Browsing by Author "Yusuf, Sezsy"

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    Aeroelastic scaling for flexible high aspect ratio wings
    (AIAA, 2019-12-31) Yusuf, Sezsy; Pontillo, Alessandro; Weber, Simone; Hayes, David; Lone, Mudassir
    This paper provides an overview of the work conducted as part of the Cranfield BEAmReduction and Dynamic Scaling (BeaRDS ) programme, which aims to develop a methodologyfor 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 methodologythat adopts scaling laws to allow experimental testing of a conceptual flexible-wing planformas part of the design process. Based on the Buckinghamπtheorem, a set of scaling lawsare determined that enable the relationship between a full-scale and sub-scale model. Thedynamically sub-scaled model is manufactured as a combination of spar, skin, and addedmass representing the stiffness, aerodynamic profile, and aeroelastic behaviour respectively.The spar was manufactured as a cross-sectional shape using Aluminium material, while theskin was manufactured using PolyJet technology. Compromises due to the manufacturingprocess are outlined and lessons learned during the development of the sub-scaled model arehighlighted.
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    Identification of in-flight wingtip folding effects on the roll characteristics of a flexible aircraft
    (MDPI, 2019-05-30) Dussart, Gaétan; Yusuf, Sezsy; Lone, Mudassir
    Wingtip folding is a means by which an aircraft’s wingspan can be extended, allowing designers to take advantage of the associated reduction in induced drag. This type of device can provide other benefits if used in flight, such as flight control and load alleviation. In this paper, the authors present a method to develop reduced order flight dynamic models for in-flight wingtip folding, which are suitable for implementation in real-time pilot-in-the-loop simulations. Aspects such as the impact of wingtip size and folding angle on aircraft roll dynamics are investigated along with failure scenarios using a time domain aeroservoelastic framework and an established system identification method. The process discussed in this paper helps remove the need for direct connection of complex physics based models to engineering flight simulators and the need for tedious programming of large look-up-tables in simulators. Instead, it has been shown that a generic polynomial model for roll aeroderivatives can be used in small roll perturbation conditions to simulate the roll characteristics of an aerodynamic derivative based large transport aircraft equipped with varying fold hinge lines and tip deflections. Moreover, the effects of wing flexibility are also considered.
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    Regressor time-shifting to identify longitudinal stability and control derivatives of the Jetstream 3102
    (Elsevier, 2017-06-20) Yusuf, Sezsy; Lone, Mudassir; Cooke, Alastair; Lawson, Nicholas J.
    The Jetstream 31 G-NFLA aircraft is used as a national flying laboratory test vehicle for flight dynamics research and teaching purposes. It has been the subject of much theoretical and experimental modelling and therefore, the need for generating validation data through flight testing is critical. In this paper, the aircraft's short period pitch oscillation mode characteristics are identified using data from sixteen flight tests. An identification procedure based on the least squares method and reduced order state-space model is used and the need for pre-processing regressors due to the effects of sensor location and instrumentation delays is highlighted. It has been shown that time-shifting the regressors based on relative locations of the angle of attack vanes and the inertial measurement unit results in significant reductions in uncertainty bounds of the estimated aeroderivatives and also a model that provides a closer match to flight test data. The estimated models are validated using separate flight test data and the variations in aeroderivatives over a range of airspeeds and centre of gravity positions are also presented.