Wing Construction 100% complete

 

Here is an overview of the wing construction. 

 The wings fold back alongside the fuselage for easy transport and storage.  The two wing spars are reinforced where they attach to the fuselage.  The holes in the wing spars for the hinges must be precisely in the right position for the wings to be rigged correctly so much care was taken to insure that it was perfect.
Because the wings fold, the lift strut shown here is the only thing keeping the wings from folding up like a butterfly - its gotta be defect free! The jury strut supports the lift strut in the middle to keep the lift strut from bowing under negative G forces.  The lift strut attaches to the spars with a steel bracket which is epoxied and riveted securely to both spars.

With the wing hinge and lift strut complete, the butt rib can be attached to the fuselage.  The butt rib will be flush with the wing with the wings unfolded.

There is one 13 gallon gas tank in each wing for a total of 26 gallons.  The gas tank is fiberglass and is molded to the precise contour of the airfoil so it can sit securely between ribs 1 and 3.  The gas tank is held in place with ammonia-free caulk and the transition from the leading edge of the wing to the tank is contoured by filling and sanding with epoxy/microballoons.

The all-important leading edge profile is made by epoxying a formed plastic extrusion onto the front of the 3" aluminum leading edge spar.  This gives the airfoil the proper shape as well as protecting the spar from dings.  After the plastic extrusion has been epoxied on, the transition between the extrusion and the ribs is made perfectly smooth by using superfil (epoxy and glass microballoons) and then sanding down to the desired profile.

The leading edge is checked along its entire length to insure the profile is correct.

This design combines flaps and ailerons into one control surface, the flapperon.  The flapperons are full span which improves the ability to get in and out of short strips.  Here I am fabricating the brackets which hold the flapperons onto the wing, there are 10 of them.  The brackets are first epoxied, then riveted.

Here I am finishing up the flapperon by installing the counterweights, the blue plastic protective film is still on the aluminum at this point.

Like all structures on the aircraft, the flapperon is only strong enough for its intended purpose - no sense wasting weight making it stronger than is required for safety.  The flapperon is actually quite fragile when not supported by the wing so great care is required in its transport and installation, holding it up at one spot in the middle is not advisable.  The pulley system holding the wing up saves the day again as I can easily lower the wing into the correct position to mate with the flapperon which is laying on top of the table without any help.

The wingtips take considerable time and effort to construct.  Because I plan on using the airplane as a platform for developing avionics, I need the wingtips to be easily removable for installation and inspection of electronics.   In this picture I am fabricating the attach strips so the wingtip can be attached with machine screws.  The wingtips also needed to be modified to mount the navigation lights.

First the fiberglass is trimmed so it precisely mates with the end of the rib, this took many iterations to get exactly perfect.  In this photo the wingtip is held on with the attach strips.  The bronze colored pegs are called 'clecos' and are a temporary fastener used where rivets will eventually be used.  The landing light is also installed in the wingtip.

Rigging the flapperons is very important.  Too much deflection and the wing might stall, too little and the plane will not be responsive enough to control inputs.  The rigging procedure is quite involved and took an entire day.
The wing lift struts are 1.0" in diameter and 8' long so they create a lot of drag, 7mph worth, so they are streamlined with PVC fairings.  First step is to cut and trim them to the proper shape.  The trailing edge needs to be trimmed so that when the wings fold the strut does not pierce the fabric.  To hold the trailing edge together in profile where it was trimmed, I drilled and used rib lacing cord to hold it tightly together then put fiberglass cloth on top of that.
Then I put superfill on top of the fiberglass and sanded it to a nice smooth profile.  A lot of work but it will look better.

 

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