bluuebunny/crossref_metadata_2025 huggingface dataset:
Towards Validation of a Dynamic Interface Simulation using Flight Test Data
Authors:   The Pennsylvania State University, Christoffel Tyler , Hendrick Chris , Thedin Regis , Horn Joseph , Schmitz Sven
Published: July 2023

A method for developing and performing a rotorcraft flight simulation in a bluff body airwake is investigated and compared to flight test data. This method is broadly composed of two parts: an atmospheric boundary layer computational solution that is unsteady and time-accurate, and a UH-60 flight dynamics program that can be coupled with an airwake developed from the atmospheric boundary layer solution. The flight dynamics program is a MATLAB/SIMULINK implementation of the GENHEL model. The computational fluid dynamics airwake solution is developed to recreate the airwake present for the validation case flight tests that were used to collect the flight test data. The validation case f light test data was collected from a variety of station-keeping tasks performed in the wake of a hangar on land. Two kinds of flight simulations were performed: piloted simulations in a flight simulator facility and flight simulations performed using a pilot model. Comparisons of the power spectral density analyses of pilot control stick activity reveal that pilots in the simulated flight tests use a generally higher level of control activity energy than the pilots of the f light test validation case. Limited simulator flight test data showed sizeable differences in pilot control activity for the same simulated flight task flown by different pilots. Significant unknowns remain in comparing a simulated flight to a physical flight. The pilot model was not used to compare simulated flights to validation case flights, but was useful for comparing different flight simulation cases to each other as well as for analyzing sensitivity of flight simulations to positioning error within a simulated airwake. The pilot model flight simulations show that flight tasks performed in an airwake produced using a high-fidelity atmospheric boundary layer simulation require more pilot control input power than airwakes made using a comparable mean wind speed uniform inflow.
A Virtual Reality Approach to Piloted Flight Simulation
Authors:   Politecnico di Milano, Daniele Matteo , Zanoni Andrea , Quaranta Giuseppe , Masarati Pierangelo
Published: July 2023

A pilot-in-the-loop simulation environment aimed at increasing pilot visual cues without the need of expensive visualization hardware is presented. The proposed solution relies on Virtual Reality (VR) to enhance the pilot immersion in the simulated environment. The project is integrated in the development of the complete simulation framework FRAME-Sim, focused on simulating rotorcraft in early conceptual design stages, and therefore relying on physics-based multibody simulation of the rotorcraft flight dynamics and free/open source software. FRAME-Sim visual environments that are being used include products available to the market as well as homemade solutions developed to obtain the highest level of versatility during the simulation.
A Concept of Operations for Advanced Manufacturing of Small Unmanned Aircraft Systems for Marine Squads
Authors:   CCDC ARL, Gerdes John , Holder Eric , Beals Nathan , Humann James
Published: July 2023

A concept of operations (CONOPS) is proposed for providing U.S. Marine Corps squads with mission-tailored small unmanned aerial systems (SUASs) using additive manufacturing. This is done on a tactically relevant timescale, ensuring that design improvements can be fielded far faster than with a traditional acquisition process. The CONOPS includes the following stages: mission planning and UAS selection/allocation/modification, order production and transmission, additive manufacturing, assembly and quality control, packaging and delivery, field assembly, field training and guidance, pre-mission checks, and mission use. The stages were developed through extensive discussions and interviews with Marine end users and iterated through several rounds of realistic wargaming. A comprehensive one-week training session was created that equipped Marines to demonstrate all design, manufacturing, and operational skills outlined in the CONOPS.
Dynamic Performance Investigation for Tilt-rotor Aircraft
Authors:   University of Glasgow, Yuan Ye , Thomson Douglas , Anderson David
Published: July 2023

The tiltrotor aircraft has the capability to extend its performance characteristics compared to the conventional helicopter. However, the performance features, namely the maximum flight duration and flight range, are determined by a series of factors, such as the nacelle angle, the aerodynamic interference, and the effect of the fuel consumption. In this article, a novel performance investigation method is put forward combining the flight dynamics model, the automatic differentiation arithmetic embedded inverse simulation method, and the fuel consumption model. Then, the maximum flight duration and range are calculated and analyzed. The results indicate that the maximum flight range of the example XV-15 tiltrotor is 837 km, and its maximum flight duration is 3.86 h, and both of the results occurs when the tiltrotor aircraft is in the airplane mode. Also, the fuel consumption is an influential aspect, and the control strategy should be altered across the flight to maintain the best performance. Lastly, the calculation efficiency of the method is validated, and the results show that the time-cost is lower than the real-time period, suggesting the real-time requirement is still satisfied.
Additive Manufacturing Implementation in Rotorcraft Sustainment
Authors:   Sikorsky a Lockheed Martin Company, C. William
Published: July 2023

The use of additive manufacturing to produce rotorcraft components is challenging due to demanding material property performance requirements. The need to contend with high cycle fatigue, fretting, and vibratory loading conditions has driven our industry to use high pedigree materials that are fully characterized and with well established and understood processes to transform them into parts. No additive manufacturing processes or materials approach this level of understanding today, making it difficult to utilize the technology to manufacture components designed to be produced using conventional methods. This has limited consideration of the technology in the sustainment segment of our business.

Customers have a quite different perspective. Additive manufacturing has been identified by the Department of Defense as a critical technology for the sustainment of their vehicles and weapons systems. Each branch of the military and the Defense Logistics Agency has resources and facilities established to support the proliferation of 3D printing capability. They have all experienced success producing shop aides, tools, prototypes, and surrogate parts to address real time, point of use challenges in depots and in some cases, at or near the battlefield. This success has prompted the DoD to challenge our industry to find ways to utilize this technology to address component shortages due to obsolescence, lost tooling, or a lack of qualified sources.

This paper presents Sikorsky's activities and programs that have been initiated to meet this challenge. This will include approaches for component characterization and business case analysis used to evaluate the practicality of using additively manufactured surrogate parts in legacy vehicles.
Manned-Unmanned Teaming Challenges in the Maritime Environment
Authors:   ESG Elektroniksystem-und Logistik GmbH, Banas Jacquelyn , Mehling Tim , Paul Tobias , Cords Andreas
Published: July 2023

When properly implemented, Manned-Unmanned Teaming (MUM-T) allows for an optimized blending of high-value, manned airborne vehicles with expendable, relatively inexpensive unmanned resources within a coordinated mission. This enables human operators and crew to focus on the most sensitive and complex mission tasks, while limiting their usage and exposure to dangerous environments. The sensor and communication capabilities of even simple unmanned vehicles can enhance the situational awareness and reach of manned vehicle crews; however, controlling, monitoring, and avoiding collisions with these additional vehicles can also quickly increase crew workload in an already overtaxed environment. This paper discusses the challenges associated with bringing MUM-T operations into the maritime environment and offers suggestions for modifications to the teaming structure, operations, and equipment in this setting. The experimental setup and results from the German Army Aviation's MUM-T program1 are compared to maritime requirements and available assets, based on interviews with professional maritime test pilots and relevant operator publications. Expected roles for UAVs in maritime MUM-T operations would include intelligence-gathering, BLOS target designating, and relaying communications. Results of prior research and testing suggest that maritime crews will see little benefit today from MUM-T operations, given their current capabilities and technologies. More sophisticated displays for manned assets, advanced autonomy and robustness for unmanned assets, modified CONOPS, and improved long-range communication methods would be necessary for proper resource management in maritime missions. In particular, teams should require task-based UAV control, weather-proofed and reliable autonomous vehicles, and TLD datalink systems (such as Link 16).
Development of Automatic Controllers and Piloting Aid Functions for Enhancement of UAV/OPV Autorotation Management
Authors:   The French Aerospace Lab ONERA, Binet Laurent ,   US Army CCDC AvMC, Brackbill Dr. , Quinn David
Published: July 2023

An automated approach for autorotation management is proposed for unmanned or optionally piloted rotary wing air vehicles. The intent of this approach is to take into account all aspects of the traditional helicopter autorotation maneuver, from the initial system failure, through autorotation entry, stabilized descent, guidance and control, to the final flare and landing. Wind conditions as well as landing zone constraints (e.g. final heading) are considered in this approach. The overall goal is to develop a modeling and simulation framework where different aspects of the problem can be tested and validated towards qualification for use on board an aircraft. A secondary aim is to determine what aspects of the automated control for unmanned vehicles can be applied as aids (cues, guidance) or automated functions to optionally piloted vehicles. This modular simulation framework has been developed and various individual, purpose-built control or guidance algorithms can be independently tested and validated.
Fuel Cell Application for Small eVTOL UAVs
Authors:   Technical University of Munich (TUM), Seren Thomas , Hornung Mirko
Published: July 2023

This paper analyses the possibility of using hydrogen fuel cells as main energy provider for small to medium-sized eVTOL UAVs. A simplified model for eVTOL UAVs, which covers all relevant areas of aircraft design, including aerodynamics, structural mechanics, propulsion and systems modelling, is presented. Sensitivity studies with various design parameters, including aspect ratio and design cruise speed are performed to show their influence on the configurations’ performance. A comparison between pure battery electric and fuel cell hybrid UAVs is taken. The result of this paper is, that a hydrogen fuel cell hybrid configuration can have a better performance than a battery electric and it can be worth the effort to implement the fuel cell. To achieve this, the mission should require a long endurance and have hover and transition times reduced as far as possible, which both enable the high energy density of the hydrogen system to unfold its full potential. Also, the aircraft needs to be as aerodynamic efficient as possible in order to reduce the fixed weight of the hydrogen fuel cell. Respecting these requirements and accepting a reduced versatility of the aircraft, a fuel cell hybrid eVTOL UAV can easily outperform one with a pure battery electric power supply.
Prediction on Nonlinear Flight Dynamics of a Quad-rotor UAV with rotor aerodynamic analysis under Gust
Authors:   Seoul National University, Park SunHoo ,   Korea Aerospace Research Institute, Park Youngmin , Lee Sihun , Shin SangJoon , Yoo JeongUk
Published: July 2023

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.
An Empirical Inlet Pressure Recovery Model for Engine Inlet Barrier Filters for Rotorcraft Applications
Authors:   US Army CCDC AvMC, Zhang Man , Beeman Mark
Published: July 2023

From the Navier-Stokes momentum equation, this paper presents the application of Darcy's law for flows at moderate Reynolds numbers and thin filter media in the development of an empirical model of engine inlet total pressure recovery for rotorcraft (helicopters in particular) equipped with an Engine Inlet Barrier Filter (EIBF). The assumptions and limitations of the empirical model are discussed. The model treats the inlet filter media, structural features, and geometry as an integrated entity and has been validated using flight test data for three inlet configurations. The validation has been performed by directly comparing the model-predicted inlet recovery map with inlet total pressure measurements. The potential applications of the model are also discussed.
Computational Thermal Analysis and Testing to Improve Loss of Lubrication Performance of Helicopter Transmissions
Authors:   Kawasaki Heavy Industries Ltd., Ogasawara Kenta , Arisawa Hidenori , Hashimoto Hironori , Hayasaka Akira , Shinoda Yuji , Yamamoto Hiroki
Published: July 2023

The subject of the research in this paper is to achieve longer and more reliable loss of lubrication (LoL) performance. The research developed the computational thermal analysis model including airflow inside and outside transmissions to predict thermal behavior under LoL. And the research conducted the LoL performance test using the modified BK117D2 (EC145T2) main transmission optimally designed with the computational analysis. Data measurement during the test included temperatures of rotating components such as gears and bearings, temperature distribution on the gear teeth, and airflow speeds and heat fluxes around the transmission in order to analysis the test result. The test procedure was according to the EASA new rule, which has severer test condition than the past rule. The test result shows longer LoL performance than the past test of the BK117D2 main transmission. And the computational analysis model was validated with the measured data. Then, the failure cause and possible future improvements were investigated based on the measured data and the analysis model. Finally the research concluded the modifications on the transmission, the computational analysis model and the measured data are able to make LoL performance longer and more reliable.
Contact Pattern Development of the CH-53K MGB with Split-Path Gear-Train
Authors:   Sikorsky a Lockheed Martin Company, He Shulin ,   NAVAIRSYSCOM HQ, Leigh Leslie , Gmiyra Yryiy , Pierce Chris
Published: July 2023

The US Marines CH-53K King Stallion replaces the venerable CH-53E Super Stallion and delivers almost triple the payload over the primary mission radius of 110 nm, while maintaining the same shipboard footprint. In order to achieve this the main gearbox design had to achieve an unprecedented power density. The main gearbox is a split torque gear box with three input clusters and four dual herringbone drive pinions per cluster. This paper addresses the challenges related to contact pattern development of the MGB 3rd-stage gear meshes.
Static Transmission Error Analysis of a Hybrid Spur Gear Drivetrain
Authors:   The Pennsylvania State University, Gauntt Sean , Campbell Robert , McIntyre Sean
Published: July 2023

This study presents static analyses of transmission error in a single gear pair gearbox for six pairs of hybrid composite-steel spur gear designs developed in a previously presented optimization effort. The results were compared to those of the same gearbox featuring a baseline all-steel gear pair. The gearbox models were developed in the commercial software RomaxDESIGNER R17. A tooth stiffness analysis was also conducted to replace the tooth stiffness values calculated in Romax with values that consider the web effects on tooth stiffness. These stiffnesses are used to calculate the mesh stiffness. This analysis showed a 2-5% difference in average tooth stiffness of the hybrid gears compared to the steel gear. The transmission error analysis with the new tooth stiffnesses showed a 1-3% increase in the transverse error in for hybrid gears compared to the baseline steel.
Performance Deterioration of Rotorcraft Engines fitted with Particle Separators
Authors:   University of Manchester, Bojdo Nicholas , Appleton Wesley , Ellis Matthew , Filippone Antonio , Hee Jee-Loong
Published: July 2023

Military rotorcraft engines operating in harsh environments routinely ingest large quantities of mineral dust, which can degrade components and ultimately reduce operability. Time off-wing for unscheduled maintenance is a costly burden, both financially and operationally. Rapidly predicting engine deterioration rates as a function of the mission presents an opportunity to optimise flow of supplies, better manage fleets, and perform safety risk assessments when dust loading is expected to be particularly high. In the current contribution, we present our ongoing efforts in this field with a new methodology for assessing the effectiveness of inertial particle separators and quantifying the changes they impart to the inbound dust. We demonstrate that both the concentration reduction and the modification to the particle size distribution can be made on the basis of a single independent variable- a generalised Stokes number for inertial particle separators- and a single performance parameter- the corrected separation efficiency. To develop these parameters we conduct numerical simulations of the flow through a generic axi-symmetric inertial particle separator, over a range of five mass flow rates, three scavenge mass flow rates, and 16 particle diameters. In addition to this, a framework is presented to enable an estimation of the dust concentration at the engine intake. This is achieved by correlating the total wake strength to an existing dust landing trial dataset. A coupled rotorcraft-engine model is then used to combined the two methodologies to investigate the influence of engine mass flow rate on dust ingestion rate. A weak non-linear relationship is observed, which arises due to the simultaneous increase in wake strength with engine mass flow rate as rotor power requirements increase. The additional dust stirred up by the stronger wake leads causes this non-linearity. Finally, we show that an improvement in separation efficiency caused by higher engine mass flow rate is far outweighed by the associated increase in dust loading in this condition.
Comparison of Variator Technologies for Variable Rotor Speed Drivetrains for Rotorcraft
Authors:   Zoerkler Gears GmbH, Amri Hanns ,   Vienna Univ. of Technology - TU Wien, Donner Florian , Braumann Lorenz , Huber Felix , Weigand Michael
Published: July 2023

The investigation presented in this paper is part of the international research project VARI-SPEED, which aims to invent a mass optimized speed variable drivetrain comprising a main gearbox with variable transmission ratio and a rotor suitable for rotor speed variation. A mass estimation model for the Sikorsky UH-60A drivetrain including a compound split was set up. Hydraulic, electric and mechanic variator technologies were investigated regarding their mass, torque and RPM properties. An optimization model was set up to find: 1.) The best variator technology for the mass optimized drivetrain. 2.) The best drivetrain for the mass optimized variator technology and 3.) The mass minimum if variator and drivetrain are considered both in the optimization loop. The research is performed to find out the influence of the variator technology on the mass and the design of the speed variable drivetrain. Furthermore, it is investigated, whether there is a preferable variator technology for rotor speed variation in rotorcraft. The investigation showed that the variator module has a significant influence on the optimal solution and that an individual optimization strategy is necessary for different drivetrain architectures as well as for different variator technologies. The electric variator technology seems to have the highest potential to enable an efficient variable rotor speed technology. At the moment the design is too heavy to gain benefits in efficiency. The mass estimation and optimization of the whole drivetrain including the variator is the basis to enable an assessment of usability of the variable rotor speed technology. Variation of the rotor speed within the drivetrain enables the turboshaft engine, the rotor and the auxiliary units each to operate at their optimal speeds. Rotor speed variation can overcome the divergent requirements between hover and fast forward flight, which is important for future rotorcraft like inventions in Future Vertical Lift (FVL) in the USA and CleanSky in Europe. Furthermore, it increases the efficiency, decreases fuel consumption andCO2- emission and reduces noise and environmental impact of rotorcraft.
Embedded Sensing for Gas Turbine Engine Component Health Monitoring
Authors:   US Army CCDC - ARL, Murugan Muthuvel ,   Epsilon Optics Ltd., Caesley Roger , Ghoshal Anindya , Walock Michael , Knapp Robert
Published: July 2023

Current rotorcraft gas turbine engines typically use titanium alloys and steel for compressor section and single-crystal nickel superalloys for the hot-section turbine stator vanes and rotor blades. However, these material selections are rapidly changing due to increased requirements on power-density and efficiency. Future Army gas turbine engines will be using ceramic matrix composites for many high temperature engine components due to their low density and improved durability in high temperature environment. The gas turbine industry is also actively developing adaptive concept technologies for production and assembly of modular gas turbine engine components with integrated sensing. In order to actively monitor engine components for extended seamless operation and improved reliability, it is essential to have intelligent embedded sensing to monitor the health of critical components in engines. Under this U.S. Army Foreign Technology Assessment Support (FTAS) program funded research project, surface bonded and embedded sensor patches from a U.K.-based company, Epsilon Optics Ltd., were experimentally evaluated to measure temperature responses on typical propulsion component material coupons. The temperature responses from this foreign technology sensor were assessed using a thermomechanical fatigue tester with a built-in furnace to conduct thermal cycling durability experiments. The experimental results obtained from the durability performance of this fiber-optic based embedded sensor are reported in this paper. This sensor technology upon maturation to higher TRL (Technology Readiness Level) levels can greatly reduce the lifecycle cost of future Army gas turbine engines.
Green House Gas (GHG) Reduction Study for the Rotorcraft Industry
Authors:   Bell Textron, Tjandra Albertus ,   Airbus Helicopters, Routhieau Vincent ,   National Research Council Canada, Chishty Wajid ,   The French Aerospace Lab ONERA, Basset Pierre-Marie ,   Pratt & Whitney Canada, Peluso Robert ,   Safran Helicopter Engines, Bérat Claude
Published: July 2023

The global aviation industry adopted a set of targets to mitigate CO2 emissions resulting from air transportation in 2009. The engine fuel burn is the main driver of CO2 emission; hence it will be the focus of this study. Rotorcraft are designed for supporting different types of missions or operations that are different from fixed wing aircraft. For this reason, the rotorcraft strategy for addressing the carbon impact should mainly target the new emerging technologies that will assist in reducing the fuel consumption and the deployment of Sustainable Aviation Fuels (SAF). This paper presents a forecast of the contribution level that could be achieved by rotorcraft industry in CO2 emission reduction in the period up to 2050. A projection of growth in civil rotorcraft fleet worldwide is provided as the starting point. Several new emerging technologies for both rotorcraft and engine together with the implementation scheme and their projected positive net impact on CO2 emission level are considered. Further, the contribution from SAF deployment in rotorcraft operation is analyzed. It is generally recognized that as much as 80% reduction in overall CO2 life cycle emission can be achieved from SAF relative to the fossil-based fuels or Conventional Aviation Fuels (CAF). However, some critical parameters used in predicting the SAF benefits remain uncertain. These pertain to fuel resources, economy, investment and policies. Therefore, consistent with previous studies, several fuel substitution scenarios are considered ranging from the most conservative to an optimistic projection.
Artificial Intelligence for Helicopter Safety: Head-Pose Estimation in the Cockpit
Authors:   Rowan University, Feuerstein Eric ,   Federal Aviation Administration, Johnson Charles , Rasool Dr. , Bouaynaya Dr. , Ravi Dr.
Published: July 2023

This paper discusses a novel method for improving rotorcraft safety. A new algorithm is proposed for estimating the head position of helicopter pilots and copilots using onboard cockpit videos. Cockpit videos offer the ability for crash analysts or incident investigation to understand not only the aircraft state but also the pilot and copilot's actions in a potentially unsafe situation. In addition, head pose information can also be used to improve the overall scanning techniques used by pilots or to research which technologies can assist the pilots in focusing more attention out of cockpit, rather than down at the instrument panel. Two algorithms were created to provide possible solutions to the problem of head pose estimation: a hybrid computer vision algorithm that utilizes deep learning based detectors, and a purely deep learning algorithm. The purely deep learning algorithm was able to correctly classify 91.49% of copilot head positions in a real-world flight video.
Gear Rim Failure Prediction Based on Fracture Mechanics
Authors:   Sikorsky a Lockheed Martin Company, Xu Biqiang
Published: July 2023

Gear design changes impact on gear crack propagation trajectory is investigated through numerical study. General purpose linear elastic fracture mechanics software, FRANC2D and FRANC3D, are used to simulate 2D and 3D gear crack propagation. FRANC can model non-planner, arbitrary shape crack surface for crack tip stress distributions, stress intensity factors, and crack propagation analyses. Maximum tensile stress and NASGRO4 fatigue crack growth models are employed to predict crack propagation direction and life. Three-dimensional idler gear crack propagation simulation shows the predicted crack trajectory is close to the field observation. Various 2D models are simulated to investigate the crack trajectory impact factors and design strategies to prevent gear rim failure. As shown in previous studies, the initial crack position and orientation play pivot role to control gear failure mode - tooth or rim. For a fixed crack position, this study shows the ratio between bend stress and centrifugal stress dominates gear fracture mode. The less centrifugal stress, the crack more likely to break tooth, while lower bend stress more likely lead to break rim. To prevent rim failure through increasing the rim thickness results in a significant weight penalty. The larger the gear, more the weight penalty. Based on the simulation results, the recommended design strategy is to evaluate gear rim failure risk during the gear train layout phase. It is difficult to be improved at the individual gear design phase.
Development of a Rotorcraft Structural Integrity Program Master Plan for Future Vertical Lift
Authors:   The Boeing Company, Chiu Lisa ,   Sikorsky a Lockheed Martin Company, Krastel Matthias ,   US Army CCDC AvMC, Lorthridge Derrell , McCarthy Dennis
Published: July 2023

Under the Rotorcraft Structural Integrity Program (RSIP) Pilot Demonstration effort, the requirements defined in MILSTD-3063 were applied to a Future Vertical Lift (FVL) representative, model performance specification objective aircraft to demonstrate a standardized RSIP process. This paper covers application of the MIL-STD-3063 approach on SB>1 DEFIANTTM airframe structural components and presents the evolution of the resulting RSIP Master Plan. Elements of the resulting Master Plan are discussed in detail. The Master Plan is the basis for collaborative establishment of structural integrity with an efficient and effective airworthiness substantiation footprint. The discussion includes case studies of the application of logic flow to requirements in MIL-STD-3063 for the determination of specific, relevant action items to airframe structural demonstration components. Execution of this pilot effort led to lessons learned and highlighted feedback to inform the ongoing development of the MIL-STD-3063 process, through ongoing collaboration between the SB>1 DEFIANTTM team and the U.S. Army.
Fatigue Life Improvement in Hierarchically Organized Nanocomposites for Application to Rotorcrafts
Authors:   Rensselaer Polytechnic Institute, Kamble Mithil , Koratkar Nikhil , Lakhnot Aniruddha , Picu Catain
Published: July 2023

Carbon fiber reinforced polymer composites (CFRP) are extensively used as structural components in rotorcraft applications. Here, we report considerable improvement in the fatigue life of CFRP through the infiltration of nanoscale silica particles into the epoxy resin matrix (nanoCFRP). Fumed silica nanoparticles were initially added to the epoxy resin to prepare epoxy-silica nanocomposites, which were demonstrated to have superior fracture and fatigue properties. Fractographic analysis indicated presence of various key toughening mechanisms including crack deflection, plastic void growth as well as a hitherto unreported heterogeneity induced mesoscale toughening effect. The epoxy-silica nanocomposite resin was then used as the matrix material to fabricate nanoCFRP. Cyclic flexural bending tests indicate significant fatigue life enhancement for the nanoCFRP. The enhancement is especially pronounced in the high cycle fatigue regime. This enhancement in high cycle fatigue is indicative of transfer of small-scale toughening mechanisms from the silica-epoxy nanocomposite resin to the nanoCFRP system. Such nanoCFRP show promise to improve the fatigue life and reduce the operational/maintenance cost for next generation rotorcraft.
Engineering Challenges To Reinvent The Sky
Authors:   Dassault Systèmes, Licata Roberto
Published: July 2023

Several electrical vertical take-off and landing (eVTOL) concepts have emerged from startups, to propose new sustainable mobility experiences. As opposed to traditional players in aircraft manufacturing, these "shakers" are innovating around first-of-a-kind, novel configurations of fully electric air taxis with distributed propulsion and tilt rotors. While the eVTOL development is itself a challenge, being a startup builds upon additional challenges to be successful: they need to be first on the market and reach a functioning prototype as soon as possible, they need to be agile, be unique and propose a mobility experience. Lastly, they need to reach type certificate for their vehicle - something not yet achieved and with few months-old regulatory guidance. The tools to be used by the startups and the associated business processes to be implemented are of critical importance to tackle the engineering challenges and to answer the ambition of the startups. Systems engineering and simulation are on the path for reinventing the sky, around a single business platform on the cloud.
Integration of Model-Based Systems Engineering and a Modular Open System Approach using DevSecOps with Agile Software Methods
Authors:   L3Harris, DuBois Thomas ,   JHNA Inc., Stough John ,   Leidos, Linden David ,   SigmaTech, Walsh David , Goebel Christopher , Matthews Robert
Published: July 2023

One of the most significant barriers to adoption of Model-Based Systems Engineering (MBSE) (Ref. 1) and the Modular Open System Approach (MOSA) (Ref. 2) is a cost-effective and commonly understood process that combines the best of both. Such a process must earn its way as a replacement for traditional processes used for the development of embedded software. Most, if not all, developers of embedded flight software have development processes that have evolved over many years. This creates a situation in which the one-time expense of conversion to a new process can be cost prohibitive. As such, adoption of MBSE has been limited and compliance with the intent of MOSA statutory and regulatory requirements has been mainly conformance to an open standard. Systems can be built that are modular but not open. Modularity can be a desirable design objective for quality systems engineering (such as the separation of concerns or encapsulation of functionality) apart from the open systems qualities of portability, reusability, maintainability, and so forth. This results in adoption of closed practices in the use of modeling technology that can be (and often are) done in a monolithic way without regard to the many different tools used in a multi-vendor environment. This paper presents an outline and structure to avoid such pitfalls.
Cold Weather Testing of the Bell 525 Relentless
Authors:   Bell Textron Inc., Regnier Bradley , Baden Joel , Brand Albert , Lindauer Patrick , O'Neil Joshua , Schillings John
Published: July 2023

In the winter months of January-March 2019, two Bell 525 test aircraft completed cold weather testing at Yellowknife Canada, some 1900 nm from Bell’s Flight Research Center in Arlington, TX. Testing was aimed at demonstrating aircraft stability, performance, and flight characteristics at extreme temperatures as required by CFR Part 29. Since regulations only permit limited temperature extrapolation, the cold temperature tests must include the limit of forward speed in a dive (VNE), and assessments of performance, controllability, autorotation, and static stability. This paper describes some of the unique environmental conditions and factors that any rotorcraft development program could experience in cold weather testing. The paper also gives a technical description of the required testing, where arctic conditions reached as low as -40° F or C (the temperature scales are the same at this temperature). Testing exposed the aircraft to overnight cold-soaks that brought fluids, seals, windshields, electronics, and elastomeric bearings to their low temperature specification, all at the same time. For the 525, test results demonstrated that the aircraft was ready for start-up and operation in extreme cold. The criteria necessary for meeting certification requirements in cold weather were also demonstrated in the series of tests and showed that the rotor was free from any adverse effects due to aerodynamic compressibility, had low vibration, acceptable loads and was free from any instability, even at speeds greater than VNE.
Hardware-in-the-Loop Dynamic Wind Tunnel Investigation of Slung Loads Dynamics with Application to Active Cargo Hook Stabilization of an M119 Howitzer
Authors:   Tel Aviv University, Rosen Aviv ,   Universities Space Research Association, Nadell Samuel ,   The Pennsylvania State University, Chen Zhouzhou ,   San Jose State Research Foundation, Cicolani Luigi ,   US Army CCDC AvMC - Development Directorate, Tischler Mark , Raz Reuben , Cheung Kenny , Enciu Jacob , Horn Joseph
Published: July 2023

A new hardware-in-the-loop (HIL) dynamic wind tunnel setup is used to study the behavior of a slung load at high speeds and methods of stabilizing problematic loads. The main element of the setup is a movable cargo hook. In addition the cable angles, model spatial attitude, and hook force are measured continuously. All the measurements are fed into a computer that calculates the cargo hook resultant motion in real-time by summing the rotorcraft angular motion effects (not used in the current study) and the hook motion relative to the rotorcraft fuselage. The computer output includes motion commands to the hook. The slung loads are two configurations of an M119 howitzer: folded and ready for firing. Initial wind tunnel studies showed that these loads exhibit significant LCO (Limit Cycle Oscillations) and severe instabilities at high speeds. Frequency sweep tests are used to derive dynamic models of the slung loads. These models are used to develop two controllers based on an Active Cargo Hook (ACH) approach. These controllers were implemented, tested, and studied. It was shown that both were able to suppress LCO and stabilize the slung loads along the entire airspeed range.
Experimental Measurement of Sectional Stiffness Properties of Composite Rotor Blades
Authors:   University of Maryland, Sinotte Tyler , Bauchau Olivier
Published: July 2023

This paper describes an experimental-numerical technique for evaluating the full 6 × 6 stiffness matrices for beams based on measured strains using digital image correlation (DIC). The general formulation makes the method well suited for isotropic beams with simple cross-sectional configurations or beams made of anisotropic materials with complex geometries, as typically exhibited in composite rotor blades. A 2-D finite element code, SectionBuilder, is used to generate a finite element mesh of the cross-section and evaluate the warping field, which is then combined with the experimental strain data to calculate the stiffness matrix. A detailed error analysis is performed to allow for the propagation of the experimental errors into the stiffness calculation and provide an uncertainty quantification for use in comprehensive analysis codes. Experimental results are presented for an isotropic beam and two composite rotor blades. Overall, the stiffness properties from the experimental measurements and numerical models showed good agreement and the experimental measurements were able to capture all the expected non-zero stiffness components.
Helicopter Flight Test Evaluation of an Actively Stabilized External Slung Load
Authors:   National Research Council of Canada, Alexander Marc ,   Sherbrooke University, Perron Eitenne , Craig Gregory , Rancourt David
Published: July 2023

The National Research Council of Canada and Université de Sherbrooke performed flight testing of an Actively Stabilized Slung Load on the NRC Bell 206 Research Aircraft. Hover, Attitude Capture, NRC designed Lateral Precision Hover, and Frequency Sweep mission tasks were performed for bare airframe and slung load aircraft configurations. The load mass ratio was 0.12 while the slung load pendulum mode was 1.3 rad/sec at a damping ratio of 0.2 for the 40-pound per active tether saturation load system setting. Time domain response indicated that the load remained controllable with damped and underdamped behaviors. Frequency domain analyses confirmed pilot comments indicating HQR 4 handling qualities ratings for bare airframe and stable slung load behavior. This rating degraded to HQR 5 for task execution with slung load oscillation. Pilot workload was due to lateral cycle input requirements of 2 to 3 inch amplitudes at 1 to 2 Hz frequency. Operationally, the coincidence of pilot inputs with active tether induced airframe and short period modes led to high compensation requirements for lateral axis tasks under study. The complexity of active tether management, an actuator failure, and telemetry faults represented system deficiencies. Comparable bare airframe and slung load configuration task execution results indicate the magneto-rheological actuation system’s potential to improve slung load mission task performance.
C reactive protein/Albumin ratio as predictor of prognosis in castration resistant metastatic prostate cancer
Authors: Lorigo João , Tavares Silva Edgar , Pedroso Lima João , Quaresma Vasco , Pedrosa Rui , Figueiredo Arnaldo
Published: July 2023

Objective: To assess the association of C reactive protein/Albumin ratio (CAR) with progression free survival (PFS) and overall survival (OS) in castration resistant metastatic prostate cancer (mCRPC) patients. Materials and methods: A transversal study was conducted, including all patients diagnosed with mCRPC within a Central Hospital Urological Oncology consultation between December 2019 and December 2021 (n = 178) and that were submitted to systemic therapy. CRP and albumin results were collected at the beginning of the systemic treatment for mCRPC in 103 patients and, in 75 patients already under treatment at the start of the study, on that occasion (December 2019). All patients were then followed. CAR was correlated with PFS and OS. OS and PFS were measured from the day the CRP and Alb were collected until the event of interest or the final date of follow-up. The sample was divided in two groups according to an optimal cutoff point found in a ROC curve. Results: The sample showed a median age of 75.76 ± 9.17 years old. Using a cut-off point of 0.22, patients with a CAR ≤ 0.22 (63.2%) showed, compared to CAR > 0.22, longer PFS (15.92 vs. 9.46 months, r = -0.13, p < 0.05) and OS (p = < 0.05, 25,72 vs. 15.79 months, r = -0,24, p < 0.05). Better OS in patients with CAR ≤ 0.22 vs > 0.22 was detected on both the group evaluated at the beginning of systemic treatment (26.96 vs 17.63 months, p < 0.05) and the group of patients already under treatment (23.90 vs 11.54 months, p < 0.05). Dividing the sample according to the first line treatment chosen, we found OS of 26.25 vs 5.9 months (p < 0.05), 27.71 vs 22.57 months (p < 0.05) and 27.36 vs 23.75 months (p = 0.12), for docetaxel, abiraterone and enzalutamide, respectively. Conclusions: According to this study, higher values of CAR are associated with lower PFS and OS in mCRPC patients. We found a cut-off value of 0.22 providing the best discrimination for prognosis. CAR is a good prognosis biomarker, irrespective of the moment of evaluation and chosen treatment option.
Gestione non farmacologica delle emorragie nel setting pre-ospedaliero
Authors: Sorrentino Davide , Guasconi Massimo , CalÃ² Federica , Lucenti Enrico
Published: July 2023

Lâ€™emorragia esterna continua ad essere una grande sfida nel setting pre-ospedaliero perchÃ© spesso di difficile gestione. Essa Ã¨ generalmente dovuta a traumi e se non controllata numerose possono essere le complicanze che determina. A tal proposito sono stati ideati diversi presidi che hanno come obiettivo il controllo precoce dellâ€™emorragia e quindi la sopravvivenza del paziente. Lâ€™obiettivo di questo studio Ã¨ indagare sui metodi non farmacologici per trattare le emorragie in ambito pre-ospedaliero da parte dellâ€™infermiere di emergenza territoriale
Physiotherapy students’ knowledge and attitudes about their role in mental health
Authors: Gunduza Ropafadzo R. , Lord Sandy , Keller Monique M.
Published: July 2023

Background: As the prevalence of mental health disorders (MHD) increases, physiotherapy students will be increasingly exposed to patients with MHD in their undergraduate studies. International research has shown that students who have mental health included in their curriculum have more knowledge and positive attitudes towards patients with MHD. In South Africa, little is known about physiotherapy students’ attitudes towards and knowledge of mental health.Objectives: To establish the knowledge of and attitudes towards the role of physiotherapy in determining the mental health attitudes.Method: In our cross-sectional, descriptive study, third- and fourth-year physiotherapy students at the University of the Witwatersrand were purposefully sampled. Online questionnaires, based on the Mental Health Knowledge Schedule (MAKS) and Mental Illness Clinicians’ Attitudes (MICA) scales were completed.Results: Thirty-four students participated in our study. Overall, all students indicated a moderate level of knowledge and a positive attitude towards mental health with mean MAKS score: 26.94 (standard deviation [s.d.]: 3.57) and MICA-4 score: 39.12 (s.d.: 16.12). Fourth-year students had more knowledge and a better attitude towards mental health when compared to the third-year students.Conclusion: Third- and fourth-year University of the Witwatersrand physiotherapy students have moderate knowledge and a positive attitude towards the role of physiotherapy in mental health.Clinical implications: The inclusion of mental health in the physiotherapy curriculum may improve students’ knowledge and attitudes towards mental health and prepare them for managing these complex patients in the future.
Determination of the Strength of SNAPPE II Score (Score for Neonatal Acute Physiology with Perinatal Extension-II) to Predict Neonatal Mortality in a Neonatal Intensive Care Unit of Tertiary Care Hospital: A Prospective Observational Study
Authors: Bansode Swapnali , Bhandekar Heena , Tiwari Manish , Pazare Pradeep
Published: July 2023

Aim:

The Score for Neonatal Acute Physiology with Perinatal Extension-II (SNAPPE-II) is a novel risk prediction system for neonatal mortality. This observational study aims to determine its ability to predict mortality risk in neonates admitted to the neonatal intensive care unit (NICU).

Methodology:

This prospective observational research was conducted for 12 months, from October 2021 to September 2022. Seventy-eight newborns, who fulfilled the inclusion criteria, were enrolled in our study. The outcomes of neonates were compared with the degree of SNAPPE II score calculated for respective neonates after admission. A receiver operating characteristic (ROC) curve was generated to determine the optimum SNAPPE-II cutoff score for mortality.

Results:

During the period of research, 292 newborns got admitted to our NICU. Among these, 78 neonates met the requirements for inclusion. Thirty-two infants (39.71%) of the 78 neonates died, while 47 were discharged. Newborns who died had substantially higher SNAPPE-II scores than those who lived (median [interquartile range] 37 [5–67] vs. 13 [0–48], P = 0.001). The area under the ROC curve (area under the curve): 0.837 (95% confidence interval, 0.73–0.91); SNAPPE II score demonstrated the ability to predict mortality. The cutoff score with the highest sensitivity and specificity for predicting death was 29. Compared to newborns with a SNAPPE II score of 29 or less, those over 29 had a considerably increased chance of mortality. The odds ratio estimate was 15.27, which indicates that neonates with high scores have around 15 times the risk of dying, as do those with low scores.

Conclusion:

This study suggests that the SNAPPE II score is a valuable tool for predicting mortality in neonates admitted to the NICU.