1,720,971 research outputs found
Prediction and simulator verification of state-space rotor modelling on helicopter manoeuvring flight
No full textAmong the many fundamental components of a flight simulator, the mathematical representation of the vehicle dynamics stands out for complexity and importance. This is especially true for helicopters, for which the complex dynamics involved prevents simple models to be sufficiently accurate without the need of a certain amount of artificial tuning. In this work, a methodology to obtain a computationally efficient, finite-state representation of the aeroelastic response of helicopter main rotors suitable for realtime flight simulation is proposed. It is capable of introducing rotor dynamics effects usually neglected in models commonly applied to flight simulations. This rotor model has been implemented in the SIMONA Research Simulator at the Delft University of Technology, and the results obtained from dedicated flight tests carried out by two experienced pilots are presented and discussed.Control and SimulationAerospace Engineerin
Rotorcraft Safety: A Simulator-based Training Perspective
Full text linkTraining has the potential to inject a “safety vaccination” into the rotorcraft community by reducing the number of accidents. The term training should not be intended only in a strict sense, i.e., as pilot technical skills training, but more broadly as risk avoidance and safety culture training. As in the case of vaccination, where immunity is created only when applied on a large scale, helicopter accidents will not be eradicated until every player in the rotorcraft community is involved in the safety enhancement process. In particular, as outlined by accident and safety reports, a reduction in the helicopter accident rate cannot be accomplished disregarding pilots’ training and the contribution that _ight simulators can provide to both training and certi_cation. This paper provides an overview of the research into simulator training for helicopter pilots conducted as part of the European Joint Doctorate NITROS (Network for Innovative Training on Rotorcraft Safety). An approach that requires an in-depth analysis of the actual training task is adopted for two different maneuvers, namely hover and autorotation. This approach enables the training developer to understand what are the aspects of the actual training situation that should be reproduced in the simulated training situation to avoid ineffective training and negative transfer of skills. Moreover, such an approach allows to identify differences in terms of requirements between the training of basic and advanced maneuvers and between initial and recurrent training. The results of three different pilot-in-theloop experiments, performed to explicitly con_rm the effectiveness of developed training programs and to understand whether certain elements of the simulation can foster the development of superior _ying skills, are summarized in this paper.Control & Simulatio
Investigation of the Effects of Autorotative Flare Index Variation on Helicopter Flight Dynamics in Autorotation
Full text linkAutorotation is a flight condition whereby the engine of a helicopter is no longer supplying power to the main rotor system, which is driven solely by the upward flow of the air moving through the rotor. For helicopters, autorotation is a common emergency procedure performed by pilots to safely land the vehicle in the event of a power failure or tail-rotor failure. In the classic analysis of dynamic stability of helicopters in powered flight, it is common practice to neglect the effect of variation of rotor angular velocity, as the rotorspeed is constant. However, this assumption is no longer justified in case of autorotative flight. Therefore, the rotorspeed becomes an additional degree-of-freedom in autorotation, giving rise to a new stability mode that couples with classical rigid-body modes. The present paper aims at understanding the role of the rotorspeed degree-of-freedom in modifying the stability characteristics in autorotation of rotor systems with different autorotative flare indexes. Results show that the helicopter dynamics are considerably affected in autorotation as a consequence of the fact that the rotorspeed degree of freedom couples with the heave subsidence mode. Therefore, autorotation requires a different control strategy by the pilot and should not be mistakenly considered only as an energy management task. Furthermore, the autorotative flare index, used to characterize the autorotative performance during the preliminary design phase of a new helicopter, provides only energy information. Indeed, this paper demonstrates that high values of this index, representative of good autorotative performance in terms of available energy over required energy, may lead to degraded stability characteristics of the helicopter in autorotation.Control & Simulatio
Supplementary material for the paper: The effect of steering-system linearity, simulator motion, and truck driving experience on steering of an articulated tractor-semitrailer combination
No full textSupplementary data that produces all tables and figures in the paper
Shyrokau, B., De Winter, J. C. F., Stroosma, O., Dijksterhuis, C., Loof, J., Van Paassen, M. M., & Happee, R. (2018). The effect of steering-system linearity, simulator motion, and truck driving experience on steering of an articulated tractor-semitrailer combination. Applied Ergonomics
Effectiveness of a Computer-Based Helicopter Trainer for Initial Hover Training
Full text linkToday, simulators are achieving levels of complexity and cost that are comparable to those of the aircraft they should replace. For this reason, questions have been raised, in both the technical and training communities, on the required level of simulation fidelity for effective pilot training. Computer Based Trainers (CBTs) are not currently considered in regulatory standards, because it has not been proven yet whether they can replace or complement actual flight training hours. The aim of this paper is to better understand to what extent the low-level hover skills developed on a CBT are effectively transferred to a more realistic simulation environment. To achieve this goal, a quasi-Transfer-of-Training (qToT) experiment with task-naïve participants was performed in the CyberMotion Simulator (CMS) at the Max Planck Institute for Biological Cybernetics. Twenty-four subjects, divided in two groups, were trained to perform the hover maneuver controlling an identified model of a Robinson R44 civil light helicopter. The first group (the "experimental" group) was trained in a CBT and then transferred to the realistic setting in the CMS. The second group (the "control" group) received the entire training in the CMS. At the end of the experiment, the two groups were found to show comparable performance. This suggests that, even for the training of low-level flying skills, CBTs may be a valid alternative to high fidelity simulators, if supported by a suitable training program
Piloted simulator evaluation of low speed handling qualities of the Flying-V
No full textThe Flying-V novel aircraft design aims at reducing fuel consumption by an innovative low-drag, fuselage-free geometry. However, possible issues related to certification requirements have been noted regarding longitudinal handling qualities at low speed, the pull-up manoeuver, and the flight path angle response. This study aims at investigating these issues by means of piloted simulations. With a mathematical model of the Flying-V based on the vortex lattice method, a preliminary off-line analysis of the handling qualities is conducted. A sensitivity analysis is considered over center of gravity position (forward, nominal, aft), approach speed (between 0.225 and 0.3 Mach), maximum deflection of the control surfaces (between 20 and 30 degrees), and flight control system (Direct Law or Pitch Rate Command). The piloted experiments, supported by the preliminary analytical assessment, show that the handling qualities provided by the current design of the Flying-V with Direct Law at 0.3 Mach are satisfactory with minor improvements related to aircraft responsiveness. For lower speeds (0.225 Mach), the handling qualities degrade due to a sluggish response, high compensation workload, insufficient control authority, insufficient sight angle, and tendency to pilot induced oscillations. Shifting the center of gravity away from the nose provides larger control authority at the expense of a minor reduction of responsiveness. Control augmentation proves very effective at improving the handling qualities. It is expected that the go-around certification standards will be satisfied, but approach speed will remain critical for controllability and safety.Aerospace Engineerin
Assessing the Longitudinal Handling Qualities of the Flying-V by Pilot Evaluation
No full textThe handling qualities of an aircraft are an important aspect in aircraft design, especially for novel configurations. The Flying V is a flying wing passenger aircraft designed to transport about 300 passengers. The handling qualities of such a new configuration aircraft are to be investigated before the aircraft can continue in its design process. The first step is to investigate the longitudinal handling qualities of the Flying V in cruise conditions. The handling qualities are heavily affected by the geometry of the aircraft, which has no tail and has a shorter arm to the elevons for the pitch control. These two main differences do not affect the pitch angle control negatively, which is the focus of conventional handling qualities evaluations, but have a strong effect on the flight path angle. This effect is a non-minimum phase response due to the large change in lift needed to generate the pitching moment. To test this flight path angle behaviour, a new evaluation of the handling qualities is implemented which uses flight path angle tracking.Two control allocations were created: one where both inboard and outboard elevons deflect in the same direction, and one where the change in lift the elevons generate is countered by deploying the inboard and outboard elevons in opposite directions. The longitudinal handling qualities in cruise conditions were investigated by pilot opinion in a moving base simulator. Three experiments were conducted: a traditional pitch experiment, the novel flight path angle experiment, and the latter experiment using the second control allocation. The pilots indicated the pitch attitude control to be Level 1 handling qualities, while the normal control allocation flight path experiment was Level 2. The new control allocation improved the performance of the pilots during the experiment, but the lowered control authority was too much for most pilots to rate it at Level 1.Flying VAerospace Engineerin
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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