Thursday, July 29, 2010

Picture Progress Post

A quick summary of the week to date follows.

Installed brace channel for the ribs at each end of the trailing edge, filed and cut the trailing edge with a hacksaw carefully until the rib ends could slide easily inside and be screwed down with #4 PK screws. Then, the control cable path to the aileron was checked with more surveyor's string to make sure the brace from the corner of trailing edge and rib would not interfere when installed. Discovered the brace channel doesn't interfere with the control cable path, but the rib does; file to fit, will add a brace later.

Some of the docs we were looking through, trying to find voltage, wattage, amperage, and the charts and graphs for appropriate wire gauges when running wiring to the lights. We neither wanted to work out the long and complicated formula, nor resort to a "well, this is what a similar plane has" guess.

Checking the cockpit to see how the lights were wired to switches and bus, as well as circuit breaker amperage.

Running first batch of wires.

Hot and ground run to lighting bracket and out to wingtip.

Still to go: removed the fuel bay drag / anti-drag tie rods, as the thickness of the anti-chafe tubing was causing clearance issues. Swapped out friction tape and thick tube for lighter, thinner tube and shrinkwrap. Still need to heat the shrinkwrap very carefully with a torch, well away from any combustible sources, to overcome the heat sink that is the wire. I want it to stop raining so I can do that outside - we're experiencing the 8th wettest July in recorded history up here, and I am thoroughly sick of low grey skies and rain.

Also to come, not pictured, cutting the phenolic (must find my respirator) for a non-chafing brace & cable guide to rivet into the butt rib, a doubler for the butt rib where I had to cut it for fuel line clearance, and pitot-static tubing.


Jenny said...

Wow... I'm concerned about cutting open the rib that way - it looks like that filed away section is really introducing a serious failure point. I assume since all the load is on the spars and the strut attachment point its okay?

Why would it interfere in the first place? Is it because the original one used a built-up rib that would be open there? If so.. what changed?

Glad for Mr. P. I'd have been panicking at that point without him. :)

On a Wing and a Whim said...

The filed away section could be a problem if that was how it was going to be left, but that's why there are reinforcing doublers and plates going to be put in at those points. :-) I just... *sigh* haven't got there yet. Although it's not as bad as it seems, given the load path on the rib.

Yes, it's because I'm using a stamped rib instead of a built-up rib - built-up ribs, for all their faults and flaws, are a lot more open.

AlaskanGeekArchitect said...

Is the tubing meltable? If it a hot air gun might be a better choice then a torch.

It's really easy to overheat things with torches..

Even a lighter will set most heat shrinks... and I'm sure it'll be hard to find smokers around there... :p

Jenny said...

Yes, it's because I'm using a stamped rib instead of a built-up rib - built-up ribs, for all their faults and flaws, are a lot more open

That's my concern.. I'm assuming once they started building planes with stamped ribs, they weren't cutting through them for the cables on every plane, yes?

If so, that implies either -

(1) that's the wrong rib for that location on the wing

(2) the gearing for the aileron was moved between the old wing design and the new wing design, resulting in the cable path being a little different

(3) something is out of kilter in the wing construction, so the cable path is pooched.

I'm assuming the problem is (1), and that the factory rib was originally a little different, but these are the available parts and they have to be modded to fit?

Or something else?