Fabric Covering Wing 5 of 8

poly brush wing

Finishing Tapes, Gusset Tapes and Inspection Rings were attached per the pencil line locations by first coating the affected area with a brush coat of Poly Brush, then brushing the tape and the affected area with more Poly Brush while pressing the fabric tape into the wet glued zone.  Wet tapes are essential and it is easy to see when a tape is wet or has areas not wet.  The Poly Fiber Instructions are excellent and this Blog is not meant to replace them or even supplement them. Needless to say, their instructions include much greater detail on how the process works. The tape attachment was followed by heat smoothing the pinked edges of the tape down into the Poly Brushed surface until they were smoothed out and there were no standing ears or rough edges.

When the brushing and heat smoothing process is finished then you move to the spraying process.  This required me to relocate both wings to a spray booth which is my garage with a lot of drop cloths.  I used my wing rotator fixtures (Harbor Freight Engine Stands) to rotate the wings with the other end attached to a sling contraption.  When any of the Poly Fiber coatings came in contact with a plastic drop cloth they make for a very sticky floor. When I tried to walk across the plastic drop cloths my feet would stick to it. The solution was to use a cotton drop cloth on the floor. Another item that needed protection before spraying the wings were the aileron and flap brackets, the wing strut connection brackets and any other protrusions – so these were carefully taped off.

After two spray coats of Poly Brush the wings took on a very ruby red glossy appearance. The next phase is the protection coat of Poly Spray which is the UV silver coat that protects the fabric from the damaging effects of the sun.

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Wing Rotator Fixtures

wing rotis.

While saw horses were used during the early stages of wing construction, it would now be neccesary to have some other method to support the wing for the fabric covering process.  I would need an easy way to rotate the wing from right side up to upside down without having someone to help me.  The wing would need to rest on something flat when it was right side up and rest on something contoured to the airfoil shape when it was upside down.  I purchased two very inexpensive engine stands for each wing from the Harbor Freight store and mounted a 2 X 10 board that attaches to the rotating hub of the engine stand and connected to the front and rear wing spar connections.  When the wing was upside right I would use a simple saw horse on the opposite end.  When I needed to flip the wing upside down I would use a special plywood box that has a carpet tile covered contour that matched the airfoil contour of the Northstar wing.  I also wanted a method to hold the wing up vertically for certain fabrication reasons and also for efficient storage before final assembly to the fuse.  I used the same plywood box and created a vertical airfoil profile of the first third of the Northstar wing by kerfing a piece of plywood to create the shape and then covering it with the backside of carpet tile to protect the wings surface.  When I needed to flip the wing I would lift the wing tip and turn the wing over and use a wing box or a saw horse to support it as needed.