I'm in the process of rebuilding some PA11 wings. A local cub builder suggested I use formed aluminum tubing for the wing tip instead of the wooden wing tip bow that piper used, he says it's much more rigid. Is this a modification anyone else has done?
Thanks
Dan
What are you using to glue the wood to the steel fittings?Me neither. First, the ash bow is shaped. Second, ash bends on impact; aluminum stays bent. Third, ash absorbs shock better when you hit that fencepost or the hangar door. Fourth, it is probably lighter.
I no longer drill holes for the spar attach fitting screws. I glue the bow, then wrap it with fabric around the fittings. Seems to stay there, and they don't break at the spars.
I have had no issue with broken tip bows at the spar but I don't use nitrate/butyrate dope that continues shrinking over the life of the fabric, pulling the tip bow in my flate spots between each attach point. I have a simple plywood fixture to shape the bow in, good epoxy varnish and install just like Piper did however the PA11 probably only had braces between the front and rear spars. Later model Pipers used 4, 2 to the top spar cap and 2 to the bottom spar caps. Keeps the tip bow from twisting up over the years. Got into that on J3 and PA16 wings I have rebuild.
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The tips are preformed when made but get straightened out for shipment. I bought a gross from the original makers and paid to have them motor freighted. They came in a fixture that holds them in the proper shape. When I was buying them from Univair I would soak them in a kiddie pool and put them in a fixture I made to put the shape back into them.Do you treat the bow in some way ( steam or soak in hot water) before you put it in your plywood fixture?