Practice frames completed

I finished welding up a couple of frames to practice fabric covering before we cover real plane parts.  The frames were made from electrical conduit, and welded up with the TIG machine.  The galvanized coating on this cheap conduit causes issues with TIG welding (sparking and sputtering), so we used a buffing wheel to remove the coating before welding them up.  Hours: 3.0

Two completed frames

Tool fabrication

I had previously made a special wrench when we were going to use a Sonex connector for the vent line in the wing tanks.  But then we later realized that this connector woudn't work so we changed to an alternate aluminum fitting.  Unfortunately, this alternate fitting was a different size, and required me to make a new special "thin" wrench that will allow us to install it easily.  But it wasn't too hard since I had practice. I traced the shape out on paper, transfered it to a sheet of steel, cut it out, and buffed it smooth.  The final part came out nice and fits the new connector well.  Hours: 2.0

Paper template and fabricated wrench

More Welding

We continued to work on our practice frames.  Ed welded up the first frame while Michael started working on the second practice frame.  Since these are practice frames we're using all available pieces of conduit.  Ed is going to have to weld two pieces together in order for us to get the needed pieces.  Hours: 1

Ed welding

Fabric Covering

Ed and I decided that we'd do some practice covering before starting the covering job on the actual airplane.  We decided to to build some 18" x 18" panels with curves.  We bought some 1/2" electrical conduit from the local home improvement store.  Using a conduit bender we bent two pieces of conduit.  Then the ends were cut at 45 degrees.  A supporting brace was cut to go down the middle and the ends of it were shaped to give a nice tight fit.  Ed tack welded all the joints using his TIG welder.  All the joints were completely welded on one side.

Practice Frame being welded

We started working on the second panel.  The design is going to be a little different but the same 18"x18".  Rather than the bends being on opposite sides, they'll be on adjacent corners.  The bends were made on one piece of conduit.  More work on be done later.  Hours: 1

Conduit bent to shape

Miscellaneous Work

Long time since posting to our Blog!  We've done quite a few things and spent four days at the Triple Tree Aerodrome Fly-in.  If you've never been to Triple Tree (SC00) you should make a point of going.  It's a 7000 foot grass runway that is perfectly manicured.  Ed and I pulled a camper and spent the days watching everything from a Citation Jet to a DC-3 to quite a few Just Aircraft arriving and departing.  We also attended a fabric covering workshop.  Although the process used was the Polyfiber process and we plan to use SuperFlite, it was very similar and we got a lot of good tips. Will definitely plan to go back again next year!

Mike at the covering workshop

Ed at the covering workshop

One the building front, the template created for the left side of the cockpit are was transferred to the aluminum piece that had already been fitted.  The hole for the aileron cable was passed through the opening and it was found that it needed to be made larger.  The problem with the paper template is that is flexed enough that it appeared to have enough opening, but once it was installed on the aluminum piece it really did not.  So a slight modification to the hole and now it fits perfectly.

Side aluminum piece (F-2120) with cable hole

We've also been working on getting the Roll autopilot worked out.  The roll autopilot will us a servo with capstan to move the control cables going to the aileron.  In order to connect the autopilot into the existing control cables we needed a way to join the autopilot cable and the aileron cables.  What we needed was "bridle cable clamp".  Doing a search online, I didn't find any that were easily purchased.  I did find some "used" clamps on eBay, but they didn't quite match what we wanted.  What they did do was give us some ideas on how to construct our own clamps.  The first prototype was made by drilling through two aluminum halves.  This we extremely difficult and the results were less than perfect.  The next parts were made on Mike's mini mill and these parts came out perfect.  We purchased a 1/16" ball nose end mill for the autopilot cable and a 3/32" ball nose end mill for the aileron control cable.  The key to getting them all aligned was to mill the slots on a 6" piece of aluminum and then once completed cut the parts to size (about 1-1/4" each).  The key to a tight fit was to mill the depth of the slot a little less than half of of 1/16" and 3/32".  When they two halves are mated and clamped together they hold the cables nice and tight.

At the top if the completed clamp, and the bottom shows the opened clamp.  Correct hardware will be used in the final installation.

And finally, we've also been working on a vent line from the header tank to the right main wing tank.  In order to get the flexible tubing to the feed point on the wing and allow the wing to fold, we are going to have to cut some of the root rib webbing.  To replace some of the strength, we are going to sister an aluminum plate to the area where the web was cut.  A tracing was made of the root rib and transferred to aluminum.  After some cutting, filing, drilling and dressing a nice part was made. 0.040" aluminum plate was used to make the part.  Total hours for this update: 12

Part ready to be installed

Aluminum web fits perfectly

Fuel vent lines

We ran into several issues with the original plan for a vent line to the wing tanks.  The engine (Rotax 912is) installation manual states that a 1/2 inch vent line should run from the header tank to the wing tanks.  We reviewed the plans of other builders who have installed a vent line, but it looks like the few other builders who used this engine installed 3/8 inch lines and not 1/2".  The larger diameter is a much larger challenge because the vent holes, fittings, and hoses all have to be larger, and the area we are working in is already tight.  But we now have a plan (well, actually we had multiple plans, but had to scrap them and rework our plan until we had something that will work).

We drilled a hole in the side of the fiberglass tank for the vent hole.  Originally we planned on using a fitting from Sonex, but had to scrap that because it required access from inside the tank, so instead settled on a more common alumninum fitting. We wanted to minimize any dust or debris that ended up in the tank during drilling, so prior to drilling, we attached a blower (actually a vacuum hooked up in reverse) to the fuel door on top of the wing to put positive pressure in the tank so most of the debris would blow out of the tank.  This worked great.  We started with a small 1/8 inch drill bit, then used a step drill to increase the size of the hole until it was slightly undersized for the fitting.  Next we actually used a large (3/4" NPT) tap to thread the fiberglass hole.  We don't expect it to seal well at the threads because there are so few threads, but it will help hold the fitting in place.  We will be using West Systems epoxy and flox for final installation to assure a leak-proof seal.

Hole drilled in fiberglass tank.  Blue fitting temporarily installed

A finger-strainer will be installed inside this fitting, and then a 1/2 inch elbow (on order) will be installed.  1/2 inch fuel hose (also on order) will attach to this elbow.  The fuel hose will run to the cockpit above the door, and will have enough slack to allow the wings to be folded (same as the fuel outlet hose).

Hours: 10