electric propulsion adoption pathways through … tuesday presentations final/18...electric...

Electric Propulsion Adoption Pathways through Integrated Technology

DevelopmentNicholas K. Borer, Ph.D.

NASA Langley Research CenterAeronautics Systems Analysis Branch

[email protected] 2nd On-Demand Mobility and Emerging Aviation Technology Roadmapping Workshop

Electric Propulsion for Aviation

Benefits• High efficiency• Wide

operating envelope

• High power-to-weight ratio

• High reliability• “Scale-

invariant”

Challenges• Mass of

onboard stored energy system

• Lack of supporting infrastructure

• Certification/ safety assurance

2

http://www.berlinnh.gov/pages/berlinnh_news/airport

FAA, National Plan of Integrated Airport Systems, 2011—2015

energy.gov

Component-level technology development abounds… but what can we get out of smarter integration?


SCEPTOR – Propulsion-Airframe Integration(Scalable Convergent Electric Propulsion Technology Operations Research)

• Lead Center & Partner Centers: Langley (VA), Armstrong (CA), Glenn (OH)• External Collaborators: ESAero, Joby Aviation, Scaled Composites, Xperimental• Big Question: Can rapid, inexpensive sub-scale technology development and

testing show Distributed Electric Propulsion (DEP) capable of ultra-high efficiency, low carbon emissions, and low operating costs at high-speed?

• NASA Aeronautics Strategic Thrusts and Associated Outcomes Addressed:• Transition to Low Carbon Propulsion• Ultra Efficient Commercial Vehicles

• Idea/Concept: Design and fabricate a DEP wing system, retrofit a Tecnam P2006T with a DEP wing, flight test to show the benefit achieved.

• Feasibility Assessment: Establish baseline cruise energy required, apply new technology, determine whether 5x reduction goal is achieved at 150 knot cruise speed.

• Duration of Execution: 3.5 years, ~$16M full-cost


Wingtip Vortex Propeller Integration

SCEPTOR DEP Demonstratorwith Wing at High Cruise CL

Cruise Velocity/Propeller Tip Speed

Prop

elle

r Ef

ficie

ncy

Incr

ease

% Higher Cruise Speed Regional TurboPropCommercial Aircraft

Conventional General Aviation Aircraft

SCEPTOR Key Technologies

4

Folding High-Lift Low Tip Speed Propeller (Inboard)

NASA

NASA


Distributed Electric Propulsion High-Lift Benefit

5

0

1

2

3

4

5

6

-2 0 2 4 6 8 10

C L

α (°)

Lift Coefficient at 61 Knots (with and without 220 kW power across wing propellers)

No Flap (STAR-CCM+)

40º Flap, No Power (STAR-CCM+)

40º Flap with Power (STAR-CCM+)

40º Flap with Power (Effective, STAR-CCM+)

40º Flap with Power (FUN3D)

40º Flap with Power (Effective, FUN3D)

Unflapped Wing

Flapped Wing

DEP Flapped Wing


Wing Planform Comparison

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Tecnam P2006TWing loading

17 lb/ft2

DEP Tecnam P2006TWing loading

45 lb/ft2

Large Reduction in Wing Area Decreases the Friction Drag, and Allows Cruising at High Lift Coefficient


NASA SCEPTOR Primary Objective• Goal: 5x Lower Energy Use (Comparative to Retrofit

GA Baseline @ 150 knots)• Motor/controller/battery conversion efficiency

from 28% to 92% (3.3x)• Integration benefits of ~1.5x (2.0x likely

achievable with non-retrofit)

NASA SCEPTOR Derivative Objectives• ~30% Lower Total Operating Cost (Comparative to

Retrofit GA Baseline)• Zero In-flight Carbon Emissions

NASA SCEPTOR Secondary Objectives• 15 dB Lower community noise (with even lower

true community annoyance).• Flight control redundancy, robustness, reliability,

with improved ride quality.• Certification basis for DEP technologies.

SCEPTOR X-Plane Objectives

7


DEP wing development and fabrication

Flight test electric motors relocated to wing-tips, with DEP wing including nacelles (but no DEP highlift system).

Flight test with integrated DEP motors and folding props (cruise motors remain in wing-tips).

PHASE I PHASE II PHASE III PHASE IV

Ground and flight test validation of electric motors, battery, and instrumentation.

Baseline TecnamP2006T testing

Ground validation of DEP highlift

system

Goals:• Establish Electric Power

System Flight Safety• Establish Electric Baseline

Goals:• Establish Baseline

Tecnam Performance • Test Pilot Familiarity

Achieves Primary Objective of High Speed Cruise Efficiency

Achieves Secondary Objectives• DEP Acoustics Testing• Low Speed Control Robustness• Certification Basis of DEP

Technologies

Schedule

8


SCEPTOR Phase III/IV Cruise Performance

9

2.6

2.7

2.72.7

2.8

2.82.8

2.9

2.92.9

2.9

33

33

33

333

33

3.13.1

3.13.1

3.13.13.13.1

3.13.1

3.13.13.1

3.2

3.23.2

3.23.2

3.23.23.23.23.2

3.33.3

3.3

3.33.33.3

3.43.4

3.4

3.53.5

3.5

3.5

3.63.6

3.6

3.6

3.7

3.7

3.7

3.83.8

3.8

3.8

3.93.9

3.9

44

4

4

4.1

4.1

4.2

4.2

4.3

4.34.34.44.44.5

4.5

4.5

4.6 4.6

4.6

4.74.7

4.7

4.8 4.8

4.8

4.94.9

4.9

55 55.1

5.1

5.1

5.25.25.3 5.45.5 5.6

Efficiency Multiplier

V, KTAS

h, ft

80 100 120 140 160 180 200 2200

0.5

1

1.5

2

2.5

3

3.5

4

4.5x 104

5055 55

6060

606565

65

707070

70

7575

75

80

859090

90

959595

95

100100100100100

100

105

10510

110110 1

110

115 1

115

120

Cruise Power Required, kW

V, KTASh,

ft80 100 120 140 160 180 200 2200

0.5

1

1.5

2

2.5

3

3.5

4

4.5x 104


Heavy Fuel Hybrid-Electric SOFCLeverage Existing Infrastructure with Compelling On-Board Efficiency

• Developing dual-use system concept for hybrid-electric Solid Oxide Fuel Cell (SOFC) power system

• Leverage technology developed for DARPA by Boeing• Reforms heavy fuel onboard the aircraft• Sized for average rather than peak power• Tightly integrated to make judicious use of “waste” products

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ReformerFuel Cell

CombustorTurbocharger

Elec. Bus

SteamElectrical power

Electrical power

Exhaust

Pressurized air

Hydrogen CO, CO2

Heat Heat

Heavy fuel

NASA

US Coast Guard

Boeing


Hybrid SOFC Power System Work in Progress

• Developed conceptual system for Cessna 172 retrofit as potential fast concept-to-flight vehicle

• COTS motor, no integration benefits, ~100kW

• Total system >300 W/kg at >60% efficiency• Translates to ~2-3x reduction in fuel cost, 2x

reduction in carbon emissions, zero NOx for primary propulsion

• Can use typical hydrocarbon fuel infrastructure

• Developing follow-up effort for design and tested of dual-use system targeting >100kW power class

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Cessna 172P w/ SuperHawk STC

Takeoff gross mass, kg 1159 Typical unmodified empty mass, kg 695 Unmodified fuel flow at cruise, kg/hr 25 Exchange mass, kg -161 Hybrid power system mass, kg 309 Electric powertrain mass, kg 85 Fuel mass remaining to gross weight, kg 51 Estimated cruise fuel flow, kg/hr 13.4 Change in cruise fuel flow, % mass -46% Change in cruise fuel flow, % volume -54%

NASA

Questions?

12


Phase I Ground Testing Validation

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