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!