Browse Topic: Fixed-wing aircraft
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.
This SAE Aerospace Recommended Practice (ARP) covers a brief discussion of the icing problem in aircraft fuel systems and the different means that have been used to test for icing. Fuel preparation and icing test procedures for aircraft fuel systems and components are proposed herein as a recommended practice to be used for fixed wing and rotary-wing aircraft within their operational environment. This ARP mostly addresses aircraft fuel system level testing and provides a means to address the requirements of FAR 14 CFR § 23.951(c), § 25.951(c), § 27.951(c), and § 29.951(c). In the context of this ARP, the engine and the auxiliary power unit (APU) are not considered to be components of the aircraft fuel system. However, some of the methods described in this document can be applied to the engine, APU, and other aircraft (system or component level) icing tests. This revision does not completely address new developments in ice accretion and release resulting from internal flow in tubing
ABSTRACT 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
ABSTRACT 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
ABSTRACT 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.
ABSTRACT 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
ABSTRACT 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
ABSTRACT 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
ABSTRACT 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
ABSTRACT 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
ABSTRACT 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.
ABSTRACT 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
ABSTRACT 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.
ABSTRACT 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
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
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
This SAE Aerospace Standard (AS) contains landing gear strength and rigidity requirements which, in combination with other applicable specifications, define the structural design, analysis, test, and data requirements for fixed wing piloted airplanes. These requirements include, but are not limited to, the following: a General specifications: 1 The shock-absorption characteristics and strength of landing-gear units and the strength and rigidity of their control systems and of their carry-through structures. Requirements for wheels, tires, and brakes as they affect air vehicle ground loads are also included. 2 The strength of structures integral with the airplane provided for transmitting catapulting forces to the airplanes, and for engaging shipboard and shore-based arresting gear, and barricades. 3 The strength of anchor-line clamps, and the airplane strength for hoisting, jacking, towing, tie-down, and other ground- or deck-handling conditions. 4 Structural design, analysis, and test
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This SAE Aerospace Recommended Practice (ARP) provides the qualification test procedure requirements for low wattage halogen lamps (less than 35 watts) intended for use primarily in aircraft applications. The purpose of these tests is to provide a laboratory means of determining the performance characteristics of lamps under airplane power and other environmental conditions and to verify the integrity of the lamp design and production processes.
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.
Gust load alleviation is an increasing concern for the design of fixed-wing aircraft with ultra-high aspect wings. It may have detrimental impacts on flight including increased structural and aerodynamic loads, structural deformation, and decreased flight dynamic performance. Innovators at NASA's Langley Research Center have developed a mechanical solution to control gust-load on fixed plane wings enabling significant improvement over alleviation devices currently in use.
This SAE Aerospace Recommended Practice (ARP) covers the recommended criteria and performance requirements for the design and installation of land-based aircraft emergency and operational arresting hooks for use on runway arresting systems. Design criteria for fully operational hooks and for carrier-based aircraft hook installations are contained in specification MIL-A-18717.
This document provides information regarding ice detector technology and design. The SAE document AS5498 provides detailed information regarding the requirements, specifications, qualification, and certification of icing detection systems. This document is not meant to replace AS5498, but to enhance it by considering unique aspects of sensing technology and, in particular, those that may not be certificated at the time of this revision. To that end, an effort has been made not to duplicate information contained in AS5498. Icing rate information is included where applicable. The primary application is associated with ice forming on the leading edges of airfoils and inlets while the aircraft is in flight. Information related to detection of ice over cold fuel tanks and icing at low-velocity operation is included. The material is primarily applicable to fixed-wing aircraft. Unique requirements for engine inlets and rotorcraft are also provided.
ABSTRACT This paper presents results of a human machine interface (HMI) evaluation that examined representative flight deck tasks with a large area touchscreen installed in a ride quality simulator that replicated rotary wing vibration profiles. Touchscreens have made their way onto the flight deck of many fixed-wing aircraft and recently into rotary-wing cockpits as well. As such, there is a need to better understand how task performance is impacted by the unique vibratory environment encountered in helicopters. A large area touchscreen (LAD) was evaluated by 14 pilots conducting various touch tasks (target selection, data entry, swiping, long press and zoom), under three varying levels of vibration with and without flight gloves. Performance was assessed objectively (time to completion, touch accuracy, error rates) and subjectively (usability, musculoskeletal discomfort, and video footage). Design recommendations are made for display interface design, including target size, data
ABSTRACT Joby Aviation is developing a six propeller, all electric vertical takeoff and landing piloted air taxi aircraft. The aircraft is designed for high density operations near residences and workplaces, so it is imperative that the acoustic emissions of the aircraft are minimized for community acceptance. It is important to compare not just the absolute sound levels but also the sound quality with conventional aircraft already known to the public. To showcase the difference between the Joby aircraft and similarly sized aircraft for a level flyover condition, Joby arranged a flight demonstration with two conventional fixed-wing aircraft and three commercial helicopters. All the aircraft were flown at approximately 100 knots (51 m/s) and 1500 feet (457 m) above ground level within minutes of each other in the same location to minimize variability. They were measured with the same equipment and processing methods. The results show that the peak Joby aircraft sound pressure level was
ABSTRACT After crossing the North Atlantic Ocean in the early morning hours of September 18, 1946, a Sabena Airlines DC-4 OO-CBG, carrying 37 passengers and seven crew members, crashed in dense fog and drizzle 22 miles short of the Gander, Newfoundland Airport. Considered by many to be the first major civilian airliner crash, it was also the first major U.S. Coast Guard rescue mission with helicopters. Working together, the Coast Guard, the U.S. Army, and Canadian personnel used Sikorsky helicopters and fixed-wing aircraft to successfully complete this heroic rescue of 18 survivors in what the media considered “the Miracle at Gander.†This inter-service and civilian team exhibited unrivaled courage, innovation, and compassion, resulting in a nearly flawless operation. What happened at Gander would also serve as the turning point for future Coast Guard rescue mission use of the helicopter, which many, then and since, have considered to be “God’s machine.â€
ABSTRACT Cold expansion has been successfully used in aerospace structures, including vertical lift airframes to repair and prevent fatigue damage for more than 50 years. PartWorks is innovating the cold expansion process, parts and tooling for use in repairing corroded fastener holes (U.S. Patent 11,255,371). PartWorks is participating in a two phase development and demonstration program, first for the US Navy (Office of Naval Research/ONR) starting in 2017, and more recently for the United States Air Force (Air Force Research Lab/AFRL) for repairs to bolt holes on aerospace structures with metal/carbon-fiber composite skins. These locations in aerospace structures for vertical lift or fixed wing have demonstrated greater levels of corrosion when compared to all-metal structural skin due to galvanic corrosion between metal and carbon fiber composites. Existing repair methods for these metal/carbon fiber composite skin bolt hole/fastener sites often involve extensive removal of
ABSTRACT This paper investigates the application of K-Means Clustering algorithms to traditional aircraft conceptual-level weight estimation techniques. As a proof of concept demonstration, application was narrowed to fuselage basic weight estimation with expansion to additional component weights as a planned follow on activity. A variety of weight sources were parsed and curated to produce a large, diverse dataset consisting of 82 separate aircraft with a corresponding new universal baseline regression to compare against. A K-Means Clustering algorithm was then employed that sorted aircraft into groupings based on configuration as well as topology and created an associated regression for each grouping. Configuration-based groupings utilized information such as a high-level abstraction of the structural layout as well as whether the aircraft is a fixed-wing or rotary-wing vehicle. Topology-cased groupings utilized information such as landing gear location and possession of a cargo ramp
This document contains minimum operational performance specification (MOPS) of active on-board INFLIGHT ICING DETECTION SYSTEMS (FIDS). This MOPS specifies FIDS operational performance which is the minimum necessary to satisfy regulatory requirements for the design and manufacture of the equipment to a minimum standard and guidance towards acceptable means of compliance when installed on an AIRCRAFT. Detection of ICE accreted on the AIRCRAFT during ground operations is not considered in this document. This MOPS was written for the use of FIDS on AIRCRAFT as defined in 1.3 and 2.3. Expected minimum performance specifications for FIDS and their functions are provided in Section 3. The minimum performance requirements as defined in Section 3 do not consider SYSTEM performance as installed on the AIRCRAFT. Performance in excess of the minimum performance may be required by the SYSTEM installed on an AIRCRAFT in order to meet regulatory or operational requirements. This topic is considered
Over the last decade the numbers, types, and capabilities of unmanned aerial vehicles (UAVs) available to military forces, domestic security forces, non-state actors, commercial interests, and even private citizens have grown substantially. Offerings range from large, expensive fixed-wing high-altitude/long- endurance UAVs, which are affordable only to nation states, down to low-cost, low-flying small and micro vertical take-off- and-landing (VTOL) models available to everyone. Both armed and unarmed models are marketed. Some unarmed models are being upgraded with aftermarket lethal capabilities by third parties or private individuals using do-it-yourself techniques.
This SAE Aerospace Information Report (AIR) provides descriptions of trimmable horizontal stabilizer actuators that are installed on a variety of transport and business aircraft systems.
This document deals with ground and flight test of airplane installed Environmental Control Systems (ECS), Figure 1. The ECS provide an environment, controlled within specified operational limits of comfort and safety, for humans, animals, and equipment. These limits include the following: pressure, temperature, humidity, ventilation air velocity, ventilation rate, wall temperature, audible noise, vibration, and environment composition (ozone, contaminants, etc.). The ECS are composed of equipment, controls, and indicators that supply, distribute, recycle and exhaust air to maintain the desired environment.
This SAE Aerospace Recommended Practice (ARP) sets forth criteria for the installation, inflation, inspection, and maintenance of aircraft tires and the maintenance of the operating environment to ensure the safety of support personnel and the safe operation of the aircraft.
This SAE Aerospace Recommended Practice (ARP) reviews the basics of NVIS compatibility and discusses the specific illuminated pushbutton switch and indicator requirements for sunlight readability, color, luminance, and NVIS radiance when used in NVIS compatible cockpits. The recommendations and special considerations set forth in this document are made to give the design engineer a better understanding of MIL-L-85762A and MIL-STD-3009 NVIS compatibility requirements and to provide information on the visual characteristics of NVIS compatible pushbutton switch and indicators. The recommendations are primarly for military aircraft since civilian aircraft FAR requirements typically do not cover NVIS applications with the exception of those covered by RTCA/DO-275.
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