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Optical fibre strain and shape measurement sensors were deployed on a 5-m long rotor blade during a full-speed (rotation rate 6.6 Hz) helicopter ground run, with real-time data wirelessly streamed from rotor hub-mounted sensor interrogators. In part 1 of a 2-part paper series, the strain sensing capabilities of the two optical fibre-based sensing techniques, optical fibre Bragg grating (FBG) and fibre segment interferometry (FSI), are compared, while Part 2 [1] specifically investigates the blade shape measurement based on the FSI approach. In part 1, the rotor hub-mounted instrumentation is described, and data on the dynamics of the blade obtained from a sequence of controlled pilot inputs are analysed both in the time and spectral domains. It is shown that this can provide insights into the√ aeroelastic properties of the blade. Noise standard deviations of 0.2 n√ ε/ Hz and 30 nε/ Hz for the FSI and FBG-based sensing approaches, respectively, were observed over a strain range of 3500 µε.

The use of a new aeroelastic computer framework called Flexit is described and the framework is used to analyse the dynamic aeroelastic behaviour of a four-bladed helicopter main rotor. Flexit implements a loose coupling between unsteady vortex lattice method (UVLM) and numerical solution of the inhomogeneous Euler-Bernoulli partial differential equation (PDE). The framework is fast because most of the intensive computational functionality is performed on GPU using NVIDIA CUDA technology, and this makes it suitable for use in the early design stages. The UVLM algorithm uses a free wake model, and solution of the Euler-Bernoulli PDE is approximated using a finite difference algorithm that includes a term to take account of centrifugal forces. The results of simulations are compared with analysis performed with CFD and FSI tools.

This paper provides an overview of the work conducted as part of the Cranfield BEAm Reduction and Dynamic Scaling (B R D S) programme, which aims to develop a methodology for designing, manufacturing and testing of a dynamically scaled High Aspect Ratio (HAR) Wing inside Cranfield 8'x6' wind tunnel. The aim of this paper is to develop a methodology that adopts scaling laws to allow experimental testing of a conceptual flexible-wing planform as part of the design process. Based on the Buckingham π theorem, a set of scaling laws are determined that enable the relationship between a full-scale and sub-scale model. The dynamically sub-scaled model is manufactured as a combination of spar, skin, and added mass representing the stiffness, aerodynamic profile, and aeroelastic behaviour respectively. The spar was manufactured as a cross-sectional shape using Aluminium material, while the skin was manufactured using PolyJet technology. Compromises due to the manufacturing process are outlined and lessons learned during the development of the sub-scaled model are highlighted.