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The prop-fan propulsion system is being investigated as part of the NASA Aircraft Energy Efficiency program which includes both analytical studies and experimental tests.

There are future military and commercial propulsion requirements, however, where the anticipated market may not be sufficiently large or firm to provide the basis for a new development, for example, a medium size commercial or military STOL aircraft.

This paper describes how the MEE (More Electric Engine) system contributes toward an integrated propulsion control system, with a particular focus on commercial aircraft. Current aircraft systems control the engine rotational speed or pressure ratio to control propulsion, but in future aircraft systems, control of the engine thrust itself will be required. ...Current aircraft systems control the engine rotational speed or pressure ratio to control propulsion, but in future aircraft systems, control of the engine thrust itself will be required.

In developing a modern commercial aircraft, the airframe and engine manufacturers work as a team to develop the propulsion system and verify the high standards of safety, reliability, and performance the airlines and the public expect. ...An extremely important part of this undertaking is the testing of the propulsion system components and finally the entire system in realistic simulated operating conditions before the airplane goes into service.

Two decades of turboprop technology advances are discussed along with their application to a Prop-Fan propulsion system for modern high-speed commercial aircraft. The Prop-Fan propulsion system features a small diameter, multibladed propulsor geared to an advanced gas turbine engine. ...Several advanced technologies in the airframe and propulsion disciplines have been identified by NASA, with the turboprop being one of these. Two decades of turboprop technology advances are discussed along with their application to a Prop-Fan propulsion system for modern high-speed commercial aircraft.

According to some, electric propulsion is already on its way down the “trough of disillusionment.” This report argues that while there are some concerns with associated technologies, such pessimism is unwarranted. ...Yes, these unsettled questions may take a little longer to solve than originally estimated, but there is full expectation within the industry that electric propulsion for commercial aircraft will succeed. In this SAE EDGE Research Report we present points of view from leading researchers in the industry who are thinking deeply about solving these problems.

The application of digital electronic technology to the control of advanced commercial aircraft engines is expected to reduce fuel consumption by approximately 1% and hot section maintenance costs by as much as 50% because of the ability of electronic controls to operate more precisely than their hydromechanical counterparts. Other advantages, which will accrue from the use of electronic digital controls, will be the virtual elimination of engine control trimming, a greatly simplified interface with aircraft condition monitoring equipment, and more rapid and less costly control maintenance procedures. Digital electronic control is still an emerging technology, but it offers potential benefits which should justify the investment to bring it into commercial service.

Turboelectric Distributed Propulsion (TeDP) describes a power train consisting of a turboshaft engine which is used solely to provide electrical power through a generator to electric motors driving multiple propulsive fans which are distributed above, below, or inside a wing. ...Recent advancements in electronics, computers, and power distribution have made distributed propulsion feasible and the purpose of the studies described here has been to integrate this new type of propulsion with real airframes designed to specific civilian and military missions. ...Recent advancements in electronics, computers, and power distribution have made distributed propulsion feasible and the purpose of the studies described here has been to integrate this new type of propulsion with real airframes designed to specific civilian and military missions. Empirical Systems Aerospace, Inc.

In order to investigate the powered characteristics of such aircraft, a propulsion simulator for wind tunnel installation testing is required. The design requirements, development, initial testing, and planned application of this propulsion simulator will be discussed. ...The design requirements, development, initial testing, and planned application of this propulsion simulator will be discussed. Applications will include powered aspects of stability and control, and aerodynamic considerations of propulsion integration. ...Applications will include powered aspects of stability and control, and aerodynamic considerations of propulsion integration.

Among these are its aerodynamics, propulsion system, structural concept, materials, avionics and passenger seat. Advanced technology in the 340 design will result in a quality airliner better able to provide economical, reliable service with greater passenger comfort.

The key technical issues involved are engine reliability and the ability of the propulsion and airplane systems to provide safe, sustained operation during the anticipated time period of the diversion after an inflight engine and/or system failure.

These efforts were part of a cooperative program between Boeing Commercial Airplane Company, Pratt & Whitney Aircraft (Commercial Products Division), Bendix Energy Controls Division, and Hamilton Standard to demonstrate the improved capability of a totally Electronic Propulsion Control System (EPCS). Interest in fully electronic engine control systems was generated by their potential for low weight, high operational reliability, easy maintenance, and low life-cycle cost.

Noise sources are classified into three groups -- propulsion system, external flow and on-board equipment -- and their frequency characteristics are described.

There are, in addition, a number of interesting possibilities in structures, propulsion and systems design. The characteristics of medium range aircraft, having cruise Mach numbers of 0.85, 0.92, 0.95, and 0.98, are presented.

Turbofan engine technology has been widely used for propulsion of commercial airplanes in the subsonic range. Since the early 70's, turbofan's efficiency has greatly evolved, driven firstly by the core (thermodynamic) efficiency improvement, followed by a continuous increase in the bypass ratio (BPR), i.e. the rate between the engine fan airflow and the engine core airflow mass, with a focus on propulsive efficiency improvement. ...Nevertheless, the aeronautic propulsion industry, currently driven by the continuously stringent energy efficiency and environmental standards, has been encouraged to pursue additional energy efficiency and environmental performance improvements. ...One of the viable technological pathways, is the use of even higher BPR, with the so called Ultra High Bypass Ratio (UHBPR) engine approach, which uses BPR higher that 13:1 and can be seen as the turbofan engine efficiency frontier, to be used as a promising technology for near future airplane propulsion. Despite the propulsive efficiency improvements, the increase in the BPR sets some technological challenges in the engine design, associated with an increase in the engine's aerodynamic drag and weight (due to the larger fan&nacelle diameters), fan and core engine aerodynamics stability control, as well as aerodynamic engine and airframe & lifting devices integration issues.

The renewed interest in the fuel efficient and low CO2 emission CROR (contra-rotating open rotor) propulsion system for future commercial aircrafts has recently led to a series of isolated and installed CROR wind tunnel test campaigns performed in close collaboration between Airbus and the engine manufacturers.

This work serves as a feasibility study for continued research into the detection and mitigation of engine rollback using the propulsion control system.

A frequently used method of starting aircraft prime propulsion gas turbine engines is by means of a small auxiliary power unit (APU) providing compressed (bleed) air to an accessory drive gearbox-mounted air turbine starter.

In the present investigation the tools has been applied to a regional airliner (ATR 72-600) as a case study and two options for the propulsion system were considered: conventional and More Electric Aircraft. In order to validate the proposed turboprop model, the results obtained with PLA.N.E.S. were compared to nominal literature data and numerical values obtained with the Gas Turbine Simulation Program (GSP).

Demonstrators and research projects about electric aircraft taxi systems testify the current interest in low- or zero-emission ground propulsion technologies to lower the overall fuel consumption and emissions of commercial flights.