Deploying the Flaps

flap drawing

The Wag Aero wing plans use spoilers instead of flaps.  The spoilers have almost no similarity to flaps. They are very small panels above and below the wing that you deploy upward and downward by pulling a “T” handle just before you flare to land.  They are designed to kill the lift of the wing. The Northstar wing kit on the other hand has massive Fowler-like flaps.  I decided to use a lever to deploy the flaps manually using a standard Johnson bar flap handle located between the seats. The challenge was how to rout the cables and pulleys from the underside of the belly and back up to the ceiling of the cabin. I bought a used Johnson bar from an old parted out Piper and designed a mount and ratcheting system for the bar to attach.  The first set of 3 inch pulleys were welded offset to the centerline of the fuse to avoid competing with the push-pull tube that operates the elevator.  I made the cables turn at a right angle behind the baggage panel to keep the turtle deck opening clear and useable. Bringing the cables up and along the side of the fuse allowed for a solid and secure location for a welded pivot point for the bell crank to attach. The Johnson bar had a welded horn centered on the lower bar and the horn had two holes for cable shackles which led me to design a twin cable system all the way to both ends of the bell crank. The theory in my mind was that one of the two cables would always be pulling when raising or lowering the flaps.  It was not until I was attaching the wings during the aircraft’s final assembly that I discovered that the travel movement of the bell crank was not sufficient to operate the flap operating range of the wings. To correct this I used only one cable that attaches directly to the cables from both wings and removed the fuse bell crank location entirely.  The flaps have a very strong return spring on the rear spar that assure flap retraction as soon as the flap handle is lowered.

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