Browse Topic: Fixed-wing aircraft
The FAA VR-HeliSTART (Virtual Reality-Helicopter Simulator Training for Airplane to Rotorcraft Transition) is a 15-week study conducted at Marshall University (WV) to determine the effectiveness of an H125 VR reduced-motion platform simulator in training fixed-wing pilots to fly helicopters. Eleven students received three four-week blocks of instruction in the flight simulator, each followed by a simulator evaluation and a helicopter evaluation. This paper presents results for eleven hovering maneuvers trained and evaluated in the study. The evaluation of the students relied on both an objective and a subjective evaluation: a flight parameter analysis against Airman Certification Standards criteria, and an assessment by certified flight instructors. A key finding is that simulator training enabled all pilots to perform most hover maneuvers on their first helicopter flight without intervention, although sometimes below standards. Overall, results also suggest that while the simulator provides a useful learning environment for basic hover control, the further refinement of the core hovering skills acquired in the simulator did not appear to transfer effectively to the actual helicopter within the time frame of the study. Therefore, this indicates that initial hover training in the simulator is beneficial, but additional improvements still seem to require practice in the actual helicopter.
This paper introduces an eigenvalue-based whirl flutter prediction method accounting for aerodynamic interactions between a wing and propeller. The linearized unsteady vortex lattice method was utilized to model fixed-wing aerodynamics while the linearized viscous vortex particle method was utilized to model rotary-wing aerodynamics. The complete aerodynamics model was then coupled with computational structural models to demonstrate the capabilities of the model to predict whirl flutter using an eigenvalue-based method. Two computational structural models were used: the first being an analytical propeller model affixed to a rigid wing via root springs and dampers, and the second being the University of Michigan's Nonlinear Aeroelastic Simulation Toolbox. These models demonstrate the capabilities of the linearized aerodynamics model in predicting instability with structural models of different fidelities, both considering and not considering aerodynamic interactions. The linearized aerodynamics model predicts a reasonable aeroelastic solution when coupled with the structural models, but requires more investigation as to whether aerodynamic interactions are being sufficiently captured.
Future military operations are expected to take place in highly dynamic, contested and multi-domain environment, where speed, flexibility and survivability are essential. Fast rotorcraft are emerging as critical asset to meet future operational requirements, offering a hybrid solution that bridges the gap between conventional helicopters and fixed-wing aircraft. Given the increasing complexity of both operational requirements and system architectures, a Model-Based System Engineering (MBSE) approach has become fundamental to support concept design. However, MBSE is often neglected in the earliest phases of aircraft concept definition and proposal process, when business and mission requirements are agreed between Contractor and Supplier, due to the fast pacing of Parties interactions with respect to the time and effort required to perform modelling activities. This prevents nurturing the benefits of MBSE in this crucial phase, and it generates omissions in the systems engineering data to perform design validation in future phases. This paper describes a tailored methodology to make MBSE feasible to support project requirements agreement and initial aircraft sizing.
The United Kingdom's convertible rotorcraft studies of the 1960s and early 1970s represent a systematic effort to combine vertical take-off and landing capability of helicopters with the speed and efficiency of fixed-wing transport aircraft. Conducted primarily by Westland Helicopters under the Short Range Transport (SRT) programme, these investigations explored both tiltrotor and tiltwing configurations for civil and military applications. Early work focused on the WE-01 tiltrotor, conceived as a research and demonstrator aircraft to investigate transition aerodynamics, control integration, and rotor–wing interactions, and subsequently scaled to the larger WE-02, intended for intercity and tactical transport missions. In parallel, Westland pursued the more ambitious WG.22 tiltwing, a 100-seat intercity VTOL transport incorporating high-incidence stall wing technology, large prop-rotors, and mechanically scheduled flight controls to ensure benign handling through transition. Although none of these aircraft were built, the studies addressed aerodynamics, structures, propulsion, flight controls, noise, and socio-economic viability with exceptional depth. Shaping the future through the past, this paper revisits Westland's early involvement in tiltrotor and tiltwing research, with the aim of assessing the technical maturity of these configurations and evaluating their lasting relevance to contemporary vertical lift aircraft design.
A generalized turbulence model for rotorcraft, analogous to the Dryden or von Kármán models commonly used for fixed-wing aircraft, does not yet exist. The closest available formulations are Control-Equivalent Turbulence Input (CETI) models, which reproduce the portion of the vehicle response attributable to atmospheric disturbances through equivalent control inputs applied at the inceptor or effector level. While the underlying concept is broadly applicable, these models are highly configuration dependent, making their broader generalizability uncertain. This paper adopts a recently developed methodology to extract CETI models directly from simulation and extends it to the identification of State-Equivalent Turbulence Input (STETI) models, which are Dryden-like in form and inject turbulence-equivalent excitations directly into the state dynamics. The approach is applied to six conventional main-tail rotor helicopters spanning trainer, light, intermediate, medium, heavy, and ultra-heavy classes, from the Robinson R-22 to the Mil Mi-26, and to four tiltrotors spanning the current range of tiltrotor weight classes, from the Bell XV-15 to the Bell Boeing V-22. The resulting CETI and STETI models are used to examine cross-vehicle trends, assess the extent to which they generalize across configurations, and evaluate whether they can be parameterized in terms of fundamental rotorcraft properties, including gross weight and rotor radius, as well as derived parameters such as disk loading.
Tiltrotor aircraft attracts sustained interest due to their capacity to combine the advantages of both rotary- and fixed-wing aircraft. Recently, alternative nacelle tilting concepts have emerged, in which only the forward section of the nacelle rotates during mode conversion, differing from conventional full-nacelle tilt mechanisms. So-called "tilt-rotor-only" mechanism, it is known to suggest lots of advantages. This paper presents a baseline main wing-nacelle configuration of the XV-15 tiltrotor aircraft as a reference and comparison model. Based on this baseline, a structurally equivalent configuration employing a tilt-rotor-only mechanism is designed. Followingly, some characteristic analyses are performed to evaluate the structural robustness and operational safety. Structural, dynamic, modal, and aeroelastic characteristics are examined to identify the distinctive features induced by the tilt-rotor-only mechanism compared to the conventional tiltrotor wing-nacelle configuration.
The FAA VR-HeliSTART (Virtual Reality-Helicopter Simulator Training for Airplane to Rotorcraft Transition) is a 15-week study conducted at Marshall University (WV) to determine the effectiveness of an H125 VR reduced-motion platform simulator in training fixed-wing pilots to fly helicopters. 11 students received three four-week blocks of instruction from certified flight instructors in the flight simulator, each followed by evaluations in both the simulator and an actual H125 helicopter, covering 36 maneuvers drawn from the commercial helicopter Airman Certification Standards. A mixed-methods approach combined objective flight parameter analysis with subjective assessments from evaluators, instructors, and students. Results indicate broadly positive transfer of training, with students demonstrating at least private pilot level performance on 70% or more of maneuvers on their first helicopter flight, and consistent improvement across subsequent evaluations. However, specific areas of negative or limited transfer were identified, most notably Vortex Ring State recovery, approaches, and hover work, driven by limitations of the head-mounted display and motion platform. This paper presents the methodology and overall results, with future papers addressing individual maneuver groups in greater detail.
This paper presents the design, development, and successful demonstration of the first-ever ballistically tube-launched tailsitter unmanned aerial system. The vehicle expands upon the capabilities of existing tube-launched systems by simultaneously integrating the hovering capability of a rotary-wing aircraft with the efficiency and speed of a fixed-wing aircraft. To achieve this, the platform's design incorporates a novel coaxial thrust-vectoring propeller system for control in vertical flight and a unique foldable wing design for ultra-compact storage in the launch tube. The aeromechanics of the foldable wings during deployment are studied through a combination of wind tunnel experiments and flight dynamics model simulations, and the results are used to formulate a methodology for executing the ballistic launch. Simulations are also performed to characterize the robustness of the system against asynchronous deployment of the left and right wings. Experimental data, collected from flying a prototype in vertical, horizontal, and transitioning flight, demonstrate the aircraft’s flying performance. The study ultimately culminates with a demonstration of the prototype being rapidly launched from a tube at 25 m/s (56 mph) and autonomously unfolding, stabilizing, and transitioning into self-powered cruising flight.
Enterprises that develop complex products or systems often struggle to reuse technology efficiently across their portfolios. This challenge is especially prevalent in aerospace, transportation, energy, and defense industries, where preserving freedom of action is critical. In this context, freedom of action is defined as the ability to avoid vendor lock imposed by integrators or third parties, while enabling competition within clearly defined functional boundaries that establish effective market segments for system components. This paper presents eight best practices for Enterprise Reference Architecture (ERA) development to address this challenge and applies them to aviation functionality spanning both vertical lift and fixed wing platforms. Because complex systems can be modularized in many ways, a consistent set of guiding rules is required to produce an organized set of modules that are reusable across an enterprise portfolio. The best practices presented in this paper are intended to fulfill that role.
In this study, a multifidelity aeroelastic framework is presented for predicting trim conditions in rotary-wing aircraft, with the main focus placed on the DUST implementation and its application to helicopters and quadrotors. The methodology combines aerodynamic and structural solvers of different fidelity, specifically DUST and the multibody dynamics solver MBDyn, through the preCICE coupling interface to enable direct comparison with rigid and coupled aeroelastic solutions. The trim problem is formulated from the six degree of freedom rigid body equilibrium equations in a helical turn reference frame, naturally covering both steady and maneuvering flight. Although the same formulation can be extended to fixed-wing configurations, the present paper is focused on rotorcraft applications. The framework is first applied to the SA330 Puma helicopter, chosen for the availability of validated flight test data. The methodology is then extended to a multirotor derived from a NASA quadrotor, demonstrating that the same trim strategy can be transferred to distributed-lift rotorcraft. Results highlight the potential of the proposed approach to provide physically consistent and computationally affordable predictions of helicopter and multirotor equilibrium states.
Helicopter maintenance troubleshooting faces significant challenges due to fragmented documentation, outdated procedural manuals, and reliance on human expertise, all of which threaten flight safety and operational efficiency. While Knowledge Graphs (KGs) effectively model hierarchical system relationships and causal dependencies, they struggle with dynamic unstructured data. Conversely, Retrieval-Augmented Generation (RAG) systems access technical manuals but risk hallucinating unsafe procedures without structural grounding. This paper introduces KG-RAG, a novel hybrid troubleshooting framework specifically engineered for helicopter systems, addressing a critical gap as existing work focuses predominantly on fixed-wing aircraft. The framework merges knowledge graphs modeling fault causality and maintenance history with multi-dimensional retrieval combining graph-based reasoning, vector embeddings, and keyword-based search. This integration enables contextual interpretation of ambiguous fault descriptions, generation of precise diagnostics aligned with operational constraints, and dynamic adaptation to new fault patterns without retraining. By transforming fragmented maintenance knowledge into a verifiable, context-aware troubleshooting guide, the framework directly addresses aviation's persistent obstacles: data incompleteness, knowledge erosion, and slow safety-critical decisions. This work positions KG-RAG not merely as a tool but as a foundational shift toward cognitively augmented maintenance, elevating human expertise through AI that reasons like an engineer and contextualizes like a veteran technician for enhanced safety-critical decision-making in complex helicopter operations.
This paper considers the opportunities and challenges of supporting Disaster Relief and Emergency Response (DRER) missions employing new aerial vehicle and systems concepts. This paper is a broad survey of the possible aerial-vehicle-assisted approaches to aid in DRER missions. The intent of this paper is to elevate this DRER mission application domain as a critical area of investigation for rotorcraft, robotics, intelligent systems, and other research. Current work is primarily focused on assessing air space integration challenges for Commercial Off-The-Shelf (COTS) aerial platforms (typically small multirotor drones and/or small fixed-wing uncrewed aerial vehicles (UAVs)) in disasters such as earthquakes and wildfires. Though this is an important area of investigation, truly efficient and effective DRER systems and response efforts will not be possible without the development of novel aircraft, technologies, and system architectures of COTS DRER drones/UAVs. This paper seeks to address that knowledge gap and encourage government, academia, and industry to pursue DRER mission research.
A technique for rapidly designing roughness tolerant low drag airfoils has been developed. Airfoils of varying thickness to chord ratio, ranging from 10% to 22% have been designed. A target pressure distribution is specified by the designer for a notional lift coefficient, Reynolds number, and Mach number. The specified pressure distribution is first analyzed using classical integral boundary layer analyses and empirical transition criteria for smooth and rough airfoils to ensure laminar flow over much of the airfoil under design conditions. The resulting airfoil is subsequently analyzed under natural transition, and forced transition caused by the tripping of the boundary layer due to roughness near the leading edge. It is found that the present approach performs well for a broad range of lift coefficients. An in-house propeller design and analysis tool has been used to examine the impact of the low drag airfoil on the pusher propeller performance designed for a fixed wing UAV drone configuration.
Electric Vertical Take-Off and Landing (eVTOL) aircraft, conceptualized to be used as air taxis for transporting cargo or passengers, are generally lighter in weight than jet-fueled aircraft, and fly at lower altitudes than commercial aircraft. These differences render them more susceptible to turbulence, leading to the possibility of instabilities such as Dutch-roll oscillations. In traditional fixed-wing aircraft, active mechanisms used to suppress oscillations include control surfaces such as flaps, ailerons, tabs, and rudders, but eVTOL aircraft do not have the control surfaces necessary for suppressing Dutch-roll oscillations.
The biography of Henrich Focke is well known and documented. During a small period from October 1954 to February 1956 he held lectures at the Technical University of Stuttgart during the winter semester. In the summer period he returned to Brazil for continuation of his contract work on the "Convertiplane" (a quad-tiltrotor aircraft) and the "Bei-jaflor" (a small single rotor helicopter). The topic of Focke's lecture in the winter semester 1954-55 was "Design of Fixed-Wing Aircraft", but the lecture manuscript of it is unavailable. In the following period 1955-56 Focke lectured about "Helicopter Design" and the manuscript was recently found in the central archive of DLR. It covers 123 pages of text with sketches and graphs and provides deep insights into the helicopter design philosophy of Henrich Focke.
This paper details the development of a tailsitter unmanned aerial system (UAS) that has the potential to be airlaunched in the near future. By simultaneously integrating air-launch capability with both rotary-wing vertical flight and fixed-wing horizontal flight, the vehicle can be rapidly deployed, perform hovering flight, and achieve high-speed and efficient cruising flight. The aircraft prototype has a mass of 1 kg (2.2 lbs) with wings that can fold to allow the aircraft to fit inside a 6-inch launch tube. A coaxial propeller with vectored thrust is used for control in vertical flight, and a unique avian-inspired wing-folding mechanism is used for stowing and deploying the wings. The aerodynamic design was characterized through a series of wind tunnel experiments, propeller tests, and flight dynamics simulations. High-fidelity simulations of vehicle dynamics validated its air-launch capability and flight tests performed with the prototype demonstrated the ability of the aircraft to perform hovering, transitioning, and fixed-wing cruising flight. To date, this aircraft has achieved speeds of up to 130 km/hr (81 mph), and range up to 10 km (6.2 miles).
This paper outlines observations from an FAA-sponsored research project that examined aviation Fly-By-Wire (FBW) accidents. The goal was to identify risk areas that will help guide a focus for FAA certification testing. Part of this study specifically focused on current powered-lift tiltrotors, identifying six general categories of causal factors for accidents, which will be discussed in detail regarding how they influenced flight control designs. The results of this survey, along with extrapolation to current designs, will be discussed and will illustrate why manufacturers are moving toward state-based flight control designs. In a state-based flight control scheme, the pilot does not have direct control over aircraft attitudes and motor tilt angles. Instead, the pilot requests a speed and or flight path with inceptor input, and the commanded attitudes and motor tilts are scheduled by the flight control computer. Additionally, recent lessons learned from electric Vertical Takeoff and Landing (eVTOL) aircraft accidents will be discussed, along with a comparison of powered-lift causal factors to accidents in the transport category FBW fixed-wing aircraft. From this analysis, broad observations will be offered about the trend of how accident-causal factors may evolve with greater maturity in aircraft design. This accident survey will be detailed further as part of an upcoming FAA Research Report.
Adapting mission task elements (MTE) to a wildfire environment would help characterize how aircraft handling qualities may change in the presence of a wildfire. It would also provide insight into how a (often retrofitted) vehicle may degrade in its operational environment, allowing pilots to be more informed making “go/ no go” calls in real-time during a crisis. This work focuses on rotorcraft applications, although some lessons learned may be relevant to fixed wing aircraft. A review of wildfire-related aviation casualties and pilot accounts from fighting wildfires informed critical areas of risk during each segment of a generalized Wildfire Scenario. MTEs from ADS-33/ MIL-DTL-32742 such as the Decelerating Approach, Depart/Abort, and Missed Approach were mapped to this scenario and then altered to focus on the relevant wildfire scenario. Slung loads (such as supplies, water, or fire suppressant) also change vehicle dynamics which may significantly impact handling qualities. One of the most challenging scenarios is when a rotorcraft must quickly climb to avoid terrain during or shortly after dropping water/fire suppressant. A custom MTE is presented that would challenge the vehicle in a similar way to this type of maneuver. Variations of conditions that could be explored using these MTEs are also discussed, as well as which variations would benefit the most from motion-based simulation.
Rotorcraft continue to experience higher fatal accident rates compared to fixed-wing aircraft, primarily due to low altitude flight operations and reduced situational awareness in complex environments. A critical factor is the limited availability of accurate, up-to-date information on helipads and surrounding obstacles - such as trees, poles, and buildings - that pose significant risks during takeoff and landing. Existing resources, including the Federal Aviation Administration's heliport registry, are often outdated and incomplete, particularly for private or state-operated sites, and fail to report nearby obstacles. This lack of up-to-date data is largely due to privacy restrictions at certain locations and the high cost associated with comprehensive obstacle surveys. To address this challenge, we develop a deep learning (DL) framework that automatically detects helipads and nearby obstacles from high-resolution satellite imagery. Our approach combines Mask R-CNN for precise pixel-level helipad segmentation with Grounding DINO, a zero-shot vision-language model that identifies obstacles using flexible text prompts (e.g., "Pole", "Tree") without task-specific training. This text-guided, scalable detection method adapts to diverse and evolving operational settings. We validate our framework across helipads in the United States, and demonstrate strong performance in both helipad localization and obstacle detection. In addition, we build a web-based application that automates image processing, updates incorrect heliport coordinates, and provides obstacle reports. This work aims to enhance aviation safety, modernize infrastructure records, and deliver scalable tools to the aviation and machine learning communities.
This paper presents a robust and adaptable control system for tilt-wing aircraft, developed by Dufour Aerospace. The transitional tilt-wing aircraft, Aero2, combines the vertical takeoff/landing capabilities of helicopters with the high-speed range of fixed-wing aircraft. Addressing the inherent control complexities required to maintain control and stability, the developed system employs established control techniques, utilizing linearization at trim points and gain scheduling based on wing tilt. The architecture comprises a Control Allocation module for optimal actuator management, a Control Augmentation System utilizing an LQRI controller enhanced with a feedforward component for precise attitude tracking, and a Unified Velocity Controller for seamless transitions between ground speed tracking in hover and airspeed tracking in cruise. Special challenges unique to transitioning aircraft to ensure control in all axes, including in windy conditions are addressed with operational strategies and control system modifications, validated through flight testing of a subscale and Aero2 aircraft. The resulting control system demonstrates effective velocity and attitude tracking across the flight envelope, enabling reliable piloted flight and automated missions.
This paper presents insights into a comparative approach to down-select on the most suitable pilot control schemes for eVTOL and powered-lift aircraft. The investigation examines three main areas: (1) experimental flight test performance, (2) flight control analysis, and (3) Human-Machine Interface (HMI) factors. Experiments were conducted to evaluate how various inceptor control schemes were perceived by people of various experience levels, ranging from manned aviation pilots with experience in flying F-16 jets, AH-64D helicopters and high-performance turboprop trainers, to unmanned aviation pilots of various backgrounds, such as with remote control (RC) rotorcraft and RC fixed-wing aircraft, and finally to participants with zero experience with either of these. In this experimental surveying study, all participants were briefed on a standardized mission profile and tasked to fly a VTOL drone and a computer based flight simulator using various flight control schemes. Videos were recorded for each test and reviewed for in-depth flight performance and controls scoring and analysis. At the end, feedback on key Human Machine Interface (HMI) factors for each flight control method is obtained. These results in totality provided insights, strengths and weaknesses for each flight control scheme. Upon identification of the most optimal control methodology, a novel energy-based control method to unify both multirotor drone and fixed wing aircraft control logics was developed, future testing will involve incorporating the 3+1 control inceptor scheme with the energy-based control method for further testing and optimization in a simulation environment. The goal of this study is providing a design framework to help eVTOL and powered-lift aircraft designers optimize their pilot control methodology; to become more instinctive, easier to operate, safer and more cost-effective to train new eVTOL and powered-lift pilots and operators.
The transition between hover and forward flight is a critical consideration for eVTOL aircraft development. This transient and aeromechanically complex maneuver is often analyzed using computationally expensive methods that may not be practical for conceptual design. This paper presents a quasi-steady method capable of optimizing transition paths for multi-tiltrotor aircraft using low- to mid-fidelity models while approximating the transient nature of transition. A 3-degree-of-freedom aircraft model with surrogate models for rotor and airframe aerodynamics was developed along with a novel download model based on momentum theory. The optimization formulation minimizes a thrust-based surrogate for induced power while enforcing trim. This allows estimates for energy-optimal transition paths to be calculated even when accurate rotor power predictions are unavailable during early design phases. Important considerations for operating lift-only rotors through transition are identified and an iteratively refined speed schedule for such rotors is presented. The method presented is applied to analyze the RAVEN multi-tiltrotor aircraft. Transition paths at various fixed angles of attack are first developed to characterize operational stall limits. Optimal paths are then calculated for both accelerating and decelerating transition for RAVEN, with results showing that the aircraft behaves optimally as a multicopter at low airspeed and increasingly like a fixed-wing aircraft at higher airspeeds.
The Shake-The-Box technique was applied to experimentally quantify the time-resolved volumetric flow field around a free-flying quadcopter UAV with an overall span of about 0.5 m. State-of-the-art LED illumination and high-speed camera equipment was combined with modern Lagrangian tracer particle tracking and data assimilation techniques, facilitating a measurement volume larger than 1.5m3. The setup allowed for both hover and limited maneuvering of the quadcopter, while resolving even small details of the complex interactional aerodynamics. In hover out of ground effect, the four individual rotor wakes merged into a single jet within a few rotor radii below the rotor planes. Evaluating the mass and momentum fluxes over suitable control volumes yields accurate estimates for the quadcopter's total thrust, the asymmetric thrust distribution between front and back rotors, and the entrainment of external flow through turbulent mixing. Hover in ground effect decreases the power requirement and induces recirculating flow in the center of the four rotors. The outwash pattern is non-uniform with jets developing between the rotors and pointing in radially outward directions. Forward flight cases result in a skewed, rapidly merging wake flanked by the roll-up of two "super-vortices" similar to the wingtip vortices of fixed-wing vehicles.
This paper examines the effect of automation on learning for two different types of pilots, rotary-wing and fixed-wing, on flight maneuvers including hovering, vertical takeoff, en route navigation, and approach and landing. Building on existing research, the performance of 11 rotary-wing pilots and 28 fixed-wing pilots was examined during the final repetition of a flight profile to evaluate the level of proficiency gained in approximately 2 hours of training. Our findings suggest that although rotary-wing pilots benefit from their previous hover and take off experience, automation still improved their performance for these maneuvers. Additionally, fixed-wing pilots benefited from higher automation for hovering, en route navigation, and approach and landing maneuvers. These results are discussed in detail in the following sections, along with recommendations for training programs, curricula designers, and manufacturers in the evolving eVTOL landscape.
Over the last 90 years, many concepts of lifting payload with a single tethered fixed-wing aircraft have been proposed. In this concept, an airplane flies along a quasi-circular flight path and the payload should remain at the center of this circle. The main challenge encountered has been payload stability in hover (i.e., when the payload is fixed in space and the aircraft flies along a quasi-circular path above). In calm conditions, lengthening the tether to reach two or three kilometers (1.5 mile) has been proven to stabilize the payload in an orbit with a radius of the order of 1 meter (3 ft). However, the presence of wind has shown a drastic reduction in payload stability. At the end of the 1990s, a patent proposed to add a thruster-based stabilization device onto the payload but no further studies explored such a concept. This study proposes a new concept inspired by the former. The main difference lies in the addition of a reel-in mechanism to control and stabilize the payload in the vertical direction. This work analyzes the impact of the wind on this new concept in hover. The results have shown a maximum power requirement of 37 kW (60 hp) for the aircraft and 15 kW (20 hp) for the stabilization device to lift a 300 kg (660 lbm) payload fixed in the inertial frame with a 400 m (1,300 ft) long tether. This work has highlighted the high impact of the tether force on the towing airplane and therefore a means to reduce this impact is required.
The rotorcraft community faces significantly higher accident rates compared to fixed-wing commercial aircraft, underscoring the critical need for enhanced safety measures. While Helicopter Flight Data Monitoring programs hold promise in improving safety, their widespread adoption remains limited, partly due to challenges associated with the acquisition and analysis of flight data. This paper proposes a Deep Learning (DL) solution to address safety concerns within the rotorcraft community by efficiently acquiring and analyzing flight data for a more automated and comprehensive safety assessment. Specifically, we leverage data obtained with cost-effective off-the-shelf cameras, and process it through Convolutional Neural Networks for automated detection and classification of gauges from several helicopters' cockpits. Our DL pipeline integrates a classifier for helicopter identification, an object detector for cockpit gauges detection and classification, and a network to infer the reading of each detected gauge. The contribution of this work is two-fold: (1) enhance rotorcraft safety by developing a DL framework capable of detecting, classifying, and inferring gauge readings for different helicopter types, and (2) boost research in the field by constructing a curated dataset valuable for aviation and machine learning communities.
Full flight regime trim strategies are examined for a Lift+Cruise eVTOL aircraft. Control laws are designed for hover, transition, and cruise conditions to satisfy standard flying-qualities requirements based on the characteristic behavior of the vehicle (rotorcraft versus fixed wing) while ensuring realistic motor limits (peak and continuous) are satisfied. CONDUIT® is used to optimize control laws to minimize actuator activity while meeting flying-qualities constraints. Variable-RPM control is shown to be sufficient to satisfy Level 1 flying-qualities requirements in hover and low-speed flight where control surfaces have inadequate control authority. Time domain simulations are presented to verify controller performance and ensure actuator limits are not violated while following step commands. The aircraft is able to follow commands well in all axes and flight regimes. Transition through the full flight regime (hover to cruise) is simulated using a stitched model.
Vertical lifting methods using circling airplanes tethered to a centralized payload have been studied since the 1940s. These methods combine the high efficiency of fixed-wing airplanes with the vertical lifting ability of helicopters. However, such lifting systems must tackle the challenge of accurately controlling the position of the centralized payload in order to be viable. Typically, a kilometer-long tether configuration, subject to aerodynamic damping, is studied to achieve a small orbit radius for the payload, resulting in nearly stationary movement. This article presents the development of a payload control system (PCS) for a circling single-airplane tethered lifting system. A PCS mounted onto the payload compensates for flight path deviations of the airplane and allows the use of a shorter tether because it removes the dependency on aerodynamic forces to position the payload. This article presents the mechanical architecture and the control strategy of the PCS, along with experimental flights done under a DJI Matrice 600 drone to mimic the trajectory of a circling single-airplane. The DJI drone followed a circular path of 16 m in diameter with a period of 14 s during which a payload, including the PCS, was linked to the drone with a 31 m (102 ft) tether. During the experiments, the PCS maintained payloads ranging from 1.6 kg (3.5 lb) to 4.8 kg (10.6 lb) at ∼10 cm (∼4 in) of the target position, regardless of the trajectory deviations of the DJI drone. The PCS is a key feature of this novel vertical lifting method which has the potential to provide an alternative to rotorcraft and multi-rotor drones for cargo delivery
Direct debugging of a vertical takeoff and landing (VTOL) fixed-wing aircraft’s control system can easily result in risk and personnel damage. It is effectively to employ simulation and numerical methods to validate control performance. In this paper, the attitude stabilization controller for VTOL fixed-wing aircraft is designed, and the controller performance is verified by MATLAB and visual simulation software, which significantly increases designed efficiency and safety of the controller. In detail, we first develop the VTOL fixed-wing aircraft’s six degrees of freedom kinematics and dynamics models using Simulink module, and the cascade PID control technique is applied to the VTOL aircraft’s attitude stabilization control. Then the visual simulation program records the flight data and displays the flight course and condition, which can validate the designed controller performance effectively. It can be concluded that the designed VTOL fixed-wing aircraft control visual simulation system, can demonstrate the effectiveness of the control algorithm, which has a wide range of potential applications.
Electric vertical takeoff and landing (eVTOL) aircraft, which is used extensively in both military and civilian fields, has the advantages of good maneuverability, high cruising speed, and low requirements for the takeoff and landing modes. Robust and stable control is crucial to ensuring its safety because the dynamics model of an eVTOL aircraft will change significantly between fixed-wing and vertical takeoff and landing mode. In this paper, we first study the structural characteristics of the eVTOL aircraft and establish its dynamic model by considering typical flight modes and mechanical parameters. Then we design a closed-loop controller based on cascade PID technique. Finally, the effectiveness of the control algorithms is verified based on the semi-physical flight simulation platform, which can lower the development cost of control algorithms significantly. The simulation results demonstrate that the cascade PID control scheme accelerates the implementation of the robust controller, and significantly enhance the stabilization control performance of the aircraft in vertical takeoff and landing mode as well as autonomous navigation mode.
This SAE Aerospace Recommended Practice (ARP) provides design guidelines for aircraft mechanical control systems and components. Topics contained in this document include design requirements, system design and installation guidelines, and component design practices for primary flight controls, secondary flight controls, and utility controls.
While aeromechanics and system element interactions for typical fixed- and rotary-wing aircraft are historically well defined, the complex aerodynamic interactions for tiltrotor aircraft introduces multiple added levels of complexity. This added complexity of an aircraft that operates with the properties of both a vertical takeoff and landing (VTOL) rotary-wing and a fixed-wing aircraft adds dimensions of analysis that are not typically found in other aircraft. Unique complexities arise due to architecture where a wing, used for lift in fast forward flight configuration, is located below a rotor, being used for lift in a VTOL configuration1. Here, the rotor downwash creates a lift-opposing force on the wing, termed 'download'. As such, model-based design and engineering approaches with parallel simulation and system design phases are required, in conjunction with a multi-disciplinary team, in order to solve the complex interactions during the design phases. Given the issue of download on the wings due to rotor downwash reducing fuel-efficiency during VTOL operations, a need to minimize this download arose. This necessitated the design of a system that would lower the download in VTOL and hover operations, while keeping the aerodynamic wing properties in airplane mode; a "morphing wing system" (MoWS). The basis of the morphing wing was to design a wing element which could articulate out of the rotor downwash in VTOL mode and articulate up into a standard wing configuration for aircraft mode. While these goals were unique to tiltrotor aircraft, they were in line with the European Union (EU) Clean Sky 2 (CS2) initiative to reduce CO2 emissions by 20-30% by increasing aircraft fuel efficiency. Since the least fuel-efficient phases of tiltrotor operations are during VTOL and hover, increasing efficiency in these phases, through the design and implementation of the morphing wing system, is shown to reduce overall high-speed VTOL (HSVTOL) operational CO2 emissions4. This paper presents the design of a morphing wing element applied to the Next Generation Civil Tiltrotor – Technology Demonstrator (NGCTR-TD), using a multi-disciplinary design team, in conjunction with the parallel use of a set of simulation models during the design phases. Given the complex interactions of the design, each model in the set took into account different aspects of the design and were integrated together to give a pseudo-live representation of the current design state, as it progressed through the iterative design loops. This led to a rapid design phase, culminating in the successful design of a morphing wing system that could reduce the download on the wing during VTOL and hover operations of a tiltrotor aircraft.
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