Phil,

...what he said...

plus one other thing. Can't remember where I read it, but I daubed some proseal around each of the ribs where the conduit went through to guard against possible vibration chafing and rubbing through. Don't know if it was necessary, but I felt good about doing it! I take the approach that if I do everything I can to mitigate risks and stuff still happens, well at least I did all I could :)

Cheers,
 
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