Browse Topic: Entry, descent, and landing
A high-fidelity computational study is conducted to investigate the aerodynamic behavior and flight response of an electric Vertical Take-Off and Landing (eVTOL) multirotor configuration using unsteady computational fluid dynamics (CFD) framework. Four simulation cases are considered to examine the vehicle aerodynamics under both prescribed and fully coupled conditions. Prescribed hover and forward-flight cases isolate rotor aerodynamics and rotor-airframe interactions under constrained kinematics. Six-degree-of-freedom (6-DoF) free-flight maneuvering simulations capture the coupled evolution of aerodynamic loads, vehicle attitude, and translational motion. The results demonstrate that the high-fidelity unsteady CFD framework, coupled with rigid-body dynamics, effectively resolves the tightly coupled aerodynamic–dynamic interactions inherent to eVTOL configurations. This work provides a foundation for future investigations into trim strategies, control modeling, and expanded flight envelopes.
Vertical Take-Off and Landing (VTOL) aircraft introduce complex monitoring challenges due to distributed propulsion, lightweight structures, and variable operating conditions. This paper presents advanced Frequency and Orders domain techniques that repurpose existing flight control, propulsion, and structural sensor data to enhance observability without additional instrumentation. By transforming vibration, acoustic, and electrical signals into frequency and order domains, the approach enables detection of harmonics, resonance, and fault signatures tied to rotor dynamics, supporting adaptive control and predictive maintenance. Beyond rotor systems, these techniques are equally effective for monitoring electric motor health, gearbox wear, bearing degradation, and structural coupling effects in composite airframes. They also provide insight into power electronics and thermal management systems by identifying spectral anomalies linked to electrical imbalance or cooling inefficiencies. Aggregated fleet data strengthens prognostic capabilities, enabling early detection of systemic issues and trend analysis. Applications include mitigating ground resonance and modal instabilities, as well as improving reliability of propulsion and structural subsystems. Integration into avionics emphasizes computational efficiency, scalability, and compliance with standards such as DO-160 [1], DO-178 [2], ARP4761 [3] and ARP4764 [4]. Simulation and bench testing confirm feasibility, demonstrating potential to enhance safety, reliability, and lifecycle cost for next-generation urban air mobility platforms.
The Rotor Blown Wing (RBW) is a tailsitter Vertical Takeoff and Landing (VTOL) Unmanned Aerial System (UAS) configuration that leverages cutting-edge autonomous flight controls through Sikorsky's MATRIX™ technology to create a highly capable, efficient, and scalable technology platform. By combining the benefits of fixed- and rotary-wing aircraft, the RBW configuration eliminates the need for traditional UAS launch and recovery infrastructure. This paper describes the RBW-5 prototype, a 100-pound, dual 5-foot diameter proprotor demonstrator, and discusses the comprehensive evaluation of its design and operability through a combination of flight tests, wind tunnel experiments, and computational fluid dynamics (CFD) simulations. The results demonstrate the maturity of the UAS and highlights key accomplishments of the RBW-5 program, including successful autonomous takeoff and landing and transitions between hover and forward flight, the extraction of critical "blown-physics" underlying RBW aerodynamics, and the validation of CFD models against unpowered and powered wind tunnel data.
By its seventh flight after the first take-off, the RACER (Rapid And Cost-Effective Rotorcraft) demonstrator smoothly reached the targeted 220kts speed in stabilized forward flight, validating the high-speed compound architecture developed by Airbus Helicopters in the frame of Clean Sky 2 programme. During the flight envelope exploration, the dynamic behavior of the main rotor was carefully assessed, by monitoring the vibratory loads and validating its aeroelastic stability. Particular care was taken to validate the predicted stability domain of the Dual Rotor phenomenon, a particular case of flap-lag coupling associated with high-speed flight conditions. This paper presents the most significant results shaping the success of RACER flight test campaign. After having introduced the theoretical background and the associated analytical equations, the simulation framework based on the comprehensive analysis tool STORM is presented to discuss the numerical resolution of the stability problem. Then, the rotor dynamics loads and airframe vibratory behavior of RACER are closely examined to demonstrate the absence of any sign of instability, in the various flight conditions offered by its rotor and wing configuration. At last the flight test results are compared to the computed stability domain to assess the margins and estimate the high-speed potential of the rotorcraft.
Electric Vertical Takeoff and Landing (eVTOL) aircraft present a series of challenges to traditional aviation infrastructure that was designed for conventional rotorcraft. Questions have arisen within the vertical flight community as to the validity and applicability of applying current heliport markings and symbology to vertiports. Several of these questions were addressed in a previous paper from VFS Forum 80: "A Comparison of Proposed Concepts for Vertiport Markings and Symbology" (Ref. 6). In contrast, this paper extends that work and presents the results of additional research to enhance the visibility of the Federal Aviation Administration’s (FAA) “Broken Wheel” symbology. These notional enhancements to the "Broken Wheel" symbology were evaluated over the course of an experimental study using helicopter-rated pilots in the FAA William J. Hughes Technical Center’s S76-D and Loft Dynamics H125 and R22 rotorcraft flight simulators.
Helicopters' Vertical Take-Off and Landing (VTOL) capabilities are essential for maritime operations, especially for small-deck naval vessels. Unmanned Aerial Vehicles (UAVs) offer a cheaper, expendable, and efficient alternative for certain tasks, such as reducing pilot risk and lowering fuel consumption. While the procedures to approach and land on (moving) ships are standardized and bound to established operational limits in the case of crewed helicopters, UAVs lack such guidelines. This study investigates optimal rotary-wing UAV approach trajectories to a moving ship, for varying wind conditions and relative initial positions, and for different objectives. The goal is to provide preliminary guidelines for maritime UAV recovery operations, and a preliminary estimation of performance-based operational limits. The optimal trajectories are obtained using a global path-performance optimization framework based on Optimal Control Theory. The trajectories are compared to each other and to reference cases using the Longest Common SubSequence (LCSS) similarity measure, revealing how the unmanned helicopter adjusts its path to exploit the wind direction and profile for more efficient ground speeds. The violation of performance and/or geometric constraints is used to preliminarily indicate the presence of operational boundaries. The control effort and energy consumption are used to identify optimal starting positions for the helicopter approach phase for a given wind profile and intensity.
Revealed in 1941, the Dirigible Helicopter or 'Koun's Craft,' was an ambitious but ill-fated fusion of convertiplane and lighter-than-air technology. This S/VTOL (Short/Vertical Take Off and Landing) concept (a veritable puzzle of diverse airplane parts) was powered by a single, tilting propeller engine and was affixed with wing mounted, helium filled enclosures for additional buoyancy. Dismissed historically as being an eccentric folly of its layman inventor, Korean-American Young Ha Koun, the development of the Dirigible Helicopter has never been thoroughly studied. This paper will examine the origins of this unique design, its creator's possible motivations for building such an aircraft, and successor convertiplane concepts that attempt to achieve the same purpose to this day.
ABSTRACT For many rotorcraft platforms, incorrect timing of the autorotation flare and deceleration maneuvers may result in significant aircraft damage and injury to the crew, or worse. There is a clear need for new pilot cueing and control augmentation technologies that lead to a higher probability of a successful autorotation landing. This paper describes a recent effort to develop two different Tau (time-to-contact)-based autorotation controllers that can be used to drive visual aids to help guide a pilot to apply the required control inputs to complete a safe autorotative landing. Such controllers may also be useful for fully autonomous autorotation landing for unmanned vehicles.
This paper deals with the influence of engine failure during hover on the wiring harness mass of electrical Vertical Take-Off and Landing (eVTOL) aircraft. It starts by presenting possible strategies which can be used to distribute the additional thrust needed during an engine failure among the remaining engines. The most efficient strategy is selected and the impact of different single engine failures on the overall thrust share, while using this strategy, is discussed. The paper proceeds by applying the selected thrust compensation strategy to the mission simulation of three common reference models, which are representative of current eVTOL aircraft configurations. This simulation is used to determine the worst flight phase for the One Engine Inoperative (OEI) condition to occur. The main purpose of the simulation is to optimize the wire sizes of the wiring harness of each configuration while satisfying different design objectives. The results of these optimizations are used to discuss the criticality of each engine failure and its influence on the wiring harness design, especially its mass. It concludes with design recommendations for the wiring harness of eVTOL aircraft.
The unique designs and capabilities of electric Vertical Takeoff and Landing (eVTOL) aircraft present a series of challenges to traditional infrastructure that was designed for conventional rotorcraft. Currently, several civil aviation authorities have released interim, preliminary guidance on aspects of vertical flight infrastructure. This paper presents a comparison of two of the proposed concepts for vertiport markings and symbology, the Federal Aviation Administration (FAA) "Broken Wheel" and the European Union Aviation Safety Association (EASA) "V". These concepts were evaluated over the course of two experimental studies using helicopter-rated pilots in the FAA William J. Hughes Technical Center's S76-D and Loft Dynamics H125 & R22 rotorcraft flight simulators.
Joby Aviation is developing an all-electric air taxi for commercial passenger service. The aircraft takes off and lands vertically using six tilting propellers. Classified as powered lift aircraft by the Federal Aviation Administration, it has many similarities with, and important differences from, traditional helicopters. Joby Aviation partnered with the Federal Aviation Administration to measure the outwash of the Joby Aviation S4 pre-production prototype aircraft and a Robinson R44 light helicopter. The measured data shows that the Joby S4 has similar outwash magnitudes to the R44 despite being flown at approximately twice the weight. It also shows that the caution and hazard zones for outwash based on the 95% maximum velocity and PAXman analysis are very close to the aircraft and well within the established safety areas. The data shows that the outwash of the Joby S4 aircraft does not present an increased risk over traditional light helicopters.
No Abstract - 40th Annual VFS Student Design Competition, Graduate Category
This paper investigates optimal wing arrangements for electric Vertical Take-Off and Landing (eVTOL) aircraft, leveraging on their design flexibility with electric propulsion system. The study employs a multidisciplinary approach with the objective of integrating aerodynamic analysis, static and dynamic stability assessments, and pilot feedback to evaluate various wing configurations. Analytical techniques were adopted to evaluate aerodynamic performance and static stability, while experimental flight testing on scale models was conducted to validate these findings. Additionally, the Cooper-Harper rating system was introduced to capture pilot perceptions of aircraft handling qualities. Results inform eVTOL designers on wing arrangements that offer enhanced aerodynamic efficiency, stability, and handling qualities, ultimately expanding the operational scope and applications of eVTOL aircraft. The study concludes the versatility of the high aspect ratio conventional wing on eVTOL aircraft, providing excellent overall performance in the various aspects. This research aims to provide a comprehensive understanding on how different wing configurations influence range and handling qualities in eVTOL aircraft.
This study addresses safety concerns within the rapidly evolving Electric Vertical Takeoff and Landing (eVTOL) aircraft domain, focusing on efficient tools to quantify uncertainties in lithium-ion battery behavior - a critical aspect of eVTOL. One major issue with quantifying uncertainty is the prohibitive computational cost associated with many queries of an expensive-to-evaluate computational model. This work employs three physics-based battery models models of varying fidelity and cost to estimate the mean and the variance of the selected quantities of interest through a multifidelity method to reduce the computation cost. By combining information from multiple cheaper, lower-fidelity models through the Multifidelity Monte Carlo method, we significantly reduce the number of high-fidelity samples required for a prescribed mean-squared error, consequently reducing computational costs down to a tractable level. The proposed methodology is applied to estimate the mean and the variance of the battery temperature and voltage, accounting for uncertainties in flight conditions and materials. The first example focuses on a 580-second flight and is benchmarked against a standard Monte Carlo sampling technique. Results indicate a notable fourfold speed-up using the Multifidelity Monte Carlo method compared to the standard Monte Carlo method for the same mean-squared error for the voltage estimate. To showcase the method's generality, the multifidelity method is then applied to a longer flight of 3580 seconds for estimating the mean and the variance and utilizing these statistics to approximately estimate the probability of the flight completion. This demonstrates the adaptability of the methodology to various power profiles and considered uncertainties, with potential extensions to any battery chemistry. In conclusion, the presented multifidelity method offers a robust approach to enhance eVTOL safety by efficiently estimating uncertainties in battery behavior.
This paper addresses the urgent need to enhance rotorcraft safety and performance by developing a prediction methodology for the onset of the Vortex Ring State (VRS), and therefore verifying the VRS avoidance diagram. The objectives of this research are to assess the correlation between predictions generated by a comprehensive flight dynamics code and the latest and most accurate VRS boundary models, validate the VRS avoidance diagram across diverse descending flight conditions, and identify specific parameters indicating the rotor's entry into the VRS. The methodology involves a detailed investigation of 8 descent manoeuvres using a comprehensive flight dynamics code coupled with an advanced free vortex wake model. Results show that the pitch and roll oscillations and thrust fluctuations experienced by helicopters during the VRS are also observed in the model response to steep descent maneuvers. The findings confirm the reliability and applicability of the VRS avoidance diagram, providing valuable insights for improving rotorcraft design and flight control systems. Furthermore, this study presents novel findings regarding the identification of the VRS onset boundary through the observation of pitch and roll rate fluctuations, which contribute to the systematic detection and prevention of the VRS.
No Abstract - 40th Annual VFS Student Design Competition, Undergraduate Category
The development of turbulence criteria to provide early guidance for the design of vertiports is presented in this paper. For any aircraft, winds, in particular crosswinds and gusty winds, are top of mind for all pilots engaging in take-off and landing maneuvers. It is anticipated that the same will be true for VTOL and eVTOLs landing on vertiports, in particular as new vertiports are built closer and closer to urban centres. First, a review of the current design criteria for vertiports around the world related to wind is presented, highlighting the commonality between the guidance and the gaps in their content. Second, the controllability criteria that VTOL and eVTOLs will likely need to meet in the pursuit of an airworthiness certification are reviewed and their pertinence with regards to vertiport design are discussed. Third, the characters of the wind and their impact on eVTOL flights at or near take-off and landing infrastructure is explored. Finally, a set of turbulence criteria for vertiports and a turbulence index are proposed. The index includes a scale for conditions ranging from favorable for take-off and landing; to more and more demanding conditions; up to turbulence conditions to be firmly avoided.
The paper presents a novel strategy for minimum energy consumption in automatic conversion control of tiltrotor eVTOL aircraft, exemplified by the Aston Martin Volante Vision model. We introduce a tilt schedule methodology that strategically balances conversion and reconversion performance with climb, descent, and cruise phases to minimize overall energy expenditure. Our approach accounts for critical factors such as blade loading, operation handling qualities, and passenger ride comfort within a predefined conversion corridor. The optimized trajectories approximate the minimum energy pathway, essential for operational efficiency in urban air mobility. Analytical results demonstrate that our proposed conversion and reconversion phase profiles significantly reduce energy consumption, contributing to the sustainability of tiltrotor flight operations. This research not only enhances understanding of tiltrotor dynamics but also serves as a pivotal step toward achieving globally optimized energy usage, marking a significant advancement in autonomous flight technology for advanced air mobility systems.
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To aid in the development of electric Vertical Take-off and Landing (eVTOL) technology, the National Aeronautics and Space Administration has undertaken research initiatives to evaluate and optimize design features of eVTOL aircraft. One such initiative has been to develop energy attenuating design mechanisms to improve eVTOL vehicle crashworthiness. In this study, crashworthiness design mechanisms, implemented within a six-passenger lift plus cruise (LPC) eVTOL concept vehicle, were evaluated under multi-axis dynamic loading conditions. This work builds upon crashworthiness design concepts previously optimized within a simplified vehicle-loading environment. The results of this study found the effectiveness of energy attenuating design mechanisms to be dependent on the complexity of load environment in which they were employed. An increase in off-axis loading resulted in a decrease in occupant protective capability. These results indicate the necessity for evaluating vehicle design across the range of possible dynamic impact conditions to characterize crashworthiness. This work provides preliminary methodology for implementing energy attenuating design mechanisms and evaluating crashworthiness for future UAM markets.
The paper discusses the application of the Array Controlled Turn-less Structures (ACTS) motor for VTOL application. The motor enhances the three main competing characteristics of electric motors; namely specific power, efficiency and reliability. The motor arrays an ensemble of elemental turn-less motors which include turn-less elements each with their dedicated inverters which are operated in synchronism. The resulting small pole size enhances the power density, the enhanced conductor packing enhances the efficiency, and the massive parallelism enhance the reliability. Vertical takeoff requires much higher thrust compared to wing assisted takeoff. With limited on-board power, this higher thrust is presently provided by in ordinary larger propulsion disk area which reduces the craft aerodynamics, and the cruising Lift-to-Drag (L/D) ratio and accordingly the flight efficiency and range. The high specific power of the ACTS motor allows for a different scenario and thus craft architecture. By substantially increasing the takeoff power which is now possible with the higher specific power of the ACTS motor, the propulsion disk area can be substantially reduced, with the resulting greater streamlined, high L/D craft, and thus longer range. The paper discusses key aspect of the motor and inverter architecture and technology. Furthermore, it discusses its application to a high L/D VTOL and prospective performance.
The objective of this investigation is three-fold. First, to assess the flight dynamics of an electric Vertical Take-Off and Landing (eVTOL) concept aircraft with a propeller-driven rotor. Second, to develop a Stability and Control Augmentation System (SCAS) for this concept aircraft. Third, to verify the potential safety benefits of the concept aircraft by analyzing the autorotation performance following a total loss of power. The paper begins with a description of the simulation model, including a detailed discussion on the inflow model of the propellers that drive the main rotor. Next, the flight dynamics are assessed at hover and in forward flight. A SCAS based on Dynamic Inversion (DI) is developed to provide stability and desired response characteristics about the roll, pitch, yaw, and heave axes for speeds ranging from hover to 80 kts. Additionally, an RPM governor is implemented to hold the main rotor angular speed constant at its nominal value. Finally, simulations that make use of the SCAS are performed to analyze the autorotation performance following total loss of power.
The Urban/Advanced Air Mobility (UAM/AAM) transportation concept has been studied and shown to offer advantages in travel time-savings to individuals over the automobile, mass transit, and in many cases, commercial air transport alternatives. This paper presents a study of this new market using a parametric approach that accounts for the performance of Electric Vertical Takeoff and Landing (eVTOL) aircraft, takeoff and landing infrastructure (vertiports), and the demand for ridership given a ticket price and time saved. One of the key mode choice drivers in switching from existing transportation options to an AAM service is the value gained in saving time, which is also tightly correlated with people's income level. The analysis framework can facilitate market feasibility analysis by considering various scenarios and constraints. The results suggest that near-term profitability is possible even though vertiport throughput capacities are limited by existing footprint and operational constraints. Vertiport expansion can increase throughput and demand up to a point of maximum aircraft utilization. This new limit is due in part to ground turnaround time and battery charging requirements. Improvement in battery charging rates or implementing battery swap strategies could dramatically improve profitability while maximizing vehicle utilization. As operations increase to hundreds of flights at certain vertiports, local airspace congestion and aircraft vertiport mobility become the next bottleneck.
In application, the Aeronautical Design Standard for the handling qualities of military rotorcraft, ADS-33E-PRF, provides the means to effectively predict rotorcraft handling qualities via validated criteria and demonstrate actual handling qualities in flight test using mission task elements. Besides a definition, a note that rotorcraft shall have no tendencies, and a note regarding Attitude Command Response-Types and gain bandwidth frequency, the topic of pilotinduced oscillations (PIO) is not addressed via specific criteria or flight test techniques. As the use of full authority fly-by-wire flight control continues to expand in Vertical Takeoff and Landing (VTOL) aircraft, the likelihood of encountering PIO will also expand. In the fixed wing world where PIO has been commonplace, at least in developmental test if not operations, predictive analytical methods that can also be used for detection of PIO in realtime have been developed, which can also be applied to rotorcraft. Furthermore, recent time-frequency domain methods that have been developed to differentiate VTOL piloting techniques are directly applicable to PIO scenarios. Using a flight test database generated with the UH-60L in-flight simulators at the U.S. Naval Test Pilot School (USNTPS), this paper explores the utility of these methods for identifying rotorcraft PIO tendencies.
Recently, studies on the flight dynamics of unmanned aerial vehicle (UAV) affected by gust have been performed. However, only few studies focused on the aspect of the robust controller design and those did not consider aerodynamic effect by gust. Therefore, the goal of this paper is establishing a non-linear flight dynamics simulation which is intended to analyze gust. First, the aerodynamic analysis is composed with dynamic inflow, blade element theory (BET), and ring vortex method for descent. A nonlinear flight simulation is constructed based on aerodynamic analysis and a procedure is established to verify it. To estimate the controller gain, system identification and parametric estimation are performed. Based on such estimation, a position controller is designed and reliability of the controller is validated by the two-point flight test. Additionally, wind tunnel test is performed and the trajectory of UAV shows a good tendency when compared with experiment. As a result, the nonlinear flight dynamics presented in this paper will be used to estimate the trend of UAV dynamics under gust.
Jaunt Air Mobility LLC is developing an all-electric Vertical Take-off and Landing (VTOL) aircraft suitable for Urban Air Mobility (UAM) and On-Demand Mobility (ODM) markets. Salient features of Jaunt include the quietest, safest, and most efficient hovering and cruise flight air vehicle than any other configuration suitable for UAM missions. Jaunt represents a Reduced Rotor Operating Speed Aircraft (ROSA™) with core technologies proven in over 250 hours of successful demonstration flights. Jaunt represents the metamorphosis of the best features available from helicopters and fixed-wing airplanes. ROSA™ technologies offers several innovative features that significantly reduce total noise. These include all-electric powertrain, 75 percent reduction in main rotor tip speed from hover to cruise flight, scimitar design propellers offering a 60% speed reduction from hover to cruise flight, and a tilting mast which provides efficient management of the resulting thrust vector. Jaunt represents flight-proven aircraft technologies that are superior to existing helicopters which are the gold standard in efficient Vertical Take-off and Landing (VTOL) aircraft. Jaunt Air Mobility LLC is developing an all-electric Vertical Take-off and Landing (VTOL) aircraft suitable for Urban Air Mobility (UAM) and On-Demand Mobility (ODM) markets. Salient features of Jaunt include the quietest, safest, and most efficient hovering and cruise flight air vehicle than any other configuration suitable for UAM missions. Jaunt represents a Reduced Rotor Operating Speed Aircraft (ROSA™) with core technologies proven in over 250 hours of successful demonstration flights. Jaunt represents the metamorphosis of the best features available from helicopters and fixed-wing airplanes. ROSA™ technologies offers several innovative features that significantly reduce total noise. These include all-electric powertrain, 75percent reduction in main rotor tip speed from hover to cruise flight, scimitar design propellers offering a 60 percent speed reduction from hover to cruise flight, and a tilting mast which provides efficient management of the resulting thrust vector. Jaunt represents flight-proven aircraft technologies that are superior to existing helicopters which are the gold standard in efficient Vertical Take-off and Landing (VTOL) aircraft.
In the history of flight, starting from first gliders of Otto Lilienthal to first powered fixed-wing aircraft designed by Wright brothers or first Vertical Take Off and Landing (VTOL) technology based VS-300 invented by Sikorsky; the notion of human flying machine has always enticed imaginations of the pioneers and observers alike. In the realm of powered VTOL individual flying machines, various inventors have explored several unique and innovative technology concepts (for example tilt rotor, tilting ducted fan, tilt jets, etc.) Georgia Tech Hummingbuzz concept is exploring one such possibility of integrating shrouded coaxial rotors in motorcycle/Jet Ski like configuration to provide a thrilling, quiet and unobstructed view based flying experience. This paper discusses how the concept resulted as a by-product of the Boeing sponsored GoFly competition and Georgia Tech Integrated Product and Process Development (IPPD) methodology used in its Aerospace Design and Systems Engineering program. The paper will also describe in detail the Preliminary Design process used to select the hardware and software required to achieve the design that meets GoFly competition requirements. The paper will discuss the scaled prototype test results and the lessons derived from the tests. In the end, the paper will conclude by providing the future roadmap for the design and development of the full-scale prototype with the end goal of competing in the final phase of GoFly competition in first quarter of 2020.
A real-time path planning algorithm is developed to generate time-optimal trajectory for helicopter shipboard landing. The trajectory optimization problem is translated to the lower dimensional flat output space by exploiting the differential flatness property of the simplified helicopter model. Then, the flat outputs are parameterized using piecewise spline functions with adjustable coefficients, which are used to shape the trajectory and approximate the optimal solution. Further, by allowing the flexible selection of each spline segment's time-duration and enforcing additional path constraints, the time-optimality of the planned trajectory is largely preserved without violation of state and input bounds. Compared to pure temporal discretization methods, the proposed algorithm employs considerably less decision variables and significantly reduces the computational time by 75%, which only leads to a 0.5% growth in the optimal flight time as the trade-off. The improvement in computational efficiency enables the real-time recalculation of the time-optimal trajectories on-the-fly if there are unforeseen deviations from the planned flight path.
Landing helicopters in Degraded Visual Environments (DVE) is one of the most challenging maneuvers pilots perform. The U.S. Army Combat Capabilities Development Command, Aviation & Missile Center, Aviation Development Directorate has been working to develop flight guidance and sensor systems to provide the pilot with guidance and pilot cueing to land a helicopter, hover, and take off in DVE. During flight testing of the Brown Out Symbology System (BOSS) on an EH-60L Black Hawk, pilots reported very high workload requiring full concentration on the displays during approaches to landing in brownout. In order to reduce pilot workload, an approach to provide the pilot with a collective tactile cue based on coupling of the output of the approach to landing algorithms to the EH-60L collective trim servo was developed and flight tested. Flight testing of the coupled collective system demonstrated a reduction in pilot workload and increase in the pilot's situational awareness during landing in brownout. To further reduce pilot workload, the pilot cyclic and pedals have been coupled with the guidance symbology to allow for fully coupled landings. Details of the system are provided along with the initial results of flight testing of the system at Felker Army Airfield, Ft. Eustis VA.
Rotorcraft shipboard landing is one of the most challenging operations for rotorcraft pilots owing to the workload associated with the task, which can be attributed to a variety of environmental conditions like random ship motion, heavy sea states and unsteady aerodynamic conditions. This paper explores the effectiveness of Model Predictive Path Integral (MPPI) approach, a stochastic optimal control method, for parallel trajectory optimization as a guidance solution to the rotorcraft shipboard landing problem. Specifically, the computational efficiency for real time guidance solutions afforded by the MPPI approach in comparison to its sequential counterpart is evaluated. Furthermore, a sensitivity analysis of MPPI parameter selection on its performance is carried out. The performance of the developed MPPI algorithms for real time guidance in helicopter ship board landing is demonstrated using nonlinear model simulations of a helicopter executing a symmetric landing profile aligned with the ship deck centerline.
The present study proposes an augmentation to the existing control mixing on the UH-60 Black Hawk to utilize the horizontal stabilator as an available control effector in the feedback loop to compensate for locked-in-place failure in the main rotor swashplate actuators. This modification has previously been shown to work in an adaptive sense, where once failure is detected the control mixing is remapped in flight. Now it is shown to perform well when the defined mixing includes the stabilator for all time, including the undamaged case, removing the need to detect and identify specific failures on the aircraft. Further investigation considered the benefit of allowing for more or less longitudinal authority to be given to the stabilator in different flight conditions, which include main rotor swashplate actuators locked-in-place, in the context of handling qualities ratings for the aircraft in pitch attitude and vertical rate response. Post-failure, the aircraft is demonstrated to retain level 1 performance in the pitch axis, whereas only aft actuator failure remains level 1 in the vertical rate response. Both cases show general improvement in handling qualities ratings with increased authority given to the horizontal stabilator. Finally, the aircraft is simulated flying a trajectory to a recoverable aircraft state, where the descent rate and forward speed are appropriate for a rolling landing.
Helicopter is a complex system regarding integration of systems. During development phase of a new H/C, design office deal with MMEL (Master Minimum List Equipment), Optional equipment package for specific missions (i.e. Oil & Gas, SAR...) and Manufacturing constraints for lead-time and cost optimization. The Geometrical Management presented today is derived from ARP4754A standard in Aeronautics. The Aerospace Recommended Practice (ARP) is a guideline for development of civil aircraft and systems. This process, based on end to end philosophy defines the way of managing geometrical specifications concerning the aircraft during its complete lifecycle. System geometrical Management starts with System Engineering by functional analysis of the Helicopter vehicle during Design development phase, then APQP focus on industrial maturity and repeatability during industrialization phase and finally control plan is deployed after Entry into service for serial life This is a top-down approach leading to systems specification at each level of the Aircraft assembly, as in Final assembly line for H/C assembly and tests, Systems level and elementary parts. Handling capacity, Modularity and Maintenance capacity (Interchangeability), Tightness, Etc.
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