by Martin Hollmann
Book on how to design and build propellers and ducts using a PC.
This book tells you the theory of propeller aerodynamics and how to size a propeller. The program allows you to optimize a propeller for a given horsepower and airspeed. Such variables as number of blades, blade pitch, blade airfoil, blade thickness and planform shape and air density are variables. Thrust coefficient, power coefficient, prop efficiency versus advance ratio and airspeed and power and thrust versus airspeed are plotted on the screen. Airfoil section data for such airfoils as the Clark Y are presented and a prop airfoil section plot program called Prop Plot is given. This program allows you plot the full size airfoil section for any chord and thickness. It also calculates blade cross section area and section moment of inertia for the stress analysis. A Prop Thickness program allows you to calculate prop thickness for every blade station. A Prop Loads program is presented which allows you to determine the blade bending moments and centrifugal force at 10 blade stations. This program uses a finite difference method which accounts for blade stiffness, airload and centrifugal force. Finally, to complete the blade design process, properties of materials for woods and metals and composites are given and a stress check is made at every blade station. The criteria of FAR Part 35 is used. Also, how to determine natural prop frequencies for different prop speeds. The last section of the book deals with duct theory and tells you how and when to use a duct. Simple calculations for the performance of a ducted propeller are given.
This book is a necessity for anyone who not only wants to design a propeller but who wants to determine the best performance he can get from a prop airplane with an optimized propeller design. Computer disc for PC sold separately for $99.00