The H145 Bearingless Main Rotor - Earnings of the H135 heritage

Abstract

The H135 helicopter family is the first serial helicopter with a Bearingless Main Rotor (BMR) after fully articulated and hingeless systems. Since 1996 the fleet of more than 1.300 aircraft has accumulated over 5 million flight hours. In parallel to this success a series of research projects have coalesced to the current status of the next generation BMR which is now the latest improvement for the H145 type to enter the market in 2020. The main rotor system of a helicopter has direct effects on a multitude of characteristics which form a set of requirements posing a sophisticated optimization challenge. In the financial category we have the manufacturing cost, which not only drive sales prices for a new helicopter and spare parts but also contribute to the cost of operation for the customer. Technically/operationally the performance - in absolute values as well as in relation to the fuel consumption -, reliability, comfort of ride, compact blade folding and maintainability play an important role. Finally, regulatory rules regarding safety and noise are an indispensable base layer. Solutions acquired encompass several new design solutions: the modular concept by separating the integrated blade of the H135 from the flexbeam/control cuff, a modified attachment area with a reduced flapping hinge offset and a new blade attachment design with bearing laminate. On the manufacturing side the introduction of Liquid Resin Infusion (LRI) technologies for cuff and blade helps to reduce cost while in the aeromechanic field a 5-bladed rotor layout with an advanced, optimized aerodynamic blade improves comfort of ride and performances. Flight tests have confirmed the expectations of a rotor system with low complexity, well balanced performances and excellent comfort of ride. The gains materialize in form of reduced cost, low weight and diminished maintenance effort and expenses. Due to this combination of benefits and the achieved maturity the H145 will profit from implementation of this next generation BMR.