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1 – 10 of 20Abderrahmane Baïri, Bruno Chanetz, Jean Delery and Jean-Denis Parisse
Lutz Taubert, Garrett Kay, Israel Wygnanski and Michael Ol
This paper aims to address shortcomings of current tiltrotor designs, such as the small aspect ratio of the wings, large download and the close proximity of the rotor tips. It…
Abstract
Purpose
This paper aims to address shortcomings of current tiltrotor designs, such as the small aspect ratio of the wings, large download and the close proximity of the rotor tips. It also aims to avoid the complex transition of tiltrotors to normal airplane mode.
Design/methodology/approach
This design combines tiltrotor and tiltwing aircraft designs into a hybrid that is augmented by active flow control, using a gimbaled channel wing for attitude control in hover.
Findings
The proposed hybrid design is based on experimental results of components that were tested individually for potential use in hover and steep ascend from a stationary position.
Originality/value
This research was inspired by the extremely short take-off of the V-22, when its rotors were tilted forward. It combines several design approaches in a unique way to achieve extremely short take-off capabilities combined with high-speed and reduced maintenance costs.
Details
Keywords
Laurène Muller, Michel Libsig, Yannick Bailly and Jean-Claude Roy
This paper aims to propose a dedicated measurement methodology able to simultaneously determine the stability derivative Cmα and the pitch damping coefficient sum Cmq + Cmα in a…
Abstract
Purpose
This paper aims to propose a dedicated measurement methodology able to simultaneously determine the stability derivative Cmα and the pitch damping coefficient sum Cmq + Cmα in a wind tunnel using a single and almost non-intrusive metrological setup called MiRo.
Design/methodology/approach
To assess the MiRo method’s reliability, repeatability and accuracy, the measurements obtained with this technique are compared to other sources like aerodynamic balance measurements, alternative wind tunnel measurements, Ludwieg tube measurements, free-flight measurements and computational fluid dynamics (CFD) simulations. Two different numerical approaches are compared and used to validate the MiRo method. The first numerical method forces the projectile to describe a pure oscillation motion with small amplitude along the pitch axis during a rectilinear flight, whereas the second numerical approach couples the one degrees of freedom simulation motion equations with CFD methods.
Findings
MiRo, a novel and almost non-intrusive technique for dynamic wind tunnel measurements, has been validated by comparison with five other experimental and numerical methodologies. Despite two completely different approaches, both numerical methods give almost identical results and show that the holding system has nearly no impact on the dynamic aerodynamic coefficients. Therefore, it could be assessed that the attitude of MiRo model in the wind tunnel is very close to the free-flight one.
Originality/value
The MiRo method allows studying the attitude of a projectile in a wind tunnel with the least possible impact on the flow around a model.
Details
Keywords
This paper proposes a framework for understanding the concept of a learning organization from a normative perspective. A questionnaire was developed to operationally measure the…
Abstract
This paper proposes a framework for understanding the concept of a learning organization from a normative perspective. A questionnaire was developed to operationally measure the described management practice attributes of a learning organization. Using a sample of four organizations and 612 subjects, support was found for three a priori predictive hypotheses derived from a conceptual framework. Implications of the results and further empirical research are discussed, especially for linking learning organization attributes to performance using larger samples and multiple measures.