Here is a SIMPLIFIED WIND POWER SYSTEMS FOR EXPERIMENTERS by JACK PARK Softcover Book, 2nd edition Published privately by HELION. Contains 80 pages with photographs, tables and mathematical diagrams and charts. Has sections on BASIC DESIGN, AERODYNAMIC DESIGN, STRUCTURAL and MECHANICAL DESIGN, POWER SYSTEMS, Bibliography, WINDMILL DATA, AIRFOIL DATA, HOW TO READ A GRAPH, DETAILED WINDMILL PERFORMANCE and STRENGTH OF CONSTRUCTION MATERIALS. Book is in very good overall condition with some soiling to front and back cover, no rips or tears to pages. last page has a previous owners name and address in light pencil in top upper margin. one statistical cahrt has previous owners own added column in outside box in very tiny faint pencil. please view all pics. I ship within 24hrs of cleared payment. FREE USA SHIPPING.