Westland Helicopters was a British aircraft manufacturer. Originally Westland Aircraft, the company focused on helicopters after the Second World War. It was amalgamated with several other British firms in 1960 and 1961.In 2000, it merged with Italian helicopter manufacturer Agusta to form AgustaWestland. In 2016, AgustaWestland merged into Leonardo, where it became the company's helicopters division under the Leonardo Helicopters brand.
The research presented in this paper investigates the possibility of precise experimental identification of steady damper characteristics. The paper considers velocity sensitive and nominally symmetric hydraulic dampers. The proposed identification methodology is based on a piecewise constant velocity excitation. One goal of the paper is to analyze the transient nature of the damper response in the context of finite permissible piston displacements and first order transient effects due to elastic elements in the damper structure. The proposed methodology is formalized in a framework suitable for experimental design, allowing the detailed study of steady state damper performance. The second goal of the paper is to demonstrate the practical application of the proposed methodology. It is applied to the case of a safety critical hydraulic damper used for stability augmentation in production helicopters. The research work presented shows that this methodology can be used for identification in a finite but relatively wide range of piston velocities. The case study demonstrates a successful example of damper property identification where the resulting characteristics prove useful as a tool for model validation. Finally, the identification results are related to the results of a more traditional test with harmonic piston excitation.
This paper describes some of the work which is being undertaken within a UK National programme entitled 'Future Optical Network Distribution for Aerospace' (FONDA). As part of the FONDA programme, studies have been undertaken to investigate the impact that optical technology can have on solving the problems faced by the next generation of avionic data network
Two highly efficient fully-coupled methods of predicting the resonant forced response of turbomachinery blades have been developed with the intention of increased computational efficiency over a decoupled method. The flow and structural equations are solved simultaneously, based on the frequency-domain nonlinear harmonic method and the modal reduction technique. By combining the aerodynamic forcing and damping calculations into a single analysis, the coupled solution at a single excitation frequency is approximately half that of the decoupled method. Significant flow–structure coupling effects were discovered, leading to a study into the impact of frequency shift on the fully-coupled solution. A case study on the NASA Rotor 67 transonic aero fan rotor shows a significant reduction in vibration amplitude for the fully-coupled solution due to the resonant frequency shift, caused by the aerodynamic added mass effect. Prompting the development of a novel resonance-tracking algorithm to solve the additional degree-of-freedom in resonant frequency, the increase in computational efficiency in the fully-coupled method is lost due to the need for multiple solutions. A study into the added mass effect and the implications on the coupled solution is undertaken and an evaluation is made between the use of decoupled and fully-coupled forced response systems. It is shown that the decoupled method can accurately predict the resonant vibration level from a single calculation at the natural frequency and is insensitive to frequency shift for lightly damped cases.
