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Cable Impedance Calculations Employed in Designing Aerospace Electrical Power Systems

Astronics AES-Jon Fifield
  • Technical Paper
  • 2020-01-0037
To be published on 2020-03-10 by SAE International in United States
This paper presents design considerations in utilizing cable impedance calculations in the design of an aerospace electrical power system. (EPS) Past wiring design guidelines featured a tabular constructed single-point design reference. This results in a cable selection which adds unnecessary weight and under-utilized the wire’s performance ability when considering a vehicle’s design requirements. Present wiring design guidelines have lagged behind the growing movement to achieve an optimized wire selection. Understanding the shortfalls with past and present wiring design methods will improve future methods to comply with increasingly restrictive vehicle performance requirements. This paper will discuss two of the most important design requirements for future aerospace electrical power and distribution feeders, which are weight and thermal limits assigned to an EPS design.
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Design of Elevons for a Hybrid VTOL-Blended Wing Body Unmanned Aerial Vehicle

Delhi Technological University-Amit Bainsla, Vikas Rastogi, Pranav Bahl
  • Technical Paper
  • 2020-01-0047
To be published on 2020-03-10 by SAE International in United States
The two primary requirements for a safe flight of a UAV are its stability and manoeuvrability. The purpose of this study is to design and validate elevons for a UAV having Blended Wing Body configuration which requires knowledge of various domains applied in a complex combination. Elevons are the unconventional control surfaces for the flying wings which will cause a pitching moment when moved in same direction and will cause a rolling moment when moved differentially and their preliminary design is affected by the function which is dominant. A MATLAB© code was written to decide the position, shape and size of elevons and later on accurately evaluated using high fidelity Computational Fluid Dynamics simulations. The MATLAB© code calculates the required roll time rate taking into consideration the longitudinal and lateral control requirements. Using this coupled approach of MATLAB© code and Computational Fluid Dynamics simulations significant optimization is achieved in designing the elevons.
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Integrated Electrical UAV Propulsion Design and Testing For High Efficiency

DARcorporation-Wanbo Liu, Drew Darrah, Joel Eppler
  • Technical Paper
  • 2020-01-0053
To be published on 2020-03-10 by SAE International in United States
This paper covers the design, modeling and analysis of an electric ducted fan system for sUAV (<55 lb) and the verification of predicted performance with test data. Analysis shows that the operating condition of the motor can significantly affect performance and should be considered when selecting or designing a rotor and vice versa. Motor manufacturers usually provide a list of compatible propellers for a motor design with thrust at RPM data coupled with gram per Watt efficiency. However, the gram per Watt value is not constant across the range of operation and a better modeling is needed depending on thrust requirements. Many of the electrical losses can be difficult to calculate directly, such as flux and iron losses in the motor and switching losses in the ESC. Incorporating an estimation/approximation of such losses during the rotor design phase enables a more accurate performance predication and a better overall system efficiency. Two rotors are designed to work inside of the duct and both have identical geometry except for a small blade pitch changes to increase maximum…
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An Approach to Verification of Interference Concerns for Multicore Systems (CAST-32A)

Rapita Systems, Inc., Ltd.-Steven H. VanderLeest, Christos Evripidou
  • Technical Paper
  • 2020-01-0016
To be published on 2020-03-10 by SAE International in United States
The avionics industry is moving towards the use of multicore systems to meet the demands of modern avionics applications. In multicore systems, interference can affect execution timing behavior, including worst case execution time (WCET), as identified in the FAA CAST-32A position paper. Examining and verifying the effects of interference is critical in the production of safety-critical avionics software for multicore architectures. Multicore processor hardware along with aerospace RTOS providers increasingly offers robust partitioning technologies to help developers mitigate the effects of interference. These technologies enable the partitioning of cores for different applications at different criticalities and make it possible to run multiple applications on one specific core. When incorporated into system-design considerations, these partitioning mechanisms can be used to reduce the effects of interference on software performance. In this paper we describe a novel approach to verifying the effectiveness of RTOS interference mitigation on the final hosted software. We showcase the use of the proposed approach on the NXP T2080 multicore board. The approach follows a V-model based methodology in which high- and low-level requirements…
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High Altitude Platform System Airship for telecommunication and border monitoring design and physical model

Henri Coanda Labs LLC-Michele Trancossi
  • Technical Paper
  • 2020-01-0044
To be published on 2020-03-10 by SAE International in United States
This paper presents an accurate analysis of a high altitude platform with an unconventional ellipsoidal shape during the most critical operation with the support of a large CFD analysis. The airship is designed accordingly to the specifications which have been analysed in terms of the required CONOPS (Concepts of Operations). Concepts of Operation (CONOPS) associated with the proposed High Altitude Pseudo-Satellite (HAPS) technology and special operations and to analyze the operational scenarios which are relevant to HAPS technology. An innovative cruiser feeder system is defined and studied. The CONOPS includes communications relays, support of intelligence, surveillance, target acquisition monitor “mobile targets”, and reconnaissance, including long-range ISTAR missions performed by the feeder, combining satellite vision and HAPS vision for a forest fire, disasters, naval accidents, maritime and ground borders. The paper realizes a multidisciplinary analysis that allows creating the design of the HAPS, referring to both cruiser and feeder according to the in different operative scenarios. Inside the digital twin model simulations will be performed in multiple cases allowing generating the best possible configuration by mean…
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A Study on the development of Aerostructures Design for Assembly guidelines and their effective use to proactively identify opportunities for improvement in mitigating common defects of the Aerostructures Assembly.

GITAM School of Technology, Hyderabad-Mani Rathinam Rajamani, Eshwaraiah Punna
  • Technical Paper
  • 2020-01-0009
To be published on 2020-03-10 by SAE International in United States
An Aircraft’s assembly process plays a vital part in its design, development and production phases and contributes to about half of the Total cost spent in its entire product lifecycle. DFA principles have been one of the proven effective methodologies in Automotive and Process industries. Use of DFA principles have resulted in proactively simplifying and optimizing engineering designs with reduced product costs, and improved inefficiencies in product design and performance. Standardization of Assembly guidelines is vital for “Design and Build” and “Build-To-Print” manufacturing supplier organizations. However, Standardizing design methodologies, through use of proven tools like Advanced Product Quality Planning, (APQP) are still in the initial stages in Aerospace part and process design processes. Thus, there is a tremendous opportunity for research on the application of the existing DFA guidelines to optimize Engineering Aerospace Assembly processes aiming to simplify, standardize design methodologies by building on existing industry practices which have a common platform for design communication and are easy to adopt within the existing process/systems. This technical paper is to discuss the framework for application of…
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Development of Hydrogen Powered Fuel Cell e-Snowmobiles

BRP-Rotax GmbH &amp; Co KG-Walter Hinterberger, Nigel Foxhall
HyCentA Research GmbH-Patrick Pertl, Martin Aggarwal, Alexander Trattner
  • Technical Paper
  • 2019-32-0555
To be published on 2020-01-24 by Society of Automotive Engineers of Japan in Japan
In the highly innovative and holistic flagship project HySnow (Decarbonisation of Winter Tourism by Hydrogen Powered Fuel Cell Snowmobiles), funded by the Austrian Climate and Energy Fund, the decarbonization of winter tourism is being demonstrated. Within this project, two prototype e-snowmobiles have been developed including the adaption of a Polymer Electrolyte Membrane Fuel Cell (PEM-FC) system for the low temperature and high-performance targets and the integration of the drivetrain into the vehicle.In this paper the drivetrain development process of the prototype e-snowmobiles will be presented with the aim to derive specifications for the drivetrain components as PEM-FC system, hydrogen storage system, electric drive, battery and power electronics. Based on typical use cases for snowmobiles overall vehicle specifications and requirements are defined. Associated driving cycles are investigated and used as input for the development process. Subsequently, analyses regarding possible drivetrain topologies based on technical and economical vehicle requirements are carried out. In parallel, vehicle implementation concepts based on standardized development processes are performed. The development and the design process are verified by verification and optimization loops.The…
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Advanced Bench Test Methodology for Generating Wet Clutch Torque Transfer Functions for Enhanced Drivability Simulations

F.C.C. CO., LTD.-Takahiro Tsuchiya, Masatoshi Miyagawa, Shinji Nakamura, Matthew Wendel, Hiroya Miyoshi
Ford Motor Company-Hiral Haria, Yuji Fujii, Gregory M. Pietron, Anna Sun
  • Technical Paper
  • 2019-01-2340
Published 2019-12-19 by SAE International in United States
A wet clutch continues to play a critical role for step-ratio automatic transmissions and finds new utilities in hybrid and electrified propulsion systems. A torque transfer function is often employed in practice for sophisticated clutch slip controls. It provides a simple, yet practical framework to represent clutch torque as a function of actuator force. An accurate transfer function is also increasingly desired in today's vehicle design process to enable upfront assessment of clutch controls through simulations. The most common approach is based on Coulomb's linear friction model, where the coefficients are adaptively identified based on vehicle data. However, it is generally difficult to tune Coulomb's model for hydrodynamic behaviors even if the reference vehicle data are available. It also remains a challenge to produce in-vehicle clutch behaviors on a component test bench to determine realistic transfer function before prototype vehicles are built. SAE#2 test procedure is the industry standard for evaluating clutch frictional behaviors. It is a viable tool for durability assessment, but not designed to characterize hydrodynamic behaviors for clutch controls. This research focuses…
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Aircraft Fuel System Design Guidelines

AE-5A Aerospace Fuel, Inerting and Lubrication Sys Committee
  • Aerospace Standard
  • AIR7975
  • Current
Published 2019-12-05 by SAE International in United States

This document describes the major design drivers and considerations when designing a fuel system for a large commercial aircraft. It discusses the design at a system/aircraft level, and is not intended as a design manual for individual system components, though it does refer out to other SAE specifications where more detail on specific components and sub systems is given. It does include examples of a number of calculations associated with sizing of fuel systems, based on those given in NAV-AIR-06-5-504, as well as an appendix summarizing basic fluid mechanical equations which are key for fuel system design. It is acknowledged that most of these calculations would today be performed by modelling tools, rather than by hand, but it is considered important for the designer to understand the principles.

Fundamentals of GD&T 2018 3-day

  • Professional Development
  • ET1920024
Published 2019-12-03

This course teaches the terms, rules, symbols, and concepts of GD&T as prescribed in the ASME Y14.5-2018 Standard.

This course offers an in-depth explanation of geometric tolerancing symbols, their tolerance zones, applicable modifiers, common applications, and verification principles. The class includes a comparison of GD&T to the directly toleranced dimensioning method; Rules #1 and #2; form and orientation controls; tolerance of position; runout and profile controls. Newly acquired learning is reinforced throughout the class with more than 150 practice problems.  

Each attendee receives a Fundamentals of Geometric Dimensioning and Tolerancing 2018,  Using Critical Thinking Skills textbook by Alex Krulikowski (Based on the ASME Y14.5-2018)

Students who attend courses like this one walk away with more than knowledge - they gain on-the-job skills because the learning materials are performance-based and taught by industry professionals.