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SAE Aerospace Applied Thermodynamics Manual Aerothermodynamic Systems Engineering and Design

AC-9 Aircraft Environmental Systems Committee
  • Aerospace Standard
  • AIR1168/3A
  • Current
Published 2019-09-24 by SAE International in United States
This section presents methods and examples of computing the steady-state heating and cooling loads of aircraft compartments. In a steady-state process the flows of heat throughout the system are stabilized and thus do not change with time. In an aircraft compartment, several elements compose the steady-state air conditioning load. Transfer of heat occurs between these sources and sinks by the combined processes of convection, radiation, and conduction in the following manner: 1 Convection between the boundary layer and the outer airplane skin. 2 Radiation between the external skin and the external environment. 3 Solar radiation through transparent areas directly on flight personnel and equipment and on the cabin interior surfaces. 4 Conduction through the cabin walls and structural members. 5 Convection between the interior cabin surface and the cabin air. 6 Convection between cabin air and flight personnel or equipment. 7 Convection and radiation from internal sources of heat such as electrical equipment. The subsequent paragraphs discuss methods of determining each of the heat transfer rates listed above, as well as the physiological considerations involved…
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Gradationally Controlled Voltage Inverter for More Electric Aircrafts

IHI Corporation-Hitoshi Oyori
Mitsubishi Electric Corp.-Tetsuya Kojima, Masahiro Sugahara, Yusuke Shirouchi, Hisatoshi Fukumoto, Akihiko Iwata
Published 2019-09-16 by SAE International in United States
The more electric aircraft (MEA) concept has been attracting attention over recent decades to reduce emissions and fuel consumption. In MEAs, many subsystems that previously used hydraulic or pneumatic power have been replaced by electrical systems, and hence the weight of inverters has significant importance. The weight of inverters is largely attributed to passive filters that reduce the derivative of output voltages dv/dt and electromagnetic interference noises caused by common-mode voltages. To reduce the size of passive filters, multilevel inverters with 5 or more voltage steps are preferred. However, classic multilevel inverters have some challenges to achieve these step numbers without using plural dc power supplies that require massive transformers. In this work, a gradationally controlled voltage (GCV) inverter is proposed for MEAs. The GCV inverter can supply gradational quasi-sinusoidal voltages with 7 voltage steps, combining two different voltages from a three-level (main) inverter and H-bridge (sub) inverters. In addition, only one dc power supply is required for the main inverter. Furthermore, when sub inverters have faults, the GCV inverter can continue operation using the…
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Design and Experimental Verification of a High Force Density Tubular Permanent Magnet Linear Motor for Aerospace Application

Daido University-Yoshiaki Kano
KYB Corporation-Kousuke Satou
Published 2019-09-16 by SAE International in United States
This paper presents the design and construction of a high force density tubular permanent-magnet (PM) linear motor. A strut structure of a tubular PM linear motor developed to improve resistance to impurities and structural rigidity is described.In the design, computationally efficient two-dimensional finite-element analysis is used to estimate the motor force density. The motor’s design is optimized for the major pole number/slot number combinations of 8/24, 16/24, 20/24, 28/24, 32/24, and 40/24. The optimized motor design of a three-phase 16/24 combination with one-layer winding achieved the highest force-to-mass density. The force-to-mass density of the designed motor is higher than that of the first prototype motor by a factor of 5. The validity of the proposed design method and the expected drive characteristics are experimentally verified using the prototype.
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Flight Optimization Model on Global and Interval Ranges for Conceptual Studies of MEA Systems

Akita University-Yotsugi Shibuya
IHI Corporation-Hitoshi Oyori, Hirotaka Sugawara, Naoki Seki
Published 2019-09-16 by SAE International in United States
In development of more electric aircraft applications, it is important to discuss aircraft energy management on various level of aircraft operation. This paper presents a computationally efficient optimization model for evaluating flight efficiency on global and interval flight ranges. The model is described as an optimal control problem with an objective functional subjected to state condition and control input constraints along a flight path range. A flight model consists of aircraft point-mass equations of motion including engine and aerodynamic models. The engine model generates the engine thrust and fuel consumption rate for operation condition and the aerodynamic model generates the drag force and lift force of an aircraft for flight conditions. These models is identified by data taken from a published literature as an example. First, approximate optimization process is performed for climb, cruise, decent and approach as each interval range path. Next, optimization for global range path involves whole flight path to find optimal operation condition in the flight. In aircraft energy management, fuel consumption converts into not only thrust power, but power of…
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Electromagnetic Characteristic Comparison of Superconducting Synchronous Motor Characteristics for Electric Aircraft Propulsion Systems

IHI Corporation-Hitoshi Oyori
The University of Tokyo-Yutaka Terao, Yusuke Ishida, Hiroyuki Ohsaki
Published 2019-09-16 by SAE International in United States
This paper describes the comparison of electromagnetic characteristics of two different superconducting-motor structures for electrified aircraft propulsion systems. Future electrified aircraft demand higher output (over 16 kW/kg) and higher efficiency (> 98%) for their motors in comparison with current ones. To satisfy the demands, two kinds of superconducting motors are dealt in this study: one is partially superconducting motors (PSCMs), made of superconducting field coils and copper armature windings; the other is the fully superconducting motors (FSCMs) made of superconducting field/armature windings. They are cooled at 20 K with liquid hydrogen. We designed these two motors with finite element method to obtain the output density of 16-20 kW/kg for future electrified propulsion systems. We selected 3.0- and 5.0 MW superconducting motors, considering the application to aircraft for almost 180 passengers and 44 MW rated power for take-off. Also, we evaluated the motor weight using two kinds of cryostat materials: stainless steel (SUS) and fiber-reinforced plastic (FRP). The results show that the 5.0 MW PSCM using FRP achieved the output density of 16.9 kW/kg and the…
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Preventing Ice Buildup on Electric Aircraft

  • Magazine Article
  • TBMG-34869
Published 2019-08-01 by Tech Briefs Media Group in United States

Fuel economy is one of the biggest challenges facing the aviation industry. To overcome these challenges, researchers are working on next generation aviation systems.

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Preventing Ice Buildup on Electric Aircraft

Aerospace & Defense Technology: August 2019

  • Magazine Article
  • 19AERP08_04
Published 2019-08-01 by SAE International in United States

Fuel economy is one of the biggest challenges facing the aviation industry. To overcome these challenges, researchers are working on next generation aviation systems. Next generation aircraft will be either hybrid power, or all-electric power, which would help with fuel consumption. But electric aircraft present challenges in other areas such as the prevention of ice formation. Ice formation on aircraft can degrade the aerodynamic performance significantly by reducing lift while increasing drag. Tech Briefs Media Group (TBMG) editor, Billy Hurley, interviewed researcher Afaq Ahmed Abbasi of Northwestern Polytechnical University's Department of Fluid Mechanics to learn more about these challenges.

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A Predictive Reference Governor for Synchronous Generator Regulation with a Pulsed Constant Power Load

US Air Force Research Laboratory-Jon Zumberge, Brandon Hencey
University of Dayton-Raul Ordonez
Published 2019-03-19 by SAE International in United States
In this paper, first an analytical model of a synchronous generator with a pulsed constant power load (CPL) is developed and numerically compared with a detailed simulation model. The analytical model is shown to possess good predictive abilities, thus enabling its use for control purposes. Second, the generator has a proportionalintegral (PI) control inner-loop, whose task is to regulate the generator’s output voltage to a desired reference. A novel outer-loop predictive reference governor (PRG) is designed and tested via simulation. The PRG uses the analytical model to predict the output behavior of the generator over a short time window, and continuously modifies the reference given to the inner-loop in order to maintain stringent steady-state requirements, in spite of demanding power requirements at the CPL. Simulation results illustrate the significant performance advantages of using the PRG versus using the inner-loop PI controller alone. The paper also discusses challenges of implementing standard model predictive control (MPC) on this problem, thus further strengthening the case for the potential usefulness of the PRG.
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Information on Electric Brakes

A-5A Wheels, Brakes and Skid Controls Committee
  • Aerospace Standard
  • AIR5937
  • Current
Published 2019-02-15 by SAE International in United States
This SAE Aerospace Information Report (AIR) describes the design, operation, and attributes of electrical braking systems for both military and commercial aircraft. At this time, the document focuses only on brakes utilizing electromechanical actuators (EMAs), as that is the present state of the art. As such, the discussions herein assume that EMAs can simply replace the hydraulic actuation portion of typical brake system leaving things such as the wheel and heat sink unchanged. Furthermore, the document provides detail information from the perspective of brake system design and operation. The document also addresses failure modes, certification issues, and past development efforts. Details on the design and control of electric motors, gear train design, ball or roller screw selection are available in the reference documents and elsewhere, but are outside the scope of this document. Other all-electric technologies such as piezoelectric actuation or more exotic methods of applying drag to a rotating wheel may be included at a later time. Important: Electric braking systems for aircraft are at the early stages of production implementation. There are also…
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Fundamentals of Electric Aircraft

Pascal Thalin
INSA-Jean-Charles Maré
  • Book
  • R-462
Published 2018-12-18 by SAE International in United States
Fundamentals of Electric Aircraft was developed to explain what the electric aircraft stands for by offering an objective view of what can be expected from the giant strides in innovative architectures and technologies enabling aircraft electrification. Through tangible case studies, a deep insight is provided into this paradigm shift cutting across various aircraft segments – from General Aviation to Large Aircraft. Addressing design constraints and timelines foreseen to reach acceptable performance and maturity levels, Fundamentals of Electric Aircraft puts forward a general view of the progress made to date and what to expect in the years to come. Drawing from the expertise of four industry veterans, Pascal Thalin (editor), Ravi Rajamani, Jean-Charles Mare and Sven Taubert (contributors), it addresses futuristic approaches but does not depart too far from the operational down-to-earth realities of everyday business. Fundamentals of Electric Aircraft also offers analyses on how performance enhancements and fuel burn savings may bring more value for money as long as new electric technologies deliver on their promises.
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