Browse Topic: Data management
This SAE Information Report contains definitions for hydrogen fuel cell powered vehicle terminology. It is intended that this document be a resource for those writing other hydrogen fuel cell vehicle documents, specifically, Standards or Recommended Practices.
This digital standard is a requirements extract of AS50881H Wiring Aerospace Vehicle. This file contains a general requirements extraction as well as files that are optimized for use with Doors Classic, Siemens Polarian, and PTC. 
Urban Air Mobility (UAM) concepts require multidisciplinary analyses across multiple modes of operation and often involve discrete architectural differences such as propulsion type, rotor configuration, and mission context. Existing optimization and workflow frameworks support continuous design variables but provide limited mechanisms for handling discrete variants, multi-modal vehicle definitions, and vehicle management for UAM vehicles. This paper presents uam4x, an open-source Python framework that addresses these challenges through a structured problem definition representation, a plugin-based execution engine, integrated version control, and a function-based branching script mechanism for constructing analysis scenarios. The framework provides integration of existing tools including Open Vehicle Sketch Pad (OpenVSP), NASA Design and Analysis of Rotorcraft (NDARC), M4 Structures Studio (M4SS), and Intelligent Cross Section Generator (IXGEN) through unified plugin interfaces. Parameter sweeps, nested analyses, and optimization via OpenMDAO are supported within the same architecture. This paper also presents demonstrations that were created to illustrate the various capabilities and integration efforts of the framework.
This paper introduces a comprehensive model, specifically developed to inherently capture interactional effects. Due to the high computational cost associated with the large analysis matrix including variations in angle of attack, angle of sideslip, velocity, and weight, a surrogate model is used in creating aerodynamic databases. This database, which reflects interactional effects under a wide range of flight speed, angle of attack, angle of sideslip, and weight configuration, is integrated into a rotorcraft analysis tool. Simulations are performed, and results are compared against flight test data for the T625 Gökbey, covering low-speed, high-speed, rightward and climb conditions. The results highlight the impact of interactional aerodynamics on flight characteristics and load predictions. Overall, the study emphasizes the importance of including interactional effects to ensure accurate and reliable rotorcraft design in the early design stages without requiring flight test data.
As part of a human factors research project aimed at optimizing technical documentation used in helicopter maintenance with multimedia elements, we compared different instruction formats to observe their effects on the performance of an assembly task. This task offers us the opportunity to test procedures that call for similar actions as a maintenance task (e.g., localization, action sequencing, assembly). Static (i.e., image and image with text) and dynamic instruction formats (i.e., video, video with text and video with audio) were compared to determine if dynamic formats allowed a better motor performance of the task for assembly reaction time (time needed to complete the assembly) and accuracy. We were also interested in how the use of the text instructions interacted with both visual dynamic and static instructions. Reaction times were recorded and measured with eye tracking data. Subjective data was collected in questionnaires during and after the experiment. Results showed significant differences in the time spent on the instructions and the time spent on the assembly, depending on the format of instructions. Overall, assembly time is shorter with video instruction formats, but videos took longer to be consulted than static formats. Results also showed a difference in the number of actions required to do the assembly. Videos facilitated the right path of action sequence in comparison with static formats. With the analysis of both subjective and objective data, the results give us a better idea of the advantages and drawbacks of using dynamic formats in technical documentation.
This investigation reveals many DoD contractors do not treat integration as a stand-alone activity. Instead, integration is an inherent part of the development process. The contractors did not have a specific documented process for integration beyond calling out integration as an activity in the development process. Integration is an integrator unique step within the development process to meet functional and performance requirements. Identification of the interfaces and engineering to match the interfaces requires substantial individual expertise and heuristics for each integration effort resulting in inconsistent non-repeatable integrations. This increases risk, and limits third party integration effectiveness and utility. This paper identifies steps that can be taken to increase the speed and effectiveness of integration while decreasing the effort and dependency on individual expertise.
Axial velocity measurements were performed in the wake of a hovering rotor with constant and sinusoidal cyclic pitch inputs ranging from 0.05/rev to 0.4/rev using a fixed, 2D-3C PIV system. Measurements were taken at 36 azimuths of the rotor with a constant cyclic input producing a pitching moment of CM = -0.00037. Using a Pitt-Peters definition, a longitudinal inflow state of λ1c = 0.0059 was extracted from the velocity measurements. A phase-resolved, undersampling approach was used to reconstruct the time history of the wake for the dynamic inputs. Simultaneous rotor hub loads measurements were used to obtain the frequency response of the longitudinal inflow state to pitching moment perturbations. The pitching moment perturbations ranged from ΔCM = 0.00027 at f=0.05/rev to 0.00046 at f=0.4/rev. The inflow perturbations ranged from Δλ1c = 0.0085 at f=0.1/rev to 0.0085 at f=0.4/rev. A first order transfer function was fit to the frequency response to compute Pitt-Peters dynamic inflow model parameters, but the low signal strength of λ1c produced high uncertainties in the model parameters.
This standard establishes supplemental requirements for 9100 and 9145 and applies to any organization receiving it as part of a Purchase Order or other contractual document from a customer. AS13100 also provides details of the Reference Materials (RM13xxx) developed by the SAE G-22 AESQ committee and listed in Section 2 - Applicable Documents, that can also be used by organizations in conjunction with this standard.
Test Scope
ABSTRACT At the end of 2014, the Group for Aeronautical Research and Technology in EURope (GARTEUR) launched an action group (named AG22) in order to address both experimentally and numerically the issue of rotor wake interacting with obstacles. Within this group, several different experiments were set up and the results were provided to all the partners in order to compare and improve their numerical methods aimed at capturing interaction effects. In the present paper, we numerically investigate the experimental database provided by Politecnico di Milano (Polimi). A low fidelity method based on free wake approach and also CFD computations with different level of modeling are compared to experimental data. It shows that free wake approach is perfectly suitable to predict interaction effects on the rotor loads as long as there is no wake re-ingestion by the rotor. In other cases, the use of CFD is mandatory. However, computational cost can greatly be reduced using some approximation (no fuselage, immersed boundary method approach for the building, wall slip boundary condition on the ground) without significant loss in the rotor loads accuracy. Moreover, such approximation still gives acceptable results with regards to the effects of the rotor wake on the building itself and across the flowfield.
In over actuated aircrafts a simple relationship between control inputs and forces/moments generated does not exist, however they have become very attractive for their wide range of applications. Control allocation aims at finding a unique surface control distribution as function of flight condition to perform the desired maneuver. The goal of this paper is to present a control allocation methodology applied on a generic over actuated aircraft aimed to determine the surface gearing matrix weights in different operative conditions to minimize the total power consumption. First, the non-linear model of the control forces and moments is derived for an over actuated aircraft. Then, two different optimization problems are introduced: the first to compute the trim equilibrium for any flight condition to minimize power consumption by the aircraft; the second to minimize the surface deflections required to produce desired control forces/moments starting from the trim point previously found. Finally, the optimized solution is subjected to engineering judgement to neglect the ineffective surfaces that do not provide a significant contribution to the required maneuver.
Launch, recovery, and deck handling operational performance on smaller ship platforms like Corvettes, Frigates and Destroyers are qualified as the most challenging tasks in the UAS ship-deployment of a VTOL Uncrewed Air System (UAS). One of the main hurdles is the random nature of seaway-created deck motions coupled with ship structure disturbed air wake patterns. The MoD has supported a range of work aimed at bringing Quiescent Period Prediction (QPP) technology to fruition. QPP firstly requires Wave Profiling RADAR to measure the sea wave system out to approximately 2km in the region around a vessel. Secondly these measurements are employed in a wave propagation model to predict the actual wave forces acting on a vessel. Using the wave predictions as inputs to a vessel model makes possible to predict the actual (deterministic as opposed to statistical) motions of a vessel. Wave systems naturally alternate groups of large waves with smaller waves, this property, combined with the predictive ability, allows to identify the quietest (most quiescent) periods in which to conduct wave limited naval operations. Naval mission planners in the Royal Navy, and elsewhere in the World, appreciate the need to maintain rapid, but safe, deck tempo. The fundamental concept is to measure remote sea surface profiles to predict the future wave forces acting upon a vessel. The objective is to expand ship operating deck limits to approximately Sea State 6+. The deck definitions generally empirically measured by using standard rating scales, are replaced by instrumented devices reporting the status of the deck prior to touch-down. In this paper, a thorough discussion describing the QPP deck measuring devices designed to replace piloted cueing is provided. Theory, previous simulation studies and current at-sea testing along with data results, are also discussed. To conclude, the interface of the deck measuring device into the next version of the UK UAS system, is provided. The results of the RADAR trial indicated that the RADAR data was reliable, with the RADAR images matching the physical map. The two-dimensional surface plot showed both the RADAR blocking fence along with an additional target. An additional observation concerning the operation over the deck whilst the ship is experiencing a quiescent ship motion period. The coupled secondary effect documents minimized air wake confusion. This is owing to fewer ship structure excursions into and out of the air flow. To better define deck airflow around the ship the integration of a Doppler LIDAR instrumented federate is proposed. This is meant to predict the future vessel air wake and look for quiescent periods in this paralleling the vessel motion QPP technique.
NASA's 4th New Frontiers Mission is the Titan Dragonfly relocatable lander. This coaxial quadrotor vehicle will be launched on a rocket to Titan in 2028. Following a gravity assisted Earth flyby and an approximate 6-year transit, Dragonfly will enter the Titan atmosphere around 2034 with the goal of exploring Titan's pre-biotic chemistry and habitability. The multirotor design for this unique application has continually evolved since 2016 with constraints such as Titan's cryogenic atmosphere at 95 Kelvin (-288 F), gravity 14% that of Earth's, atmospheric density 440% of standard sea-level air, and the inability to test the entire system together under all these conditions until the first flight on Titan. This paper focuses on rotor design aspects of the Dragonfly lander and introduces a novel framework for multirotor design optimization considering multiple flight conditions. The methodology leverages machine learning methods and is demonstrated in the context of Dragonfly. A new OVERFLOW Machine Learning Airfoil Performance (PALMO) database is first presented. PALMO is then wrapped inside a Bayesian optimization framework and applied to a 4-rotor system (one side of the Dragonfly lander). Training data is generated on each iteration of the optimization using the CAMRAD-II comprehensive analysis software to evaluate successive rotor designs in multiple relevant flight conditions. An optimal design for the 4-rotor system was found with approximately 900 rotor designs analyzed in CAMRAD-II, which required 9 million queries of the PALMO surrogate models. This demonstration case evaluated 10,000,000 potential candidate rotor designs in 5.5 hours on 114 CPU cores using uniform inflow, and in 27.8 hours using the prescribed wake model. This work thus enables mid-fidelity rotor design optimization without requiring access to high-performance computing.
ABSTRACT A proof of concept test to measure the unsteady boundary layer transition locations on the lower surface of a Machscaled rotor in forward flight was performed during the Summer of 2017 in the NASA Langley 14- by 22-Foot Subsonic Tunnel. The transition locations were measured using high-speed infrared thermography with a rotating mirror assembly that could be remotely actuated to acquire data at several rotor azimuths. Data were acquired for eight unique rotor flight conditions for a range of advance ratios (μ=0:10 : 0:38), thrust coefficients (CT/α =0:04 : 0:12) and rotor shaft angles (αs = -6 deg : 0 deg). This paper presents the transition locations as a function of azimuth and radius for an advance ratio of, μ, of 0.30, and thrust coefficent, CT/α, of 0.08. At this condition, the lower surface is fully laminar on the retreating side and mostly turbulent on the advancing side except near the tip. The tip airfoils were greater than 60 percent laminar on the lower surface advancing side. Capturing the location of natural transition on a rotating blade in forward flight represents a new advancement toward understanding the boundary layer state and its important contribution to rotor aerodynamics. Documentation of the boundary layer transition location during testing is critical to understanding scaling model to full-scale performance data, validation of newly developed turbulence models, and the design of the next generation of high performance rotor blades.
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 process development.
The findings of the parametric Harris-Scully cost model, also known as the "Cost Too Much" model, are reviewed and re-examined using an updated database of rotorcraft surveyed from government and commercial sources. The sensitivity of flyaway cost as assessed by the updated model is compared to trends in helicopter design and economic inflation to review the recommendations made by original set of helicopter affordability analysis published between 1995 and 1998.
From 2008 to 2021, 48 helicopter accidents have involved Vortex Ring State (VRS) encounters in the United States. For dangerous situations such as VRS encounters and recoveries, Scenario-Based Training (SBT) in flight simulators could supplement flight training, allowing pilots to practice in a safe environment. In this study, we created and tested a proof of concept for scenario-based training in flight simulators, dedicated to VRS-related accident prevention. The goal is to evaluate pilots' awareness, avoidance, detection, and recovery skills during VRS-inducing scenarios. Moreover, this study intends to provide a holistic analysis of VRS encounters and recoveries by examining the situations and factors leading to VRS-related crashes, and to lay out the pilot's decision-making process during the event. For that purpose, a comprehensive set of scenarios was developed based on an analysis of VRS-related accidents from the National Transportation Safety Board (NTSB) database. Overall, the scenarios successfully triggered VRS encounters as well as avoidance actions, providing insight into pilots' behavior in and around VRS conditions.
ABSTRACT
This SAE Standard applies to cranes which are equipped to adjust the boom angle by hoisting and lowering means through rope reeving.
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