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Takeoff and landing
Published in Mohammad H. Sadraey, Aircraft Performance, 2017
So far, we have assumed that ground speed and airspeed are equal. In reality, this assumption is unrealistic and usually there is wind. Wind strongly affects takeoff and landing performance (i.e., distance). In general, headwind will reduce takeoff and landing distances (including ground roll). Conversely, tailwind will increase takeoff and landing distances (including ground roll).
Autonomous tracking and landing of an unmanned aerial vehicle on a ground vehicle in rough terrain
Published in Advanced Robotics, 2023
The simulations depicted in this subsection were conducted to evaluate the performance of our autonomous landing system, including the state machine (Section 2). In this study, we define the landing performance as the success rate of landing, landing error, and time elapsed for approaching and landing on the UGV. The example movies of the UAV landing simulations are shown in the link1.1 Figures 8 and 9 show example trajectories of the UAV and UGV, along with the estimated UGV position. These simulations validate the relative pose estimator, as well as the results obtained in the last subsection. Figure 8(c) depicts the UAV state transitioning between Track and Land, which occur if the UAV failed to keep its relative position and velocity within the thresholds, as discussed in Section 2.
Operational availability analysis of short-haul electric aeroplane using polynomial chaos expansion
Published in Transportmetrica B: Transport Dynamics, 2022
Mingkai Wang, Shuguang Zhang, Dalong Shi, Florian Holzapfel
In this context, the paper is focused on the operational availability of electric aeroplane in a certain area. The aim is to optimise the aircraft fleet for the intended operation area or to be integrated into aircraft design in an early stage. As such, operational availability of one route is specifically defined as the ratio of feasible flights in the selected time period. The index is beneficial to aircraft scheduling and policymaking, especially for electric aircraft with limited historical data. Researchers have been investigating techniques to predict operational availability (Wei and Hansen 2005; Cui et al. 2017; Wandelt, Sun, and Zhang 2019). Some studies highlight the take-off and landing phase in operational availability analysis. For instance, Sun, Wandelt, and Stumpf (2018) propose an estimation framework for electric aircraft arrival time. The method is applied to analysing the competitiveness and operational availability of urban air mobility in Europe. Kleinbekman, Mitici, and Peng (2019) employ a rolling-horizon-based algorithm to explore the electric aircraft landing sequence. Specifically, the aircraft motion and battery model are taken into account, which yields more precise estimation of landing performance. Wu and Zhang (2020) investigate the influence of battery charging time on operational availability.
The biomechanical effect of warm-up stretching strategies on landing mechanics in female volleyball athletes
Published in Sports Biomechanics, 2020
Jason M. Avedesian, Lawrence W. Judge, Henry Wang, D. Clark Dickin
Data were processed in Visual 3D (Version 6, C-Motion, Inc., Germantown, MD, USA) to quantify lower extremity landing kinematics. The independent variables in this study were warm-up, limb and time. The dependent variables of interest were hip and knee flexion angle at initial ground contact, along with maximum values of the following variables during the landing phase (defined as initial limb contact until peak knee flexion): hip and knee flexion, hip adduction and internal rotation, and knee abduction and external/internal rotation. All variables were reported in degrees. These variables were analysed due to their associated injury risk in female athletes performing landing manoeuvres (Quatman & Hewett, 2009; Swartz, Decoster, Russell, & Croce, 2005). Marker trajectory data were smoothed with a fourth-order Butterworth low pass- filter at 8 Hz (Brown, Wang, Dickin, & Weiss, 2014). Kinematic data were analysed as the average of five landing trials at each of the three time points for the dominant and non-dominant limbs. Prior research on landing performance has deemed an average of at least four trials to be sufficient for landing performance stability (ICC > 0.75; James, Herman, Dufek, & Bates, 2007).