DEVELOPMENT AND TEST OF THE BO 105 RIGID ROTOR HELICOPTER

A helicopter layout study made by Bölkow in 1962 resulted in the definition of the twin engined five seater helicopter BO 105 using a four bladed rigid rotor. The specific properties of the fiberglass material (high elasticity, low specific weight, high fatigue strength capability) have been found to be very important to meet the design objectives. Due to a license and cooperation agreement with the French Sud-Aviation Company the three bladed version of the rotor was flight tested on an Alouette II helicopter. The flight test program started in Spring 1966. The handling qualities proved to be excellent, the stresses were well below the permissible and the vibration level was low after the proper tuning of the rotor blades. The BO 105 which is a light utility helicopter uses two different types of engines. The Allison 250-C18 free turbine engine and the MAN 6022 fixed shaft engine. The first flight of the BO 105 took place in Febr. 1967. The handling qualities were as expected. In particular the hovering of the aircraft is simpler than with conventional rotor systems. Static and dynamic stability was satisfactory.