Cruise Efficient Short Take-Off and Landing (CESTOL)Subsonic Transport System(Revolutionary System Concepts for Aeronautics 05)

Hyun Dae KimNASA Glenn Research Center

Jan. 26, 2006

Background Brief Concept Vehicle DescriptionStudy PlanGraphical AnimationPresentation by Boeing Technology / Phantom Works on Vehicle ConfigurationQ & ACruise Efficient Short Take-Off & Landing (CESTOL)

Description of the Problem Saturation of airports and the impact to the surrounding airspace and terrestrial communities are a rapidly increasing limit to world aviation travel. Subsonic commercial concepts appearing on the 25 year horizon must facilitate a more than 4X increase in air traffic, while complying with more stringent respect for the surrounding communities across the expanding world market. Under-utilization of small regional airports (e.g., Clevelands Burke Lakefront Airport) OBJECTIVE Need fuel efficient low noise aircrafts that utilize small regional airports to address air traffic growth.-> Low Noise Cruise Efficient STOL (CESTOL) VehicleCruise Efficient Short Take-Off & Landing (CESTOL)

Boeing 707De Havilland Comet Northrop YB-49Historical High Subsonic Transport Aircraft Configurations

Embedded Distributed Propulsion Vehicle will have: High lift capability via spanwide vectored thrust providing powered and/or circulation control lift to enable STOL operation. Efficient cruise performance through drag reduction by wing wake fill-in with engine thrust stream. Reduction in aircraft noise through airframe shielding and acoustic treatment of the large available surface area of propulsion system. Improvement in safety through a redundant multiple propulsion system. Reduction or elimination of a number of aircraft control surfaces through differential and vectoring thrust for pitch, roll, and yaw moments. Synergistic vehicle-propulsion integration is the key!New Vehicle ConceptCruise Efficient Short Take-Off & Landing (CESTOL)

Study Plan

TaskOrganizationDeliverablesDateDefine mission design requirements GRC/BoeingMission Reqs7/30/05Define vehicle configurationBoeingVehicle Definition10/30/051st order engine cycle analysisGRCEngine Deck10/30/05Explore noise benefits of distributed propulsion systemDiversitechDetailed Final Report1/31/06Assess system benefits and perform comparison studyBoeingDetailed Final Report1/31/06Assess noise benefits of the defined vehicleDiversitechDetailed Final Report1/31/06Summarize results and recommend research approachesAllFinal Report1/31/06

Graphical Animation of CESTOL Aircraft At Clevelands Burke Lakefront Regional Airport

Cruise Efficient Short Take-Off and Landing (CESTOL)Subsonic Transport System(Revolutionary System Concepts for Aeronautics 05)

Ronald KawaiBoeing Technology/Phantom Works Huntington Beach

Boeing Technology/Phantom Works Huntington Beach Creates Revolutionary Concept and Develops Characteristics, Performance, and Identifies Technology Needs for an Airplane Configuration EmbodyingVery Low Noise Features Capable of Operations from Regional Airports

NASA GRC Separate Contractor Quantifies Low Noise Potential Study Scope

LITERATURE REVIEW Powered lift can provide high CL for STOL

Past STOL transport studies for regional/short range at cruise speedsless than Mach 0.8

DSS turboprops have lowest GW & Cost but speed limited to belowMach 0.7

Efficient Mach 0.8 possible with turbofans or UHB unducted fans

Mach 0.8 requires supersonic tip speed fans or counter-rotating fansbut the later have high take off and enroute noise

A shrouded fan, i.e. turbofan is needed for high speed with low noise

IBF/USB/Augmentor Wing have highest high lift efficiency

Other Studies Show Internally Blow Flap HasBetter High Lift PerformanceBut Judged Complex

YC-14 and YC-15 where straight wing airplanes With efficient cruise below Mach 0.7Extensive studies and analyses resulted in AF AMST programfly-off between YC-14 and YC-15

IBF and Augmentor Wing ruled out by hot ducting complexity

AFFDL-TR-77-128YC-14 Interior NoisePeak at 70 - 100 hz

AF SELECTED THE C-17 WITH EBF TO BECOME THE ONLY SUCCESSFUL LARGE TURBOFAN POWERED STOL TRANSPORT (Swept Wing for Mach 0.74 0.77 Cruise, 2750 nmi range w/164,900 lb payload, First flight Sept 15, 1991)

FUTURE STOL TRANSPORT CONCEPT IMROVEMENT OPPORTUNIES: - IMPROVE CRUISE EFFICIENCY (INCREASE SPEED AND RANGE) - LOWER NOISEBOEING C-17A

Extrapolation of growth forecast would predict average airplane size to remain near constant with increased flight frequencies and city pairs

Future Demand continues for 90 to 175 passenger size

Operating from regional airports would relieve long pre-departure times2005 Boeing Current Market Outlook

Noise Restrictions can be expected to escalate with increasing number of flights

Very low noise will be required to enable growth for expanded operations at existing and new commercial airports while minimizing noise penalties

Noise Restrictions Continue to Grow

Number of Airports in Database: 600

Noise AbatementProcedures

Curfews

Charges

Levels

Number of Airports

Quotas

Reference 1

AIAA 2003-2891, Regional Jet Operational Improvements resulting from Short Field Performance and DesignIncluding a minimum 100 ft runway width for larger aircraftshowed that 84% or 813 of 973 civil airports have 5,000 ft +

Noise Footprint Would Be Very Important at Many Other Airports:

Expanded use of regional airports

Allow relaxation of curfews/operating at night

Allow increased operations per day

Allow conversion of military closing to commercial use

Neighbors want low noise regardless of airplane weight:

Goal should be cum noise as to Stage 3 minus XX

Take OffSidelineApproachSteep ApproachRapid Climb Out2000mSTOL to Reduce Noise Footprints

Low Sideline Noise would be of high value at Burke Lakefront Airport.TOSideline.Approach

10PM to 7AM curfew41 flight/day limit can be raised if aircraft noise decreasedLong Beach, CA Airport

El Toro Marine Air Base in SoCal could not be converted to relieve congestion at LAX because of neighborhood opposition

Traffic Growth Forecasts generally for next 20 years

For 2025+, extrapolate trends from Boeing Current Market Outlook

Noise sensitive regions are U.S. and Europe

Twin aisles and large airplanes for trans oceanic flights

Single aisle dominates size and generally with many more take-offand landing operations/day than twin aisle and large aircraft

Reducing noise for greatest noise growth is thus single aisle 90-175passenger size

Focus on high end for growth, 170 passenger size, but with BWB,It becomes multiple aisle airplane

Study for use at regional airports for air traffic expansion that mayprovide dual use technology for multi-role military applications2025+ Summary

BLENDED WING BODY IS FUTURE CONCEPT FORIMPROVED EFFICIENCY AND LOWER NOISE

LOW NOISE FEATURES: Forward noise shielding No aft noise reflection No flap noise Low approach thrust Body suppression of landing gear noise

Benefits From Embedded Distributed Propulsion Embedded engines for quiet powered lift Close coupled engine to slot with cold low pressure fan bleed

Smaller nozzle diameters for improved jet noise shielding More rapid mixing moving jet noise source forward Longer flap chord shielding / nozzle diameter Increased atmospheric attenuation form higher frequency jet noise

Reducing engine size enables embedding in mid wing sections for moreforward Cp and Cg

Reduces the thrust of individual engines reducing engine out thrust yaw control moments

Freestream InletChevrons for mixingDistributed propulsion: Smaller exhaust diameters enhances jet noise shielding Smaller engines enable direct fan bleed for low pressure powered IBF Slotted ejector reduces powered lift noise Minimal engine out rolling moment with powered liftFan Bleed IBFForward Fan Noise ShieldingAft Turbo-machinery and Combustion Noise ShieldingJet Noise Shielding

Concept Development ProcessSOW 2025 technology for traffic growth using untapped regional airspace Cruise efficient configuration with Embedded Wing PropulsionReview/Summarize Previous Studies IBF most efficient powered lift for STOLMission Requirements for CESTOL 170 pax, 3,000 nmi, Mach 0.8 Very low noise Minimum 5,000 ft TOFLDefine Configuration with STOL characteristics WingMOD planform development Digital configuration developmentAssess System Benefits of Distributed Propulsion on CESTOL Boeing Integrated Vehicle Design System (BIVDS) synthesis Very low noise features on Quiet Powered Lift Concept Foundational Technology Needs Outlined

WingMOD: Multidisciplinary OptimizationHard ConstraintsPayloadRangeApproach Speedetc.Design ConstraintsRunning LoadsBuffet CharacteristicsDFMAetc.AerodynamicsVortex Lattice ModelEmpirical Profile Drag, Compressibility Drag, & Sectional Maximum LiftCFD, Wind Tunnel CalibrationWingMOD OptimizerStructuresMonocoque Beam ModelStress & Buckling SizingStatic AeroelasticsControlsElevon ModelBalance AnalysisBaseline Config.Optimized Config.Configuration EstimateConfiguration LayoutClosed.Balanced.Trimmed.Min. OEW

137 ftQuiet Distributed PropulsionStarting Point272.4 in272.4 in Fan bleed slot ejector IBF for quiet powered lift Short inlet diffuser w/AFC Inlet and exhaust noise shielding4 engines4 engines4 enginesInjectionSlots100 optimization runs to evolve controllable planformIBF sizing 12 x 6 K lb thrust engines Slot width per engine = 68.1 inSlot height = 2.36 inFan pressure ratio = 1.69

Configuration Components All

Control Surface UsageYaw and roll controlPitch controlLift effect, pitch and roll controlLift effectors geared to pitch effectors -0.64:1 for trim, 0.44:1 for control10.2 deg flap deflection on lift effectorsTransition flap geared to pitch effectors -0.29:1 for trim, 0.16:1 for controlPitch and roll control

BIVDS EvaluationMission Performance

Performance analyses resulted in about the same take-off flight paths with the same altitude over the take-off measuring point at 6,500 m or 21,325 ft from brake releaseAccel to FinalClimb SpeedTO1st and 2ndSegment Climb6,500 m

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CE-STOL Performance 1/6/05

Aero: IBF (rbwbdemo1x18)

Prop: rcestol01x00

Wts: Kimoto

SW4,834

FN7,341

TOGW189,140

OEW105,042

(3000 nmi design mission)(500 nmi mission)(150 nmi mission)

Block Fuel37,723Block Fuel7946Block Fuel4098

ICAICAICA

Altitude39,000Altitude43,000Altitude31,000

Mach0.80Mach0.80Mach0.80

sfc0.520sfc0.521sfc0.522

L/D16.79L/D16.57L/D12.29

tau0.93tau0.95tau0.70

TakeoffTakeoffTakeoff

WTO189,140WTO157,874WTO153,835

D_lo (EO)1,588D_lo (EO)1,067D_lo (EO)1,004

D_obs (EO)2,452D_obs (EO)1,772D_obs (EO)1,694

gamma obs (EO)3.98gamma obs (EO)4.9gamma obs (EO)5.01

D_lo (AE)1,391D_lo (AE)913D_lo (AE)855

D_obs (AE)2,043D_obs (AE)1,477D_obs (AE)1,409

gamma obs (AE)5.83gamma obs (AE)6.84gamma obs (AE)6.97

TOFL2452TOFL1772TOFL1694

Approach & LandingApproach & LandingApproach & Landing

Wt land152,548Wt land151,052Wt land150,866

Glide Slope6.0Glide Slope6.0Glide Slope6.0

flap defl. ()20.0flap defl. ()20.0flap defl. ()20.0

air run*776air run776air run776

ground run1,310ground run1,298ground run1,296

LFL3,477LFL3,457LFL3,454

Vapproach115.5Vapproach115.0Vapproach114.9

Alpha13.8Alpha13.8Alpha13.8

Net Thrust54,664Net Thrust54,729Net Thrust54,736

Gross Thrust70,992Gross Thrust71,077Gross Thrust71,086

tau**20%tau**20%tau**20%

** requires aerobraking** requires aerobraking** requires aerobraking

* includes flare distance* includes flare distance* includes flare distance

Note: BIVDS is run as a 4 engine airplane. Thrust values are for 3 engines. Total thrust is 4 x values

Range

TOGW

Total Thrust

Altitude at 6500 m from brake release

Velocity over microphone

In all cases, flight over the TO measuring point occurs at the same altitude because it is during the acceleration to climb speed

The lower range flights will have lower noise because flight over the microphone will be at higher speed

Very Low Noise FeaturesForward Noise ShieldedAft Noise ShieldedConsider PartSpan Verticalsto Improve SidelineShielding if NecessaryNote: Powered lift is off during climb Differential elevons positions could be optimized for noise shielding Embedded Distributedpropulsion enablesquiet powered lift with jet noise shieldingBoeing Technology/Phantom Works Huntington Beach provides missiondata for very low noise concept for NASA to make noise assessmentRapid Climb (3000+ ft over T.0. noise point)Could Use Cutback or Higher Altitude Before Acceleration to Climb SpeedSteep Descent (6 degree glide slope) 3,500 ft TOFL

Foundational Technologies NeededNoise Shielding Codes Reflections Turbo-machinery noise Jet noiseQuiet Powered Lift: Low Pressure IBF performance and noiseFlow Control Inlets Active, Passive and Hybrid EvaluationsRevolutionary Engine Concepts Short Cruise EfficientVariable Geometry Noise Reflection Nozzles Forward noise sourceInlet/airframe Aero Integration Inlets in high Mach flow field

Reduce Nozzle Height and Create Vortices to Move Jet Noise Source Forward

Modify with quiet turbofanfor very low noise and IRvalidation Current X-48B program to validatelow speed characteristicsNeed Small Turbofan for X-48BFoundational Technology for Jet Noise ShieldingShielding Code Development

Calibration Wind Tunnel Tests Shielded Jet Noise NozzleCFD DevelopmentModel TestsFlight ValidationsSmall Turbofan(s)

ConclusionsContinuing growth in air travel demand is forecast. This growth is expected to increasedaily departures operating from an increasing number of city pairs.

This growth is forecast to go with increasing GDP providing a need for very quiet airplaneoperating from regional airports which can have current economics

Studies have shown eliminating noise reflections while providing noise shielding cansignificantly reduce flyover noise

Extending these principals to jet noise source downstream in the exhaust wakeshould provide more dramatic noise reductions

Large surface area planforms such as the BWB provides opportunities for increasedsource noise shielding

Embedded distributed propulsion offers the potential for quiet powered lift with jet noiseshielding for small noise footprints operating from regional airports

Configuration studies were made to evolve a BWB STOL planform that is trimmable with total noise shielding

Low noise footprints would also have low IR footprints for passive protection from terrorists

Development of foundational technologies are needed that would be generic and dual use

Historically, there have been two distinctive commercial transport configurations.One is a podded engine configuration like the original Boeing 707 and its derivatives.The other is an embedded engine configuration like the British De Havilland Comet aircraft which later became current British Nimrod military aircraft.

Now, here are the proposed concept description.The Key to the concept is Synergistic

Thick wing/box structure weight savingsWeight savings thru common structure in inlets, wings, nozzles, etc.No tail.Significant drag reduction possilble

Increased internal dragEngine maintenance diffuculty -> Not so. Engines can be installed between wing ribs and lowered thru lower wing surface.Adverse flow interation between wing and propulsion aerodynamcs -> this can be overcome thru prudent CFD design.The BWB configurations studied have inherently much lower approach noise. The take-off noise benefits from no wing noise reflection..