Wing Tanks Installation, Part 1

Before I get started, let me recognize another RV-12 builder, who is also a Viking RV-12 Wing Tanks builder and has been at this gig for bit longer than myself.  Bill Dye has pioneered a very nice installation and I am unabashedly following almost all of his techniques.  He has made a thorough analysis and resulting thoughtful installation.  Give credit where credit is due.  He has taken a very rough and quite frankly, unfinished installation procedure rendered by Viking Aircraft Engines and re-engineered it into a very nice and complete assembly.

Now, some of the more significant procedures for wing tank installation.  First picture shows the "saddle" into which the tubular wing tanks will be seated.  McMaster-Carr describes it simply as an edge grip with rubber seal.  A 15" long piece with appropriately sized cutouts is manufactured for each of the designated rib lightening holes.  Upon installing the edge grip onto the edge of the circumference of each hole, I elected to follow that up with some Right Stuff adhesive on the outboard side of each rib for some extra (and probably unneeded) holding power.

Edge grip installed with other tank temporarily resting in place.  This shot is looking at the "root" side of the ribs.

A shot below of the 3 inch diameter rear wing tank laying in its new home.  The dish soap was very successfully used to ease the friction of the tank as it passed through each of the edge grips.  The soap made the installation through the 8 or so edge-gripped holes a non-event.  It worked great.

Next shots show both tanks installed.  Looking at the tip end of the wing on the right.

 
Looking from the root on the left, to the tip on the right.

Wing is now inverted and the filler neck assembly is starting to get rigged at the wing tip.  The large rubber filler neck hose was another major coup that Bill pioneered for this installation.  Viking's proposed use of Kinar elbows was lacking and this solution proves to be a major improvement.  The brass tee fitting at the base of the filler neck was discarded in favor of AN fittings as will be seen in later photos.

With the filler neck hoses removed, the vent line plumbing can commence.  Below is the vent line interconnect between the two tanks at the wing tip.

Next, a mechanism for securing the tanks from any potential span-wise movement was improvised using a trimmed aluminum angle and hose clamp with some rubber padding.

Backside of the rib where the angle is riveted.

Next, the main tank fixture is in work.

Viking did provide a pair of access panels for the wing tank installation.  Below, the process of marking the location of the panel in the wing skin and then the removal of the material is under way.

The finished cut out is ready for the access panel frame to be fitted, drilled and finally riveted into position.

Next up is the vent line plumbing from the wing tip to the wing root.  Shown below is an intermediate termination point in rib #2.  From that elbow bulkhead fitting, a final run of aluminum tubing will proceed to the mid-rib point and then across to the root rib, where it will terminate in another elbow bulkhead fitting.  That fitting will transition to rubber hose and a quick disconnect fitting, which will interface with the rubber hose from the fuselage pickup point. 

More to come. It's getting exciting!

At Long Last - Wing Tanks Arrive!

After a considerable wait, the wing tanks have arrived as shown by their crate below.

Of course the first task was to clean and prime them like everything else in this project.  They are 6061-T6 extruded aluminum tubes and as such are pretty corrosion resistant, but I primed anyway.

The finished tanks in their primer skin.

This is what one of the filler caps looks like when one removes the vent.

Sorry for this slight teaser, but I don't really have any additional pictures, but more will be forthcoming in the next post; stay tuned!

More Micro Projects While Waiting

For those of you still following along, you know that I am playing a marathon waiting game with Jan Eggenfellner, Viking Aircraft Engines, for the delivery of the long overdue wing tanks.  Oshkosh ended yesterday and the promised deliveries of wing tanks never occurred as promised.  Tantalizing pictures of fabricated wing tanks loaded in the back of a pickup truck appeared on the Viking Aircraft Engines portal.  A friend, also awaiting delivery, forwarded an email he received from Eggenfellner stating that he ran out of time prior to the big show to deliver to customers.  The drama continues.

In the meantime, I am trying to fill my time with any tasks I can see that need to be done independent of the wing tank installation.  I can't even finish the fuselage as flaperons must be fitted to the forward fuselage before I can install the tailcone, roll servo, back window and many other dependent parts.

So, here is what I've been doing:

Micro project #1. Replacing and re-wiring the control grips as I had apparently burned  out one of my grips by somehow backfeeding 12 volts through a ground wire, according to Kevin Tosten.  Being the great guy he is, he had me ship both grips back to him and he reworked them by installing new, upgraded and more conventional DPDT hat switches that have a much improved feel than the original hats (even though they were completely acceptable).  The guy charged me the princely sum of $10 for all his time and new parts!  I just can't say enough good things about Tosten Manufacturing and Kevin's products.  Below are a couple of shots of the re-worked unit going back into the shortened control stick.

Micro project #2. "Skinning" the instrument panels with a synthetic carbon fiber vinyl.  No in-process shots taken, just the final product.  I'm very  happy with the look and I must say that I got the three panel skins (patterns) all in pretty darned nice alignment.

The process consisted of cleaning and then priming the surface to be covered with 3M's Primer 94.  The primer promotes greater adhesion to the vinyl than just the adhesive of the vinyl itself.  The vinyl I chose is the 3M Di-Noc product in a flat black carbon fiber pattern.

I ordered a 24 x 48 inch piece of material and have about 1/3 left over after skinning all 3 panels plus the glove box door and a switch sub-panel.  As I progress in final assembly of the aircraft I will see if I have enough material left over to skin the center console between the pilot and passenger.

That's about all for now.  Stay tuned....one day, the project will resume it's normal pace.

Catching Up

Unfortunately, there is precious little to catch up on.  All of the nice things I previously stated about Jan...well, guess I have to re-think that again.  More promises of deliveries and more delays on receiving said wing tanks.  They were promised for about the fourth time in June and now it's July.  Not going to dwell on it; you can draw your own conclusions.

I do have some other stuff to catch you up on.

First, continued preparations for the wing tanks, whenever they arrive.  The first picture below shows the heart of the fuselage components of the wing/fuel tank assembly.  It is actually shown 90 degrees out of it's installed orientation.  In other words, the larger black tube is the standpipe which is mounted vertically in the baggage compartment, in place of the conventional RV-12 "box" tank.

Here is what the standpipe looks like installed on the passenger side of the baggage compartment.  It's a big (small in size..minimum fuel in fuselage) improvement in the replacement of the box tank.

 
 The picture below shows the passenger side brass elbow connection to the standpipe.  In this instance, fuel will run to the standpipe from the right wing.

Note in the picture below the rubber hoses running for partial lengths along the various tubes.  These are in place to mitigate any chaffing and/or bouncing from the rudder and stabilator control cables.  From left to right, the black sleeved tube is the left wing fuel supply line that runs to a similar elbow fitting (shown above) on the pilot side of the aircraft.  The next tube with the AN elbow/coupler will connect to the Viking engine's fuel return line.  Don't forget that a fuel injected engine is a pressurized system.  Finally, the third tube with the clear sleeved hose is the fuel supply line to the engine.

 Close up of the terminus of two of the tubes and the left supply line running further.

The long fuel supply line had to be trimmed to the proper length and then threaded with 1/8 inch pipe threads for the brass elbow fitting.  So how do you put threads onto a nearly 48 inch length of light weight aluminum tubing?  Well, use a huge lathe or in the absence of such, anchor one end to a vice on your workbench and get on a stool and cut the threads by hand with your favorite die.

Contortions and more contortions later...you arrive at the promised land of a threaded tube.

 Next item to tackle was the positive ventilated crankcase.  Seems some Viking engine drivers are experiencing very dark colored oil after just a few hours between oil changes.  Signs seem to point to a lot of combustion blow by, so perhaps application of a positive ventilation to the crankcase can minimize that.  The oil tank (not pictured) is actually going to be vented into the intake manifold, courtesy of a tube running from the filler neck (of the oil tank) into the air cleaner.  This will provide a slight lower pressure (vacuum) for the crankcase which will draw a supply of fresh air from an inlet tube attached to the valve cover.

BTW, from here to the conclusion of this blog, please disregard the errant date stamp on the photos, as the year should not be 2016.

Here is a shot of the existing unvented, valve Viking cover.

And here is a picture of the new cover, being modified, prior to installation.  In this case, the inlet hose barb was removed and the remaining inlet tube is being threaded to accept a plug.  The Viking valve cover vent inlet will be in another location.

The next picture shows the new valve cover with it's new vent tube installed on the top, running parallel to the cover itself.  It is also black and does not show up very well.

Here's another vantage point, where you might be able to see it better.  It is a 5/8 OD aluminum tube, with a small brass filter affixed at the aft end.

With the new valve cover (btw, it's a stock Honda part) comes a new requirement for attaching the engine's wiring harness.  Out with the old adele clamps and in with the new Honda loom clamps that handily snap into place on the valve cover.  The new plumbing actually cleaned up the harness assembly.

To conclude this Catching Up installment, I will post a few pictures of the control cable fitment.

First up are the rudder cables running from the baggage compartment forward to the console, with the tail cone not yet connected but in close proximity.  Notice the plastic sheath which will insulate the cable as it runs beneath the fuselage seating area of the fuselage.

The rudder cable is secured forward, onto the rudder pedal and it now trails on back toward the tail.

The last shot shows the stabilator's most forward termination to the torque tube for the control sticks.

Stay patient...and stay tuned.  No telling where/when this wing tank saga may end!

Wing Miscellaneous - Follow Up

After my previous entry complaining about Viking Aircraft Engines, I have to give credit where credit is due: in a word, Jan Eggenfellner.

Jan has finally responded to my wing tank inquiries and acknowledged a shipment date of sometime in June, 2015.  While nothing is guaranteed, he has in the past, been true to his word to me.

As of this morning, Jan has also publicly stated his intentions to return the Honda Viking 110 engine back to the front burner and solve any issues as they might arise.  I am relieved to at least hear his rational declaration to prioritize his existing product and customer base.

I am more hopeful than I was a week ago.  Time will tell....but this is EXPERIMENTAL aviation with products that are provided by very small companies.

Continued good luck and prosperity to Jan and Viking Aircraft Engines...onward and upward.

Wing Miscellaneous

First, a brief narrative for my delay in posting more updates.  In a word - Eggenfellner.  In more than a word - Jan Eggenfellner and Viking Aircraft Engines...and a long overdue shipment of RV-12 wing tanks.

Jan decided he did not like the thin-walled wing tank design (not to mention any other problems that might be lurking, like the lack of sufficient venting and specifically a siphon break).  This original design utilized a TIG welded rolled sheet of thin aluminum of a custom diameter.  The custom diameter would maximize usable fuel for the tanks that rest in the wing rib lightening holes.  Since abandoning the original design in the January/February timeframe, there has been little progress revealed to purchasers.  He has implied the use of regular extruded tubing instead of the welded tanks, which will result in a significant reduction in tank volume and increase in weight.

His new project involving a Viking 135 engine, as he calls it, is a V-configuration motorcycle-derived engine of 135 horsepower.  He is currently fitting the prototype engine on a highly modified Zenith Cruzer....and it is taking away from everything else.  Combine this distraction with preparation to wow the Sun n Fun airshow crowds along with the recently "upgraded" oil tank for the Viking 110 (Honda) engine that appears to have some teething problems and you have delays upon delays.  And I'm ticked!  Texan speak for angry.

The only response so far to my email inquiries has been a single post stating wing tanks will ship at the rate of 1 per week.  Don't know where I am on the list, but it's not for lack of asking.  I hope to hear something soon.  The one builder who has received his tanks, submitted a one sentence review to the Viking portal stating something to effect that the welds look great....okay, that's helpful - not.

Alright, enough of the negativism.  I'm just mad about the lack of progress.  I have done a few small tasks as follows:

First was the prep for the install of the landing light in the right wing leading edge.  Apply the template to the leading edge skin, aligned with the appropriate rivet holes.

Next, go slow and make the initial rough cuts followed by the more precise cuts with some dremel metal working bits.

The finished cut out for the landing light!

 
Below are two of the mounting brackets with riveted doublers for the wing tip landing light.

Now, we switch over to the left wing because there is an existing inspection hole/cover for the stall warner installation.  Below is a shot of the pitot tube with it's simple circular mount aligned with freshly drilled hole in the wing skin.  It took a bit of head scratching to arrive at my ideal location, which was in relatively close proximity to the adjacent wing rib.

A profile view of the pitot tube's improper orientation.  It will have to be "bent" such that it remains parallel to the freestream air and not pointing upward (remember, it is inverted in this picture).

Looking at the pitot from the other direction.

The pitot projects into a hole of a small angle bracket that will be riveted on the wing rib with a doubler (not shown).

Primed parts: wing rib doubler, wing skin doubler and the previously shown angle bracket.
 

Wing skin doubler from the inside, cleco'd into place.

Hole drilled and deburred.

Skin doubler with pitot mount riveted to wing skin.

Pitot angle bracket/rib doubler cleco'd into place awaiting rivets.

Final assembly awaiting the skins and pitot tube.

The next mini-project of this installment is stringing the wiring for the lights and stall warner to both wings.  Shown below is the right wing and the mounting points for the stall warner.

And the root end of the same wing showing the termination of the harness about to be installed on the rib.

Full span shot of wiring of right wing.

The final installment of this blog is the second of two firewall stiffeners.  The Vans upgrade was already installed on the passenger side of the aircraft and I elected to repeat one for the pilot's side.   I never took any pictures during the process, so the finished product is all you get.

Hopefully the next blog will find me in a better mood with some real wing progress to report...otherwise it's back to other incidental stuff with the fuselage and cowling, which I was hoping to defer to the end of the project.