feather project in jaxa toward future electric aircraft wednesday presentations...

FEATHER project in JAXA FEATHER project in JAXA FEATHER project in JAXA FEATHER project in JAXA and and and and

toward future electric aircrafttoward future electric aircrafttoward future electric aircrafttoward future electric aircraftAkira Nishizawa

Section leader of emission free aircraft sectionInnovative Aircraft Systems Research Aircraft Systems Research Team

Next Generation Aeronautical Innovation Hub Center

Japan Aerospace Exploration Agency(JAXA)Hiroshi Kobayashi(JAXA) and Hiroshi Fujimoto(The Univ. of Tokyo)

2nd On-Demand Mobility and Emerging Aviation Technology Roadmapping Workshop, 8-9 March 2016 Lockheed Martin Global Vision CenterArlington VA1

Outline1. Future Vision and Issues 2. FEATHER project3. Toward future electric aircraft

2

1. 1 Future vision

3http://publicdomainreview.org/collections/france-in-the-year-2000-1899-1910/

A 19th-Century Vision of the Year 2000

1. Future Vision and Issues

1. 2 Problems of Small Aircraft

4

0.00.00.00.0

0.20.20.20.2

0.40.40.40.4

0.60.60.60.6

0.80.80.80.8

1.01.01.01.0

1111 10101010 100100100100 1000100010001000

Tic

ket

fee[U

S$/A

SK

Tic

ket

fee[U

S$/A

SK

Tic

ket

fee[U

S$/A

SK

Tic

ket

fee[U

S$/A

SK]] ]]

No. of seatsNo. of seatsNo. of seatsNo. of seats

Regular feeRegular feeRegular feeRegular fee

Discount feeDiscount feeDiscount feeDiscount fee

0.342.35

10.53 16.57

Higher CostHigher CostHigher CostHigher Cost Lower SafetyLower SafetyLower SafetyLower Safety

Air taxi & Commuter General aviation

Air carrierAir Line

Unit ticket fees for domestic flights (in JAPAN, 2014)

Number of fatal accidents per 1 million flight time (average during 1982-1999 in USA)

The fatal accident rate of small aircraft is about 10X higher 10X higher 10X higher 10X higher than that of large aircraft

Source: NTSB Aviation Accident Database


1.3 Major issues and solution

5

Popularization of General AviationPopularization of General Aviation

Reduction of operating costReduction of operating cost

Reduction of fatal accidentsReduction of fatal accidents

Electric Electric Electric Electric aircraft aircraft aircraft aircraft

technologiestechnologiestechnologiestechnologiesSolutionSolutionSolutionSolution

Potential strength of Japanese industriesPotential strength of Japanese industriesPotential strength of Japanese industriesPotential strength of Japanese industries(electric motor, battery, power device,...)(electric motor, battery, power device,...)(electric motor, battery, power device,...)(electric motor, battery, power device,...)

JAXA JAXA JAXA JAXA Current：3～5X higher than airliner

PAV, AirTaxi, ODMGoal

Issues

utilizationutilizationutilizationutilizationCurrent：10X higher than airliner



6

2.1 Outline of FEATHER project2.1 Outline of FEATHER project2.1 Outline of FEATHER project2.1 Outline of FEATHER project

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Mission�Development of JAXA’s unique electric propulsion systems

2. FEATHER Project

FY2012Design

FY2013Fabrication

FY2014 Integration and flight test

1. Multiplexed motor 2. Regenerative air brake

Reduction gear

①①①①Multiplexed motorMultiplexed motorMultiplexed motorMultiplexed motor ②②②②Pilot interfacePilot interfacePilot interfacePilot interface ③③③③LiLiLiLi----ion batteryion batteryion batteryion battery

Display

Power lever

Electric motor Under wing container

Battery pack

2.2 Overview of the demonstrator2.2 Overview of the demonstrator2.2 Overview of the demonstrator2.2 Overview of the demonstrator

Original aircraft: Diamond aircraft type HK36TTC-ECO

Monitoring unit

8

2. FEATHER Project

Electric motorInverterReduction

gear Radiator

Electric propulsion system

2.3 Electric propulsion system

9

2. FEATHER Project

SpecificationsSpecificationsSpecificationsSpecificationsWing span 16.33mTake-off weight at the flight test 800kgCrew member 1 personTypes of electric motor and inverter Permanent magnet type synchronous motor

(three-phase) and IGBT inverterMotor control method FOC (Field-oriented control)Maximum total shaft power (at RPM) 60kW (2.5min. at 6586RPM), 63kW(proven at

flight)Type of power source Lithium-ion battery (32 cells in series)System voltage (open circuit at 100%SOC) and Current

128V, 750A

2.4 Specifications

10

2. FEATHER Project

2.5 Multiplexed electric motor system

inverters

232mm220mm

3.75㎏ 1

2

3

4 CharacteristicsCharacteristicsCharacteristicsCharacteristics� Compact� Light weight(2.17kW/kg)� High efficiency(95%)� High strength of structure

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0

0.5

1

1.5

2

2.5

3

70

75

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30 40 50 60 70 80

Po

we

r d

en

sity

[kW

/kg

]

Eff

icie

ncy

[%]

Maximum output[kW]

＋：Efficiency

◆：Power density

Rapid200FC11)

Electric Waiex12)

Antares20E1)

e-Genius13) FEATHER(JAXA)

EV motor(LEAF)

Aircraft piston engine

2. FEATHER Project

2.6 Regenerative air brake system(1/4)Characteristicfeatures

1. Augmentation of descent rate by only pulling the power lever w/o conventional air brake2. No weight penalty based on the field-oriented control method3. Maximization of the regenerative electricity for variable air speeds

12

Motor Generator

InverterRectifier

Capacitor

DC/DCBattery

Field-oriented control

Motor / Generator

Inverter

Battery

ConventionalPower lever

2. FEATHER Project

13

Power lever

displacement

Torque command value

PWRRGN

2.6 Regenerative air brake system(2/4)Motor torque is used as a command value in field-oriented control methodT

δPL

T = CRGNδPL

(-100%≤δPL≤0%)

T = CPWRδPL

(0%≤δPL≤100%)

ConstantVariable

2. FEATHER Project

14

Rotational

speed

Torque

0

2.6 Regenerative air brake system(3/4)

（PWR）

（RGN）


（corresponding to power lever max）

Maximization of the regenerative electricity

� Pitch angle of a blade = constant

2. FEATHER Project

The torque command value has to intersect with counter torque curve of propeller, otherwise the rotational number becomes zero or negative.

Counter torque of

Prop.

Free rotation(NTL)


Specially designed power lever to facilitate the control of descent rate and regeneration

Block diagram of the regenerative air brake system

Vair is not necessary as the feedback parameter to maximize the regenerative power in this system.

Motor/ Generator Inverter

System control unit

Battery

Target Torque Target Torque Target Torque Target Torque NNNNpppp Power lever

PropellerDisplay

displacement

Pitot tubeVair Regenerative power

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2. FEATHER Project

2.7 Flight demonstration

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2. FEATHER Project

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360 480 600 720 840 960 1080 1200 1320 1440 1560

H[m]

Pm[kW], Vair[m/s],Np[rps], SOC[%]

t[s]

Pm[kW]

Vair[m/s]

Np[rps]

SOC[%]

Motor power, Pm

Absolute altitude, H

Airspeed, Vair

Rotational speed of prop, Np

Take-off

Battery SOC

Touch-downSim. fail climb Regenerative

soaring Regenerative descend

w/o airbrake

An example of flight test data 17

2. FEATHER Project 2.7 Flight demonstration

Airbrake

2.7 Flight demonstration

Descent by using the conventional airbrake

Descent by using the “regenerative airbrake system”

-120

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0

-6

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-4

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-1

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490 495 500 505 510 515 520

Pow

er le

ver[%

]

Pm[k

W],

dH/d

t[m/s

]t[s]

Pm[kW]dH/dt[m/s]Power lever [%]

Correlation of the power lever displacement, regenerative power and consequent descent rate, dH/dt during descent by using regenerative airbrake

system 18

2. FEATHER Project


19

3. Toward 3. Toward 3. Toward 3. Toward future electric aircraftfuture electric aircraftfuture electric aircraftfuture electric aircraft

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0

200

400

600

800

1000

0 100 200 300 400 500

Ran

ge/k

mR

ange

/km

Ran

ge/k

mR

ange

/km

Energy density/WhkgEnergy density/WhkgEnergy density/WhkgEnergy density/Whkg----1111

Drag reduction (L/D>25)

Simple conversion of petrol to battery(4PAX, L/D<10)

High AR wingHigh AR wingHigh AR wingHigh AR wing

High energy density Li-ion battery

http://www.hitachi.com/New/cnews/month/2014/11/141114.html

Fuel cell & H2Range Extension

Hitachi demonstrated

335Wh/kg and 30Ah on

Nov. 2014 and they have

developed by 2020 .

®Skyhawk172

®Taurus G4

TOYOTA ‘s ®MIRAI with

2.0kW/kg FC stack.

3. Toward 3. Toward 3. Toward 3. Toward future electric aircraftfuture electric aircraftfuture electric aircraftfuture electric aircraft

21

Automatization 1. Electric propulsion system have a high affinity for automatization.

2. Electric motor have a high response performance.

3. Electric motor can be flexibly arranged on a wing or a fuselage.

Power by wire Key technology

ComputerComputerComputerComputerInverterInverterInverterInverter

MotorMotorMotorMotor SensorsSensorsSensorsSensors

Sensing ActuatorSensing ActuatorSensing ActuatorSensing Actuator Control AlgorithmControl AlgorithmControl AlgorithmControl Algorithm Alternative S&CAlternative S&CAlternative S&CAlternative S&C

Collaborative work

22

Thank youThank youThank youThank you

http://www.aero.jaxa.jp/eng/research/frontier/feather/

http://hflab.k.u-tokyo.ac.jp/index.html

1. Backgrounds & Objectives

24

Electric and hybrid

propulsion system for

aircraft

1. FEATHER project

2. Concept study of fuel

cell–gas turbine hybrid

aircraft

LongLongLongLong----term term term term research toward research toward research toward research toward zerozerozerozero----emission aircraft emission aircraft emission aircraft emission aircraft

collaborative work

Aeronautical Technology DirectorateIn JAXA

Target and mission of FEATHERTarget and mission of FEATHERTarget and mission of FEATHERTarget and mission of FEATHER

http://www.aero.jaxa.jp/publication/pamphlets/pdf/apg2012‐kouen03.pdf25

Small airplane for

FEATHER

Mission of FEATHER project�To get flight permission from JCAB as the first case of electric manned flight in Japan �Development of JAXA’s unique electric propulsion system�Flight validation of the new functions and system performance


Mile stones

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2012-2013 2014 2015June March July November February

StartStartStartStart IntegrationIntegrationIntegrationIntegration Approval for Approval for Approval for Approval for flight testflight testflight testflight test

Maiden flightMaiden flightMaiden flightMaiden flight

Complete of electric Complete of electric Complete of electric Complete of electric propulsion systempropulsion systempropulsion systempropulsion system

FY2012Design

FY2013Fabrication

FY2014 Integration and flight test

Final flightFinal flightFinal flightFinal flight

600ｍ Runway

～10m

～0.5min.

Jump test

2700ｍ Runway

120～150km/h

～600m

～20min.

Short traffic pattern flight testJump test2000ｍ Runway

～80m

～5min.

Approval for Approval for Approval for Approval for flight testflight testflight testflight test


A) Electric motor-glider system

A1-1）Driving system

Multiplexed motorInverter

Radiator & PumpReduction gear

Propeller

A2) Measurement system

A3) Airframe system

A4) Charging system

Li-ion battery

A1-2）Power source

A1-3）Pilot interface

A1-4）Management system

DisplayPower lever

System control unit

A1) Electric propulsion system

2. Systems

System configuration

Electric motor-glider system(Flight demonstrator)

27

3. Concepts1. Multiplexed motor 2. Regenerative air brake

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3.1 Multiplexed electric motor system(1/3)Our motivations

1. Avoidance of “loss of engine power” for single piston engine aircraft.2. Redundancy of electric motors.

Other researches

1. Distributed motors and fans for VTOL (Alex M. Stoll et al. of Joby Aviation, 14th AIAA Aviation Technology, Integration and Operations Conference 2014, AIAA2014-2407)

2. Electric Propulsion for Vertical Flight (Michael Ricci of LaunchPoint Technologies; AHS Transformative Vertical Flight Workshop 2014, Arlington, VA )

Our selection of approach

Putting multiplexed motor on a propeller shaft

3. Concepts

29

Technical issues for us

1. Reduction of the size and weight

2. Optimization of the number of motors

3. Isolation of failuresOur solutions

1. Directly coupling with each motor (additionaljoint parts are unnecessary)

2. Quadruplex motor based on the trade-off analysis

3. Individual contactors0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0

10

20

30

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50

60

70

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90

100

0 5 10 15 20

Wth/W

thmin

Wth[kgf]

n

Wth[kgf]

Wth/Wthminnopt

#1 #2 #3 #4

motor housing

motor axis

3.1 Multiplexed electric motor system(2/3)3. Concepts

30Number of motors

3.2 Regenerative air brake system(1/5)Our motivations

1. Elimination of conventional systems by multifunctionality of electric motor.2. Regeneration of electricity by electric motor.

Other researches

1. Feasibility study of regenerative soaring (J.Philip Barnes, Perican Aero Group, SAE Tech. Paper 2006-01-2422, 2006)2. WATTsUP can recuperate 13% of energy on every approach and reduce the field length of landing(Pipistrel, Aircraft News,31 Mar 2015)

Our selection of approach

1. Utilization of aerodynamic drag on the prop. due to regeneration2. Simultaneously harvesting a certain amount of energy

3. Concepts

31

Regenerative air brake system

2.6 Regenerative air brake system(1/4)Technical issues for us

1. Simplify the control of descent rate2. Avoidance of weight penalty and hardware complexity3. Maximization of the regenerative electricity

Our solutions 1. Augmentation of descent rate by pulling the power lever2. The simplest system configuration based on the field-oriented control method3. Formulation of control algorithm based on the aerodynamic features

32

Motor Generator

InverterRectifier

Capacitor

DC/DCBattery

Field-oriented control

Motor / Generator

Inverter

Battery

ConventionalPower lever

2. FEATHER Project

33

Power lever

displacement


PWRRGN

3.2 Regenerative air brake system(3/5)3. Concepts

Motor torque is used as a command value in field-oriented control method

34

Rotational

speed

Motor torque Aerodynamic

feature of Prop.

0

Airspeed = constant

Pitch angle of a blade = constant


Free rotation(NTL)

（PWR）

（RGN）

Reverse

Rotation

Torque command value（RGN maximum）

Significant

Drag!!

Disadvantage of FOC

35

Rotational

speed


feature of Prop.

0

Airspeed = constant



Free rotation(NTL)

（PWR）

（RGN）


opportunity loss

36

Rotational

speed


feature of Prop.

0

Airspeed = constant



Free rotation(NTL)

（PWR）

（RGN）


Maximization of the regenerative electricity

-50.0-40.0-30.0-20.0-10.0

0.010.020.030.040.050.0

-10 0 10 20 30 40

Torq

ue[N

m]

Revolution speed of propeller [rps]

β=10deg(Vair=35m/s) β=20deg(Vair=35m/s)β=30deg(Vair=35m/s) β=116deg(Vair=35m/s)β=10deg(Vair=25m/s) β=20deg(Vair=25m/s)β=30deg(Vair=25m/s) β=116deg(Vair=25m/s)


Wind tunnel tests results for the actual propeller in RGN mode(The flight demonstration was mainly conducted at angle of propeller pitch, β=14deg)

PWR

RGN

SmallSmallSmallSmall----scaled scaled scaled scaled prop. testprop. testprop. testprop. test

Actual prop. testActual prop. testActual prop. testActual prop. test

　52

maxmax 2 ppPP DNC ρπτ =

The maximum torque is proportional to Np

2 at a βvalue independent of Vair.

,pN

3. Concepts

37

35.38

35.382

35.384

35.386

35.388

35.39

35.392

35.394

35.396

35.398

35.4

136.845 136.85 136.855 136.86 136.865 136.87 136.875 136.88 136.885 136.89 136.895

Lat[deg]

Long[deg]1km

Typical example of the short traffic path

Tower

Runway

4. Flight demonstration

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H[m]

Pm[kW], Vair[m/s],Np[rps], SOC[%]

t[s]

Pm[kW]

Vair[m/s]

Np[rps]

SOC[%]

Motor power, Pm

Absolute altitude, H

Airspeed, Vair

Rotational speed of prop, Np

Take-off

Battery SOC

Touch-downSim. fail climb Regenerative

soaring Regenerative descend

w/o airbrake

An example of flight test data 39

2. FEATHER Project 2.7 Flight demonstration

5. SummaryWe have succeeded in flight demonstration as follows:

1. Avoidance Avoidance Avoidance Avoidance of complete of complete of complete of complete power power power power loss loss loss loss in engine failure during climb by using the multiplexed electric motor2. RegenerationRegenerationRegenerationRegeneration of of of of electricity electricity electricity electricity about 8% of maximum motor output during descent3. Control of descent rate by the proposed regenerative regenerative regenerative regenerative airbrake systemairbrake systemairbrake systemairbrake system without conventional airbrake4. Continuous “regenerative soaringregenerative soaringregenerative soaringregenerative soaring” free from descent in thermal condition

Acknowledgement: The wind tunnel test in this research was partly supported by the Ministry of Education, Culture, Sports, Science, and Technology grant (Basic Research A, number: 26249061). 40

41

∆∆∆∆Np ∆∆∆∆VS ∆∆∆∆L

� Torque

� Thrust

� Airspeed

feather project in jaxa toward future electric aircraft wednesday presentations...

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