H. Stabilizer doilies & tape

We create fabric doilies for added protection at the points where the flying wires will attach to the horizontal stabilizers.  This may be overkill since we already have finishing tape at those points, but we added them anyway.  We pre-shrunk a section of fabric, then traced circles out with a compass, and cut them out with pinking shears.  The doilies were about 3.5" in diameter.

Doilies cut from pre-shrunk fabric

Doilies glued in place (2 on front side, and 2 on back)

We also glued one of the longer horizontal perimeter tapes (at the leading edge) to the horizontal stabilizers.  Ran out of time so will glue on second long tape (hinge side) another day.  Hours: 2.5

More Horizontal Stabilizer Covering Work

We continued to work on our horizontal stabilizers.   We used pencils to mark the area that needed adhesive applied.  Tape was added to make the application of glue easier and cleaner.  Three coats of the U500 adhesive was applied to the outer perimeter and left to dry.  Hours: 1.5

Adding Glue to the perimeter

Finishing Tapes on Horizontal Stabilizers

After completing the top and bottom fabric attachment on the horizontal stabilizers, next up is to attach 2" tapes over the metal support areas to strengthen the areas due to possible rubbing.  The center of the supports were identified and then a 2-1/8" band was drawn centered on the metal supports.  Three coats of the 2:1 thinned U500 adhesive was brushed on the stabilizers making sure we stayed within the drawn lines.  Once the adhesive was allowed to dry, the tapes were added.  The tapes were first attached with adhesive in the center and then worked outward from there toward each end.  Both the top and bottom surfaces were done this way.  Where tapes would overlap, we considered how the air would be passing over the surface and overlapped the areas such that the air stream would not peal up an area.  Hours: 3

Laying out Glue areas in Pencil

Working on Finishing Tapes

Horizontal Stabilizer fabric

Attached 2nd sheet of Superflite fabric to the other side of the two horizontal stabilizers.  The fabric was glued and shrunk using the same process as described in a previous blog entry.  Hours: 3

Horizontal Stabilizer Covering continued

We decided to buy new irons for our covering.  After some research, we decided on the two Toko T14 Waxing Irons.  They get high praise from other builders.  With the new irons, on low heat (250F) we went back over the previously adhered fabric removing all bubbles and glue buildup.  We then shrunk the fabric with temps of 300F and 350F.  It was very rewarding seeing the fabric tighten up.  We then marked the the fabric where we needed to apply U500 adhesive.  Finally we added two coats of  thinned U500 adhesive up to the previous applied marks.  Hours: 1

Horiz Stabilizer Covering Cont.

We finished attaching pieces of Superflite fabric to one side of each horizontal stabilizer.  We had previously attached the fabric to one edge, so finished attaching to the other 3 perimeter tubes of the horiz. stablizers.   The fabric was wrapped around the tubes (which had 2 coats of U500 adhesive applied), and then another coat was applied to the fabric surface which soaked through the fabric and ensured good adhesion.  We went slow since these are the first 2 plane pieces we are covering, and didn't want to screw it up.  The process is a little tricky, but with practice we should get better.  Irons were used to help tame wrinkles and get the fabric to lay nicely against the tubes.  Hours: 2.0

Fabric attached to one side of horizontal stabilizers

Officially Started Covering

We re-calibrated our irons which took a bit of time.  We plan to cover the horizontal stabilizers first.  We first cut the fabric.  Four pieces was cut from the Superflite SF102 fabric.  Next we applied three coats of the U500 adhesive to the outer members of the horizontal stabilizers.  Finally we trimmed and attached the fabric to the rear edge of the stabilizers.  Small bubbles were removed with a iron at 250F.  Hours: 4

Started working on the horizontal stabilizers

Finished Tapes on Practice Parts

Ed and I finished the 3" edge tapes on our practice parts.  We again had to work with curved corners that take a lot of time to get the tapes to lay down nicely.  Once the tapes were worked with the irons to fit correctly a 2:1 Superflite U500 adhesive mixture was added to the tapes to secure them.  Hours: 1.5

Two Practice parts complete with edge tapes

More Fabric Practice

We continued our work on the practice pieces we are covering.  We are now adding the finishing tapes to the center members and we started work on the perimeter tapes.  We are learning a lot,  especially on the curved corners. Hours: 2

Adding perimeter tapes

Fabric covering the practice frames

Today we began covering the practice frames with fabric to get ready for the next stage of our airplane project.  Adhesive was first painted around the edges of the steel frames, and fabric is then applied (glued) to the tubular frames.  We intentionally made the frames with curves on 2 corners because that is a challenge to cover cleanly.  Yeah, we made some mistakes (but hey, that's why these are practice fames), but overall I think they came out pretty nice.  Once the fabric was glued in place, we shrunk it in stages at 250, 300, and then 350 degrees with irons that we calibrated yesterday.   Hours: 5

Two practice frames covered with fabric

Practice Fabric Covering Started

We've been doing a lot of cleaning and straightening of the garage in preparation of doing fabric.   We setup two "covering" tables for the process.  We bought a new wheeled rack for storing chemicals and tools.    And we've had to buy a few things, brushes, strainers, zahn cup (for checking viscosity).  Finally we started working on the practice parts.  We mixed up the U-500 adhesive (1 part glue/2 parts Acetone) and applied 2 coats to the trailing edge of the practice part.  Hours: 2

Glue added to one side of the practice pieces

Painting Practice Parts

The two frames that Ed welded up earlier were sanded to remove the galvanized coating.  The parts were wiped down with Acetone and then hung on the painting rack.  The painting rack was nothing more than a board between two ladders and the parts were suspended with safety wire.

Once the parts were hung, Michael mixed up some epoxy primer paint (4:1, epoxy paint to catalyst ratio).  Three good coats were applied to the parts and allowed to dry before moving them into the garage for a complete cure of the paint.  Hours: 1.5

Painting the Practice Frames

Fuselage moved to hangar

Today we towed the fuselage to Cox Airport. The modified trailer (with the new upper deck) worked great.  We had to drive down a long winding road to access the hangar, and there were several trees with low-hanging limbs in the way.  Michael drove slowly while I moved the branches out of the way with a large push broom so that they wouldn't catch on any part of the fuselage.  But we made it to the hangar just fine.

Michael had added an electric winch at the front end of the trailer, and this made loading and unloading the fuselage a piece of cake.   After  backing the fuselage down the ramps, we wheeled it into the hangar.  We then covered the fuselage with thin plastic sheets to help keep the dust off.   Forgot to take pictures, but we had a few visitors (including a hangar mate and also the airport owner) that were pleasant distractions.  Hours: 3.0

Loading Fuselage for Transport

We spent the day building and attaching ramps to the flatbed trailer.   The fuselage was then wheeled out of the garage and a winch was used to slowly get the fuselage onto the trailer.  Then the whole fuselage was strapped down and a few blocks were attached to make sure the fuselage doesn't move during the transport to Cox Airport.  Hours: 3

Ramps in place awaiting Fuselage

Fuselage extracted from garage and dollies removed from mail wheels

Strapping down the airplane

Strapping down the airplane II

Covered for the night, ready to head to Cox Airport

Removing Horizontal Stabilizer

We continued our work on getting the fuselage ready to transport to the hangar at Cox Airport.  Today we removed the flying guy wires supporting the horizontal stabilizer and placed all the hardware into labeled bags.  The two attach pins were removed, labeled and bagged as well.  The two, now free, horizontal stabilizers were set aside and will  be one of the first items to be covered with fabric.  Hours: 0.5

Wings removed and stored

We are going to start the next phase of the airplane construction soon (fabric covering).  But in order to do this, we need more room in the garage, so we removed the wings this past weekend, and moved them to the shed.  We stored them by hoisting them up in the rafters (same way we had stored them earlier).  We also removed the struts and hung those on the walls in the shed to get them out of the way.  We still need to transport the fuselage to a hangar to get more space in the garage, but that is a task for another day.  Originally, we planned on storing the wings in the hangar, but figured they would be safer in the shed since hangar space it currently tight with 2 other airplanes sharing the space.   Hours: 3.0

Wings stored near roof;  lift struts attached to sides of shed

Transport Trailer Work

We are getting close to the point of adding fabric to our project.  In order to do this, we need more room in our garage.  We plan on taking the fuselage and wings to Cox Aerodrome where Michael has a hangar.

In order to transport the fuselage with gear attached, we needed to create a platform on top of Michael's utility trailer.  Holes were drilled in the railing at uniform spacing.  These holes were later used to up-drill into the 5/8" plywood deck.  A 2x6 backbone/joist was placed down the middle with 4x4 posts.  1/4" carriage bolts were placed in the holes going through the plywood and aluminum railing.  A nice 45 degree corner cut was done for looks.  Hours: 5

Center Joist being constructed

Ed cutting the plywood deck

Decking cut to shape, rear view

Decking cut to shape, front view

Vent line work

We made good progress after finally coming up with a good plan (probably the 10th plan after the first 9 "good plans" didn't work out).  We had planned on using 1/2" rubber fuel hose to connect the vent line to the header tank, but after a test run, we found that it was not flexible enough and was getting crimps (which closed up the tubing) when we tried to snake it from the wing tank vent to the fuselage.

So instead, we decided to use a flexible fuel line with PTFE lining. The brand we used was Earl's UltraPro hose.  Of course, it's more expensive, but it's really the right material for the job.  It is super flexible, smaller outer diameter, lighter, and (reportedly) lasts longer.  The connectors also swivel which makes installation much simpler. Below is a picture of the hose with a 120 degree connector attached on one end.

Flexible fuel line (Earl's Ultrapro Hose)

We sistered a brace (manufactured by Mike) to the root rib in order to strengthen it because we needed to make some cuts in the rib to make room for the vent line.  The brace is epoxied in place, and a few rivets were added to keep it in place.  This brace may not have even been required since the fuel tank provides a lot of support at the root of the wing; but we figured it's better to be safe than sorry, so we added it.

Brace sistered to root rib

Next we epoxied (and screwed in) the aluminum vent fitting to the fiberglass tank.  This is a relatively large fitting, but it allows us to install a larger finger-strainer, and still accomodate 1/2" tubing which is recommended for venting the header tank to the wings when using a  Rotax 912is engine.  We used Hysol 9460 epoxy which is fuel resistant. Hours: 4.0

Vent line fitting (finally) installed

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

Aileron Cable Routing

Decided to make a paper template for the cockpit side pieces (F-2120) located on the outside of each seat.  A hole/slot needs to be located and cut where the aileron cable goes from the top side to the bottom side.  After quite a bit of experimenting the hole was located in the template.  We'll transfer this to the actual aluminum part later.  Hours: 1

Paper Template. 
You can see the orange temporary string going through slot

Fuel Feed

Finished the supply side of the fuel line from the header tank to the fuel cut off switch.  Installed some mounting adel clamps to make the fuel line more stable.  Finally the fuel like was cut to length, fuel fittings were installed and the end flared for connection to the fuel cut off switch.   Hours: 1

Fuel supply line to the cut off switch

Aileron Autopilot Servo

Had to make a slight adjustment to the aileron servo mount.  When I fitted the parts, I found that two moutning bolt heads for the servo interfered a bit with a bracket.  This was a bummer, and I contemplated drilling out all the rivets on the bracket to fix it.  But then I thought it might be easier to use Michael's mill and (very) carefully mill out a slot in part of the bracket to fix the interference.  This worked out pretty good, and I didn't have to remove any rivets.

Milling the right angle bracket to fix some interference

Notch in right angle bracket provides room for bolt

I spent some time aligning the position of the motor, and found that I needed to make some additional 1/4" alum. spacers to drop the servo down a little bit.  By doing this, the cable that runs to the pulleys (that are doubled up under the existing aileron pulleys) lines up nicely with the pulley on the capstan servo.

Servo with 1/4 inch spacers under the servo bracket

Next I mounted the whole shebang in the airplane, right under the control stick mixer.  I double checked alignment with some orange string just to make sure I didn't screw anything up.  Alignment looks great, and one of the next steps will be to get a cable made that will replace the string.  I'm attaching several pictures below of the installation as it is hard to see how it all fits together from just one angle.  Hours: 6

Autopilot Servo pic1

Autopilot Servo pic2

Autopilot Servo pic3

Autopilot servo pic4

Autopilot Servo pic5

Autopilot Servo pic6

Autopilot Servo pic7

Fuel Lines

The past few days, we've been running 3/8" aluminum fuel line from the header tank to the front of the fuselage.  The hardest part was finding points on the fuselage to install adel clamps for mounting.  The first line to be run was the fuel return line.  The fuel return line runs from the firewall directly to the header tank. The fuel line runs through a notch in the floor panel, turns 90 degrees and then runs down the middle of the fuselage.  

The next line to run was the fuel supply line.  The fuel supply line will run from the header tank to the fuel selector valve.  Like the return line, the supply line runs through the notch in the floor panel, turns 90 degrees and runs down the middle of the fuselage.  The supply run still needs it's installation completed.  Hours: 3

Header Tank with Fuel Lines

Fuel Lines with Adel Clamps for mounting

Fuel Line heading toward the firewall