Rowell has performed every job in the prop-making process. He spent 10 years hand-carving more than 10,000 rough-cut hardwood blanks into perfectly balanced, laminated-wood props. In 1994 ...

They needed to have some very large propellers built for wind tunnel testing ... and then the excess wood is removed with pneumatic planes designed and developed by [NACA] to constantly blow ...

The propeller blades were typically made of laminated wood and the impacts, despite being deflected away by the steel deflectors, would cause the glue to weaken and the layers to separate.