Browse Topic: Design processes
This study presents computational analyses of coaxial rotor hub flows and validation against experimental data obtained from the fifth Rotor Hub Flow Prediction Workshop. Experiments were conducted in a 12-inch diameter water tunnel at Pennsylvania State Applied Research Laboratory, employing tomographic particle-image velocimetry (Tomo-PIV) and precise hub drag measurements. Three CFD codes (UMD Mercury, CREATETM-AV Helios, and OVERFLOW) utilizing hybrid Reynolds-Averaged Navier-Stokes (RANS) / Large Eddy Simulation (LES) modeling based on Spalart–Allmaras turbulence model, were applied to replicate and analyze hub flows. Counter-rotating coaxial rotor hubs under free-air condition was simulated as the simplest case and the hub drags are compared between the three CFD codes. The full water tunnel configuration, consisting of two hubs, a fairing, and shafts, was also simulated and compared to experimental results, with a focus on hub drag, wake velocity fields, and turbulence
U.S. Army Combat Capabilities Development Command (DEVCOM), Aviation & Missile Center (AvMC) developed a Digital Backbone for the Rotorcraft Applied Systems Concepts Airborne Lab (RASCAL-X) UH-60M for rapid Modular Open Systems Approach (MOSA) mission system integrations. The RASCAL-X Digital Backbone is the cornerstone of a unique experimental flight test capability connecting the experimental research flight control system with the Mission Systems Flying Testbed (MSFTB) and other mission system components. The Digital Backbone with MSFTB provides a suite of capabilities to integrate, assess, and flight test Mission Systems Under Test. The RASCAL-X Digital Backbone supports many of the physical aspects of mission system integration by providing Nodal Points with provisioning for power, data, and connectivity. Numerous challenges in Digital Backbone design, fabrication and installation were successfully addressed and solved during the development effort. The RASCAL-X Digital Backbone
The advent of electric propulsion technology has led to a paradigm shift in aircraft design over the past few decades. This shift has expanded the possibilities for design and optimization processes more than at any previous time. To support these advancements, efficient flight dynamics simulation models that can be employed in iterative optimization and design processes are essential. Among the modules of a typical flight dynamics framework—namely, control, flight dynamics, and aerodynamics—the aerodynamics module, which includes the rotor performance model, generally demands the most computational effort, thereby limiting simulation efficiency. In this study, a novel machine learning (ML)-assisted flight dynamics framework is developed, incorporating a Neural Network Blade Element Theory (NN-BET) model as the rotor performance module. The results show a 7- to 8-fold reduction in computational time compared to fast, physics-based frameworks utilizing efficient Blade Element Momentum
Accurate simulation of fluid-structure interactions (FSI) is critical for designing aircraft systems, particularly for applications involving fuel tank sloshing and large deformations. Traditional added mass methods often fail to capture the nonlinear and frequency-dependent behavior of these coupled systems. This study applies the Finite Pointset Method (FPM), a mesh-free computational fluid dynamics (CFD) technique, coupled with an explicit finite element solver, to predict complex FSI phenomena. Validation is performed using benchmark experiments, including a harmonic tank sloshing test and a guided plate ditching scenario, with results demonstrating strong agreement with measured pressures and structural responses. Additional validation on a composite fuel tank drop impact test confirms FPM's ability to model large deformations and rupture under dynamic loading. The findings highlight FPM's robustness and adaptability for aerospace FSI problems, offering a powerful alternative for
With performance advances proposed for the Future Vertical Lift suite of aircraft and advancements in the electronic battlefield, it is imperative that advanced materials and concepts be included in the vehicle designs to meet the aggressive weight reduction objectives, structural requirements, and operational environment capabilities. Integrating electromagnetic (EM) shielding during the design process offers an opportunity to make progress towards the performance goals. To this end, efforts must be made to minimize the impact of this shielding to platform weight and structural performance. This article presents work to develop a hybrid multifunctional composite material technology that incorporates copper mesh into a carbon fiber and thermoplastic matrix structural composite material to achieve required levels of EM shielding and high levels of structural efficiency while reducing the overall weight of the system. This article focuses on the design of a representative helicopter
An extensive test campaign was conducted at the National Full-Scale Aerodynamics Complex 40- by- 80-Foot wind tunnel to acquire performance, loads, and acoustics measurements of the Joby Aviation propeller across a variety of operating conditions. The dataset provided validation of the design methodology as well as verification of computational tools. The Vold-Kalman filter was used to extract the shaft-coherent propeller noise in hover to obtain the residual noise, representing the broadband noise. This data verified broadband noise tip speed scaling laws as well as a low-order empirical model for overall sound pressure level. The OVERFLOW/PSU-WOPWOP method was used to simulate the propeller in pure edgewise flight and shown to accurately predict propeller performance. The low-frequency acoustics were predicted well but the solver underpredicted frequencies above 300 Hz, possibly due to the inability to capture the turbulent component of the blade-wake and blade-vortex interaction
This paper will present the use of a licensed open-source software application based on commercially available off-the-shelf hardware for the control and data acquisition of aerospace system integration test rigs. System integration test rigs are complex systems requiring real-time deterministic control and high-speed data acquisition. Various aircraft flight systems and subsystems can be tested to see if they interact as they would on the aircraft without an airframe. These systems are critical to ensure interoperability during the development phase and facilitate the interchangeability of actual flight hardware, prototypes, and simulation models throughout the development cycle. Deploying open, flexible, and highly configurable real-time control and data acquisition systems ensures that development milestones will be achieved cost-effectively, whether using actual flight hardware or working with a simulation. This is because, as the prototype hardware is developed, the remaining
A cooperative acoustics flight test campaign between the US Army and NASA was performed in which design of experiments (DOE) approaches were used to plan the flight test conditions. Three DOE designs were used, a face centered central composite design, circumscribed central composite design, and a hexagonal design. A traditional one-factor-at-a-time approach was also used, and interpolation points were planned to test for the strength of the DOE approaches. This paper documents the design methodology, discusses how response surface models were fit to the data, evaluates the overall response of the models, and evaluates the individual DOE designs. The response surface models were also used to design new test conditions of interest during the experiment, and that process is also documented. For the first time, DOE was shown to be an exceptionally useful tool for rotorcraft acoustics flight test planning, while the full power of the approach has yet to be reached.
As military organizations internationally assess life extension and replacement actions for current legacy helicopter fleets and next generation rotorcraft are under development, novel rotor system technologies are required to fulfill challenging low-speed and high-speed flight envelopes and mission requirements. Proposed by the Department of National Defense (DND) and in collaboration with the National Research Council of Canada (NRC), a TTCP AER CP13A.1 Collaborative Project (CP) has been initiated supporting multi-nation development of numerical methods for optimizing and designing next generation main rotor blades. Four NRC laboratories collaborated to assemble a data set comprising design, performance, aerodynamics, structures, dynamics, and flight sciences elements. Acquired through research and testing, this information provides reference, technical, and engineering knowledge to support aero-structural model definition, model output validation, and the numerical optimization
On April 19, 2021, Ingenuity became the first helicopter to fly on Mars at Jezero Crater, completing a total of 72 flights by the end of its mission. The success of Ingenuity resulted in various research efforts to further exploreMars via vertical flight, including two optimized Ingenuity-sized helicopters proposed to retrieve samples for the 2028 Mars Sample Return mission. To aid in the design process for the two proposed Sample Retrieval Helicopters, both heritage and optimized, increased diameter rotors were tested at the NASA Jet Propulsion Laboratory in the 25-ft Space Simulator. Three test campaigns were performed using the Ingenuity rotors and optimized Sample Retrieval Helicopter (SRH) rotors for several rotor speeds, densities, configurations, and collectives to identify performance limitations. These three test campaigns included the Ingenuity Engineering Design Model 1 (EDM-1) with and without a cruciform box, Transonic Rotor Test (TRT) rig, and SRH Dual Rotor Test (DRT
This work proposes an experimental and numerical activity aimed at developing methods to evaluate the strength and toughness of Kevlar/Epoxy composite fastened joints used in aeronautical structures and exposed to high energy impacts. Experiments were conducted using an Arcan rig that allowed applying various loading conditions, ranging from pull-through to bearing. A non-linear model of the material based on a bi-phasic decomposition and hybrid meshing technique was built and calibrated. The material model was used to develop a high-fidelity model of the junction to simulate the pull-through test with the Abaqus/Explicit finite element solver. The results of the analysis point out that the implemented progressive damage laws are capable of achieving an appreciable experimental-numerical correlation, both from the qualitative and the quantitative standpoint. Therefore, the combined experimental-numerical approach is promising for developing a validated numerical tool capable of
This paper proposes a highly integrated 3-in-1 e-Propulsion unit that exceeds current state-of-the-art power density, utilising low-risk, high TRL technologies. The design process of the e-Propulsion unit is outlined, including the development of a high integrity, fault-tolerant system design targeting DAL-A safety levels. The resulting system concept embodies redundancy throughout the electrical system - two sets of windings in the motor and redundancy built into the power electronics create a robust and efficient architecture. The electrical machine is connected to an optimised single stage planetary gearbox to realise output shaft speed and torque suitable for an eVTOL or eCTOL type application. Both systems are cooled and lubricated by a standalone cooling loop.
The Advanced Helicopter Seating System (AHSS) was started as an effort to evaluate and improve the current state of military rotorcraft seating. The overall goal of the program has been to improve pilot ergonomics and safety through the integration of advanced energy absorption and vibration reduction mechanisms as well as a broad approach to system integration based around updated occupant anthropometrics. An entirely new seating solution has been developed, with intent to integrate with the AH-64 Apache platform for demonstration purposes. The AH-64 development culminated with a series of static tests and dynamic test events to measure the effectiveness of the safety systems integrated on the seat as compared to the legacy AH-64 seating system. While lumbar load data and seat stroke data was obtained, issues with the anthropomorphic test device (ATD) configuration at the 95th male configuration caused some data to be suspect, and premature failure of several components also caused
As part of the design process, structural assessment represents an important aspect in the development of new airand rotorcraft. It plays a critical role in supporting the weight of the aircraft, transmitting loads from the rotors to the airframe, and ensuring the overall safety and integrity of the vehicle. The conceptual design phase is characterized by exploration and evaluation of broad design concepts, with minimal detail regarding structural design. In contrast, the preliminary design phase involves refining the chosen design concept and conducting more detailed structural analysis and optimization to prepare for the subsequent detailed design phase. In order to evaluate the airframe, the opensource based design environment PANDORA has been developed at DLR. This paper presents an overview of model generation, topology optimization, sizing, and crashworthiness aspects in PANDORA using validation examples and generic rotorcraft models.
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