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This digital standard is a requirements extract of AS13100A Quality Management System Requirements for Aero Engine Design and Production Organizations. This file contains a general requirements extraction as well as files that are optimized for use with Doors Classic, Siemens Polarian, and PTC.
SCOPE IS UNAVAILABLE.1
This standard provides background information and a hydrogen fuel quality standard for commercial proton exchange membrane (PEM) fuel cell vehicles. This report also provides background information on how this standard was developed by the Hydrogen Quality Task Force (HQTF) of the Interface Working Group (IWG) of the SAE Fuel Cell Standards Committee.
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.
Drain and Fill plugs used on engines, transmissions, transfer cases and front and rear drive axles for class 5 – 8 vehicles.
This specification covers a corrosion and heat-resistant steel in the form of welding wire.
This document specifies performance and quality requirements for the qualification and manufacture of 24 degree cone fittings to ensure reliable performance in aircraft hydraulic systems.This document specifies baseline criteria for the design and manufacture of system fittings that are qualification tested on engines.This document covers fittings of temperature types and pressure classes specified in MA2001.
This paper investigates the impact of aerodynamic interactions on the whirl flutter boundary of wing-twin-propeller configurations. A coupled wing-pylon-propeller model is developed in the Rotorcraft Comprehensive Analysis System (RCAS), where the wing is modeled using uniform inflow and the propeller wake is modeled using the viscous vortex particle method (VVPM). The study examines the effects of spanwise propeller placement and rotation direction by first analyzing a single-propeller configuration and subsequently extending the analysis to twin-propeller configurations. The analyses are performed for both rigid and flexible wings, with the latter designed such that whirl flutter governs the instability boundary. Results show that spanwise propeller placement strongly influences whirl flutter stability, with outboard locations exhibiting higher flutter speeds. Aerodynamic interactions between the wing and the propeller are found to be generally destabilizing, reducing the whirl
This paper introduces an eigenvalue-based whirl flutter prediction method accounting for aerodynamic interactions between a wing and propeller. The linearized unsteady vortex lattice method was utilized to model fixed-wing aerodynamics while the linearized viscous vortex particle method was utilized to model rotary-wing aerodynamics. The complete aerodynamics model was then coupled with computational structural models to demonstrate the capabilities of the model to predict whirl flutter using an eigenvalue-based method. Two computational structural models were used: the first being an analytical propeller model affixed to a rigid wing via root springs and dampers, and the second being the University of Michigan's Nonlinear Aeroelastic Simulation Toolbox. These models demonstrate the capabilities of the linearized aerodynamics model in predicting instability with structural models of different fidelities, both considering and not considering aerodynamic interactions. The linearized
This study investigates the acoustic performance of a single rotor representative of those seen on multi-passenger UAM-sized vehicles, focusing on the effects of blade count, disk loading, solidity, and tip Mach number in both hover and propeller operating conditions. Using PSU-WOPWOP and ANOPP2, unweighted and A-weighted overall sound pressure levels (OASPL) are computed in-plane for 2- and 5-bladed rotors across a range of design parameters and operating conditions. Unweighted results show that reducing blade count significantly increases total noise levels (14.1 dB on average) and reduces sensitivity to design parameters. In contrast, A-weighted results demonstrate that broadband noise dominates perceived acoustic performance and shows a decreased sensitivity to blade count (1.9 dBA average difference). Minimum noise levels occur at tip Mach numbers ranging from 0.35-0.45 for unweighted results and 0.4-0.5 for A-weighted results, and are primarily governed by broadband noise
For many years there has been a keen focus on pilot workload and its associated assessment methods, and it remains a highly relevant aspect of flight testing. This paper provides a synopsis of a novel workload rating scale and index, the Comeau-Duggan Pilot Workload Index, designed to bridge the gaps in existing subjective workload metrics – such as casual factor identification – that are present in the most widely used rating scales in flight tests. The conceptualization and development of this index represent a multi-year, dual-national research effort that builds on the foundational concepts and core principles underlying widely accepted workload rating scales used in Human Factors and Handling Qualities engineering. The Pilot Workload Index provides a structured and rigorous methodology for ascertaining and distinguishing factors that have contributed to the pilot workload of a given flying task, evaluating their impact using a systematic suffix-flowchart framework. The Pilot
Urban Air Mobility (UAM) represents a paradigm shift in metropolitan transportation, introducing electric vertical takeoff and landing (eVTOL) aircraft into dense urban ecosystems. This transformation is driven by advances in electrification, digital infrastructure, and integrated airspace management. According to the U.S. Department of Transportation's Advanced Air Mobility National Strategy 2025, UAM is expected to become a cornerstone of multimodal urban transport, with commercial operations projected in multiple U.S. cities before 2030 [1].
After four decades of research and 3.5 year prototype testing campaign, Penn State's pericyclic transmission technology demonstrator, dubbed the 'Pericycler', has achieved its operating speed of 5,000 RPM at 17 HP. The characterization of this system by experimental efficiency and vibration represents a major milestone in pericyclic gear technology. A post-test inspection procedure was performed to analyze component wear and validate hypotheses on mesh behavior. This work concludes with structural, tribological, and instrumentation modifications to the Pericycler for future testing.
This experimental study showcases the aeroacoustic sources measured on a NACA0012 airfoil subjected to dynamic stall due to sinusoidal plunging motions. The flow fields are measured on the upper surface of the airfoil using time-resolved particle image velocimetry (PIV), and the broadband surface pressure fluctuations were measured using a flush-mounted microphone probe and the reconstructed pressure field from PIV. Boundary layer separation occurs as the plunging airfoil approaches the maximum plunging velocity. A dynamic stall vortex (DSV) forms on the upper surface near the leading edge. Pressure distribution over the upper surface evolves in response to the movement of the DSV, with the lowest surface pressure observed at the DSV location. Full boundary layer separation results in a temporary reversal of the adverse pressure gradient, and the lowest pressure during moments of full detachment is at the trailing edge. The overall magnitude of the power spectral density (PSD) of the
This paper experimentally investigates the effect of positioning of individual blades of a two bladed propeller around the rotor hub on overall noise generated by it. An experimental setup was created to measure noise and performance in an anechoic chamber to carry out parametric study in which axial and azimuthal separations between the two blades were introduced through a custom built rotor hub and balancing weight. The propeller noise that is dominated by tonal components associated with blade passage frequency appears to be influenced by azimuthal separation between individual blades and the broadband components generated by turbulent blade-wake interactions is primarily affected by the axial separation between individual blades. From the present study, it is identified that the rotor configurations with 60° azimuthal and 6 mm (3.2% of rotor radius) axial separation resulted in up to 4.4 dB reduction in Overall Sound Pressure Level (OASPL) and 63.9% reduction in acoustic energy
After systematic testing of scaled propeller-driven rotor models in hover, and successful correlation of the test data with prediction methodology, a scaling study was conducted for a range of aircraft gross weights from 100 lbs to 20,000 lbs. From previous studies it became evident that propeller sizing and spanwise location on the main rotor blade were key for overall good main rotor performance. The impact of propeller design and placement on propeller-driven rotor hover power was estimated from the isolated propeller performance and propeller-driven rotor configuration. Propeller-driven rotor hover power was compared to a conventional shaft-driven isolated main rotor and a shaft-driven single-main rotor helicopter. The scaling study showed that, for a well designed propeller-driven rotor, the hover power was comparable between the propeller-driven and shaft-driven isolated rotor/single main rotor designs. Finally, a disk loading sensitivity analysis was performed which found that
A wind tunnel investigation to assess the impact of rotor-fuselage spacing on the development of the Vortex Ring State and flow topology is presented. Particle Image Velocimetry was utilised to investigate flow mechanisms across a range of rotor-fuselage spacings and descent ratios, which were compared to that of an isolated rotor configuration. Mean flow data was used to identify coherent flow structures, whilst flow unsteadiness was investigated through statistical analysis of the velocity fluctuations. It was found at cases of Vortex Ring State onset, the presence of the fuselage delays the development of the Vortex Ring State for all rotor-fuselage separation distances tested. Furthermore, certain cases of rotor-fuselage spacings display a rotor-fuselage aerodynamic interaction that results in an increased effective descent ratio.
A single pilot, full-scale, proton exchange membrane fuel cell powered helicopter is flight tested with 700 bar compressed gaseous hydrogen as fuel. Models are developed for the fuel cell, hydrogen and the helicopter and validated with flight test data. The data covers powerplant architecture, stack electrical characteristics, hydrogen flow, detailed component weights, radiator drag, and full aircraft power measured in hover and forward fight. The validated models are then used to conceptually explore the conversion of a larger, more capable, turbine engine Robinson R66-like airframe with liquid hydrogen supplied fuel cell. Predictions indicate that payloads of 300−600 lb can be carried over a range of 200 nautical miles with current fuel cell technology if hydrogen storage weight fractions of 0.2−0.3 can be achieved and the tank and baggage compartment both are used for fuel. The key conclusion is that hydrogen fuel cell helicopters are feasible and the test data and validations
This paper presents the integration and use of state-space free-vortex wake models within closed-loop rotorcraft flight dynamics simulations. The free-vortex wake models are formulated in state-variable form, such that they constitute a system of nonlinear, time-varying ordinary differential equations in first-order form that augment the baseline rigid-body and rotor dynamics. The wake models considered include a tip-vortex-only formulation, as well as a formulation combining a vortex-lattice near wake with a tip-vortex representation of the far wake. Following trimming, linearization, and model-order reduction of the flight dynamics at discrete increments in flight speed, Dynamic Inversion (DI) flight control laws are synthesized to enable automatic transition from hover to cruise flight. Two-way-coupled losed-loop simulations are then performed for a generic utility helicopter representative of an H-60 in transition from hover to forward flight using three inflow models: (i) Pitt
An aspect of the ship-helicopter dynamic interface (DI) is the highly unsteady flow environment generated by ship-rotor aerodynamic interactions, which challenges safe launch and recovery operations. To investigate these interactions without the constraints of conventional rotor scaling, a novel airflow-and-blade-frequency (ABF) system was developed, decoupling rotor thrust from blade-passing frequency and enabling independent control of disk loading and periodic excitation. Mean-flow superposition and spectral analyses were used to assess the validity of linear-superposition approaches for DI modeling. While superposition reproduced portions of the interacting mean flow, it failed to capture key features such as superstructure sheltering. Spectral results showed that momentum injection and blade-passing frequency modified the interacting flow through distinct mechanisms. Across all operating conditions, the interacting flow exhibited elevated turbulent kinetic energy at pilot-relevant
T-tail architectures show potential for enhancing vertical tail-efficiency and lowering fuselage download and hub load cycles during low-speed transition. However, a horizontal stabilizer is principally susceptible to rotor wake impingement during cruise flight, which, in unfavorable conditions, could induce dynamic loads along with associated vibrations and structural fatigue. Predicting this phenomenon is challenging due to the complex aerodynamics and sensitive structural dynamics involved. This paper demonstrates the capabilities of a mid-fidelity simulation methodology for predicting empennage structural loads and vibrations. The approach utilizes mid-fidelity interactional aerodynamics modeling, building upon previously published Vortex-Lattice Model (VLM) results and extending them to include a Viscous Vortex Particle Wake (VVPM) analysis, coupled with a modal structural dynamics model of the fuselage. The study extends the simulation model's validation against experimental data