Attaching the Leading & Trailing Edges

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 With the drag wires squared up and firmly tightened, it was time to lock the wing into place. The Trailing Edge sheet metal came in preformed “S” shaped sheets approximately four feet wide.  The first sheet was attached at the root end and then each subsequent sheet was added with a slight over lap.  The preformed “S” shaped profile fit nicely against the shape of the trailing edge of the ribs and the predrilled holes allowed an easy way to back drill through the ribs and into the sheet metal.  As holes were drilled, Clecos were attached to keep the sheet in position.   Before  final riveting, the sheets were removed, holes were deburred and dimpled to receive countersunk Avex rivets. 

The Northstar Wing uses .020 for the Leading Edge and is designed to extend further down  creating a firmer and truer airfoil shape.  The Leading Edge sheet metal also came in preformed sheets and were also attached starting at the wing root however they had to be stretched over the wing in tension to assure that the sheet metal came in contact with the edges of the ribs.  This was done by first attaching the sheet metal on the underside of the ribs with a set of Clecos and then using tension straps and racheting the sheet down in place.  When the sheet metal was in place holes were back drilled and Clecos held the sheet in place. The sheet was later removed, holes were deburred and dimpled and countersunk Avex rivets were installed for final assembly  

The tip of the wing Leading Edge  ends with a raked wing tip bow and tip rib covered with a wrap around fiberglass termination cover that is also attached with Avex rivets. With the Leading and Trailing edges firmly attached the wing no longer twists and is permanently locked into shape.

 

Assembly Details

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 The wing spar brackets on the fuselage must be 30″ on center to agree with the spar attachment points on the wings.  This has to be a precise fit.  Unfortunately my welding experience or lack thereof caused me to not compensate for all the distortion that can happen during a weld and thus I ended up with a fractional difference between the spar brackets.  Fortunately Morgan Williams had an easy solution using a series of thin precision made aluminum plates stacked between the aluminum spars and the steel attach brackets accommodated the measurement difference to thus make a precise fit.  

The Northstar wing like the standard Super Cub wing uses the forward wing strut to carry the aileron cable up to the wing. I wanted the aileron cable concealed and run inside the leading edge zone of the wing.  The lower right photo shows a preliminary rigging set-up of the proposed forward pulley location and it’s necessary alignment of the pulley behind the spar. The carry through hole in the spar had to be kept  small and avoid interfering with the adjacent hard riveted reinforcement plate.

The lower left photo shows the aileron hinge bracket located at the rear wing strut attach point and it’s alignment with the aluminum wing compression strut. Also note that there is an additional steel tube strut providing additional triangulation strength where the wing struts will be attached. The hinge bracket, compression struts and the rear wing strut bracket all come together in a collective assembly of precision made aluminum and steel plates all held firmly together with AN stop nut hardware.