MISSION ADAPTIVE COMPLIANTWINGS

BY S TIWARI

LOOK AT THESE BIRDS

NOW LOOK AT THESE AIRCRAFT

MISSION ADAPTIVE

COMPLIANTWINGS

INTRODUCTIONImproving aircrafts efficiency is one of the key element of Aeronautics.

For increasing aircraft efficiency, 50% of the researches are aimed To reduce drag.To increase lift.To reduce structural weight.To reduce system power take up.

BALANCING THE FOUR FORCESTHE BIGGEST CHALLANGE

DRAG AND LIFT(a) Drag reduction is achieved by

Reducing surface friction drag.Reducing form drag.Reducing induced drag.

(b) Lift increase is achieved byFinding the most efficient Angle of

Attack. Inventing new lift augmenting

devices.Changing wing shape and size.

NEW TRENDS IN AERODYNAMICS

Blended wing body or BWB.Twisteron.Fanwing.Spiroid Winglets.Mission adaptive compliant wings.

BLENDED WING BODY OR BWB

TWISTERON

SPIROID WINGLETS

FANWING

MISSION ADAPTIVE COMPLIANTWINGS

MISSION ADAPTIVE WINGS

The mission adaptive wings are the wings which should be able to adapt itself to different flying conditions and should be able to fulfil conflicting mission requirements by morphing their wings.

CONFLICTING MISSION REQUIREMENTS

We want our aircraft to be used as fighter i.e for high speed as well as bomber i.e for high lift.

FIGHTER BOMBER

CONFLICTING MISSION REQUIREMENTS

We want our aircrafts to cruise at relatively high speeds and at the same time it should be, easily or efficiently, able to support lower speeds such as those required for loitering, taking off, or landing.

MORPHINGMorphing can be defined as “to cause

something to change its outward Appearance”.

Wing that can sense its environment and adapt its shape to perform optimally in a wide range of flight conditions.

SWIFT MORPHING OR ADAPTION

HIGH SPEED LOW SPEED

CAN WE DO THIS?

MISSION ADAPTIVE COMPIANT WINGS

AERODYNAMICS BEHIND DIFFERENT SHAPES

Different shapes and size produces different aerodynamic effects and different advantages.

AERODYNAMICS

MORPHING REQUIREMENTS Morphing requirements are:-Actuation system-

Change in the airfoil shape in a controlled manner by different methods.

Wing structural characteristics- withstand the aerodynamic forces and wing

loadings. Must be able to achieve a seamless morphCompromise between stiffness and flexibility in the

selected materials.

Aerodynamic characteristics -Must ensure that the change in shape will result in

measurable changes in flight characteristics.

MORPHING METHODSMULTIPLE ACTUATORS.

•To control the camber of the aerofoil multiple actuators distributed throughout the wings were used. •Fibre glass flexi panels were bent by conventional rigid link mechanism. •These are aerodynamically superior than conventional flaps as their were no discontinuities and seams.

INCHWORM ACTUATORS

Wing camber can be varied by employing inchworm actuators arranged in a truss manner within the wing ribs.

INTELLIGENT ACTUATORS.

INTELLIGENT ACTUATORS

PIEZOELECTRIC MATERIALS. Relation between mechanical stress and an electrical voltage. Its reversible process.

Disadvantages. Inadequate displacement. Require excessive power, and/or are complex and heavy.

Shape Memory Alloy. Shape memory alloys (SMAs) are metals that "remember" their original shapes. SMAs actuators are materials that "change shape and mechanical characteristics in response to temperature or electromagnetic fields.

Disadvantages. Insufficient Bandwidth. Require excessive power, and/or are complex and heavy.

THE MOST SUITABLE ALTERNATIVE APPROACH

COMPLIANT MECHANISM

The energy was drawn from a few remotely located actuators and then this energy was distributed to the structure through some intermediary mechanism.

Methodology employed is distributed compliance rather than distributed actuation

Compliant Mechanisms (Structures) are structures that are specifically optimized to distribute localized actuation (strain) to change the shape of the structure.

COMPLIANT MECHANISMSSHEET GRIPPER

COMPLIANT MECHANISMS•Monolithic.

•Joint Less Structures

•These structures exploits elasticity of the material to produce desired functionalities.

•These functionalities can include force or motion transmission, motion guidance, shape morphing and energy storage and release.

COMPLIANT MECHANISMThe arrangement of the material within the

compliant mechanism is optimized so compliance is distributed through small strains to produce large deformations.

Note that the design does not embody any flexural joints, which create stress concentrations and poor fatigue life.

Compliant structure deforms as a whole and avoids high-stress concentrations in which the flexion is concentrated in localized regions.

COMPLIANT MECHANISM

AMPLIFYING MOTION OR FORCE

COMPLIANT MECHANISM

These are flexible mechanisms that transfer an input force or displacement to another point through elastic body deformation. These are usually monolithic (single-piece) or joint less structure.

ADVANTAGESMinimize or eliminate assembly requirements.Excellent repeatability since there is no

backlash.No joints mean no joint friction, backlash, or

need for lubrication.Can easily couple with modern actuators.Can create motions not possible with

conventional rigid devices.Materials friendly.Weight reduction.Fatigue resistant.

COMPLIANT MECHANISM WINGS

When normal aerofoils or wings are made mission adaptive by using the new technology called compliant mechanism then they are termed as mission adaptive compliant wings.

The MACW technology provides lightweight,

low-power, variable geometry re-shaping of the upper and lower surface with no seams or discontinuities.

COMPLIANT MECHANISM WINGS

MAKING OF MAW BY COMPLIANT MECHANISM FlexSys Inc, has developed a unique, variable-

geometry, trailing edge flap that can re-contour the airfoil upper and lower surface.

Combined compliant flap system to a Natural Laminar Flow (NLF) airfoil.

This airfoil can theoretically achieve up to 65% chord laminar flow on the upper surface and up to 90% chord laminar flow on the lower surface as opposed to a conventional hinged flap which can introduce flow separation at the flap knee.

The airfoil flap system is optimized to maximize the laminar boundary layer extent over a broad lift coefficient range.

Data from flight testing revealed laminar flow was maintained over approximately 60% of the airfoil chord for much of the lift range.

Drag results revealed that that was considerable decrease in drag and hence good lift/ drag ratio.

FlexSys has developed morphing surfaces for both the leading and trailing edge.

PREVENT FLOW SEPARATION

SCHEMATIC OF COMPLIANT WING

POTENTIAL BENEFITS 25% decrease in drag and hence better lift/drag

ratio than the conventional control surfaces, which resulted in fuel saving.

AERODYNAMIC BENEFITS OVER PLAIN FLAP

MINIMIZING INDUCED DRAG

NOISE REDUCTION

Compliant structures enable development of a seamless transition between the fixed and flapped portions of the wing as shown in Figure.

• The main purpose of this region is to reduce noise associated with the turbulent airflow generated by the discontinuous surfaces at the flap ends when the high lift flaps are deployed for landing.

MAW FLAP CONVENTIONAL FLAP

MACW flaps can require less force and power than a comparably sized conventional flap.

The MACW flap required 33% less actuation force. This is because a compliant flap with 33% shorter chord than a conventional flap can provide the same CL and Cm performance.

SEAMLESS TRANSITION

ADDITIONAL BENEFITS Can move into complex predetermined positions

with minimal force.Can be locked in place at any desired

configuration.Just as stiff and strong as a conventional control

surface.The elimination of discontinuities in the flap

surface can provide lower drag and higher control authority than comparable hinged flaps.

The elimination of joints and seams make the flap more impervious to icing and fouling from debris.

CONCLUSION

Sooner or later it will be possible to make wings without ailerons, flaps and thousands of individual parts. They will have in principle only one component, which continually changes shape.

ANY

?

THANK YOU