EADSEADS Innovation Works UK

Filton, Bristol BS99 7ARUnited Kingdom

Contact: innovationworks@eads.netEAD

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EADS Innovation Works

The E-Thrust concept study is part of EADS on-going

hybrid and electrical propulsion system research,

which has seen the hybrid concept study for a full-scale

helicopter, the successful development of a Cri-Cri

ultralight modified as the worlds first four-engine all-

electric aerobatic aircraft, the demonstration flights of a

hybrid electric motor glider for which EADS Innovation

Works developed the battery system, the flight testing

of a short-range mini-unmanned aerial vehicle with an

advanced fuel cell and the integration of a piston diesel

engine into the TANAN UAV as well as the concept study

of a hybrid-electric propulsion system for this rotorcraft.

EADS Innovation Works is the corporate network of

research centres of EADS. A highly skilled workforce

of more than 800 is operating the laboratories that

guarantee EADS technical innovation potential

with a focus on the long-term. The structure of the

network and the teams within EADS Innovation Works

are organised in global and transnational Technical

Capabilities Centres:

Composites technologies

Metallic technologies and surface engineering

Structures engineering, production processes and

aeromechanics

Sensors, electronics and system integration

Systems engineering, information technology and

applied mathematics

Energy and propulsion

Disruptive Scenarios and Concepts Center

RollS-RoyCE plC

65 Buckingham Gatelondon SW1E 6AT United Kingdom

Rolls-Royce Research and Technology

In 2012, Rolls-Royce invested 919 million on research

and development, two thirds of which had the objective

of further improving the environmental performance of

its products, in particular reducing emissions. To ensure

that there is a pipeline of technology, and a balanced

portfolio of research with target applications in both the

near and long term Rolls-Royce has adopted 5, 10 and

20 year visions for the technology it develops. Vision 5

constitutes the low risk technology ready for application

within 5 years. Vision 10 describes the next generation

of technology or capability. Vision 20 describes emerging

or as yet unproven technologies aimed at Rolls-Royces

future generations of products, much of which will be

applied right across the product range in all sectors.

A number of Vision 20 studies are currently exploring

future generations of aircraft architectures that may

provide significant improvements, particularly in areas

of fuel burn, noise and emissions, this includes electric

technologies and distributed propulsion. Rolls-Royce

has also created an extensive range of partnerships and

collaborations around the globe through our network

of 28 University Technology Centres (UTCs). UTCs are

a source of both technology and highly skilled people.

The Group has also applied a similar model in creating

a network of Advanced Manufacturing Research

Centres to develop manufacturing capability. There are

currently 6 operational facilities, the latest having opened

in Crosspointe, Virginia in late 2012. These foster

collaboration between companies at all stages of the

supply chain, from the Original Equipment Manufacturers

(OEMs) to material suppliers, measurement systems

providers and tool manufacturers.

E-ThRUST Electrical distributed propulsion system concept for lower fuel consumption, fewer emissions and less noise

ThE VISIon AnD pERSpECTIVE oF An ElECTRICAl DISTRIBUTED pRopUlSIon SySTEm

02

EADS Innovation Works and Rolls-Royce, with

Cranfield University as a partner, are jointly

engaged in the Distributed Electrical Aerospace

Propulsion (DEAP) project, which is co-funded

by the Technology Strategy Board (TSB) in the

United Kingdom. The DEAP project researches

key innovative technologies that will enable

improved fuel economy and reduced exhaust gas

and noise emissions for future aircraft designs by

incorporating a Distributed Propulsion (DP) system

architecture.

Innovative propulsion system concepts for future air

vehicle applications are being developed by EADS

Innovation Works, the corporate research and

technology network of EADS, and by Rolls-Royce,

a global provider of integrated power systems and

services to the civil aerospace, defence aerospace,

marine and energy markets. Results of their research

activities support EADS divisions in leveraging

innovation solutions to further improve the efficiency

and environmental performance of commercial aviation.

These efforts are part of the aerospace industrys

research to support its ambitious environmental

protection goals as spelled out in the European

Commissions roadmap report called Flightpath

2050 Europes Vision for Aviation. This report

sets the targets of reducing aircraft CO2 emissions by

75%, along with reductions of nitrous oxides (NOx) by

90% and noise levels by 65%, compared to standards

in the year 2000.

eConcept a future vision Airbus and EADS Innovation Works, along with

other industry players like Rolls-Royce and

Siemens, are exploring different avenues to

find innovative solutions to the challenges the

aviation industry is facing in the future. They are

investigating one such avenue for a 2050 timeframe

a hybrid/electrical distributed propulsion system

as an intermediate but necessary step towards fully

electric propulsion for airliners. Airbus, in its role as

integrator, has taken its concept plane a vision

of aviation in the future and used it to create the

eConcept, a visualisation of the architecture and

configuration of what an aircraft of the future could

look like powered by hybrid/electrical distributed

propulsion. The DEAP project (represented by

the initial E-Thrust configuration) is bringing the

technologies, while Airbus is giving its expertise

as an integrator providing regular inputs and

feedback on the technology developments.

The configuration with three fans on either side of the fuselage

represents an initial starting point for future optimisations, with the

optimum number of fans to be determined in trade-off studies in the

DEAP project.

03

Achieving these goals requires significant

performance improvements in engine technology,

systems architecture and engine/airframe

integration to enable radically more efficient

propulsion systems. Finding viable solutions requires

the pioneering of unconventional aircraft and propulsion

system concepts. In this perspective, propulsion

technologies are continuously being improved through

developments in the fields of energy storage and

conversion, in electrical motors, novel combustion

cycles, ultra-high bypass ratio configurations, along with

hybrid electric/thermodynamic and fully electric systems.

ThE DISTRIBUTED ElECTRICAl AERoSpACE pRopUlSIon (DEAp) pRojECTWith its experience in gas turbine and gas power unit

design, as well as in electric propulsion systems,

Rolls-Royce has for some time been a research partner

of EADS in the fields of energy management and

simulation, electrical machines and superconductivity,

and propulsion system integration. Since 2012,

EADS Innovation Works and Rolls-Royce, with

Cranfield University as a partner (and some testing

subcontracted to Cambridge University), are jointly

engaged in the DEAP project, which researches key

innovative technologies for distributed propulsion

systems. Compared to engines on existing commercial

airliners, such a system will require a much higher level

of integration with the airframe design than that of

todays aircraft.

The DEAP project aims to deliver a preferred electrical

DP system for future aircraft that may provide

a breakthrough and a significant contribution to

mitigating the environmental impact of the projected

increase of air traffic. Rolls-Royce will develop an

optimum electrical system propulsion plant, taking into

consideration speed range, max speed, number of

fan motors, efficiency, etc.; while EADS Innovation

Works (the DEAP project leader) will design the

electrical system and work with Airbus to optimise the

integration of the propulsion system in the airframe.

ThE BEnEFITS oF A DISTRIBUTED pRopUlSIon SySTEm ARChITECTUREFor the E-Thrust concept, distributed propulsion

means that several electrically-powered fans are

distributed in clusters along the wing span, with one

advanced gas power unit providing the electrical

power for six fans and for the re-charging of the

energy storage. The E-Thrust concept can be

described as a serial hybrid propulsion system.

This configuration represents an initial starting point

for future optimisations, with the optimum number of

fans to be determined in trade-off studies in the DEAP

project. Initial study results by Airbus indicate that a

single large gas power unit has advantages over two

or more smaller gas power units. This will give a noise

reduction and allows the filtering of particles in the long

exhaust duct at the back of the engine.

The hybrid DP architecture offers the possibility of

improving overall efficiency by allowing the separate

optimisation of the thermal efficiency of the gas power

unit (producing electrical power) and the propulsive

efficiency of the fans (producing thrust). The hybrid

concept makes it possible to down-size the gas power

unit and to optimize it for cruise. The additional power

required for take-off will be provided by the electric

energy storage.

04

A fundamental aspect of optimising the propulsive

efficiency is to increase the bypass ratio beyond

values of 12 achieved by todays most efficient podded

turbofans. For the DP concept, the bypass ratio

must be termed effective bypass ratio, because the

fan airstreams and the core airstream are physically

separated. With DP, values of over 20 in effective

bypass ratios appear achievable, which would lead

to significant reductions in fuel consumption and

emissions. having a number of small, low-power fans

integrated in the airframe instead of a few large wing-

mounted turbofans is also expected to reduce the

total propulsion system noise.

In addition to improving the propulsive efficiency, DP

offers a greater flexibility for the overall aircraft

design that could result in reduced structural weight

and aerodynamic drag, for example, by relaxed

engine-out design constraints leading to a smaller

vertical tail plane, by being able to better distribute the

weight of the propulsion system components and by

re-energising the momentum losses in the boundary

layers that grow over the wing and fuselage causing a

wake (Boundary Layer Ingestion, BLI).

An additional efficiency gain appears possible if this

boundary layer is ingested and accelerated by the

Take-off and & ClimbPower comes from the gas power unit and from the energy storage system to provide the peak power needed during the take-off and climb phase. The energy storage system will be sized to ensure a safe take-off and landing should the gas power unit fail during this phase.

CruiseIn the cruise phase, the gas power unit will provide the cruise power and the power to recharge the energy storage system. In the unlikely event of a failure of the gas power unit, power from the energy storage is available to continue the flight to a safe landing.

FlIGhT pRoFIlE EnERGy mAnAGEmEnT

fans, because it can reduce the aircrafts wake and

hence its drag. however, the implementation of a

boundary-layer ingesting system means that the airflow

into the fans is not uniform; to realize the potential

benefits, the turbo-machinery and in particular, the

fan blades must be able to withstand the associated

unsteady conditions due to the distorted intake

flow. The design of the Rolls-Royce fans is currently

being developed in collaboration with its University

Technology Centre in Cambridge, and is specifically

optimised to deliver the best performance in the

distorted flow conditions that are experienced

in a BLI configuration; its design is supported by

computer analysis as well as reduced-scale testing and

measurements.

For the power levels in the megaWatt range that

are required in an electrical distributed propulsion

network, a new high-voltage superconducting

electrical system has to be designed and validated

to stringent requirements in terms of efficiency.

Such a system must aim to reduce heat being

generated due to alternating current losses in the

superconducting wires, which are enclosed in cables

and surrounded by cryogenic fluid, so that they are

kept at a constant cryogenic temperature for their

best performance. Minimizing such losses is crucial,

as extracting 1 Watt of heat using a cryocooler at 20K

(-252 C) to ambient temperature requires 60 Watts of

electrical power.

05

EnABlInG TEChnoloGIES Superconductivity:

A key enabling technology for the DP (hybrid/

distributed propulsion) concept is using

superconductivity in the cables, generators and

motors for the transfer of electrical power from

the gas power unit and energy storage to the

fans. Superconductivity is a quantum mechanical

phenomenon of exactly zero electrical resistance,

which occurs in certain materials when they are

cooled below a critical temperature. It allows the

electrical system components to be much smaller,

lighter and more efficient compared to conventional

copper- and aluminium-based technology. The

necessary cooling can be achieved either by supplying

cryogenic fluids (for example: liquid hydrogen,

liquid helium or liquid nitrogen) from a reservoir,

or by producing the necessary cold temperatures

using a cryocooler a technology used today in

space applications (for example a turbo-Brayton

cryocooler made by Air Liquide for ESA) or in MRI

systems. A side-by-side comparison of copper and

superconducting wires demonstrates the vast size

and weight differences possible with this technology.

Magnesium DiBoride (MgB2) superconducting wires

are made by Columbus Superconductors and used

today, for example, in MRI scanners).

Energy Storage:

Scientists expect new generations of energy

storage systems to exceed energy densities of

1,000 Wh/kg (Watt hours per kilogram) within the

next two decades, more than doubling todays

best performance. Lithium-air batteries are the

most promising solution for the E-Thrust concepts

energy storage requirements. They have a higher

energy density than lithium-ion batteries because of

the lighter cathode, along with the fact that oxygen

is freely available in the environment. Lithium-air

batteries are currently under development and

are not yet commercially available. The E-Thrust

concept is based on the assumption that the

required level of energy density can be achieved

within the 25-year timeframe envisioned for the DP

concept to mature.

Descent/GlidingIn the initial descent phase, no power is provided to the fans, and the gas power unit will be switched off. The aircraft will be a glider and the energy storage system will provide the power for the aircrafts on-board systems.

Descent/WindmillingDuring the second phase of the descent, the fans will be windmilling and produce electrical power to top-up the charge in the energy storage system.

LandingFor the landing phase, the gas power unit is re-started and provides power at a low level for the propulsion system. This is a safety feature to cover a hypothetical loss of power from the energy storage system during this phase.

06

The distributed fan propulsion system provides thrust

for the aircraft, replacing conventional turbofan engines.

The large fan diameter and weight of conventional

turbofans limits where they can be located on an

airframe usually under the wing. Their location does

not enable advanced aerodynamic efficiency techniques

to be used, whereas having a number of electrically-

driven fans that are integrated into the airframe

allows for a more aerodynamic overall design.

During descent, the energy-efficient distributed fans are

turned by the airstream and, like wind turbines, they

generate electrical energy which can be stored.

To achieve an integrated distributed fan propulsion

system design that matches the overall airframe

requirements, three key innovative components

are required:

A wake re-energising fan

Structural stator vanes that pass electrical power and cryogenic coolant

A hub-mounted totally superconducting electrical machine

WAKE RE-EnERGISInG FAn As the aircraft flies through the air, it leaves a wake

behind it resulting in drag. The embedded wake

re-energising fan is designed to capture the wake

energy by re-accelerating the complex wake. By

re-energising the wake, the overall aircraft drag is

reduced. The concept uses advanced lightweight

composite fan blades that are designed to maximise

overall propulsive efficiency whilst minimising the

weight of the propulsion system.

DISTRIBUTED FAn pRopUlSIon SySTEm

07

STRUCTURAl STAToR VAnES By having an embedded propulsion system, the

conventional turbofan mounting structure is no

longer required thereby saving weight and drag. The

stator section is carefully designed to provide

a row of aerodynamic and structural stator

vanes behind the fan recovering thrust from

the swirling air. The length of the distributed fan,

propulsion system has been designed to be much

shorter than that of a conventional turbofan so that

the centre of gravity is located about the structural

stator vanes. In addition, some of the stator vanes

are designed to accommodate the internal routing

of the superconducting cables to the hub-mounted

superconducting electrical machine.

hUB-moUnTED ToTAlly SUpERConDUCTInG mAChInEThe innovative hub-mounted totally superconducting

electrical machine drives the wake re-energising

fan. Rolls-Royce and EADS Innovation Works, with

Magnifye Ltd and Cambridge University as partners,

are engaged in a Programmable Alternating

current Superconducting Machine (PSAM)

project.The PSAM project researches an innovative

programmable superconducting rotor and innovative

AC superconducting stator.This work is supported in

part by the UK Technology Strategy Board.

The superconducting stator generates a powerful

electro-magnetic field that rotates around the

circumference at a speed directly related to the

frequency of the electrical supply. The superconducting

machine replaces the copper and iron stator structure

of a conventional machine. It is a much more

powerful, lighter and low-loss design incorporating

round-wire high temperature superconducting coils

embedded within a lightweight epoxy structure.

Exploded view showing the hub-mounted totally

superconducting machine

Electromagnetic torque is created by effectively aligning

the rotors magnetic field with the field generated

electro-magnetically within the stator.

The superconducting rotor magnetic field is generated

through the use of bulk superconducting magnets in

a puck form. A superconducting magnetic puck

of this size can, when fully magnetised, generate

extremely high magnetic fields with laboratory testing

demonstrating 17 Tesla a magnetic field capable of

easily levitating a family car. The magnetic pucks are

innovatively magnetised in-situ by the stator to create

a permanent magnet field that can be programmed

to deliver different field strengths thereby improving

controllability.

The superconducting machine design is bi-

directional in that it is equally efficient at driving the

wake re-energising fan to provide aircraft thrust or

being driven by the fan rotating in the airstream to

generate electrical power, which can then be stored

within the airframe.