Longitudinal Double Wing (LDW) Concept Presented by Michael Dizdarevic AIAA Aviation 2013 Conference...

Longitudinal Double Wing Longitudinal Double Wing (LDW) (LDW) ConceptConcept

Presented by Michael DizdarevicPresented by Michael Dizdarevic

AIAA Aviation 2013 Conference - Los AIAA Aviation 2013 Conference - Los AngelesAngeles

Aug 13, 2013 2Longitudinal Double Wing (LDW) Aircraft

AgendaAgenda About the research teamAbout the research team Introduction of LDW conceptIntroduction of LDW concept General aircraft classification and characteristicsGeneral aircraft classification and characteristics LDW configuration and characteristicsLDW configuration and characteristics Similarities and differences between LDW and Similarities and differences between LDW and

tube-and-wing (TAW) aircrafttube-and-wing (TAW) aircraft Architectural impact on aircraft performanceArchitectural impact on aircraft performance Case study (LDW-200 vs. B767-300ER)Case study (LDW-200 vs. B767-300ER) Assumptions and MethodologyAssumptions and Methodology ResultsResults ConclusionConclusion Q & A Q & A


About Research TeamAbout Research TeamFARUK DIZDAREVICFARUK DIZDAREVIC (Principal Researcher) (Principal Researcher)

VP R&D Soko Aircraft Industry – the largest aircraft company in VP R&D Soko Aircraft Industry – the largest aircraft company in former Yugoslavia. former Yugoslavia.

Previously a head of company’s Aircraft and Helicopter divisions Previously a head of company’s Aircraft and Helicopter divisions involving manufacturing of their own military training and combat involving manufacturing of their own military training and combat aircraft, as well as various components for World’s major aircraft aircraft, as well as various components for World’s major aircraft including B737/757, MD-80, and A310/330/340, etc.including B737/757, MD-80, and A310/330/340, etc.

University professor in the area of aircraft manufacturing University professor in the area of aircraft manufacturing technologies for many years. technologies for many years.

Extensive experience and expertise related to the research of Flying Extensive experience and expertise related to the research of Flying Wing aerodynamic concepts for the past 20+ years. Wing aerodynamic concepts for the past 20+ years.

Holder of a number of U.S. patents related to aeronautics field. Holder of a number of U.S. patents related to aeronautics field.


About Research Team About Research Team ……cont.cont.

MICHAEL DIZDAREVICMICHAEL DIZDAREVIC (Researcher ) (Researcher )

Research of Flying Wing aerodynamic concepts for the past 20+ Research of Flying Wing aerodynamic concepts for the past 20+ years. years.

Versatile University level educational background in Mechanical and Versatile University level educational background in Mechanical and Aeronautical Engineering, as well as Finance and Computer Aeronautical Engineering, as well as Finance and Computer Science. Science.

Extensive work experience with large scale data processing, Extensive work experience with large scale data processing, integration, modeling, and analysis with major US and international integration, modeling, and analysis with major US and international corporations including project management for the past 15 years. corporations including project management for the past 15 years.


General Aircraft General Aircraft ClassificationClassification

Achieve good aerodynamic characteristics

Improved aircraft features relative to both TAW and

TFW aircraft

Achieve good aerodynamic characteristics of TAW

aircraft

High level of natural longitudinal stability

High level of flight control efficiency in all flight

conditions

High level of ride quality

Higher engine efficiency relative to both TAW and

TFW aircraft

Lower airfoil thickness than both TAW and TFW aircraft

Lower level of noise in passenger cabin and

around airports

Reduce parasitic wetted area of aircraft

Achieve high ratio between airlifting and total wetted

area

Favorable distribution between aerodynamic and inertia forces to generate low bending momentums

Longitudinal Double Wing (LDW) Aircraft Goals

Additional Goals

Use of efficient aft-camber airfoils across the wing

span

Favorable aircraft shapes to allow for application of light composite materials across the entire airframe

Tube And Wing (TAW) Aircraft

Hybrid AircraftTailless Flying

Wing (TFW) Aircraft

Goals Goals


LDW Aerodynamic ConceptLDW Aerodynamic ConceptVisualizationVisualization


LDW ConfigurationLDW Configuration

Front Wing

Architectural Configuration

V-tail Rear Wing


Aircraft CharacteristicsAircraft Characteristics

Accommodation of 90% of installations, instruments,

and equipment

Landing Gear Accommodation

Roll control of aircraft in all flight configurationsFuel Disposal

Production of extra lift needed at low speed during

take-off and landingPayload Disposal

Production of 80% of necessary lift in cruising

flight configurationCockpit

Aerodynamics

Front Wing (FW)

Architecture


Aircraft Characteristics Aircraft Characteristics ……cont.cont.

Pitch and roll control in all flight configurations

Participating in overall lift production of up to 20% in

cruise conditions

Accommodation of installations and

instruments required for engine operations and

flight control

Natural longitudinal stabilization of LDW

aircraft

Accommodation of aircraft engines

Aerodynamics

Rear Wing (RW)

Architecture

Pitch trimming in all flight configurations


Aircraft Characteristics Aircraft Characteristics ……cont.cont.

Yaw control of LDW aircraft

Accommodation of installations traversing

between Front and Rear Wing

Longitudinal and directional natural

stabilization of LDW aircraft

Reliable and safe connection between Front

and Rear Wing

Aerodynamics

V-tail (VT)

Architecture


LDW and TAW LDW and TAW SimilaritiesSimilarities Both aircraft having pronounced separate front and rear Both aircraft having pronounced separate front and rear

aerodynamic surfaces for lift production and reliable flight aerodynamic surfaces for lift production and reliable flight controlscontrols

The ratio between rear and front aerodynamic surfaces is The ratio between rear and front aerodynamic surfaces is rather close at around 0.5 for both aircraftrather close at around 0.5 for both aircraft

Span and overall length of both aircraft for a given aircraft Span and overall length of both aircraft for a given aircraft category are rather closecategory are rather close

Resulting similar flight control efficiencyResulting similar flight control efficiency


LDW and TAW LDW and TAW DifferencesDifferences

Different shape, size, architecture, and aerodynamic Different shape, size, architecture, and aerodynamic tasks of connecting bodies (V-tail and fuselage tasks of connecting bodies (V-tail and fuselage respectively)respectively)

Different inner shape, payload distribution, and Different inner shape, payload distribution, and structural integration with other sections, as well as structural integration with other sections, as well as different aerodynamic function of payload bay.different aerodynamic function of payload bay.


LDW and TAW LDW and TAW Differences Differences …cont.…cont. Different design and position of engines’ aerodynamic cover , as Different design and position of engines’ aerodynamic cover , as

well as integration with other aircraft sectionswell as integration with other aircraft sections Different size and flight mechanics task of rear aerodynamic Different size and flight mechanics task of rear aerodynamic

surfacessurfaces Different size of front aerodynamic surfaces for the same class Different size of front aerodynamic surfaces for the same class

aircraftaircraft


Architecture Architecture Performance ImpactPerformance Impact










Case study (LDW-200 vs. Case study (LDW-200 vs. B767)B767)

Dimensional analysis was performed to Dimensional analysis was performed to identify the separate impact of each identify the separate impact of each architectural element on aircraft architectural element on aircraft performanceperformance

Comparison case study was performed Comparison case study was performed for B767-300ER long-range version and for B767-300ER long-range version and the equivalent virtual LDW-200 aircraft the equivalent virtual LDW-200 aircraft with similar exploitation characteristicswith similar exploitation characteristics


Assumptions and Assumptions and MethodologyMethodology

Assumptions

Operating Weight Empty

Calculations

Flight Control

Efficiency Ratio

Calculation

Longitudinal Double Wing (LDW) Aircraft

Fuel Weight and Drag

Ratio Calculation

s

Specific Fuel

Consumption Ratio

Calculation

Calculation Methodology


AssumptionsAssumptions Both aircraft flying at the same speed and Both aircraft flying at the same speed and

altitudealtitude Same operating rangeSame operating range Same airfoil familySame airfoil family Constant CConstant CLL across the span, hence Mean across the span, hence Mean

Aerodynamic Chord (M.A.C.) becoming Aerodynamic Chord (M.A.C.) becoming identical to Mean Geometric Chord (M.G.C.) for identical to Mean Geometric Chord (M.G.C.) for dimensional analysis purposesdimensional analysis purposes

Roughly the same space for payload Roughly the same space for payload accommodationaccommodation

Same engine efficiencySame engine efficiency


Calculation MethodologyCalculation Methodology Fuel weight of B767-300ER aircraft was taken as a Fuel weight of B767-300ER aircraft was taken as a

difference between Max. T.O. weight and the sum of difference between Max. T.O. weight and the sum of operating empty weight and Max. payload weightoperating empty weight and Max. payload weight

Weights of LDW-200 airframe sections were Weights of LDW-200 airframe sections were calculated by Stanford University methodology for calculated by Stanford University methodology for commercial aircraft and then modified by taking into commercial aircraft and then modified by taking into consideration that 75% of airframe was made of consideration that 75% of airframe was made of composites except for Cabin and Rear Wing, which composites except for Cabin and Rear Wing, which were calculated based on NASA’s BWB methodologywere calculated based on NASA’s BWB methodology

Fuel weight of LDW-200 was calculated together with Fuel weight of LDW-200 was calculated together with the total drag ratio between LDW-200 and B767-the total drag ratio between LDW-200 and B767-300ER aircraft to satisfy the condition related to 300ER aircraft to satisfy the condition related to identical range of both aircraftidentical range of both aircraft

Weight calculations for both aircraft was performed Weight calculations for both aircraft was performed for mid-cruise conditionsfor mid-cruise conditions


Calculation Methodology Calculation Methodology …cont.…cont.

Pitch control efficiency was calculated as being Pitch control efficiency was calculated as being directly proportional to pitch momentum and directly proportional to pitch momentum and inversely proportional to aerodynamic and mass inversely proportional to aerodynamic and mass inertia of aircraft. Aerodynamic inertia is inertia of aircraft. Aerodynamic inertia is directly proportional to aerodynamic surface directly proportional to aerodynamic surface area and length of mean aerodynamic chord.area and length of mean aerodynamic chord.

Roll control efficiency was calculated as directly Roll control efficiency was calculated as directly

proportional to roll momentum and indirectly proportional to roll momentum and indirectly

proportional to aerodynamic and mass inertia.proportional to aerodynamic and mass inertia.


Calculation Methodology Calculation Methodology …cont.…cont.

Steps to calculate LDW-200 fuel weightSteps to calculate LDW-200 fuel weight::

Gf(LDW) = (Fd(LDW)/Fd(B767)) x Gf(B767) (1)

Assuming that the total drag distribution of B767 is the same as roughly a general drag distribution for Assuming that the total drag distribution of B767 is the same as roughly a general drag distribution for commercial TAW aircraft commercial TAW aircraft

where Induced Drag = 40%, Compression Drag = 40%, and Parasitic Friction Drag = 20% of the total drag where Induced Drag = 40%, Compression Drag = 40%, and Parasitic Friction Drag = 20% of the total drag then then

Fd(LDW)/Fd(B767) = 0.4 x (Fdi(LDW)/Fdi(B767)) + 0.4 x (Fdc(LDW)/Fdc(B767)) + 0.2 x Fdp(LDW)/Fdp(LDW) (const.) (2)

where Fdi = ki x f(G²); Fdc = kc x f(G); Fdp = kf x Cdf x Aw = kpf; ki, kc, kpf = f(geometry) for both aircraft

For example, for Inviscid Induced Drag ki = f(e, AR, Aw)

Example of quadratic function of weight FDi = q x Cdi x Aw CL = Gmid/(qAw)CDi = CL²/eπAR CL² = Gmid²/(q²Aw²) FDi = q x (CL²/eπAR) x Aw FDi = [1/(qπ)] x [Gmid²/(eAR Aw)] = f(G²)

where 1/e AR Aw is ki geometry factor for each aircraft. Therefore formula (2) becomes

Fd(LDW)/Fd(B767) = 0.4 x Ki x G²(LDW)/G²(B767) + 0.4 x Kc x G(LDW)/G(B767) + 0.2 x Kpf (3)

where Ki = ki(LDW)/ki(B767); Kc = kc(LDW)/kc(B767); Kpf = kpf(LDW)/kpf(B767)

Since G(LDW) = Goe + Gp + Gf (operating weight empty + payload + fuel) then

G(LDW) = Goe(LDW)+Gp(LDW) + (Fd(LDW)/Fd(B767)) x Gf(B767) (4)

Formulas (3) and (4) are used in iterative process until Formulas (3) and (4) are used in iterative process until G(LDW) from the current iteration is very close to the from the current iteration is very close to the one in the prior iteration.one in the prior iteration.


ResultsResults

Weight

FlightControl

Efficiency

Specific Fuel

Consumption

Categories

Viscous Induced Drag was not Viscous Induced Drag was not taken into consideration though taken into consideration though logically LDW has lower valueslogically LDW has lower values

Interference Drag was not Interference Drag was not estimated due to low impact for estimated due to low impact for both types of aircraftboth types of aircraft

Wave Drag was not estimated due Wave Drag was not estimated due to relatively minor impact at to relatively minor impact at speeds at or under Mach 0.8 speeds at or under Mach 0.8 though LDW is having clear though LDW is having clear advantages due to lower airfoil advantages due to lower airfoil thicknessthickness

ParasiticFriction

Drag

InducedDrag

Compression Drag

RollContr

ol

PitchContr

ol

TotalDrag

Yaw Control was not Yaw Control was not considered here as not considered here as not critical for LDW-200 due critical for LDW-200 due to engines being grouped to engines being grouped around symmetry axisaround symmetry axis


Results - WeightResults - Weight

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

LDW-200 vs. B767 [%](Positives and Negatives)

Diff [%] 31.04% 19.98% 56.72% 55.97% 35.54% 30.34%

Operating Empty

Max. Payload

Max. FuelMid-cruise

FuelMax. Take-

offMid-cruise


Results – Induced Drag Results – Induced Drag (Inviscid)(Inviscid)

-50.00%

0.00%

50.00%

100.00%

150.00%

200.00%

LDW-200 vs. B767 [%] (Positives and Negatives)

Diff [%] 30.34% 172.96% -12.36% -48.10%

Gmid Area (Aw )Osw ald's Factor (e)

Aspect Ratio (AR)

FDi = q x CDi x Aw; Due to CDi = CL²/eπAR FDi = q x (CL²/eπAR) x AwCL = Gmid/(qAw); CL² = Gmid²/(q²Aw²), thusFDi = [1/(qπ)] x [Gmid²/(eAR Aw)]


Results – Compression Results – Compression DragDrag

0%

5%

10%

15%

20%

25%

30%

35%


Diff [%] 9% 30% 22%

(1/ℓMGC)^0.11 Gmid t/c


Results – Parasitic Results – Parasitic Friction DragFriction Drag

-20.00%

-10.00%

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%


Diff [%] -11.00% 61.16% 56.89%

Kf x Cdf Ap Fdp = Kf x Cdf x Ap


Results – Specific Fuel Results – Specific Fuel ConsumptionConsumption

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%


Diff [%] 56.73% 19.98% 63.93%

Total Drag PayloadSFC =

(FD(LDW)/FD(B767))


Results – Pitch ControlResults – Pitch ControlApcs area of pitch control surfaces Afas area of front airlifting surfacesPA pitch armℓMGC the length of mean geometric chord of front airlifting surface

(replaced mean aerodynamic chord due to CL = const.)

-150.00%

-100.00%

-50.00%

0.00%

50.00%

100.00%


Diff [%] 74.64% -14.71% 30.34% -146.27%

Apcs/Afas PA Gmid ℓMGC


Results – Roll ControlResults – Roll ControlArcs roll control surface area around aileronsLrcs distance of resultant aerodynamic force

of Roll Control SurfacesAelv surface area around elevonsLelv distance of resultant aerodynamic force

of elevons from G.C.Aw wing areabMGC(w) distance of wing M.G.C. from G.C.AHT surface area of horizontal tailbMGC(ht) distance of horizontal tail M.G.C. from G.C.Gmid mid-cruise aircraft weight

-100.00%

-50.00%

0.00%

50.00%

100.00%

150.00%


Diff [%] 105.82% -86.87% 30.34%

[(Arcs x Lrcs) + (Aelv x Lelv)

Aw x bMGC(w ) + AHT x bMGC(ht)

Gmid


ConclusionConclusion Significantly lower operating empty weight of LDW by Significantly lower operating empty weight of LDW by

over 30% relative to TAW aircraft due to overall over 30% relative to TAW aircraft due to overall architecture and broad application of composite architecture and broad application of composite materialsmaterials

Significantly reduced total drag of LDW (>50%) at Significantly reduced total drag of LDW (>50%) at high subsonic speeds due to drastically lower lift high subsonic speeds due to drastically lower lift coefficient that depends on specific wing loading, coefficient that depends on specific wing loading, significantly lower airfoil relative thickness that significantly lower airfoil relative thickness that depends on chord lengths and wing specific loading, depends on chord lengths and wing specific loading, as well as significantly lower total parasitic wetted as well as significantly lower total parasitic wetted area with long chords and low airfoil relative area with long chords and low airfoil relative thicknessthickness

Significantly reduced specific fuel consumption of Significantly reduced specific fuel consumption of LDW aircraft (> 60%) due to overall drag reduction LDW aircraft (> 60%) due to overall drag reduction and additional payload accommodationand additional payload accommodation

Roughly the same levels of flight controlsRoughly the same levels of flight controls Significantly reduced cabin and environmental noise Significantly reduced cabin and environmental noise

levels of LDW aircraft due to longer distance of levels of LDW aircraft due to longer distance of engines from passenger cabin and upward deflection engines from passenger cabin and upward deflection of engine pitch trim surfaces respectivelyof engine pitch trim surfaces respectively


Q & AQ & A

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Longitudinal Double Wing (LDW) Concept Presented by Michael Dizdarevic AIAA Aviation 2013 Conference...

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