unconventional high aspect ratio joined wing aircraft with aft and forward swept wing tips

8/3/2019 Unconventional High Aspect Ratio Joined Wing Aircraft With Aft and Forward Swept Wing Tips

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AIAA-2003 - 0605

UNCONVENTIONAL HIGH ASPECT RATIOJOINED-WING AIRCRAFT WITH AFT- &

FORWARD- SWEPT WING-TIPS

Dr. R. K. Nangia & Dr. M. E. PalmerNangia Aero Research AssociatesWestPoint, 78-Queen's Road, CliftonBRISTOL BS8 1QX, UK

Dr. C.P. TilmannAir Force Research Laboratory

Air Vehicles DirectorateWright-Patterson AFB, Dayton, Ohio, USA

41st AIAA Aerospace Sciences Meeting & Exhibit6 - 9 January, Reno, Nevada, USA

41st Aerospace Sciences Meeting and Exhibit6-9 January 2003, Reno, Nevada

AIAA 2003-605

Copyright 2003 by the author(s). Published by the American Institute of Aeronautics and Astronautics, Inc., with permission.


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41st

AIAA Aerospace Sciences Meeting & Exhibit, 6 - 9 Jan. 2003, Reno NV, USA, AIAA -2003-0506

UNCONVENTIONAL HIGH ASPECT RATIO JOINED-WING AIRCRAFT

WITH AFT- & FORWARD- SWEPT WING-TIPS

Dr. R. K. Nangia Dr. M. E. PalmerNangia Aero Research Associates,

The West Point, 78-Queens Road, BRISTOL, BS8 1QX, UK.Tel: +44 (0)117-987 3995 Fax: +44 (0)117-987 3995

Dr. C. P. TilmannAir Force Research Laboratory, Air Vehicles Directorate,

Wright-Patterson AFB, OHIO, USA

Tel: +1 937 255 4077ABSTRACT

Unmanned SensorCraft air vehicles have been proposed as the air-breathing component of a future intelligence,surveillance, and reconnaissance (ISR) infrastructure to provide revolutionary capabilities. Such craft must takeadvantage of high aspect ratio (AR) wings for aerodynamic efficiency, and may also be required to enclose an antenna in adiamond aircraft planform. A large proportion of fuel must be carried, and "loiter" is at high altitudes for a few days ineach flight. This implies that a wide CLaltitude capability is required.

Several types of high AR joined-wing aircraft configurations can be envisaged to meet the possible flight envelope.Previous studies have considered configurations with aft-swept tips, and the implications of typical flight envelopes onwing design aspects have been mentioned. This paper extends the design and analysis to explore the possible benefits ofsweeping the wing tips forward on high AR joined-wing SensorCraft.

Using panel and Euler codes, results are presented here for configurations with simple uncambered wing sections and then for configurations with designed camber and twist, trimmed for neutral stability. The designed wings display aconsiderable reduction in leading edge suction, yet maintain the lift, drag and near-elliptic wing loading characteristics.The forward-swept tip offers an improved spanwise loading distribution which is also "consistent" with neutral pointlocation. Results of an inverse design application are shown here, and further work is proposed in several areas.

NOMENCLATURE

A = AR, Aspect Ratiob = 2s, Wing spanc Local Wing Chordcaero = c, Aerodynamic wing chordcav = c = cref, Average Wing ChordCD = D /(q S), Drag CoefficientCDi Lift Induced DragCL = L/(q S), Lift CoefficientCLL = Local Lift CoefficientCLmax Maximum Lift CoefficientCm = m/(q S cav), Pitching Moment (Body axis)Cp Coefficient of PressureD Drag forceL Lift ForceLE Leading Edge

m Pitching moment (Body-Axis)M Mach Number q = 0.5V2, Dynamic PressureRe Reynolds Number, usually based on cavs Wing semi-spanS Wing Area, (front-wing + tip-wing)t Aerofoil thicknessTE Trailing EdgeV Airstream Velocityx,y,z Orthogonal Co-ordinates, x along bodyaxisxac Location of aerodynamic centre on x-axisxcp Location of centre of pressure along x-axis =AoA, Angle of Attack, ref. to body-axis Taper Ratio LE Sweep Angle

= Air Density = y/s, Non-dimensional spanwise Distance

1. INTRODUCTION & BACKGROUNDThe Joined Wing concept conceived by Wolkovitch in

1980's (Refs.1-2) features diamond-shapes in the plan andfront views. Advantage claimed was bending moment reliefat a very small expense of span efficiency factor, Figs.1-2.Several aircraft applications were proposed (Fig.3). Someof the ideas were carried into experimental research aircraftand RPV. These generally had a "mixed reception" butconfirmed some of the advantages claimed over"equivalent" conventional aircraft in terms of aerodynamic(large AR feasibility) and structural efficiency. There arehowever some adverse problems also; e.g. spanwise flows,lack of fuel volume, junction flows, etc.

With advances in technologies of controls, propulsion, andflow control, there is emphasis on re-visiting some of theolder concepts and devising newer applications. Some have

been publicised, Fig.4, e.g. Lockheed Fuel Tanker,Goldschmied (NASA), and SensorCraft (Refs.3-5). Someshapes feature wings joined at the tips, others part way. Thetip-wings can be appropriately aft- or forward- swept.

The U.S. Air Force Research Laboratory (AFRL) has beenformulating a program to provide revolutionaryintelligence, surveillance, and reconnaissance (ISR)capabilities to the Warfighter (Ref 4). This program blendsa wide spectrum of emerging technologies to produce anUnmanned Air Vehicle (UAV), which may be configuredand optimised to conduct multiple advanced sensing modesintegrated into a single airframe that can sustain extremelylong endurance. This long endurance, combinedwith omni-directional sensing, may enable a virtual presence, allowing

vantage point flexibility / optimisation necessary forcontinuous and detailed theatre air and ground targetdetection, identification, and tracking. This uniquecombination of advanced sensors and sustained presencecould enable continuous and rapid reaction to the dynamic

Dr. R.K. Nangia 2003. Published by AIAA withpermission.

American Institute of Aeronautics and Astronautics


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combat operational requirements confronting current andevolving military operations.

The SensorCraft is envisaged as the air-breathercomponent of a fully integrated ISR enterprise thatcohesively integrates space, air, and ground components ofthe total ISR apparatus. This AFRL shared-vision programcombines critical vehicle airframe, propulsion, sensor,flight and information technologies into a highly responsive

platform concept to provide persistent detection and

surveillance of mobile, hidden targets. Several emergingsensor technologies are under assessment for platform use,including hyper-spectral imaging, active laser sensing,unattended ground sensors, and foliage penetration radar(Refs.5-6). Fig.5 illustrates envisaged advanced sensorfunctionalities and modes for SensorCraft.

Several candidate aircraft and propulsion configurations areunder consideration to determine the best trade-off betweenlong endurance, altitude, engine efficiency, and powergeneration. One of the major challenges is the integrationof the large antenna apertures required for lower frequencyoperations into the airframe. These lower frequency bandsof operation enable the SensorCraft to provide a foliage

penetration radar capability, a key sensory mode aimed at

defeating extremely difficult camouflaged, concealed, anddeceived (CC&D) targets (Ref 4).

The SensorCraft concepts must take advantage of high ARwings for endurance, as well as enclosing a large antenna ina diamond aircraft planform. Such aircraft must also carry alarge proportion of fuel and are expected to loiter at highaltitudes for a few days in each flight. This implies a wideCL - altitude capability, more so than existing operationalreconnaissance aircraft (e.g. Global Hawk). The "diamond"shapes offer useful stealth "compliance". The aerofoilshapes may need to be thick for antenna and fuel tanks. Thecruise Mach number is expected to be high subsonic. Thelow-speed near-field performance is more akin to that of a(very) high AR wing glider. Take-off and landing phases

are demanding.2. FLIGHT ENVELOPE, REYNOLDS NO. &

CONFIGURATION CONSIDERATIONS

Previous work conducted at the AFRL indicated that themain sizing driver aspect is the integration of a "rhombic"antenna in thick aerofoils. The payload/range performancedemands lead to thick aerofoils (t/c normal to the LE,

between 15 & 21%) operating at high CL values, near 1.0.

Fig.6 gives an idea of the aircraft flight envelope. Note theAltitude and Weight relationships during a typical mission.The Reynolds number variation is also depicted as well as.Mach number and CL relationships (CL based on the totalfront wing area). Take-off is near CL of 0.95 at Mach 0.2

(Re= 1.414x106

/ft), whilst landing is at CL of 0.7 at Mach0.15 (Re= 1.06x10

6/ft). The Mach 0.6 cruise CL varies from

1.58 to 0.88 (Re = 0.44x106/ft to 0.345x10

6/ft). It is

interesting to reflect that on conventional aircraft the cruiseCL values are near 0.5 and take-off / landing CL values near0.8 to 1.2.

The thick aerofoil sections with relative large LE radii givean appreciable range of CL (or AoA) operation. Predictionsshow "attained operation ranges (or bands)" for "attached"flow to be close to 4 in AoA.

Fig.7 shows three concept outlines with different swept-tipconfigurations. In the concept AT1, the front wing hascontinuous aft sweep and extends to the wing tip as shown.The concept FT1 and FT2 feature forward-swept tips, the

difference between the two is in the relative height of thewing roots of front and aft wings.

The low and high-speed design demands obviously"conflict" and this has led to a challenging work

programme towards suitable layouts. A previous paper fora limited audience, Ref.6, emphasised the design workusing Panel codes. Ref.7 extended the scope, using inaddition, an Euler code. Present work further extends theconcept research to include forward-swept tips.

3. PREDICTION METHODS

On novel layouts, often the experience is that thecomplexities "defy" an automatic "hands-off" design

process to be used with confidence (unique solutions

doubted). Therefore, we have chosen a process that allowsa significant understanding to be gained with reasonablemanual control over the design process (Refs.8 -18).

Panel & Euler codes are being utilised that enableassessment of the aerodynamic performance over the rangeof low to high speeds.

The camber and twist design, under forces and momentsconstraints, is via previously validated attained suctiondesign methods (e.g. Refs. 8, 9, 10, 10, 13, 15). In view ofthe very high aspect ratios, this process has been simplifiedand uses a restricted set of camber and twist modes.

An inverse design method using 3-D membrane analogy(Ref.15) can "tailor" and "fine-tune" aerofoil shapes for

"optimum" Cp distributions as needed.

4. DESIGN ASPECTS

At the outset, there are several aspects that need to beconsidered, for example:

Type of spanwise loadings and design of wing camberand twist.

Trimmed flight at low speeds with different CL levels.The TE geometry can be varied.

High-speed design of thick wings, tolerant to a large CLvariation (fuel usage). Use of TE flaps.

Integration of intakes / fuselages.

"Reasonable" off-design considerations, such as cross-winds, landing / take-off.

Roll, pitch and yaw stability levels, control laws.

Here we take a few of these aspects related to "high-speed"wing design. Intakes / Fuselages remain to be included.

Wing & Tail Mutual Interference on Config. AT1

Fig.8 refers to the AT1 concept. The front wing hascontinuous sweep and dihedral and extends to the wing tipas shown. For early work, the wing and tail junctions arekept simple (i.e. the tail has a finite chord wing-tip). Thewing and tail are both uncambered. AoA effects can beestablished. Chordwise Cp distributions on both wings indimensional and non-dimensional geometry context areshown. Spanwise loadings with and without mutualinterference are shown. These help to highlight thetendencies for higher LE suctions towards the tip of thefront wing, whilst the second wing has high LE suctions atthe forward-swept centre-section. The second wingoperates in the down-wash flow-field of the front wing withthe largest effects occurring near the junction.

For the next part of the work, the junction has beenmodelled more realistically ( the tail wing-tip chord "fades"into the the main wing TE)

Planar Uncambered Sections, Config. AT1

Fig.9 shows the general arrangement and a 3-D perspective. This has been modelled as three wingcomponents: front, aft and the outer tip. Fig.10 shows theuncambered aerofoil shapes.

Fig.11 shows the spanwise lift loadings arising due to AoA,on the three wing components and their sum. The forwardwing is more loaded towards the wing-juncture. At the



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centre-line, in spite of the downwash effects, the aft wingcarries more loading and this is to be expected on aforward-swept wing. For minimum drag of the totalconfiguration, a near elliptic lift loading is required, asshown. For this layout (with no camber or twist), however,relatively high loadings appear near the wing tip.

Fig.12(a-d) shows the chordwise loadings along variouswing sections at AoA= 0, 3.25, 4.25 and 5.25. Thecorresponding CL values are 0.0, 0.580, 0.759 and 0.936.

Note the increase in LE loads as AoA increases.

At a given design condition (CL and ), one could designcamber and twist for minimum drag elliptic loading, but thetendency at off-design will be to depart from the ellipticloading. This will have implications on pitch trim stability.

Designed Case, Config. AT1

The minimum CL design point is related to landing. Wehave chosen CL = 0.76 i.e. equivalent flat wing AoA of4.25. We have tried to approach the elliptic loading for thedesign. The designed case also corresponds to trim forneutral stability. In view of the thick sections andanticipated attached flow bandwidths, the operational rangeshould extend to CL of 1.5.

Fig.13 shows the aerofoil design shapes compared with theuncambered case. Note the characteristic twist and camberdifferences for the forward-swept and aft-swept wings. Thefront wing has less twist and camber, compared with therear wing.

Fig.14 shows the spanwise lift loadings due to angle ofattack, on the three wing components and their sum. Forminimum drag, a near elliptic lift loading is required, asshown. As AoA increases, the tips develop higher loadingsthan the elliptic distribution.

Fig.15(a-c) shows the chordwise loadings along variouswing sections at AoA = 3.25, 4.25 and 5.25. Thecorresponding CL values are 0.588, 0.768 and 0.946.

Note the upper surface flat-top nature of the chordwise pressure distributions (c.f. uncambered case, Fig.12).Geometry details near the wing juncture could do withsome local improvements, if required. This will be moreopportune at a later design stage when integrating theintakes and fuselages within the configuration.

5. PRELIMINARY COMPARISONS WITH EULER

METHOD RESULTS, Config. AT1

The main idea here was to determine, if the Panel and CFD(Unstructured Euler, Ref.19) codes gave comparable(understandable) results and to what AOA range. Asecondary aim was to observe the off-design performance.The junction modeling has been kept intentionally simple

for the Euler and identical results with reference to thePanel code are not expected. The CFD methods imply avery high CPU usage at subsonic speeds. In designenvironment, it is often simpler and quicker to use panelcode as far as possible. Such comparative studies help indeciding the limits of applicability of the panel code. It isuseful for such studies to use a near-design camber case soas to keep LE suctions reasonably bounded.

Fig.16 compares Cp distributions for a designed wing withPanel and Euler codes. The Euler results are for CL near0.51 and the Panel Code results are for CL = 0.59. The Cpand x-scales for presentation are not identical. The trends inCp distributions are however, very similar. Note the growthof -Cp at the centre-line of the aft-wing.

Fig.17 shows a sequence of Cp distributions with the Eulermethod as AoA is increased in 1 steps. This establishes thelocal criticality of the forward-swept root area of thesecond wing.

Fig.18 shows Mach number distributions for two AoAfrom the Euler method to support the above inference.Further work is to be continued on this aspect. It is apparentthat the Panel code can be used for design studies when LEsuctions are not too large.

Planar Uncambered Sections, Config. FT1

Fig.19 shows the general arrangement and a 3-D perspective. This has been modelled as three wingcomponents: front, aft and the outer tip with uncambered

aerofoil shapes.

Fig.20 shows the spanwise lift loadings arising due to AoA,on the three wing components and their sum. The forwardwing is more loaded towards the wing-juncture. At thecentre-line, in spite of the downwash effects, the aft wingcarries more loading and this is to be expected on aforward-swept wing. For minimum drag of the totalconfiguration, a near elliptic lift loading is required, asshown. For this layout, relatively lower loadings appearnear the wing tip.

Fig.21(a-d) shows the chordwise loadings along variouswing sections at AoA = 0, 3.25, 4.25 and 5.25. Thecorresponding CL values are 0.0, 0.580, 0.759 and 0.936.

Note the increase in LE loads as AoA increases.At a given design condition (CL and ), one could designcamber and twist for minimum drag elliptic loading, but thetendency at off-design will be to depart from the ellipticloading (with lighter loadings at the tips).

Designed Case, Config. FT1

The minimum CL design point is the same as the AT1 case,where we chose CL = 0.76 for an equivalent flat wing AoAof 4.25. We have again attempted to approach an ellipticloading for the design condition, again trimmed for neutralstability. The thick aerofoil sections should again extendthe operational range to a CL of 1.5.

Fig.22 shows the aerofoil design shapes compared with the

uncambered case. The front wing again has less twist andcamber than the rear wing. Note the characteristic twist andcamber differences for the forward-swept and aft-sweptwings. In this case however, the outboard wing sections areswept forward, and are thus twisted to have higherincidence at the tip than at the juncture. This wash-in iscontrary to the wash-out on the AT1 design, as expected.

Fig.23 shows the spanwise lift loadings due to angle ofattack, on the three wing components and their sum. Forminimum drag, a near elliptic lift loading is required, asshown. Even as AoA increases, the tips maintain lowerloadings than the elliptical distribution.

Fig.24(a-c) shows the chordwise loadings along variouswing sections at AoA = 3.25, 4.25 and 5.25. Thecorresponding CL values are 0.58, 0.76 and 0.94.

The upper surface again displays a flat-top pressuredistribution, and the flowfield near the wing juncture could

be improved through geometry changes. This will beconsidered when integrating the intakes and fuselages.

6. COMPARING AT1 & FT1 TIPS Cp DISTBNS.

Fig.25 shows a comparison of Cp distributions on the aft-swept tip of AT1 and the forward-swept tip of FT1. Notethe lower loadings on the FT1 tip through AoA range.

7. INVERSE DESIGN APPLICATION, CONFIG. AT1

A particularly interesting aspect of the design approach

used is related to adapting an Inverse Wing DesignApproach With Membrane Analogy for joined wings(based on Ref.13). To shorten time-scales for the design

phase, a general 3-D approach has been devised thatenables a "known" loading (target) to be "supplanted"



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(within reason and small tolerances) on to a wing of general planform. The aerofoil geometry, camber and twist areproduced simultaneously within an iterative approach. Forexample, we can choose the loading on a rectangularunswept wing or an elliptic planform wing as the "target".

Figs.26 illustrates a design exercise on the front wing of acomplete joined-wing layout. The starting situation is thatan unswept wing with super-critical aerofoil wing sections

provides the target loadings. Initially the front (swept-back)

wing loadings are generally lower than the target. Note thecomparison of the target loadings and the derived loadingsat 6 cycles; differences have been reduced by nearly 3/4ths.Further cycles will give a closer correlation. Because theswept wing will have stagnation Cp less than 1.0 (along thespan), perfect agreement is not expected. Note also thecomparison of the aerofoil sections at start and after 6cycles. We can observe the development of twist along thespan of the wing.

The process described can be extended for design of frontand aft wings either in turn or simultaneously. Additionalconstraints such as stability margins and structural bendingand torsion can be introduced as desired.

7. FURTHER WORK

So far, a type of SensorCraft with a joined-wing layout hasbeen considered for high-speed design at Mach 0.6. Severalinteresting features have emerged from the application ofdirect and inverse design methods. Further work isenvisaged in a number of areas:

Lower speeds, field performance considerations.

Parametric geometric studies with appropriate methoddevelopment.

Different design CL studies as required. The forward-swept root (rear wing) needs attention.

Different aerofoils incorporation, from the point of viewof validation with CFD and transonic codes.

Pitching moment, static margins control with LE / TEFlap within geometry restrictions, segmentation.

Fuselage & Intake incorporation, additional effects onforces and moments.

Inclusion of viscous effects, spanwise pressure gradientsand flow control.

Drag prediction.

Off-design performance including lateral and directionalcharacteristics.

Include aero-elastic deformation effects.

Experimental work (various aspects).

8. CONCLUDING REMARKS

A type of SensorCraft with a joined-wing layout has beenconsidered for design at Mach 0.6. Several interestingfeatures have emerged.

At the design conditions, the designed wing displaysconsiderable reductions in LE suctions when comparedwith the equivalent uncambered wing. Further, near ellipticspanwise loadings have been maintained. Special attentionneeds to be given to the forward-swept root area of the rearwing (high AoA).

The Forward-swept tip (outer wing) offers an improvedspanwise loading which is "consistent" with neutral pointlocation.

Typical results presented demonstrate the flexibility andpotential of the techniques for direct and inverse design.

Capability for study of several geometric variables ofconfigurations is offered in a timely sense. Data for detaildesign of wind tunnel models and possibly a flight

demonstrator can be enabled. An understanding of controllaws arises. The potential and limitations of the aircraft inmeeting a given design envelope can be assessed.

It is apparent that we are only at a starting post and asizeable, interesting work programme remains! Severalareas for continued work have emerged.

ACKNOWLEDGEMENTS

The work mentioned here is part of in-house R&D

activities and also supported in part by the USAF EuropeanOffice of Aerospace Research and Development (EOARD)and the U. S. Air Force Research Laboratorys Air VehicleDirectorate (AFRL/VA). The authors have pleasure inacknowledging helpful technical discussions with Mr. D.Multhopp, Dr. C. Jobe, Mr. W. Blake (all from AFRL/VA),& Mr. R.H. Doe (UK).

Lastly it should be mentioned that any opinions expressedare those of the authors.

REFERENCES

1. WOLKOVITCH, J., "The Joined Wing: An Overview", J. ofAircraft, Vol 23, pp. 161-178, March 1986.

2. WOLKOVITCH, J., "A Second Look at the Joined Wing",

Proc. of NVVL Symposium "Unconventional AircraftConcepts", Delft Uni. Press, 1987.

3. JOHNSON, F. P., SensorCraft : Tomorrows Eyes and Ears ofthe Warfighter, AIAA-2001-4370, Aug. 2001. Also seewww.afrlhorizons.com/Briefs/Mar01/SN0001.html

4. Aerospace America, Dec. 01, pp 50.

5. TYLER, C., SCHWABACHER & CARTER, D., "Comparisonof Computational and Experimental Studies for a Joined-WingAircraft", AIAA 2002-0702, January 2002.

6. NANGIA, R.K., PALMER, M.E. & TILMANN, C.P.,Towards Design of Unconventional High Aspect RatioJoined-Wing Type Aircraft Configurations, RAeSConference A 2020 Vision, April 2002, London UK.

7. NANGIA, R.K., PALMER, M.E. & TILMANN, C.P., OnDesign of Unconventional High Aspect Ratio Joined-WingType Aircraft Configurations, ICAS 2002, Toronto.

8. NANGIA, R.K., "The Design of "Manoeuvrable" Wings usingPanel Methods, Attained Thrust & Euler Codes", ICAS-92.

9. NANGIA, R.K. & GREENWELL, D.I., "Wing Design ofOblique Wing Combat Aircraft", ICAS 2000-1.6.1, 2000.

10. NANGIA, R. K. & GALPIN, S.A., "Towards Design of High-Lift Krueger Flap Systems with Mach & Reynolds No. Effectsfor Conventional & Laminar Flow Wings", CEAS EuropeanForum, Bath, UK, 1995.

11. NANGIA, R. K. & GALPIN, S.A., "Prediction of LE & TEDevices Aerodynamics in High-Lift Configurations withMach & Reynolds No. Effects", ICAS-1996-2.7.6..

12. NANGIA, "Design of Conventional & Unconventional Wingsfor UAV's", RTA-AVT Symposium, "UV for Aerial & Naval

Military Operations", Ankara, Turkey, Oct. 2000.13. NANGIA, R.K., PALMER, M.E. & DOE, R.H., "A Study of

Supersonic Aircraft with Thin Wings of Low Sweep",AIAA-2002-0709, January 2002.

14. NANGIA, R.K. & MILLER, A.S. "Vortex Flow Dilemmas &Control on Wing Planforms for High Speeds", RTO AVTSymposium, Loen, Norway, May 01.

15. NANGIA, R.K., "Developing an Inverse Design Method using3-D Membrane Analogy", Future Paper.

16. KUCHEMANN, D. "The Aerodynamic Design of Aircraft",Pergamon.

17. JUPP, J., Wing aerodynamics and the Science ofCompromise", RAeS Lanchester Lecture, 2001.

18. JONES, R.T., "Wing Theory", Princeton.

19. GUPTA, K.K. & MEEK, J.L., "Finite ElementMultidisciplinary Analysis", AIAA, 2000.



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FIG.2 BENDING MOMENTS

FIG.1 ACA RPV & EFFECT OF SPAN RATIO ON SPAN EFFICIENCY

FIG.3 JOINED-WING CRAFT (WOLKOVITCH)

FIG. 4 SEVERAL RECENT JOINED-WINGAPPLICATIONS



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FIG. 6 FLIGHT ENVELOPE, ALTITUDE - WEIGHT & CL MACH No RELATIONSHIPS

FIG. 5 SENSOR-CRAFTS ADVANCEDSENSOR MULTI-MODALITY & DIVERSEFUNCTIONALITY

AT1 FT2FT1

Identical frontalview

notenote

FIG. 7 DIFFERENT SWEPT-TIPCONFIGURATIONS: AT1, FT1 & FT2

FIG. 8 JOINED-WING CONCEPT (AT1) OFHIGH AR, SIMPLE JUNCTION,CHORDWISE Cp DISTRIBUIONS AT AoA 4 deg.,

SYMMETRICAL AEROFOILS ON BOTH WINGS



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FIG. 9 SPANWISE LOADINGS WITH & WITHOUT MUTUAL INTERFERENCE

FIG.10 JOINED-WING CONCEPT (AT1), MORE DETAILED JUNCTION MODEL & UNCAMBEREDAEROFOILS

FIG.11 CONFIG. AT1. UNCAMBERED WINGS, CLL SPANWISE LOADINGS AT 3 CL

FIG.12 CONFIG. AT1, UNCAMBERED WINGS, Cp DISTRIBUTIONS



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FIG. 13 CONCEPT AT1, DESIGNED CONFIGURATION, AIRFOIL SHAPES

FIG.14 CONCEPT AT1, DESIGNED WINGS, CLL SPANWISE LOADING

FIG.15 CONCEPT AT1, DESIGNED WINGS, CP DISTRIBUTIONS

FIG.16 DESIGN CASE, RELATING PANEL & EULER Cp DISTRIBUTIONSNote: At Present, the Euler Modelling is for a simple Junction

Euler Elliptic Domain

Simplified Joined-WingJunction Modelling



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FIG. 17 Cp DISTRIBUTIONS FROM EULER

Design AoA+1 deg. Design AoA+2 deg. Design AoA+ 3 deg. Design AoA+4 deg.

Note !

lowerupper

DesignAoA + 0

DesignAoA + 4

FIG. 18 MACH NO. DISTRIBUTIONS, EULER

FIG. 19 JOINED-WING CONCEPT (FT1), MORE DETAILED JUNCTION MODEL &

UNCAMBERED AEROFOILS



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FIG. 20 CONFIG. FT1. UNCAMBERED WINGS, CLL SPANWISE LOADINGS AT 3 CL VALUES

FIG. 21 CONFIG. FT1, UNCAMBERED WINGS, Cp DISTRIBUTIONS

FIG. 23 CONCEPT FT1, DESIGNED WINGS, CLL SPANWISE LOADING

FIG. 22 CONCEPT FT1,DESIGNED CONFIGURATIONAEROFOIL SHAPES



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FIG. 25 COMPARING Cp DISTRIBUTIONS ON AT1 & FST CONCEPTS

FIG.26 INVERSE DESIGN, START & AFTER 6 CYCLES

Target: Unswept Wing, To be Designed: FRONT WINGComplete Configuration Modelled, Chordwise Cp Distributions &Aerofoil Sections Comparisons

FIG. 24 CONCEPT FT1, DESIGNEDCAMBER WING, Cp DISTRIBUTIONS


unconventional high aspect ratio joined wing aircraft with aft and forward swept wing tips

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