Felder, Jim

Guynn, Mark

Haller, Bill

Jones, Scott

Mason, Brian

Ordaz, Irian

Quinlan, Jesse

Tong, Mike

Welstead, Jason

NASA Technical Reports Server

Overview of the NASA STARC-ABL (Rev. B) 
Advanced Concept
Jason Welstead – PI, Aeronautics Systems Analysis
Jim Felder – Propulsion Systems Analysis
Mark Guynn – Aeronautics Systems Analysis
Bill Haller – Propulsion Systems Analysis
Mike Tong – Propulsion Systems Analysis
Scott Jones – Propulsion Systems Analysis
Irian Ordaz – Aeronautics Systems Analysis
Jesse Quinlan – Aeronautics Systems Analysis
Brian Mason – Structural Mechanics 1March 22, 2017
https://ntrs.nasa.gov/search.jsp?R=20170005612 2019-08-31T07:08:27+00:00Z
Concept Germination
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SUGAR VOLT SUGAR Freeze N3X
AIAA-2013-4402
STARC-ABL Rev. B* Concept Description
• STARC-ABL: Single-aisle Turboelectric AiRCraft with Aft Boundary Layer propulsion
– Conventional single aisle tube-and-wing configuration
– Twin underwing mounted N+3 geared turbofan engines with attached generators on fan 
shaft
– Ducted, electrically driven, boundary layer ingesting tailcone propulsor
• Summary of changes from Rev. A to Rev. B
– Design cruise Mach number increased from 0.7 to 0.785
– Modified wing sweep angle to accommodate increased Mach number
– Using NASA Glenn N+3 geared turbofan model
– Empirical estimates for propulsion weight replaced by WATE++ analysis
– Improved weight estimates of thermal management system
– Onboard voltage increased from 750 to 1000 volts
– Underwing engine fan pressure ratio decreased from 1.45 to 1.3
– Modified mission constraints to provide comparable performance to N3CC
– All other assumptions and methods unchanged from previous analysis
3*STARC-ABL Rev. A published in AIAA SciTech 2016 paper (AIAA-2016-1027)
Component Spec Pwr/Wt Efficiency
Generator 8 hp/lb 96%
Motor 8 hp/lb 96%
Inverter 10 hp/lb 98%
Cable 3.9 kg/m 99.6%
STARC-ABL Rev. B Power System Architecture
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• 1.25 FPR Electric Fan
• 3500 HP (2.6 MW) motor
• 77 inch fan
• 1.3 FPR engines
• 2000 HP (1.4 MW) 
generator
• 57 inch fan
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Fraction of Total Momentum Deficit Captured
Fraction of Momentum Deficit Captured 
Vs Fraction of Boundary Layer Captured
Baseline System
• 90% efficient transmission
• 1000 Volt electrical system
1/3 Cruise 
Thrust
1/3 Cruise 
Thrust
Electrical Component Assumptions
Propulsion System Concept Description
• Normal conduction (non-superconducting) electrical system
• Constant 3500 HP to BLI propulsor except at low system throttle settings
• Underwing engine fan pressure ratio of 1.30
• BLI propulsor fan pressure ratio of 1.25
• N+3 technology assumptions on propulsion architecture
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Underwing GenFan Tailcone Propulsor
System Performance Comparison
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STARC-ABL R.B N3CC R.B Delta
Wing Area (trap) ft^2 1140 1170 -2.3%
Span ft 118 118 Fixed
Aspect Ratio - 12.2 11.9 2.3%
Sweep (LE) deg 29 29 Fixed
Wing Loading lb/ft^2 116.3 118.1 -1.5%
Empty Weight lb 72730 73920 -1.6%
Operating Empty Weight lb 77350 78540 -1.5%
Zero Fuel Weight lb 108150 109340 -1.1%
Takeoff Gross Weight lb 132480 137670 -3.8%
Excess Specific Power ft/min 650 430 51.0%
Time to Climb min 25.8 20.7 24.6%
Thrust (Sea Level Static) lb/eng 21470 21660 -0.9%
Altitude (Start of Cruise) ft 37000 36340 1.8%
CL (Start of Cruise) - 0.58 0.57 1.5%
Cruise Mach Number - 0.785 0.785 Fixed
L/D (Start of Cruise) - 20.9 20.1 4.0%
Takeoff Length ft 8160 8200 -0.5%
Landing Length ft 5960 6030 -1.1%
Approach Velocity knots 146 147 -0.7%
TSFC (Start of Cruise) lb/hr/lb 0.437 0.496 -11.8%
Design Mission BF lb 21340 25170 -15.2%
Economic Mission BF lb 6260 6910 -9.4%
SciTech 2016 Results
Start of Cruise TSFC: -14.6%
Design Mission Block Fuel: -12.2%
Economic Block Fuel: -6.8%
• Each propulsion system sized to meeting rolling takeoff and climb thrust 
requirements
• Sized propulsion systems are similar in sea level static thrust
Propulsion System Weights
STARC-ABL
(41,780 lb)
N3CC
(37,660 lb)
Turbofans* (2) 7250 10690
Tailcone w/ gearbox 2040 -
Electric motor 440 -
Inverter 350 -
Rectifier 390 -
Cable 450 -
Circuit breaker 120 -
Thermal management 110 -
Nominal total 11,150 lb 10,690 lb
Installation weight 5% 5%
Sized SLS thrust 42,940 43,320
Engine scale factor +2% +15%
Sized total 12,074 lb 13,179 lb
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*Includes generators for STARC-ABL
SLS Thrust
Quick Summary of Rev. B Results
• Significant reductions in system fuel burn
– 12% reduction in start of cruise (SOC) TSFC
– 9% reduction in economic mission block fuel
– 15% reduction in design mission block fuel
– Fuel burn benefits similar to Mach 0.7 STARC-ABL Rev. A results
• Fuselage propulsor details
– Only bottom half of boundary layer ingested
– BLI propulsor placed at most aft fuselage position
– Driven by an all-electric motor, nominally operating at 3500 HP
– Electrical system modeled assuming ~10% total system losses
• Partially turboelectric system is not a weight penalty
– Downsizing of underwing engines enabled by turboelectric offsets the 
weight addition of electrical components and tailcone propulsor
• Cable size/weight can become prohibitive if onboard voltage too low
• Electric system specific power based upon current AATT NRA efforts
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Related AATT Investments on Enabling Technologies for 
STARC-ABL
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Integrated BLI 
(Tailcone Thruster)
SPM: Chris Hughes
Hybrid Gas-Electric 
Propulsion
SPM: Amy Jankovsky
Compact High OPR Gas 
Generator
SPM: Jim Walker
Summary of Current and Near Term AATT Research Efforts
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o Improved propulsion system weight modeling
o Increased design cruise Mach to 0.785
o Better estimate of TMS requirements and weights
o Higher order analysis (Rev. C)
• Analysis of a Single-aisle non-electric distributed propulsion concept
o Turbine powered tailcone thruster
o Explore the question, “What does electric give you?”
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• CFD on objective (full) scale vehicle
o Generate a nominal design for rear aircraft shaping and nacelle 
that minimizes distortion and maximizes performance
o Use objective scale results to guide design at WT model scale
• CFD analysis and design for potential wind tunnel model OML
• Exploration of potential test facilities and wind tunnel model conceptual 
design
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FY17 FY18 FY19 FY20
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
Notional Development Roadmap
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STARC-ABL 
Rev. B
STARC-ABL scaling studies
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CFD Design of Aft Fuselage
WT 
Test
Development of Objectives 
and Requirements for Test
Wind Tunnel Model 
OML Design via CFD
Design and Fab of WT Model
CFD Assessment and 
Predictions
Post Test CFD V&V, Analysis, 
Documentation
STARC-ABL Rev. D
Funded Effort Proposed, Over Guideline
Non-Electric Concept
STARC-ABL Rev. C
Questions?
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System Performance Comparison
2016 2017
STARC-ABL R.A N3CC R.A Delta STARC-ABL R.B N3CC R.B Delta
Wing Area (trap) ft^2 1270 1220 4.3% 1140 1170 -2.3%
Span ft 118 118 Fixed 118 118 Fixed
Aspect Ratio - 11.0 11.4 -4.1% 12.2 11.9 2.3%
Sweep deg 20.1 (c/4) 20.1 (c/4) Fixed 29 (LE) 29 (LE) Fixed
Wing Loading lb/ft^2 106.1 106 0.1% 116.3 118.1 -1.5%
Empty Weight lb 76700 69020 11.1% 72730 73920 -1.6%
Operating Empty Weight lb 81380 73690 10.4% 77350 78540 -1.5%
Zero Fuel Weight lb 112180 104490 7.4% 108150 109340 -1.1%
Takeoff Gross Weight lb 135000 129260 4.4% 132480 137670 -3.8%
Excess Specific Power ft/min 980 300 222.6% 650 430 51.0%
Time to Climb min 19.7 25.3 -22.1% 25.8 20.7 24.6%
Thrust (Sea Level Static) lb/eng 21460 20510 4.6% 21470 21660 -0.9%
Altitude (Start of Cruise) ft 34400 34580 -0.5% 37000 36340 1.8%
Cruise Mach Number - 0.7 0.7 Fixed 0.785 0.785 Fixed
CL (Start of Cruise) - 0.59 0.6 -1.7% 0.58 0.57 1.5%
L/D (Start of Cruise) - 22.1 21.4 3.3% 20.9 20.1 4.0%
Takeoff Length ft 8190 8190 0.0% 8160 8200 -0.5%
Landing Length ft 5590 5580 0.1% 5960 6030 -1.1%
Approach Velocity knots 140 140 0.1% 150 150 -0.7%
TSFC (Start of Cruise) lb/hr/lb 0.377 0.437 -13.8% 0.437 0.496 -11.8%
Design Mission BF lb 19940 22050 -9.6% 21340 25170 -15.2%
Economic Mission BF lb 5860 6090 -3.7% 6260 6910 -9.4%


Overview of the NASA STARC-ABL (Rev. B) Advanced Concept

Overview of the NASA STARC-ABL (Rev. B) Advanced Concept

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