OPTImised Model for Accurately measured in-flight Loads

In recent years, Counter Rotating Open Rotors (CROR) have received considerable attention as the CROR concept promises a considerable reduction of fuel consumption over conventional ducted turbofan engines. Specifically, for Smart Fixed Wing Aircraft, CROR is expected to contribute to 20% fuel burn reduction. Despite this potential CROR engines are associated with higher noise and vibration levels and their installation pauses a challenge for the adaptation in future aircraft models. The main objective of OPTIMAL proposal was to provide a technical solution to accurately measure all the loads encountered by a pylon which supports a Counter Rotating Open Rotor (CROR) engine in flight. The work entailed the development of a methodology that enabled the assessment of flight loads on to the pylon and fuselage based on local sensor measurements. This methodology was based on an inverse Finite Element Analysis (FEA) approach where the loads at the boundaries i.e pylon-fuselage attachment can be assessed with increased accuracy and fidelity.

FEA analysis was supported by accurate strain, temperature and acceleration measurements by an appropriate sensor network. Traditional sensors such as strain gauges and accelerometers as well as optical fibre sensors Bragg Gratings were investigated and analysed. The two proposed sensor networks systems were operating side by side in an effort to evaluate optical system performance and eventual feasibility for the pylon monitoring application. To this end the proposers brought in their background knowledge and no further development of the optical measuring system is foreseen.

The proposed approach was validated by structural testing of a scaled pylon mock-up, which was be representative of the real structure. Based on the results of these investigations, a true scale measurement system configuration was proposed that should meet Flight Worthiness specifications of the future flying test bed.