Tie down ring, main strut pick-up, pitot and static tubes

Still working when I can on the left wing.  I've found it challenging to get to the shop as regularly as I would like, but a little encouragement from Brenda to get moving on Saturday morning was a big help.

First thing I wanted to do was inventory and sort some of the partial sheets of rolled aluminum I have on hand.  I've very close to having everything I need and certainly everything I will use in the immediate future.

Inboard nose skin installed on the wing.  Critical to get it straight for drilling holes on the spar line otherwise the skin will roll over the nose ribs crooked, leading to wrinkles.  A long board weighted down helps keep everything flat.

Used some strong twine to gently wrap the nose skin over and down, leaving more room beside the bench to drill the spar out to A3:

This time, before adding the nose skin, I roughed out the measurements of where the slot for the strut pickup, then translated that onto the nose skin:

I did the same thing on the rear channel where the trailing edge skin will need to be slotted for the rear pick-up:

Outboard nose skin added and rolled down like the inboard.  This makes it so much easier to reach to the spar:

Attached the strut angle to the lower wing skin and where it extends out over the nose skin.  In the picture I've leaned the strut pick-up approximately in place.  This will be bent over to act as the doubler for the strut pick-up where it protrudes through the skin from the spar inside:

Here is a picture from the right wing which explains what it looks like completed:

The correct slot in the outboard end of the skin and the tie down ring in place.  I'll wait to rivet it until the skin is ready for final riveting.

Strut pick-up slot cut and fit, forward strut pick-up in place awaiting fit up of the doubler angle:

One of the differences with the left wing vs the right one is the addition of the pitot and static tubes.

In simple terms, the pitot tube faces into the slipstream and passes that pressurized air entering the tube through a system of tubing to the instrument panel in the cockpit.  An airspeed indicator uses changes in pressure in the tube to calculate the speed of the aircraft through the air.

The static tube measures atmospheric pressure outside the aircraft which is used by other cockpit instruments to calculate altitude and the rate of climb/descent.

Systems vary from aircraft to aircraft, mine is made of simple metal tubing, formed as per the plans.

First I needed to add a plate to the location on the lower nose skin where the plans define the pitot/static tubes will be: 

In preparation to bend the plumbing for the fuel system, I bought these tube bending pliers:

The pliers were fantastic to bend the 1/4 inch outside diameter steel brake line for the tubes.  The two tubes travel parallel to each other.  The one on top is the static tube, the bottom the pitot (airspeed):

This is where things get a bit tricky.  The plate needs a figure eight shaped hole for the two tubes where they run parallel.  Once welded together, I won't be able to slide the plate off the tubes because they diverge at both ends:

Before welding the tubes together, I removed the plate from the tubes and used the hole to trace out a rough location for the hole in the nose skin:

The hole needs to be wide enough that when the tubes are welded together the ends can pass into the nose skin but still be covered by the plate.  Corner drilled the proposed hole....

....then Dremel tooled the lines to create the hole.  A bit of filing to clean up the corners and edges:

I taped the tubes back together with the plate and checked the fit in the hole - all good.

The static tube has three holes drilled around the circumference.  The end facing into the siipstream is welded closed.  Completed this way, the tube measures atmospheric pressure:

I included a photo of the drill bit (3/64") to give some idea of scale:

I cleaned up the tubes with Scotchbrite pads and again with a stainless steel brush.  I used a couple of woodens shims to clamp the tubes in proper position relative to each other and actually remembered to re-add the mounting plate:

Gentle heat up of the tubes where they join inside the wing and brazed them together:

With both tubes brazed together I placed them back on the nose skin.  I'll need to figure out how to position these accurately later when the wing gets closed up, but very pleased how they turned out.  They get some JB Weld epoxy at the hole to seal them up to the plate and primed before paint.

Good progress this last couple of sessions.  Next up, trailing edges.  Plumbing for the pitot/static tubes needs to be considered soon as the lines that go to the cockpit/panel run through the rear channel and into the trailing edge spaces as does the fuel lines.

​Thanks for following along, stay tuned for more soon.