Original Posted By: John E Fay
Subject: Re: Pietenpol-List: Piet Airfoil: Ply cover
Re: Pietenpol-List: Piet Airfoil: Ply cover
Re: Pietenpol-List: Piet Airfoil: Ply cover
Original Posted By: fishin
John in Peoria,In the early 1970's my friend used 1 mm Finish birch on his Pietenpolwing leading edge and we had to remove it because it developed waviness with increased humidity. Fortunately this took place beforecovering with fabric. We substituted 2024T3 aluminum (.016", I thinkit was) with good results.I used 1/16" mahogany ply on my Pietenpol leading edges without anyproblems and made a 1/2" scallop on the aft edge between ribs. If Iwere to do it again, I would stay with the 1/16" mahogany and use a "false rib" between regular ribs to eliminate the scallop. The false ribneed not be a truss; a properly shaped upper capstrip extending to justaft of the front spar would be fine. While smooth, my ply L.E. cover al-lows the airfoil thickness to reduce between ribs, making for a thinnersection overall. False ribs would correct this.If you use the 1/32" birch plywood, glue it in place while wet so that itwill remain smooth and taut in a high humidity environment. I understandT-88 will work with wet wood, but have only used it dry. (We didn't haveT-88 when my friend glued his ply in place during our dry winter weather.)Cheers, Graham________________________________________________________________________________Date: Wed, 17 Nov 1999 22:02:03 -0600
John in Peoria,In the early 1970's my friend used 1 mm Finish birch on his Pietenpolwing leading edge and we had to remove it because it developed waviness with increased humidity. Fortunately this took place beforecovering with fabric. We substituted 2024T3 aluminum (.016", I thinkit was) with good results.I used 1/16" mahogany ply on my Pietenpol leading edges without anyproblems and made a 1/2" scallop on the aft edge between ribs. If Iwere to do it again, I would stay with the 1/16" mahogany and use a "false rib" between regular ribs to eliminate the scallop. The false ribneed not be a truss; a properly shaped upper capstrip extending to justaft of the front spar would be fine. While smooth, my ply L.E. cover al-lows the airfoil thickness to reduce between ribs, making for a thinnersection overall. False ribs would correct this.If you use the 1/32" birch plywood, glue it in place while wet so that itwill remain smooth and taut in a high humidity environment. I understandT-88 will work with wet wood, but have only used it dry. (We didn't haveT-88 when my friend glued his ply in place during our dry winter weather.)Cheers, Graham________________________________________________________________________________Date: Wed, 17 Nov 1999 22:02:03 -0600