Designing eVTOL for the Missionutm3.com/wp-content/...eVTOL_Workshop_WJohnson_s.pdf · 1 National Aeronautics and Space Administration Designing eVTOL for the Mission NDARC — NASA

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National Aeronautics and Space AdministrationNational Aeronautics and Space Administration

Designing eVTOL for the MissionNDARC — NASA Design and Analysis of Rotorcraft

Wayne JohnsonFrom VTOL to eVTOL WorkshopMay 24, 2018

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National Aeronautics and Space Administration

Conceptual Design of eVTOL Aircraft• Conceptual design

– Define aircraft to perform required mission• Identify aircraft type, including propulsion system• Size components and subsystems (weight, power, energy)

– Component design and optimization• Estimate performance and cost

– Emphasis on breadth and speed of analysis– Followed by preliminary design and detailed design

• Of Vertical Take-Off and Landing aircraft– VTOL required for air taxi operations– Efficient VTOL requires low disk-loading rotors, flying edgewise at low

speed (possibly transition to high speed configuration)

• With electric propulsion– Including hybrid configurations

From VTOL to eVTOL Workshop, May 24, 2018

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Design Tools• Aircraft design capability is required to support

research in a government laboratory– Technology impact assessments

• Show how technology will affect future systems– System level context for research

• Support level of investment for technology maturation– Concept exploration, decision, and refinement

• Must conduct quantitative evaluation and independentsynthesis for wide array of aircraft configurations andconcepts

• Such a tool is useful in the community ofinnovation


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NDARC — NASA Design and Analysis of Rotorcraft• Conceptual/preliminary design computer program

– Design task: Develop consistent description of system to performmission and satisfy design requirements

• Size aircraft: determine dimensions, weight, power, energy of allcomponents and subsystems

– Iterate with external optimization of primary design variables (egdisk loading, tip speed)

– With aircraft and rotor optimization using higher fidelity analyses– Analysis task: Off-design mission performance, flight performance

for point operating conditions

• NDARC initial release (1.0) May 2009• Current release (1.13) May 2018• NDARC has been distributed to 140+ organizations


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Key Attributes of NDARC• General aircraft and propulsion system architecture

– Aircraft model built from set of components– Flexible sizing constraints, based on multiple missions and

performance points– Capture technology impact, at system and component levels

• Surrogate models of component performance and weight– Allows for very short runtime and rapid concept iteration– Requires calibration of the models

• Accurate prediction of future aircraft design depends on– Identification of all aircraft subsystems– Calibration of surrogate models for performance and weight– Skill at estimating technology impact


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Simple Mission

Range0

SL/ISA+20oC

Cruise @ VBR

5k/ISA+20oC

X nm

TakeoffHOGE2 min

Altitude

LandingHOGE2 min

Reserves20 min @ VBEor 10% Fuel

Mission 1

Mission 2


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More Complex Mission Profile

Altitude(ft)

Radius(km)0

4,000(95oF)

5 min (Start Up/Taxi)

30 min @ VBE(Loiter)

Cruise @ VBRBest(ISA)

324

HOGE 2 min

PayloadRetained

424

30min/10% FuelReserves

Segment Atm. Time(min)

Dist.(km)

Speed(KTAS)

VROCCap.(fpm)

EngineRating

1 Taxi 4k 95°F 5 - - - =100% MCP2 Hover 4k 95°F 2 - HOGE 500 ≤95% MRP3 Climb - ISA - Credit ~Vy Fallout ≤100% IRP4 Cruise Best ISA - 324 VBR - ≤100% MCP5 Dash 4k 95°F - 100 VDASH - =90% MCP6 Loiter 4k 95°F 30 - VBE - ≤100% MCP7 Hover 4k 95°F 2 - HOGE 500 ≤95% MRP8 Dash 4k 95°F - 100 VDASH - =90% MCP9 Climb - ISA - Credit ~Vy Fallout ≤100% IRP

10 Cruise Best ISA - 324 VBR - ≤100% MCP11 Hover 4k 95°F 1 - HOGE 500 ≤95% MRP

12 30min/10% Res. Best ISA - - VBR - ≤100% MCP

TO HOGE 2 minLD HOGE 1 min

Notes: Sizes aircraft design gross weight and power2500lb internal payloadHOGE: Hover out of ground effect; aircraft has capability for 500fpm VROCVROC: Vertical rate of climb (purely vertical flight, no horizontal component to velocity)Best: Selected for configuration’s best performanceVBE: Best endurance speed; minimum fuel flowVBR: Best range speed. May elect to use long range cruise speed; 99% of maximum specific range, high sideVDASH: Dash or penetration speedVY: Best rate of climb speedReserve fuel is that required for either 30 minutes at VBR or 10% of mission fuel, whichever is greater

Dash


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NDARC Components to Construct Aircraft

rotors,propellers,ducted fans

connectsrotating

componentsturboshaft,

motor,generator,

compressor

energy source:burned,

renewed,or storedturbojet,

turbofan,reaction drive

fuel cell,solar cell


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Aircraft with Rotors


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Lots of Rotors


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Rotors and Wings


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Aircraft without Rotors


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Fixed Geometry


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Tilting and Swiveling and Stopping Things


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NDARC Propulsion Architecture — Turboshaft


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Reciprocating Engine


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Turbojet / Turbofan


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Fuel Cell


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Solar Cell


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Electric Motor


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Hybrid


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Turbo-Electric


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Quadrotor Aircraft with Various Propulsion ConceptsElectric propulsionRotor speed control Collective control

Turboshaft or reciprocating engineCollective control


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Side-by-Side Aircraft with Various Propulsion ConceptsTurboshaft propulsion Turboshaft Hybrid

Electric propulsion


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Tiltwing Aircraft with Various Propulsion ConceptsTurbo-electric propulsion Turboshaft


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NDARC Documentation• 70 published papers and reports on NDARC development and applications

• Principal documentation of development:– Johnson, W. "NDARC. NASA Design and Analysis of Rotorcraft." NASA TP

2015-218751, April 2015.– Johnson, W. "NDARC — NASA Design and Analysis of Rotorcraft.

Theoretical Basis and Architecture." American Helicopter SocietySpecialists' Conference on Aeromechanics, San Francisco, CA, January2010.

– Johnson, W. "NDARC — NASA Design and Analysis of Rotorcraft.Validation and Demonstration." American Helicopter Society Specialists'Conference on Aeromechanics, San Francisco, CA, January 2010.

– Johnson, W. "Propulsion System Models for Rotorcraft Conceptual Design."American Helicopter Society 5th Decennial Aeromechanics Specialist'sConference, San Francisco, CA, January 2014.

– "NDARC Theory Manual, Release 1.13" and "NDARC Input Manual,Release 1.13." May 2018.


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How to Get NDARC Software• NDARC software is available to US companies, laboratories,

universities, and individuals

• Distribution controlled by Software Release Authority at NASAAmes Research Center– Request software at https://software.nasa.gov/software/ARC-16265-1 by

submitting information for Software Usage Agreement

• NDARC web page (https://rotorcraft.arc.nasa.gov/ndarc) contains– Executables for current release (PC and Mac)– Documentation, training materials, model calibration procedures– Sample cases and reference models


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28282828From VTOL to eVTOL Workshop, May 24, 2018

Documents

Designing eVTOL for the Missionutm3.com/wp-content/...eVTOL_Workshop_WJohnson_s.pdf · 1 National Aeronautics and Space Administration Designing eVTOL for the Mission NDARC — NASA