This report presents the conceptual design of the EverWing, an ultra-low-impact, 150-passenger commercial aircraft of which all parts, except the powertrain, can be remanufactured or recycled into comparable parts for a similar aircraft for entry into service in 2050.
A blended wing body configuration was chosen for its improved aerodynamic and volumetric efficiency with respect to other configurations. As a result of subsystem analyses, the aircraft features a 35.5-meter wingspan, cruise speed of Mach 0.80 at an altitude of 12.2 km, and a lift-to-drag ratio of 18.2 during cruise. Furthermore, EverWing is propelled through four ducted fans powered by liquid-hydrogen fuel cells and electric motors.
To ensure recyclability, the structure utilises CFR-PEEK and Al-Li alloys, enabling disassembly at end-of-life. Life-cycle assessment shows the end-of-life recovery avoids 394 tons of CO2-equivalent emissions and that EverWing offers a 87% reduction with respect to the A320neo throughout its whole lifetime, plus a 100% reduction in CO2 and NOx during operations. The design achieves a direct operating cost of 0.030 EUR per seat-kilometer and a 40.3% return on investment at an expected market price of 105 million EUR.
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Due to climate change and rising sea levels, a sustainable formof airborne cargo transport is needed for quick disaster response in rough sea conditions. ... Read more

The condition of Spatial Disorientation (SD) is thought to be a main contributor to aviation mishaps and accidents in the aviation industry. This study examined the cognitive effects of SD among general aviation (GA) pilots in a realistic flight environment using an operationally relevant secondary task. GA pilots (n = 34) flew four scenarios in a Pilatus PC-7 flight model, simulated using a hexapod motion platform and virtual reality visuals. During each scenario, participants experienced both regular and disorienting flying conditions. The four SD events were "false horizon", "featureless terrain", "the leans", and a novel "scattered clouds" event. Cognitive performance was measured through a secondary checklist task's completion times and error rates. The findings show that completion times, error rates, as well as heading deviations increased significantly under SD compared with baseline conditions, particularly for "the leans" and "scattered clouds". Subjective ratings indicated that participants were aware of SD cues, that they perceived increased aviating focus and SD intensity, and that scenarios provided high SD awareness training value, particularly when the secondary task was included. Overall, SD impairment on cognitive and control performance is highlighted through an operationally relevant secondary task, with implications for designing simulator-based training to raise awareness of SD effects. ... Read more

This study explores the application of cognitive work analysis (CWA) and ecological interface design (EID) in the development of a novel display system for a Dash 8 Q300 aircraft retrofitted with a hydrogen-electric fuel system. By leveraging CWA and EID, this research aimed to address the challenges of managing cognitive complexity in next-generation aviation systems, focusing on designing interfaces that enhance pilot decision-making and situational awareness. These analytical frameworks informed the design process, ensuring that the displays were tailored to the cognitive demands of the pilots. To validate the effectiveness of the proposed designs, interviews were conducted with a regional commercial pilot, an airworthiness engineer, and a test pilot. These interviews provided qualitative insights that confirmed the applicability of the CWA/EID-based designs, particularly emphasizing the need for simplicity and clarity in time-constrained regional operations. The study highlights the importance of focusing display content on critical and abnormal conditions to reduce cognitive load, aligning with rule-based behavior (RBB) frequently employed by pilots. Future work should involve controlled human-in-the-loop experiments with a larger participant pool to empirically test the proposed display designs. ... Read more

This thesis presents the development process of an aircraft control law. The control law is designed using a two-degree-of-freedom (2DoF) structured H∞ loop-shaping approach. This method allows the reuse of controller structures required by certification procedures while
directly including handling qualities and robust stability requirements in the optimization process. This strategy is employed to develop a Rate Command and Attitude Hold (RCAH) demand system aimed at satisfying longitudinal handling qualities. First, the stability of the
open-loop model and its compliance with the handling qualities guidelines are evaluated. Then, the control law is designed. In this step, a detailed description of the design specifications and how to specify them in the context of H∞ control is given. Subsequently, the controller parameters are optimized to satisfy the design specifications and a closed-loop analysis is performed. Finally, a simulator flight testing campaign is conducted to experimentally validate the designed control law. It is shown that the aircraft equipped with the RCAH system achieves better handling quality ratings (HQRs) and more favorable pilot feedback, providing a substantial improvement over the bare airframe. ... Read more

Recurrent training is crucial to helping pilots maintain or upgrade their flying skills. However, constantly monitoring and scrutinising pilots during training can lead to performance pressure. If pilots who are under pressure feel that their behaviour is affected it may ultimately reduce the effectiveness of recurrent training. To study the effects of performance pressure on pilot behaviour and learning, pilots (n=17) holding an airline transport pilot licence and type rating for large multi engine aircraft were invited to participate in a simulator experiment where they would learn a new autopilot system. The low-pressure group flew a series of training scenarios under no performance pressure whereas the high-pressure group flew the same training scenarios with prompts designed to induce performance pressure and raise their anxiety. It was hypothesised that the high-pressure group would be less incentivised to explore different functions of the autopilot due to the performance pressure, therefore leading to a lower quality of training which would be reflected in poorer knowledge of the autopilot system. Ultimately, whilst the high-pressure group did in fact undergo training with a significantly higher state anxiety. This was found to have no significant effect on their behaviour during training or their performance in a test scenario. The findings also suggest that the experiment would benefit from being repeated with more guidance given during training and more constrained scenarios to reduce the variation in the data. ... Read more

Roll reversal errors, where the pilot tries to steer the aircraft back to wings-level but unintentionally increases the bank angle instead, have contributed to several accidents. Previous studies have shown that these errors can be caused by misinterpreting the attitude indicator (AI), with the figure-ground relations cited as contributing to this misinterpretation. A modified AI was developed, which uses several static monocular depth cues (color gradient, linear perspective lines, and shadow-light relationship) to strengthen the figure-ground relationship.
The modified version of the AI was compared to a baseline AI in a two-part flight simulator experiment where pilot reaction time and error rate, severity, and duration were measured. The first part induced the leans illusion making use of physiological adaptation to roll angle, distraction, and surprise. The second part simulated the leans illusion by simply rolling the simulator to the left or right. A group of 25 experienced commercial airline pilots performed a roll-to-level task in a moving-base simulator, which also provided spatially disorienting motion cues, using both the baseline and modified versions of the AI. While the modified
display had a lower error rate in the motion-opposite scenario when using the novel method (4.91% compared to 6.07%), no significant difference was found between the error rate of the two displays. The only significant difference was found in the reaction time, where the modified AI caused an increase in reaction time. The error rates and reaction times of the first part of the experiment did not match previous research. The novel disorientation method seemed to work best in a surprise scenario. While no significant differences were found between the modified AI and the baseline AI, it is still recommended to continue testing the modified AI with a new experiment setup, especially analyzing its effect in more extreme attitudes. ... Read more

Research into analysing the feasibility of using VR headsets to train helicopter pilots is in its infancy. While enough is known about what effects VR headsets have on pilots, a research gap exists in the field of explaining what exactly causes these effects to occur. This thesis aims to develop a visual model that can be used to analytically predict how pilot behaviour will be affected by a changing Field-of-View and explain why these changes occur. The scope of this model is analysing where in the pilot’s vision, the point of most feedback lies, and what happens when this point gets clipped out of view while the pilot controls a two degree-of-freedom helicopter model. Subsequently, human-in-the-loop experiments were carried out where the participants had to do velocity disturbance rejection tasks and pitch disturbance rejection tasks for various fields-of-view, to try and validate the model. It was predicted that the performance for the pitch disturbance rejection task would not be affected by the field-of-view but the performance for the velocity disturbance rejection task would degrade as field-of-view was lowered. Overall, there was no significant trend that emerged from the experiments for either task, but significant insights were gained into the scope of the visual model. Based on these, and other findings, the model did a good job in identifying why performance changes and in setting up future researchers for success in this field. ... Read more

The Flying-V is an innovative aircraft design developed by Delft University of Technology. Its unique configuration positions passengers laterally farther away from the centre of rotation compared to conventional aircraft. In light of this unique structure, a passenger-in-the-simulator experiment was conducted using the SIMONA Research Simulator to examine to what extent the severity of motion sickness increases with greater lateral distance from the centre of rotation.

The experiment was conducted using the Time to Bank manoeuvre. Due to the rolling acceleration, as the lateral distance of the seating position from the centre of rotation increases, passengers experience a higher magnitude of heave motion in addition to the roll motion. The participants were exposed to three different lateral seating positions, including sitting at the centre of rotation, sitting laterally offset at 3.5 m, and sitting laterally offset at 7 m.

Motion sickness was predicted using the 6 Degrees of Freedom–Subjective Vertical Conflict model, which provides the Motion Sickness Incidence. According to the model’s prediction, an increase in the level of heave motion is expected to lead to a higher level of motion sickness severity for passengers. During the experiment, participants’ motion sickness severity was assessed using the MIsery SCale (MISC).

Although no statistically significant differences were observed among the conditions, sitting laterally offset at 7 m had a higher mean of the participants’ maximum MISC score of 3 than sitting laterally offset at 3.5 m, with a mean of 2.4. However, neither of these conditions showed higher scores than sitting at the centre of rotation, with a mean maximum MISC score of 3.6. Therefore, the results suggest that sitting laterally farther away from the centre of rotation in the Flying-V did not lead to increased motion sickness severity. ... Read more

This study investigated the effect of manual and autopilot control on hazard and failure detection in aviation, in cases where the autopilot can masks or diminishes cues of aircraft movement. This mechanism could result in loss of situation awareness, upsets and ultimately accidents. Twenty airline pilots participated in an experiment in which two scenarios, an engine failure and icing accumulation hazard, were flown in both manual and autopilot control conditions. Results show no significant difference in detection time for the engine failure scenario between the two modes, but a marginally significant difference in the icing accumulation scenario and a clear difference in the way pilots detected the failure/hazard. Manual control may provide clearer cues, but automation may lower workload and allow for better monitoring. Monitoring of the flight controls was found to be an important factor in hazard detection, with pilots who had their hands resting on the controls having significantly lower detection times. The study provides insights on the importance of active monitoring of flight controls and on the impact of non-backdriven controls. The findings suggest that understanding the advantages and disadvantages of autopilot use is crucial for training pilots effectively. ... Read more

As the Flying-V goes through subsequent design iterations, each new model requires dedicated handling qualities research. A part of that work, namely obtaining the handling qualities predictions, is highly repetitive and can be automated. To address that issue, a Python library for automated handling qualities prediction evaluations of the Flying-V was developed. The library's functionalities cover model implementation, trim and linearization, model reductions, identification of the modal parameters, and finally, the evaluation of the requirements. The library takes a semi 'black-box' approach toward the model structure, relying on defining it through a set of functions instead of parameters. With that, it can accommodate various sources and formulations of the model. The library was successfully validated on two different aircraft models. Part of the validation was replicating some of the previous Flying-V handling qualities research data. It is expected that the use of the library will bring time savings to future handling qualities research of the Flying-V, as well as reduce the risk of mistakes in the process. ... Read more

Spatial disorientation (SD) is one of the main causes of incidents and accidents in aviation. While most studies have investigated the effect of SD on the control task, we tested the effect of SD on cognitive performance in an operationally representative environment.
Thirteen Dutch military helicopter pilots flew scenarios with six different SD events using an AH-64 Apache flight model in virtual reality in a 6-DoF motion simulator. The SD events used were: “False Horizon”, “Featureless Terrain”, “the Leans”, “Brownout”, “Somatogyral Illusion” and “Night Vision Goggles (NVGs)”. Corresponding scenarios without the SD events were performed to obtain baseline measures of cognitive performance. When performing the scenarios, participants had either the role of pilot flying or pilot monitoring.
To test the cognitive performance, participants performed a mathematical processing task. The corrected reaction time and error rate were significantly higher during the SD events than during the baseline events.
These effects were most prominent in the “Featureless Terrain” and “the Leans” scenarios. The results indicate that SD has a negative impact on the cognitive performance of military helicopter pilots. These findings underline the importance of SD awareness training for pilots, as well as the use of workload management procedures when experiencing SD. ... Read more

When placing a Head-Mounted Display (HMD) of a Virtual Reality (VR) or Augmented Reality (AR) system in the cabin of a moving base simulator to provide a larger field-of-regard, the HMD's inertial sensors will interpret the motion of the moving base simulator as if provided by the user, thus distorting the HMD's cabin-fixed pose estimation.
In order to estimate a proper cabin-fixed HMD pose, this thesis proposes an Unscented Kalman Filter (UKF) that fuses the information from the simulator sensors, as well as the sensors of the VR/AR system, including its visual position sensor and IMU. For this, three sensor configurations are proposed and tested offline deterministically based on real data. Although an unexpected latency in the HMD's visual pose sensor prevented a full validation of the algorithms, both the configuration with an IMU attached to the motion base, and the configuration without an IMU but with second-order additive noise variables added to the UKF, resulted in a proper, tight innovation sequence, indicating accurate system state estimation. The third configuration, one using the novel approach of using setpoints, provided a tight, but out-of-bounds, innovation sequence indicative of high accuracy, but also diminished tuning efficacy. It is also sensitive to stability issues when estimating the motion system's dynamics when no movement is present on the moving base. The unaltered setpoint method is not recommended as a solution. However, a hybrid solution of the setpoint and second-order additive noise variables methods should be investigated in a follow-up study to combine stability with high accuracy. Another recommendation is to test all configurations interactively, i.e. online. ... Read more

Today, most fatal accidents in commercial aviation are caused by loss of control in flight. Due to the increased reliance on automation and pilots being moved out of the loop, startling and surprising events can be contributing factors. To more effectively train pilots, startle and surprise are to be included in training scenario’s. A subjective scale indicating the level of startle and surprise is being developed to help build these training programs, but an objective baseline of whether pilots are startled or surprised is needed in order to validate and further develop this scale. In this way, the scale can be used in flight simulators to asses the pilot’s perceived level of startle and surprise during novel training scenario’s. This work aims to test a startle and surprise detection method using physiological data. Electromyography, electrocardiography and electroencephalography data were collected. A validation of the occurrence of physiological effects related to both startle and surprise was performed, after which a detection algorithm was constructed. Validation of effects was performed on data of 22 participants using a three-stimulus oddball task with additional auditory startling stimuli. It was found that all considered physiological effects related to startle can be reliably observed. Contrary, not all physiological effects related to surprise were observed. The detection algorithm was tuned on data of twelve participants and showed to generalise well to the other ten data points. Startle detection could be performed with high accuracy, although surprise detection was poor. ... Read more

In current spatial orientation models, vertical acceleration (heave) is not coupled with pilot pitch perception, although such a coupling may be present. Therefore, in this study it is investigated whether a heave cue can increase perceived pitch in pilots.

Airline pilots (n = 20) performed a pitch perception task in a hexapod simulator. A level change maneuver, with the simulator cabin pitching up and back down, was presented with different maximum pitch angles. After the maneuver, pilots indicated the maximum perceived pitch angle. This motion was presented either with or without a brief (1.25s or 1.5s) heave cue, that was timed to the onset of the pitch motion. Two timings and magnitudes of the heave cue were used to investigate these factors.

The results indicate that the heave cue significantly increased pilot pitch perception by 1.88°, p < 0.001. The maximum pitch angle was 2.69° underestimated without heave and 1.42° underestimated with heave. A higher heave magnitude, relative to a lower, resulted in a significantly larger estimation of the pitch angle, δ = 0.47°, p = 0.009. Earlier timing of the heave cue resulted in marginally significantly higher pitch perception than later timing, δ = 0.43°, p = 0.069. Interestingly, if heave was presented without pitch motion, pilots still estimated 2.66° pitch on average.

The results suggest that heave cueing increases perceived pitch in pilots, even when the heave cues are shorter in duration than cues that would be present in the actual maneuver in flight. Heave cues timed to the onset of pitch motions can thus possibly be used to enhance pilot pitch perception in hexapod simulators. ... Read more

The 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. ... Read more

Flying wings are known for their limited lateral-directional stability and handling qualities. This study aims at assessing the lateral-directional handling qualities of a conceptual flying wing aircraft currently in development at TU Delft, the Flying-V. It focuses on two aspects: First assess the lateral-directional handling qualities of the bare-airframe Flying-V, and the compliance to quantitative requirements. Second, improve these handling qualities through a prototype flight control system, and assess its effect on the handling qualities and the requirement compliance. These assessments were performed both analytically and with a pilot-in-the-loop experiment, in order to experimentally validate analytical findings and obtain new pilot-subjective insights. The analytical and experimental assessment both show the lateral-directional handling qualities of the Flying-V to be insufficient for requirement compliance, due to a lack of pitch, roll and yaw control authority in low-speed flight conditions and an insufficiently stable Dutch Roll eigenmode. The prototype flight control system, consisting of an adapted control allocation and a stability augmentation system, showed both analytically as experimentally to improve the control authority, stability, and handling qualities of the Flying-V. While the effect on the lateral-directional stability was sufficient for stability requirement compliance, the control authority was not sufficiently increased for manoeuvrability requirement compliance. Thus, a challenge remains to improve the handling qualities of the Flying-V. An approximation of the control authority required for full requirement compliance in the flight conditions tested showed a control authority increase of over a factor four to be required for future control surface design. ... Read more

It has been shown that expert gaze behavior can be used to enhance training for novices, among others in the field of laparoscopic surgery. The research in this paper focused on the effect of changing pilot gaze behavior on flight performance and detection task performance. Two groups of novices were shown a recording of expert behavior, including an indicator of the expert's gaze. The actively trained group was additionally shown a gaze director during training, to suppress the field of view outside of a set gaze point. Said gaze point moved around in a basic scanning sequence, encouraging this scanning pattern in the participants. Both groups were then evaluated on flight and detection performance in a segment of straight level flight, during which objects around the aircraft had to be detected. The \ga showed a larger change in gaze behavior between the before and after training tests, accompanied by a reduction in flight performance. Detection task performance was comparable for both groups. The gaze director thus seemed to distract participants from the tasks. One suggestion for future improvement is to focus on tuning the gaze director's timing using questionnaires. Alternatively, further research could focus more on the passive exposure of novices to expert gaze behavior, and compare this to a control group. ... Read more

The interest in developing electric vertical takeoff and landing (eVTOL) vehicles has increased sharply in recent years. A concern for passenger acceptance of the new type of vehicle is that people may experience motion sickness. This is because eVTOL flight profiles are different from the motion conditions that people have previously experienced. The aim of this study was to predict the incidence of motion sickness amongst eVTOL passengers. To achieve this, a two degrees of freedom (2DOF) lateral theoretical motion sickness model was developed, with lateral acceleration and roll rate as inputs. The model parameters were tuned with data collected from flight simulator experiments performed in the SIMONA Research Simulator at the TU Delft. The participants (N=20) completed five trials, each time being exposed to one of five flight profiles: four eVTOL profiles (1—nominal condition, 2—high turbulence, 3—alternative control law, 4—seats turned 180°; t=24 min) and one helicopter profile (5—helicopter, t=31 min). Motion sickness severity in participants was measured using verbal ratings on the MIsery SCale (MISC). A significant difference was found between the MISC data for Profiles 1 and 2, showing that turbulence worsens motion sickness severity for passengers. No significant difference was found between Profiles 1 and 3 and between Profiles 1 and 4. The difference between the data from Profiles 1 and 5 was found to be statistically significant. However, given the discrepancy in how the two profiles were generated, further studies are needed to conclude whether flying in a helicopter in general induces more motion sickness than flying in an eVTOL. The 2DOF model was extended to 3DOF by adding vertical acceleration as input. After tuning both models with experimental data (mean MISC scores per participant), it was concluded that the 3DOF motion sickness predictions followed the trend of the measurements better than the ones of the 2DOF model. The developed models can be used for eVTOL design optimisation. To further improve the accuracy of the predictions, the 3DOF model will be extended to 6DOF in future studies. ... Read more