Browse Topic: Aircraft propulsion systems

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This SAE Aerospace Recommended Practice (ARP) is written for individuals associated with the ground-level testing of large and small gas turbine engines and particularly for those who might be interested in constructing new or adding to existing engine test cell facilities.
EG-1E Gas Turbine Test Facilities and Equipment
This document discusses, in broad and general terms, the subject of acoustical considerations in engine test cells. One of the primary purposes of an engine test cell is to control the noise emanating from the operating engine in order to reduce noise in the surrounding facility and community to acceptable levels. This is done by the design and installation of specialized acoustic elements and features, which need to be fully integrated into the overall test cell design. It should be further noted that the requirements of acoustic control are critical to the proper operation of the engine, safety of plant equipment and personnel, and meeting local and legal noise requirements.
EG-1E Gas Turbine Test Facilities and Equipment
This procurement specification covers inserts made from A286 alloy (UNS S66286) which have self-locking internal threads and integrated locking keys to positively secure the insert against rotation when properly installed in threaded holes.
E-25 General Standards for Aerospace and Propulsion Systems
This document addresses AS8879 thread inspection issues relating to selection, usage and capability of gages. It addresses the selection of calibrated measurement gages, the need for defined quality metrics, the methodology of determining the appropriate guardband factors, and the minimum inspection requirements for single element pitch diameter gages. Users of this document shall apply the information described herein for the evaluation of the capability of their measurements based on the measurement consumer risk. It involves the analysis of the measurement (product) distribution and biases of both the product and measurement system distributions. It protects the consumer from the worst case distribution results. A whitepaper has been developed to provide supporting documentation and the rationale used in the development of this standard. This whitepaper will be published by the SAE as an Aerospace Information Report (AIR6553). This document recommends the use of ASME B1.2 “Gages and
E-25 General Standards for Aerospace and Propulsion Systems
E-25 General Standards for Aerospace and Propulsion Systems
This document addresses measurement uncertainty and consumer risk as they relate to AS8879 thread inspection. It describes the rationale, theory and methodology used to generate the technical content of the AS5870. The document describes how to calculate measurement consumer risk. It documents all of the calculation methods which industry employs today to calculate what is commonly called measurement uncertainty (Appendices A, B, C, D, E and F). These, in turn, are used to calculate measurement uncertainty ratios which are required inputs to calculate measurement consumer risk. Users of this document can apply the information described herein for the evaluation of the capability of their measurements based on the measurement consumer risk. It involves the analysis of the measurement (product) distribution and biases of both the product and measurement system distributions. It protects the consumer from the worst case distribution results.
E-25 General Standards for Aerospace and Propulsion Systems
E-25 General Standards for Aerospace and Propulsion Systems
E-25 General Standards for Aerospace and Propulsion Systems
E-25 General Standards for Aerospace and Propulsion Systems
This procurement specification covers all metal, self-locking wrenching nuts, plate nuts, shank nuts, and gang channel nuts made of a corrosion and heat resistant nickel-base alloy of the type identified under the Unified Numbering System as UNS N07001.
E-25 General Standards for Aerospace and Propulsion Systems
This procurement specification covers aircraft quality metallic gaskets having a "C" shape cross-section to form a seal ring, made from a corrosion and heat resistant age hardenable nickel base alloy of the type identified under the Unified Numbering System as N07750.
E-25 General Standards for Aerospace and Propulsion Systems
E-25 General Standards for Aerospace and Propulsion Systems
This document covers all metal, self-locking wrenching nuts, plate nuts, shank nuts, and gang channel nuts made from a corrosion and heat resistant steel of the type identified under the Unified Numbering System as UNS S66286 and of 160 ksi tensile strength at room temperature, with maximum test temperature of parts at 1200 °F.
E-25 General Standards for Aerospace and Propulsion Systems
E-25 General Standards for Aerospace and Propulsion Systems
A pathway to in-flight application of filtered Rayleigh scattering (FRS) is herein presented, including a viable concept, based on recently published related work. The proposed pathway considers the key technical, operational, and regulatory challenges to enable in-flight measurements using FRS for inlet flow distortion characterization ahead of the aeroengine. Solutions to these challenges are proposed, in particular methods for light delivery, flow imaging and integration of the measurement system in the in-flight environment. This complements the experimental lab-scale demonstration of an FRS concept for flow distortion measurements and provides a route for further exploitation as a diagnostic tool for next-gen aircraft.
Lawson, Nicholas JohnMigliorini, MatteoDoll, UlrichMelnikov, SergeySteinbock, JonasDues, MichaelZachos, Pavlos K.Röhle, IngoMacManus, David G.
This document covers bolts and screws made from a corrosion- and heat-resistant, precipitation-hardenable, iron base alloy of the type identified under the Unified Numbering System as UNS S66286.
E-25 General Standards for Aerospace and Propulsion Systems
E-25 General Standards for Aerospace and Propulsion Systems
E-25 General Standards for Aerospace and Propulsion Systems
A new high-temperature resistant material exhibits great potential for applications such as energy-efficient aircraft turbines. Karlsruhe Institute of Technology, Karlsruhe, Germany A new material might contribute to a reduction of the fossil fuels consumed by aircraft engines and gas turbines in the future. A research team from Karlsruhe Institute of Technology (KIT) has developed a refractory metal-based alloy with properties unparalleled to date. The novel combination of chromium, molybdenum, and silicon is ductile at ambient temperature. With its melting temperature of about 2,000 degrees Celsius, it remains stable even at high temperatures and is at the same time oxidation resistant. The results are published in the journal Nature. High-temperature-resistant metallic materials are required for aircraft engines, gas turbines, X-ray units, and many other technical applications. Refractory metals such as tungsten, molybdenum, and chromium, whose melting points are around or higher
A new material might contribute to a reduction of the fossil fuels consumed by aircraft engines and gas turbines in the future. A research team from Karlsruhe Institute of Technology (KIT) has developed a refractory metal-based alloy with properties unparalleled to date. The novel combination of chromium, molybdenum, and silicon is ductile at ambient temperature. With its melting temperature of about 2,000 degrees Celsius, it remains stable even at high temperatures and is at the same time oxidation resistant. The results are published in the journal Nature.
Raytheon East Hartford, CT corporatepr@rtx.com
As global air traffic is expected to increase significantly in the coming decades, reducing the associated climate impact requires scalable solutions. While alternative propulsion technologies such as electric and hybrid-electric systems might offer long-term potential, their current applicability remains limited due to low energy density, limited range and scalability, and system complexity. Consequently, thermodynamic propulsion systems – such as gas turbines and piston engines – are expected to remain dominant in the medium term. In this context, sustainable hydrocarbon-based aviation fuels represent a practical and necessary solution. Certified sustainable aviation fuel (SAF) pathways are currently approved exclusively for use in gas turbines, with certification standards tailored to turbine-specific requirements. Consequently, fuel properties such as cetane number and evaporation behavior are not included in existing specifications. However, when SAF-kerosene blends are used in
Kleissner, FlorianHofmann, PeterVogd, PhilippVauhkonen, VilleKäkölä, JaanaGreve, Alina
Accurate defect quantification is crucial for ensuring the serviceability of aircraft engine parts. Traditional inspection methods, such as profile projectors and replicating compounds, suffer from inconsistencies, operator dependency, and ergonomic challenges. To address these limitations, the 4D InSpec® handheld 3D scanner was introduced as an advanced solution for defect measurement and analysis. This article evaluates the effectiveness of the 4D InSpec scanner through multiple statistical methods, including Gage Repeatability and Reproducibility (Gage R&R), Isoplot®, Youden plots, and Bland–Altman plots. A new concept of Probability of accurate Measurement (PoaM)© was introduced to capture the accuracy of the defect quantification based on their size. The results demonstrate a significant reduction in measurement variability, with Gage R&R improving from 39.9% (profile projector) to 8.5% (3D scanner), thus meeting the AS13100 Aerospace Quality Standard. Additionally, the 4D InSpec
Aust, JonasDonskoy, Gene
E-25 General Standards for Aerospace and Propulsion Systems
This document, expanding upon AIR6037A, provides technical specifications and operational protocols for instruments commonly used to measure aircraft engine nonvolatile Particulate Matter (nvPM) Particle Size Distributions (PSDs). For each instrument type, its functionality, calibration, uncertainties, and known limitations are discussed to support the development of procedures that help ARP6320B nvPM system operators reliably determine PSDs. Practical setup considerations, such as sample conditioning and instrument positioning, are highlighted, together with guidelines for maintenance, data correction, and quality control to minimize measurement uncertainty.
E-31P Particulate Matter Committee
Two-stroke engines represent an attractive solution for aviation industry applications (UAVs, VTOL aircraft, and ultralight aircraft) due to their compact size, high power-to-weight ratio, reduced number of moving parts, and the ability to operate with different fuels. This work presents a 0D/1D methodology for simulating the gas exchange, combustion, and unsteady flow of a two-stroke aviation engine. The scavenging and combustion processes, as well as the unsteady flow within the induction and exhaust systems, are investigated using a 0D/1D modeling approach. This study is motivated by the need to assess the accuracy of such models in predicting engine performance. For this purpose, the thermo-fluid dynamic code GASDYN has been applied and enhanced. The proposed 0D model is embedded into a 1D fluid-dynamic code for simulating the entire engine system. To characterize the baseline configuration, which includes tangential ports that facilitate a loop-scavenging process, computed results
Cerri, TarcisioGiussani, AlessandroLucchini, TommasoMarinoni, AndreaMontenegro, GianlucaOnorati, Angelo
This numerical study investigates a spark-ignited, two-stroke engine employing uniflow scavenging, flathead cylinder head design, and an exhaust valve system to identify the optimal bore-to-stroke (B/S) ratio for maximizing brake efficiency at fixed displacement. A single-cylinder prototype engine was constructed, and its experimental data validated a 1D GT-SUITE simulation model. This validated model was then utilized to simulate a full-scale, 1.5-liter displacement, horizontally opposed four-cylinder engine with supercharger-assisted boosting, intended for small aircraft propulsion. The simulations explored a range of B/S ratios from undersquare (0.7) to oversquare (1.5), maintaining a consistent brake power output of 60 kW at 3000 rpm and lambda 0.9. Results showed that increasing the B/S ratio enhanced brake efficiency from 26.0% at B/S=0.7 to 27.0% at B/S=1.5, largely due to reduced frictional losses attributed to shorter stroke and lower piston speeds, decreased heat transfer
Zanchin, GuilhermeHausen, RobertoFagundez, Jean LuccaLanzanova, ThompsonMartins, Mario
This SAE Aerospace Recommended Practice (ARP) provides guidance for substantiating the airworthiness of aircraft engine components. Generally, these components are associated with the engine control system, the system or systems that allow the engine to provide thrust or power as demanded by the pilot of the aircraft while also ensuring the engine operates within acceptable operating limits. But these components may also include hardware and systems associated with engine lubrication, engine or aircraft hydraulic or electrical systems, aircraft environmental control systems, thrust reverser control, or similar aircraft or engine propulsion system functions. This paper develops the concept of using a standardized 26-item checklist of environmental conditions for evaluating aircraft engine component airworthiness. This approach is compatible with current practices used in the industry and has been accepted by engine certification authorities in conjunction with other guidance as
E-36 Electronic Engine Controls Committee
This document is reissued for application to helicopters. It is primarily intended to apply to the engine or engines, but it shall also apply to fire protection of lines, tanks, combustion heaters, and auxiliary powerplants (APU). Post-crash fire protection is also discussed.
S-12 Powered Lift Propulsion Committee
This document is reissued for application to helicopters.
S-12 Powered Lift Propulsion Committee
The nvPM Mission Emissions Estimation Methodology (MEEM) was previously developed to estimate nonvolatile particulate matter (nvPM) emissions from ground certification data using the publicly available data from the International Civil Aviation Organization (ICAO) Aircraft Engine Emissions Databank (EEDB). In order to potentially improve the accuracy of nvPM emissions estimation and to enhance its usefulness to modelers, the method was revised to make use of fuel flow correlations and similar altitude corrections as used in the Boeing Fuel Flow Method 2 (BFFM2). The new fuel flow approach allows for improved trade-off-type assessments between nvPM and gaseous emissions—i.e., less relative uncertainties when assessing results from the two methods. Like the former MEEM, the new method, MEEM2, can be used with just publicly available data such as nvPM emissions indices (EI) from the EEDB as well as predicted fuel flows from publicly available aircraft performance models. MEEM2 has been
Ahrens, DeniseKim, BrianMéry, YoannZelina, JosephDudebout, RudolphMiake-Lye, Richard C.
This document is reissued for application to helicopters.
S-12 Powered Lift Propulsion Committee
Eco-sustainability is one of the main aspects focused on motor industries, including those related to air transport, which work to realize alternative propulsion systems, such as Hybrid Electric Propulsion Systems, for reducing CO2 emissions. Despite the minor CO2 emission produced by Hybrid Electric Propulsion Systems, these categories of propulsors require a proper control architecture for managing combustion and electric energies based on driver decisions and the flight mission set. A supervisory control logic, based on a Nonlinear Model Predictive Control (NMPC), is presented in this work to guarantee a specific State of Charge level of batteries coupled with the minimization of fuel consumption of an aeronautical Hybrid Propulsion System. These two goals are achieved by the designed NMPC, which provides the best amount of torque between the propulsors belonging to the analysed aeronautical powertrain, consisting of an Internal Combustion Engine and an Electric Machine. The
Tordela, CiroFornaro, Enrico
E-25 General Standards for Aerospace and Propulsion Systems
This specification defines basic physical, chemical, and performance limits for 5 cSt grades of gas turbine engine lubricating oils used in aero and aero-derived marine and industrial applications, along with standard test methods and requirements for laboratories performing them. It also defines the quality control requirements to assure batch conformance and materials traceability and the procedures to manage and communicate changes in oil formulation and brand. This specification invokes the Performance Review Institute (PRI) product qualification process. Requests for submittal information may be made to PRI at the address in 2.1.3, referencing this specification. Products qualified to this specification are listed on a Qualified Products List (QPL) managed by PRI. Additional tests and evaluations may be required by individual OEMs before an oil is approved for use in their equipment. Approval and/or certification for use of a specific gas turbine engine oil in aero and aero
E-34 Propulsion Lubricants Committee
Establishing critical useful life plays a central role to determine aeroengine health status including aeroengine parameter changes from adverse material conditions or metal fatigue. The useful life assessment serves to support maintenance teams by enabling predictive maintenance followed by part replacement or conditions improvement. The proposed research works to improve the ability of turbofan aeroengine useful life estimation while targeting practical deployment during maintenance operations at field locations. A field maintenance–oriented ensemble bagged regression model for aeroengines represents the proposed method within this research. The present study reaches an error index of 7.06 with 98.95% model fitness when applying it to critical useful life training data. The projected model received its validation through experiments on test and field datasets. Field tests revealed that among 25 machine learning models the proposed model delivered optimal results since its error index
Singh, Shaktiyavesh Nandan PratapShringi, RohitashwaChaturvedi, ManishKumar, Ajay
E-25 General Standards for Aerospace and Propulsion Systems
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