Now I knew the timber, the shape and thickness of the tips and the width of the lath at centre and the draw length. Unfortunately no-one knows the important bit- the length overall.
My first attempt was, well, let’s call it a learning experience. Too short and too knotty, it nearly worked and was over 100lb at one point, but the lath failed at a row of pin knots.
My second attempt was slightly longer, from a near perfect wych elm stave. The thickness at the end of the bending section was 11mm as per the drawing and this limited the strength of the bow. I should have got 70lb from it at least but messed things up a little to finish at 50lb. I did answer a few questions, such as how to make the recurve tip and why they were that shape. And a possible length for the stave