Lift Strut, Exit Fairing Fit-up

I trimmed and match drilled the plastic flap and aileron exit fairings to the bottom of the wings and also installed all of the fittings and hardware to the aluminum front and rear lift struts.  The struts are now ready to support the wings when they are installed.

Wings: Root Rib Modification

The aft flexible fuel line from the fuel tank on each wing needs to run under a wing structural member and then over the bottom root rib (and then into the cockpit).  Currently, there is not enough clearance to accomplish this without pinching the fuel line.  Ran's suggestion to work around this situation is that the root rib be pinched to obtain sufficient clearance.  Not the most elegant solution, but better then routing line over structural member which would introduce a high-point in the fuel line and not allow complete draining of fuel tank. 

Using a pair of channel locks and aluminum angle (the latter to distribute pressure on outer side of rib), I pinched the rib until 3/8" fuel line would fit unencumbered.

Right Wing: Ailerons, Flaps, Wing Tip, Gap Seals, Root Skins and VGs

Similar to the left wing, I've got all of the above tasks fitup or installed.

Left Wing: Install Vortex Generators

I completed my last assembly task on the left wing before I move it back on the stand and duplicate efforts on the right wing.  Vortex generators were installed to reduce the stall speed of the airplane which will reduce landing approach speed and likewise reduce landing distance.   I've been told the S7 is better capable to produce 3-point landings with VGs, as well.  The VGs were positioned such that they have the best ‘bite’ at the airflow when the wing is at the stall angle of attack; not too far forward or aft. The manufacturer recommended that the leading edge of the VG be aligned at the 7% wing chord position.   This results in the VG functionally positioned at the 9% position.  The average wing chord for the S7 is 60 inches, so I used 4.2 inches as my setback position from the LE spar. 

Here is a Stolspeed VG

Here are the VGs placed on the precut advesive pads.

It was helpful having the wings off when doing this because then the wing root was exposed.  It was a simple matter of running a string line from LE to TE spar to determine the chord line and then using a triangle square transferring the 4.2" measurement to the top of the wing.  This location mark on the wing was then carried down to the outboard end of the LE spar and a string line run through the two marks.  This line was then projected across the tip wrap area and terminated shy of the wing tip fairing.

Here is the template used to get the correct angle on successive VGs.  The 60 mm template was used for the first 3' on the outboard wing and then spacing was increased to 90 mm up to the wing root.  The manufacturer recommended this placement so that the outboard wing would not stall first and, presumably, not result in loss of aileron control.

Left Wing Root Skins Fit-Up

The root skin consists of three pieces.  The skin is riveted on with exception to the aft piece which is screwed on for internal wing access.  Here are three pieces clecoed together.

I taped the assembly in-place where optimum, i.e. where holes centered on fuel fittings and skin centered on root rib.

 I then transfer drilled into the root rib and clecoed as I went.   I also fit-up the fuel sight gauge mounting bracket.

Here is a closeup.

I'll final assemble after painting.

Left Wing Gap Seals

The gap seals were cut to length to fit between hinges and then mitred at 45 degrees using a disk sander.

Next, holes were drilled every 8-9" while maintaining specified edge distances.  A dremel drum sander was used to notch areas where underlying bolt heads on TE spar were located which would have precluded seating of seal.

Using a 4' level, I struck a line corresponding to the top of hinge elevation.  The top of gap seal matched this line.

Two-way tape was used to adhere the gaps seals while transfer drilling was done into the TE spar.  Clecos were used to hold piece during drilling.

Following deburring of holes, I then riveted gap seals to trailing edge spars.  Next, using a block plane, I then trimmed trailing edge of gap seal to create a 0.06" air space between gap seal and flap/aileron.

Here a completion pics.

Hard to see, but bolt heads underlie the covering on the TE spar.  These areas were notched on the gap seal.

The mitred ends were constructed to facilitate potential bolt removal.  The rivet holes were located 1/4" from bottom of gap seal rather than along centerline so that the pop rivet gun head would fit unobstructed.

Gear Leg Reinforcement

I've been told that the existing gear leg shaft in fuselage socket connection is the achilles heel of my vintage plane design.  A hole is drilled and a single bolt extends through the socket and shaft.  Over time, repetitive landings on rough ground and especially with bigger tires tends to over-torque the gear shaft causing the softer socket metal hole to wallow out.  The factory has since corrected by welding steel reinforcement "patches" where the bolt goes through.  I decided to address this potential problem now and avoid headaches later, especially since I plan rough field landings with bush tires in the future.  Several guys had purchased steel shaft couplings for added reinforcement.  I wanted to avoid the extra weight and purchased aluminum two-piece collars with cap screws.  I could not find an assembly long enough, so I purchased two collars and had them welded together.  Here are the collars as-purchased.

Here is an installed 1-3/8" welded double collar installed over the gear leg socket.  The gear leg shaft is inside the socket.  A longer bolt now runs through the entire shaft, socket and collar.  I applied JB weld epoxy to the inside bearing surface of the collar before tightening down the 4 cap screws.   I also stripped all of the paint from the socket bearing surface, before installing the clamps.