Rotorcraft and Rotary Wing Materials & Structures Review V1.0.0

8/18/2019 Rotorcraft and Rotary Wing Materials & Structures Review V1.0.0

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UK Air Vehicle Technology

A review by the Materials & StructuresNational Technical Committee

Rotorcraft

K Air Vehicle Technology

review by the Materials & Structuresational Technical Committee

otorcraft


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This review has been produced under the auspicesof the Materials and Structures National TechnicalCommittee, an integral part of the Knowledge TransferNetwork in Aerospace, Aviation and Defence. Thecentral requirement for the review is to provideinformed opinion on the foreseen needs andopportunities for capability in materials and structuresfor UK rotorcraft.

The review has been mounted on the Aerospace, Aviation and Defence KTN Website and is available forresponsible use throughout the UK R&D community,sponsors, users and suppliers. Weighted information

generated within can be used to guide potentialsponsors and suppliers of research and to enable endusers to maximize their involvement in the researchand its uptake. Guided research and developmentis one element essential to refresh UK’s competitiveposition.

www.aadktn.co.uk/materialsntc

Foreword by Dr Ruth Mallors 3

Foreword by Dr Mike Hicks 4

1 Executive summary 5

2 Review Scope 6 2.1 Vehicles reviewed 6

2.2 UK Strategies and Philosophies forMilitary and Civil Rotorcraft 6

2.3 Market Size and its Importance to the UK 7 2.4 Market Trends 7 2.5 International Issues 7 3 Recent history 8 3.1 Aircraft Configuration and Concepts 8

3.1.1 Structural Design and Materials Choice 8

3.1.2 Engine and Rotor Design 8 3.1.3 Transmission Systems Technology 9 3.1.4 Landing Gear and Flotation Equipment 10 3.2 Structural Design and Materials Choice 10 3.3 Manufacturing Development 10 3.4 Operational Issues 11 4 Current trends – 5 year horizon 12 4.1 Aircraft Configuration and Concepts 12 4.1.1 The Uninhabited Autonomous Rotorcraft 12 4.1.2 Diesel Engine Rotorcraft 12 4.1.3 The More Electric Rotorcraft 13 4.2 Structural Design and Materials Choice 13 4.3 Manufacturing Development 14 4.4 Operational Issues 14

5 Possible Future Scenarios - 20 Year Horizon 16 5.1 Aircraft Configuration and Concepts 16 5.2 Structural Design and Materials Choice 16 5.3 Manufacturing Development 17 5.4 Operational Issues 17

6 Requirements Perceived forMaterials and Structures Research & Development 18

6.1 Safety 18 6.2 Reliability 18 6.3 Efficiency 18 6.4 Affordability 19 6.5 Environmental Impact 19

7 Research Collaboration 20 7.1 National strategies for collaboration 20

7.2 International collaboration 20

8 Summary 21

Principal Authors 21

Materials & Structures NTC Members 22

About the Aerospace, Aviation & Defence KTN Cover

Contents Abstract


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UK Aerospace and Defence is a success story by any

measure. It is a high value, high skilled and high technology

industry that competes on the world stage, second only to

the US in size and revenue.

The sector delivers against the UK’s highest level strategic

agendas such as high-value manufacturing, low carbon,

science and innovation and of course, defence. Employing

over a hundred thousand people, UK A&D industry

delivers real value and a genuine balance to the economy.

The sector has a rich heritage of technological innovation

throughout the supply chain, which has kept the UK at

forefront of the global aerospace and defence Markets.

Numerous examples exist of how effective partnerships

between business, government and academia have

created and sustained the UK’s competitive and military

Director

Aerospace, Aviation & Defence Knowledge Transfer Network

advantage.

While today’s success story is largely the result of technology partnerships of yesterday,tomorrow remains a challenge.

The opportunity for growth is undeniable. Products that emerge from the sector are amongst

the most complex manufactured and continue to increase in complexity; global competitors

are developing capability at a formidable rate; the global security and defence climate

continues to evolve but remains uncertain. The combination of these factors only underpins

the necessity for broader and deeper collaboration and partnership.

Facilitated by the Aerospace, Aviation and Defence KTN, the National Technical Committees

provide the environment and mechanisms through which this collaborative spirit can thrive.

The NTCs are partnerships between industry, government and academia that deliver value-

add outputs from technology roadmaps, to collaborations, to knowledge assets such as this

report. I invite you to join this ‘innovation climate’ by becoming a member of the KTN and

engaging with the NTCs.

Foreword by Dr Ruth Mallors

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Foreword by Dr Mike Hicks

Chairman

Materials & Structures National Technical Committee

With collaboration being the irrefutable enabler

to innovation in any technology driven sector,

the National Technical Committees (NTCs) havebecome the foremost focal points around the

issues of science, innovation and technology

across a range of disciplines within aerospace

and defence. Through this partnership

approach between industry, government and

academia fostered within the Materials and

Structures (M&S) NTC, a number of business-

led initiatives are delivering real value to the

sector, such as comprehensive technology

roadmapping that enable collaborative research and clearly identify priorities for future funding.

This document, one in a series of such reviews prepared by the M&S NTC, contains the

consensus view of the materials community across the UK’s rotorcraft sector. Developments

in materials technology are fundamental to delivering the performance demanded in this

highly competitive market. Innovative materials solutions permeate throughout such vehicles,

delivering reduced weight, lower cost of ownership, lower environmental impact, improved

reliability and greater endurance, whilst always maintaining safety as the overriding priority.

The report includes an assessment of the requirements and opportunities for which the UK

is well-positioned to deliver, and identifies the research and technology development that are

required to ensure the UK remains world-leading and competitive in these global markets.

In an ever-evolving economic and technology climate, these reviews truly are living documents

that need to reflect the very latest thinking of the expert community. They will be periodically

reviewed and updated, with a view to continuously expanding the range of contributors. The

broadest community is encouraged to use these reports to inform their thinking and influence

their strategies. The knowledge contained in these reports needs to be widely transferred

both within and beyond the engines and power-plants sector to ensure innovations and

developments are spun in and out of the sector.

I hope you find this review both informative and engaging. Should you have any comments or

questions, please connect with the M&S NTC or the Aerospace Aviation and Defence KTN to

ensure your voice is heard.

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Executive Summary

This review has been mounted on the Aerospace, Aviationand Defence KTN Website and is available for responsibleuse throughout the UK R&D community. Weightedinformation generated within these reviews can be used toguide potential sponsors and suppliers of the research andto enable end users to maximize their involvement in theresearch and its uptake. This review is one of nine that coverthe perceived range of UK aerospace platforms and systemsincluding those that are novel or disruptive in nature. It isintended that these reviews should be regularly updated.

Initially an outline of the vehicles to be reviewed, the

underlying UK strategies and philosophies for UKrotorcraft and the size and importance of this market to

the UK are provided against perceptions of market trendsand international out-sourcing issues. Then trends instructural concepts, in structural design, materials choice,manufacturing development and operational issues areidentified against three time frames namely; current andrecent history, those seen for the next five years andspeculatively those perceived over a twenty year horizon.

This review of market led development enables commondrivers for research to be identified over the three timeframes supporting Safety, Reliability, Efficiency, Affordabilityand Environmental Impact. Against these persisting drivers

in excess of 50 specific areas for possible research anddevelopment are identified, justified and detailed.

A review considering the materials and structural requirements for

research and development to support the design, manufacture andoperation of military and civil rotorcraft in the UK has been producedunder the auspices of the Materials and Structures National TechnicalCommittee, an integral part of the Knowledge Transfer Network in Aerospace Aviation and Defence. The central requirement for thereview to is to provide informed opinion on the foreseen needs andopportunities for materials and structures research supporting UKrotorcraft.

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Review Scope

2.1 Vehicles Reviewed

This review encompasses both military and civil rotorcraftdesigned, built or deployed in the UK. Aircraft used forgeneral business and personal aviation can be found in afurther review. A complete list of reviews includes:-

• Civil transport aircraft ( > 50 seats )

• General aviation, personal and business aircraft (< 50seats)

• Sports and recreational aircraft

• Combat aircraft for strike, air defence, surveillance and

training

• Military transport aircraft including in-flight refueling

• Rotorcraft, military and civil

• Space vehicles including satellites

• Future vehicles and concepts

• Engines and power-plant

Within the context of this Review, rotorcraft will encompassthe full spectrum from short range light aircraft for inter-citycommuting, personal, corporate and business use, those

for the linking of long range hubs and long-range heavy liftaircraft. For military aircraft important functions include airfreight haulage, forces deployment, reconnaissance andsurveillance, maritime patrol, sea and ground attack. Bothcivil and military forces use rotorcraft extensively in searchand rescue operations, some of long duration. The strongUK position in aircraft engines is emphasised particularly in aseparate review on engines and powerplant.

2.2 UK Strategies and Philosophies forMilitary and Civil Rotorcraft

The UK has a long history in the design and manufactureof rotorcraft and one that encompasses major steps in theirdevelopment, such as the modern composite blades.

The levels of investment required in manufacturing capabilityand international in-service support coupled with internationalcompetition have moulded the UK’s position into that of a

major international partner with all aspects of the industry

encompassed from investment finance, through on shore-design, build and modification of military aircraft, to a majorposition as the home of civil international operators. In termsof the design and manufacturing output of rotorcraft there hasbeen a bias in the UK towards military aircraft for decades.

Traditionally, the drivers for improved rotorcraft technologystem from the need to deliver profitably high performanceaircraft to the operators that are safe, reliable, efficient andaffordable. In the military field absolute performance tendsto have high priority. It has become accepted that it isincumbent upon the manufacturer to service these driverswith operators having minimal influence on research ordevelopment in these spheres.

In terms of materials developments, the volumes consumedin the building of new rotorcraft are too small to warrant thespecific development of any dedicated materials exclusivelyfor such applications; the rotorcraft manufacturers rely ondevelopments by major airframe manufacturers, testing andadapting them as appropriate. Such restrictions do not applynecessarily to structural designs or manufacturing techniquesand developments.

This philosophy leads directly to drivers for UK capability inmaterials and structures comprising:-

• Safety . Safety has been the first imperative for decades and

whilst this high priority can be effectively “taken as read” itshould be recognized that many research programmes onimproved materials or structural techniques for rotorcraftare supporting this fundamental requirement and that morewill be identified as required in this review. In the militarycontext safety will include signature control, survivability intheatre and crashworthiness.

• Reliability . In this Review attention is drawn to reliability ofoperation that is the need for any rotorcraft to be availablefor daily use with minimal interruptions for inspectionor servicing and with optimized maximum service life.Worldwide requirements for civil and military operationshave mounted for 24 hour operations and for yet longerrange aircraft, inevitably flying for longer periods non-stop.

• Efficiency . Increased performance such as improvedrange, time on station or payload whether achieved byreduction in parasitic structural mass or the fuel consumedfor any operation are of great benefit to rotorcraft operation.

This review is one of nine produced and upgraded progressively by

the National Advisory Committee for Materials and Structures, nowthe National Technical Committee, each being to a similar format andstandard. Overlapping issues are identified. Potentially disruptivevehicle technologies are treated separately as an individual fielddescribed as “Future vehicles and concepts”.


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• Affordability . Low specific fuel consumption and minimalthrough life costs are critical for affordable operation but

initial costs of the airframe, engines and systems must notbe disregarded as these impact directly on the profitabilityof the original equipment manufacturers (OEM’s).

• Environmental Impact. Minimising environmental impacthas to be implicit within developments. Research forimproved materials or structural designs addressesreduced fuel consumption and consequential reductionin environmental impact and reducing levels of perceivednoise will continue as an issue of great significance inrotorcraft development. It is essential to consider the wholeaircraft life cycle since materials used may potentiallybecome prohibited, scarce in supply or difficult in disposaland manufacturing processes may be high in energy

consumption or environmental impact.

2.3 Market Size and Its Importance to theUK

The UK maintains design and build capabilities for militaryrotorcraft via AgustaWestland with a supporting raft ofindustrial concerns providing structural parts and systemscomponents. The value of this activity is estimated at £1000Mper annum. Some design work for rotorcraft built andassembled offshore has also been provided, for example for

the AW149. Additionally the UK supply industry manufacturesspecialized components for offshore manufacturers of bothmilitary and civil rotorcraft worth an estimated further £250M.

The UK is competent in the design and manufacture ofrotorcraft structure across the whole spectrum of aircraftmanufacturing and into operational systems includingsimulation and training aspects.

For operational aircraft, the UK has a specific activitysupplying, upgrading and maintaining AgustaWestland,Boeing, Eurocopter and Sikorsky aircraft such as the SuperLynx, the new AW159 Lynx Wildcat, Apache, the S61 SeaKing, AW101 Merlin, AS332 Super Puma and the Chinook.

Some of these are being deployed as military variantsby the UK armed forces; others are used in civilian rolesfor surveillance, transport or search and rescue. Supportactivities also include significant training roles. The value of

this activity to the UK economy is estimated at £500m perannum.

2.4 Market Trends

Whilst growth in the UK sales of military helicopters ispredicted as being sustained albeit subject to variations inoperational requirements and levels of funding available ithas been predicted that substantial growth will occur for civilrotorcraft because of increased demands from virtually allsectors including surveillance, surveying, search and rescueand short range transport.

It may be argued that the UK could be better placed to take

advantage of these growth prospects potentially expandingits onshore design and build capabilities.

2.5 International Issues

In the UK, the rotorcraft industry is principally representedby AgustaWestland, a subsidiary of Finmeccanica. Sincethe merger of Westland and Agusta, UK effort in terms ofdesign, build and refurbishment has concentrated primarilyon military aircraft whilst Italian activities have a stronger civilfocus. Rotorcraft both designed and built in Europe such as

AW101 or built and equipped in the UK under licence such

as the Apache have been accommodated. Additionallyaircraft such as the Boeing Chinook have been maintained,re-fitted and re-equipped on-shore to support the UK armedforces in partnership with Boeing and whole systems suchas the maritime AW101 Merlin have been integrated into shipdefence systems with Lockheed Martin.

International competition is very strong particularly fromEurocopter in European and export markets outside ofthe USA. The huge US military market is dominated byBell, Boeing and Sikorsky and has proved very difficult forEuropean manufacturers to penetrate. However, AW andEurocopter are making inroads into the US civil marketparticularly in the medium twin sector.

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Recent History

3.1 Aircraft Configurations and Concepts

Rotorcraft designs can perhaps best be characterized by thesize and configuration of the aircraft. Thus in terms of themilitary aircraft given preference here, aircraft span a rangefrom the ultra-light Gazelle to those of tens of tonnes withheavy lift capability such as the Chinook. Configurationsinclude single, twin and triple engined variants with singleor twin main rotors, although aircraft with singular mainand tail rotors tend still to dominate. Additionally, theseconfigurations have been extended into tilt rotor capability.

Military rotorcraft have traditionally fulfilled many rolesincluding surveillance, communication, search and rescue,maritime patrol and ship defence, ground and sea attack,transport of troops and freight including heavy lift. Civilvariants parallel these roles with air surveillance of siteand traffic flows, surveying, search and rescue, passengerand freight transportation including importantly those forhumanitarian aid and a heavy lift capability.

Obviously the unique ability of rotorcraft to deploy fromsite to site with both very localized landing and hovercapabilities defines the nature of their many applications.However, the larger payloads, speeds and range of fixed wingaircraft coupled with lower operating costs has provided acompetitive incentive for the development of hybrid aircraftsuch as the tilt rotor to attempt to combine the best of bothworlds.

3.2 Structural Design and Materials Choice

Structural design tools based on finite element modelinghave traditionally been used in the rotorcraft industry fordesign of airframe and component parts whilst dynamicmodeling has been applied to specific components of theairframe prone to dynamic and vibration issues. Couplingof aerodynamic models with structural response has beenachieved but has been limited whilst optimisation of therotorcraft as a whole system has yet to be achieved. Systemperformance modeling for the rotorcraft has therefore much

relied upon suites of disparate empirical models. Specifically,dynamic modeling including high frequency vibration aspectsand heavy landing/ crashworthiness has also developed overthe last decade but much development is still required.

3.2.1 Fuselage Design

A rotorcraft fuselage may be seen as a rigid flat platformor “raft” attached to frames that transfers lift from the rotoroverhead. The fuselage body around this platform and framemay therefore be lightly loaded or virtually non-existent inthe smallest aircraft. Normally, however, the fuselage will be

subject both to loads generated by the rotor causing aircraftaccelerations and aerodynamically by the passage of theaircraft producing lift and drag. Rotor downwash, gust andbuffeting will also occur.

The fuselage frames and floor platforms maybe constructedfrom aluminium alloys including aluminium-lithium whilst

fuselage skinning is likely to be a hybrid mixture of aluminiumalloy and composite materials locally supported by stiffening

stringers. Evaluation of highly damage tolerant hybridmaterials such as GLARE has been undertaken but little, ifany, use of such hybrids has been made primarily becauseof minimum gauge limitations. Traditionally, metal skinshave been attached to their supporting structure by eithermechanical fastening using a mixture of aluminium alloy andtitanium rivets or by metal to metal adhesive bonding usuallythe latter being reinforced by selected mechanical fastening.

For many years the tail structures, such as vertical finshousing the tail rotor and horizontal stabilizers, have beenmanufactured using composite materials for the skins withinternal stiffening, resulting in close to complete compositestructures. Engine cowlings and other fairings have exploited

composite technology for a considerable time although therehave been some difficulties with lightning strikes.

3.2.2 Engine and Rotor Design

On rotorcraft, main rotor(s) provide lift and control of aircraftattitude to achieve vectored thrust for directional flight anda tail rotor to react the torque of the main rotor and providecontrol of aircraft heading.

In general terms a rotorcraft maybe powered by gasturbine engines usually small single shaft variants of the

conventional aerospace powerplant described in a separateReview. Single, twin and triple engine configurations may beemployed, in the latter cases requiring the use of combinergearboxes. These engines drive main and tail rotors throughgear boxes and transmission drive shafts with the gear boxesreducing rotational speeds from those of the gas turbine.

Additionally engines that are normally mounted horizontallymust drive vertical shafts powering the main rotor requiring w

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right angle gear boxes. The main rotor is centred upon thecritical rotor hub where blades are attached with linkages

controlling pitch and drag and drive transmitted from themain vertical drive shaft.

To add to these complexities the rotor blades themselves areof variable pitch to accommodate demands for changes in liftand aircraft attitude requiring the use of mechanical linkagesand flexible hub designs. The dynamic performance of rotorsis complex as individual blades develop variable levels oflift and drag during a single revolution as they advance andretreat against the direction of motion of a moving aircraftor as they cross the body of the fuselage below them. Rotordesigns will continue to develop and here improved materialssuch as polymer composites used in the blades or titaniumalloys within rotor hubs have already enabled advances in

rotor design whilst adaptive structures may provide designsof the future. Stiffness in the blades is an obvious requirementto resist lift induced loads and to avoid dynamic instabilities,composite materials affording the ability to tailor the bladewhilst metal tip weights are also employed.

In addition to the mechanical and vibration loading of therotor, engine and transmissions, the blades themselves mustaccommodate impact, ballistic damage and erosion whilsttransmissions and rotor heads also must be proof againstfatigue and corrosion. As with any blade design tip speedsmay be limited by the speed of sound and the onset of shockinduced drag.

Multi-layer coating systems based on ceramic/ceramic ormetal/ceramic combinations have been used to combat theerosive effect of sand and other dusts. These systems can beoptimized for maximum performance by altering the numberand thickness of each layer and their chemical composition.

Whilst modern military and civil aircraft make use of fibrereinforced polymers for rotor blades replacing the previous

constructions of metal spar with attached metal pockets,both types of blade remain in use today. Control of signature,

especially noise, is incorporated into rotor and blade designfor military helicopters but advantage of low noise designs isalso taken in current by civil variants.

Note should be taken of the British Experimental RotorProgramme (BERP) which through successive phases hasdeveloped the aerodynamic and structural design of rotorblades to achieve world record aircraft speed and significantadvances in noise output. Attention having been paid inparticular to blade tip design.

3.2.3 Transmission Systems Technology

Much use is made of high strength steels in design oftransmissions shafts, gears, mechanical linkages andthe rotor head, the steel commonly being machined todimensions from solid bars or logs with low levels ofutilization. However, the very high stress levels imparted canreduce critical crack sizes to very low values necessitatinga safe life methodology rather than a damage toleranceapproach for fatigue life management. Surface treatments toimpart resistance to erosion, fretting, wear and corrosion areimportant and certain components of military helicopters maybe judged to vulnerable to battle damage and designed fordamage tolerance.

To save weight, improve damage tolerance by operating atlower stress levels, and to introduce more flexibility in hubdesigns progressively more use is being made of titaniumalloys, where volume constraints permit. However, thesignificantly higher cost of titanium alloys and its relativescarcity prohibit uptake somewhat. To overcome the lowutilization and hence high wastage of machining titaniumalloys from solid, closer to form manufacturing methods have

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Recent History

been sought including welding of logs, bars and attachmentsto build up structure. More recently, additive manufacturing

processes are being developed and investigated by theaerospace industry. Use of polymer composites in thisarea has been minimal to date because of the high multi-directional stresses involved. As with most moving parts sealand sealant technologies are critical and developments inthese areas should not be neglected.

3.2.4 Landing Gear and FlotationEquipment

Rotorcraft may operate from the ground, from fixed andmoving platforms such as oil rigs, lighthouses or navalvessels requiring a capability for surface movement, forlanding on fixed and moving surfaces including those thatare unstable and in extremis the aircraft must have floatationcapability. Crashworthiness and heavy landing remainsignificant issues.

3.3 Manufacture

To date most aircraft fuselages have been constructed fromthin sheet aluminium alloys with extruded or cold formedsheet stringers being pre-attached by rivets or adhesivebonding. The sheet itself may well have been locally thinnedby chemical etching, machining or selectively built up byadditional layers. Manufacturing issues generally revolvearound automating the attachment of stringers, precision andrepeatability of processes, ease of assembly on to framesor ribs, maintaining design tolerances etc., cold workingof attachment holes for fatigue resistance, if applied, andany necessary surface treatments for enhanced corrosionresistance.

Key metal fabrication techniques include cold and hot metalforming of panels and extruded profiles, including shot-peenforming techniques to correct machining distortion, plusprecision machining of close-to-form forgings using well

developed manufacturing practices. Here the handling andrecovery of scrap is an issue of significance to cost and to theenvironment, a particular issue if proposing to use aluminium-lithium alloys. Mechanical fastening, welding and adhesivebonding all feature for the manufacture of joints and moderntechniques of cold working of holes and surfaces may beapplied to critical components and in repair of damageditems but in-service fatigue cracking problems persist in metalstructure and fatigue is still a significant issue.

Finally for the metal structures in particular, long-termcorrosion protection is essential and thus remains an issuewith attendant effects upon cost, efficiency and environmentalimpact. Materials that replace cadmium and the hexavalent

chromium compounds contained in surface pre-treatments,paints and sealants have been under intensive review since itis uncertain how much longer aerospace manufacturers willbe granted special status for the use of these health hazardmaterials.

For composite component manufacture there are two main

types of material to be considered, namely thermoset andthermoplastic, and their selection depends very much onthe property required of the component and its size andshape. To date whilst thermosets have been more commonlyused, molded thermoplastic composite technology hasoccasionally been deployed.

Composite product fabrication relies on embedding therequired long-fibre (glass, kevlar or carbon) arrangementin a resin matrix, usually epoxy. This is done on a shapedtool base so that when the resin system is cured the finalproduct form is produced. Common methods employedare manual or automated lay-up of resin pre-impregnated

sheets or tapes and Resin Transfer Infusion (RTI) and ResinTransfer Moulding (RTM) where dry fibres/woven fabrics areused. In each case resin cure is completed by applicationof heat and pressure either through the use of autoclavesor heated tooling e.g. presses. It is evident that for ResinTransfer Moulding tool design plays an important part in theachievement of high quality composite products, the toolsrequired can be both complex and expensive.

The joining and assembly of composite parts is stillfrequently accomplished by mechanical fastening howeverthe technology offers the opportunity to increase the use ofadhesive bonding (second cure cycle required) or to co-cureusing the resin cure cycle to concurrently join partially cured

parts. These techniques remove the requirement for drillingwhich can significantly disrupt the inherent property of thecomposite.

For composite structure the corrosion issue is clearlyremoved for the component, however the effects of galvaniccorrosion between materials of differing electrical potential

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have to be considered eg when using mechanical fasteningto join either composite/composite or composite/metallic.This is the prime reason for increased use of titanium incomposite structures (titanium has better electrochemicalcompatibility with carbon-epoxy matrix than aluminium alloyor steel).

3.4 Operational Issues

Historically, military and civil rotorcraft have remained inservice for decades and the safe reliable maintenance

of large fleets of aircraft has been developed and honedto a very successful level of performance. Problems arestill encountered due to the severe fatigue and corrosionenvironment in which rotorcraft structures operate, frettingdamage often being the precursor to fatigue and corrosion.Rotorcraft designers specify high levels of corrosionprotection and also cold working of surfaces and holes, butsignificant in-service husbandry is still required.

Damage developed in rotating machinery including engines,transmissions and the blades of rotorcraft can be extremein hostile environments where fine sands, particulate matterand sea water maybe swept up by the rotors and ingestedfrom desert and marine environments. Filtration systems

and surface coating techniques are vitally important. Thenature of operations of civil and military rotorcraft make theissue of inadvertent damage by impact and/or weapon strikea significant issue especially for blades, natural damagetolerance in these structures is hard to achieve when rotatingparts may become out of balance. Wear and erosion ofcomposite blade leading edges has to be offset by the use of

thin metal strips, usually a nickel alloy.

Structural and transmission fatigue management techniqueshave evolved from the traditional “safe-life” approach toa combination of safe-life and intrinsic damage tolerance.Simply put the early appearance of damage has majoroperational and financial penalties even if intrinsically highlevels of damage tolerance enable any such damage to bereadily detected, repaired or contained. So long safe livesare sought to maximize cost effective operation whilst intrinsicdamage tolerance delivers a safe aircraft.

Matching techniques for non destructive evaluation both

during manufacture and for in service situations, on-demand,have also been thoroughly developed. Here again thebasic principle must be that the time-to-first inspection forany aircraft structure must be maximized and intrusion in-service, for non destructive evaluation, minimized. Whilstthis philosophy applies both to metallic and polymercomposite structures, techniques are also being developedfor continuous health and usage monitoring whilst in-service(HUMS). This stems from an initial need to establish levels ofstrain seen in composite wing structures on combat aircraftand from decades of close monitoring of the numbers andamplitudes of cyclic loads seen in metal structures and theconsequent rate of consumption of fatigue life.

The purpose behind establishing data for the rate ofadvancement of damage, in whatever form, is to substantiateever increasing precision in the prediction of residual life andconsequently confidence in life extensions. Ever increasingunderstanding and precision in modeling has been a majoradvance of the recent past but yet more is possible.

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Current Trends - 5 Year Horizon


4.1.1 The Uninhabited AutonomousRotorcraft.

In searching for autonomous air vehicles for surveillance,monitoring and military engagement some systems havebeen demonstrated based upon rotorcraft since such aircraft

have the inherent ability to loiter as well as their obviousvertical take-off and landing capabilities. Even craft withcounter rotating “main” rotors and no tail assembly havebeen launched. As with the fixed wing variants of suchuninhabited aircraft civil applications follow the militaryin short order. It is not clear whether the systems alreadydemonstrated will see major application and furtherdevelopment in a five year time scale but their future useseems assured. For example, new programmes are beingsought in the United States to fulfill certain intelligence,surveillance and reconnaissance (ISR) requirements witha VTOL UAV for the US Army. The army is outfitting a USDefense Advanced Research Projects Agency-owned Boeing

A160 Hummingbird with an autonomous real-time groundubiquitous surveillance-imaging system payload. It will alsocarry wide-area surveillance and signal intelligence packagesand see active deployment as a prototype.

Removing the human element of the rotorcraft payloadshould have a significant effect on functionality of craftengaged in surveillance or combat functions simply byreleasing usable mass but further refinements can be madeby simplifying the structure, removing canopies, possibly tailassemblies etc. It would seem likely that the existing raft ofmaterials currently deployed in rotorcraft manufacture wouldbe sufficient for such novel craft and that development willfocus strongly on concept and structural design.

4.1.2 Diesel Engine Powerplant

For several decades rotorcraft have deployed gas turbinesas powerplant. Although perhaps simpler than civil aircraftcounterparts being typically single spool engines designedto operate at constant rotational speed, the gas turbine isnot of necessity most efficient when aircraft motion andconsequent airflow into the engine is low. Light aircraft havevery successfully deployed relatively low cost high efficiencyturbocharged diesel engines and the rotorcraft communityis investigating possible applications. It is not currentlyenvisaged that such a development will give rise to structural

or materials difficulties or new requirements and powerplantissues per se are considered elsewhere in this series ofReviews.

Developments current within a five year time frame aimed at bothmilitary and civil rotorcraft are mostly refinements of current technology

with some notable trends.


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4.1.3 The More Electric Rotorcraft.

Rotor designs may be subject to yet further improvementsto achieve greater aircraft speed, lift capacity and noisesuppression. Blade tip speeds that approach the speedof sound limit blade length and rotor speed whilst theuse of more, shorter blades compounds the difficultiescaused by loss of lift as the blades wash over the bodyand the difficulties inherent in controlling multiple blades

on a single hub. For example, current rotorcraft design iscritically dependent upon the need to tailor the attitude of therotorblade during one rotation to accommodate variationsin lift and drag experienced by advancing and retreatingblades as well as of course effecting controlled flight. Severalapproaches loosely characterized as Smart blades are underinvestigation to aerodynamically tailor the blade itself in flight.It has been shown that blade shape may be modified or “morphed” by internal electrical actuation at a sufficiently highfrequency to enable its aerodynamic characteristics to betuned or that trailing edge tabs can be physically deployed toachieve much the same effect, trimming the rotor in rotation.

Additionally and quite separately electromechanical actuationis being studied as a means to replace mechanical andhydraulic linkages, to reduce power losses and fatigueproblems or obviate environmental concerns respectively.Electromechanical actuation is being studied including acomponent of the European Green Rotorcraft programme.


The key short term development goals are to improveproduct competitiveness through reduced empty weight,reduced cost of ownership, improved crashworthinessand reduced vibratory response. To reduce structuralweight, manufacturing techniques which produce largersingle piece components are a promising avenue. Thesetechniques include more use of “welded” thermoplasticstructures or metallic sub-assemblies which have been

joined by friction stir welding. Reduced cost of ownershipis generally improved by the increased use of compositematerials. However, it is worth pointing out that installedavionics equipment requires good structural electricalconductivity which, with a composite structure, is achievedby the addition of copper mesh layers – these are themselvessubject to a significant corrosion risk. Automated addition ofmetallic elements, in the form of thin layers or coatings arebeing developed to provide conductive paths in compositestructures, for lightning protection, de-icing elements,antennae and other uses.

Previously, monolithic composite skins with co-cured orbonded stiffeners have not been widely used in helicopterdesigns simply for reasons of weight. Such designs areonly competitive if designed as a post-buckled structure anddesigners and Airworthiness Authorities have been reluctantto adopt this approach with composites. This is due, in part,to the difficulty in predicting the behaviour analytically, but

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Current Trends - 5 Year Horizon

also because the buckling imparts high peel loads to thebond between skin and stiffeners. In fact, for certification,

any bonded stiffener would require a mechanical fastenerto provide fail safe attachment in the event of a bondfailure which in turn would require a thicker skin or stiffenerwhich would further penalize the design. The adoption ofthermoplastic composites, which allow the use of weldedintegral stiffeners and a post-buckled design philosophy (seesection below), may offer an opportunity for a paradigm shiftin this regard.

Reducing the dynamic response of the helicopter structureis something of a “holy-grail”. The engineering problemis highly complex with multiple dynamic and aerodynamicforcings and multiple structural modes. The future will seeimproved mathematical modeling, the more widespread use

of active vibration reduction systems and the increased use ofmaterials with higher damping.

Structural modeling and design tools for dynamic responsehave been following two different routes namely in adaptingand deploying Euler based dynamic codes such as DYNAand DYTRAN including those with coupled Euler/Lagrangecapabilities and the use of Statistical Energy Analysis (SEA ) the analogue of Finite Element Analysis operatingin the frequency domain. The ever increasing capabilityobvious in computer modelling based upon rapid increase incomputing power will make whole body dynamic models forvibration analysis quite possible provided attention is givento the specific aspects pertinent to the rotorcraft namely the

multiplicity of loadings and structural modes. Additionally thisincreased capability will allow multi-disciplinary optimizationand performance modeling to be enhanced. Correlation ofsuch models with comprehensive test data will be required.It must be clarified that at present the complexity inherentin rotorcraft responses through the flight envelope requiresa large sustained effort to improve basic understandingand modeling capability. For example, the rotor unsteadyaerodynamics are still beyond our ability to predict, thefuselage response varies during manoeuvre as the loadchanges, the blades pass through the vortices left by

preceding blades and their position and energies vary withtime, the rotor and fuselage dynamics are coupled, there are

other complex interactions between the rotor wake and theairframe including “shuffle” and pitch-up. Significant effortis anticipated in this area critical to support future designcapability.

4.3 Manufacturing Development

It is thought that specific development in thin skinnedmonolithic thermoplastic structures joined by inductionwelding, designed as a post-buckled structure is requiredin the UK following trends developed by Europeanmanufacturers who are well ahead in this field.

For metal structure complex three dimensionally loadedcomponents are critical, the rotor hub providing a primeexample. Use is increasingly made of titanium despite itsrelatively high cost and relatively long lead times. Processesproviding the means to build up and qualify such partsperhaps by metal deposition, linear friction welding or frictionstir welding are under investigation and of immediate interestespecially when they enable the use of simple stock sectionsrather than complex forged or cast sections.


Fatigue and corrosion damage remain persistent problemsfor rotorcraft perhaps more so than for fixed wing aircraft.This stems from the severe operational environment ofthe rotorcraft particularly with its high frequency vibrationcontent. The use of cold working technology for fatiguelife enhancement tends to be only applied in retrospect forrepaired items being too difficult and expensive to applyroutinely over the whole airframe and its components, abinitio. Vibration loadings tend to induce fretting damage in

joints that leads to breakdown of protection, jointing andsealing at interfaces and the onset of corrosion. Moreresearch and development is needed to understand the


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root causes of such damage, modeling the loading sourcesand subsequent fretting and corrosion damage with a view

to enhanced life prediction or design improvement andenhanced surface treatments.

For Composite structures, repair is a major issue. Repairmethods for composite materials and structures have longbeen a topic for research and development. One aspect isthe ability to be assured of the subsequent performance ofany repair, to avoid excess over-engineering of any suchrepair. That is it is not yet permitted to employ adhesive repairtechniques on primary aircraft structure as the process isdifficult to fully assure in an operational environment. Today,mechanical fastening remains the only acceptable repairtechnique. This is an issue for composite structure as thecertification requirement to permit mechanical repair severely

impairs the low weight design potential.

The issue of materials availability is going to becomeincreasingly important for example certain metals are inscarce supply and are yet critical to aerospace, copper forelectrical/electronic components or rhenium in enginesfor example. Secure provision or the identification andqualification of alternatives may become the most acute issuefacing aerospace long term. Obviously affecting the moreexotic materials, this difficulty might also be seen in wellestablished materials types with subtle yet important changes

in alloy chemistry being dictated by shortage of materialssupply or developments driven off-shore. It would seem that

a capability for rapid insertion and qualification of substituteswhether metal or composite would be important and of realintrinsic value.

The same comments apply to materials that may becomeunavailable through legislation designed to protect theenvironment and personnel such as REACH. The rotorcraftindustry has traditionally made significant use of cadmiumand chromium for the protection of corrosion pronecomponents. Flexible, rapid insertion and approval of newmaterials and techniques may well be key.

The tightening of legislation covering disposal willprogressively affect aircraft design and manufacture and

moreover pressures to recycle materials will increasebecause certain metals critical to aerospace are becomingmore scarce in supply, copper for electrical/electroniccomponents or rhenium in engines. Secure provision or theidentification and qualification of alternatives may become anacute issue facing aerospace long term.

As composite structures come of age disposal techniquesare being sought to recover value from obsolete structure,in much the same way as metallic components can enter asecondary recycling chain.

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Possible Future Scenarios - 20 Year Horizon


Future military requirements will persist for rotorcraftsince no loss in role or function is envisaged. However,developments in unmanned and autonomous flight mayextend beyond fixed wing versions into the rotorcraft field,military demonstrators already existing. Such systems wouldsupplement unmanned fixed wing aircraft already used for

surveillance and ground attack providing hover capability. Again hybrid designs such as the tilt rotor may prove of worthin military deployment, particularly for larger aircraft capabilitywhere currently fixed wing aircraft are deployed withextremely short take-off and landing techniques but requiringmaintained landing strips. The position of UK industry inthis arena should perhaps be challenged being capable,it is believed, of expansion particularly exploiting the UK’scapability in autonomous systems.

Within a twenty year timescale the nature of civil airtransportation may well have changed in its balance betweenmass transportation of passengers and freight, and personalair transportation including corporate business travel. For thetraditional major market of mass movement of passengersand freight, paradigm shifts might be required to maintaincompetitiveness with other forms of surface transportation,especially for the shorter route lengths. A simple exampleis the current uptake of ultra high speed trains connectingmodern hubs or terminals. It maybe that ground or surfaceeffect vehicles will gain credibility and concepts such as theadvanced tube trains, electromagnetic lift and propulsionsteadily displace the standard short haul air transport (androtorcraft) traditionally used in this role. For the rotorcraftcurrently the tilt rotor is seen as potentially providing asolution to some of these problems but other concepts maywell emerge.

In any event, air traffic congestion and terminal passengerthroughput has to be much improved to improve thecompetitive position of air transport, particularly overshorter routes. It seems likely that the current trend towardspersonalized forms of transport for the better financedwill persist with sustained growth in the “private wings” or‘personal plane’ market. Rotorcraft should have a strongerrole to play in this arena because their prime advantages ofsite to site flight, restricted take-off and landing areas andhover capability will persist. Key technologies may prove tobe the development of autonomy in rotorcraft flight controland navigation allowing de-skilling of the pilot and cheaperdesigns overall.

It would seem that traditional civil roles for rotorcraft inaccessing remote fields, off-shore platforms and installations,surveillance of borders and traffic etc will persist indeed growwith the ever increasing use of marine and desert resourcesfor wind/solar and tidal power generation and explorationfollowed by exploitation of natural resources in yet more

inaccessible locations.


For the future it must be the case, that an area for intensedevelopment will be the ability of designers and engineersto model every aspect of the design, development, build,

proving and operation of a rotorcraft addressing thefundamental issues of “right-first-time” for designs andenhanced flexibility for adaption, modification and operation.The next twenty years will see massive increases incomputational power that should be sufficient to revolutionisethe design, manufacture and operation of rotorcraft. Inparticular there remain issues with the ability to predictthe performance of rotorcraft in flight stemming from thecomplexities of rotor performance.

However, whilst individual modeling capabilities have beendeveloped separately over decades, integrated modeling ofwhole bodies for different functionality such as aerodynamicdrag and lift, control performance, structural response,

cost, environmental impact etc. etc. etc. has hardly beenaddressed being previously limited by computing powerto individual disparate modeling approaches. Typicallyaerodynamics might operate with large surface areas, whilststructural modeling will require high grid densities in fullstructure to achieve accurate prediction of local events.Beyond increasingly potent links between say fluid dynamicsand structural performance, much more needs to be done toinclude rafts of disparate modeling capability into the samefunctionality. A simple metric might be the near eradicationof structural test for designs that can be optimized, realizedand proven virtually. For the rotorcraft the very pertinent issueof dynamic modeling of multi-modal structural response to

complex loadings and forcings cannot be over-emphasised.Enhanced rotor and blade designs are still sought manypossibilities exist such as the use of co-axial rotor drives hubsand transmissions, counter rotating rotors and even multirotor systems. For example, miniature automated four rotorsystems have been demonstrated offering great precisionin positioning of the rotorcraft sufficient for the placement ofcomponents in manufacture. One key issue for future designsmay well prove to be computer based multi-disciplinaryoptimization and more work in this area both building andapplying capabilities is sought.

Yet further electric developments. In terms of concept,architecture and structure one issue of some importance

might prove to be developing a more electric aircraft inparticular it may prove possible to make the coupling,transmission and control of power from the engines into therotors more electric, basically coupling electrical generatorsto electric motors. Whilst a reduction in the number movingparts and complex linkages thereby achieved should beadvantageous, it is not clear whether such an arrangement


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would be weight efficient and more or less damage tolerant.

On the materials front, the traditional metrics for highperformance aerospace materials must surely persist for thecoming generations in terms of the need for lower density,higher strength, stiffness and damage tolerance etc. etc. toproduce low mass affordable structures that are safe, reliableand readily sourced. However, it might be noted that the basealuminium alloys currently in use are modified versions ofalloy systems that are between sixty and one hundred yearsold whilst the current forms of fibre reinforced polymers areat least half this age. Further refinement must be possible forthese materials but it may well be the case that a step changein materials performance should now be sought at least whenthis time scale is envisaged. It is restated that developmentsfor rotorcraft may well have to follow those adopted for thefixed wing manufacturers.

The environment sustainability issue has begun to be a majordriver for material selection and development in the future.It maybe that carbon fibre could be replaced by a naturallygrown fibre or that the need to recover/recycle materialswill cause the revisiting metallic solutions. If materials couldbe produced that were inherently self-protecting, it mightprove possible to dispense with the use of large volumes ofchemical treatments.

5.3 Manufacturing Development

For current and long term developments, the main drivehere is for greater flexibility and the ability to rapidly build-upstructures from common simple forms of stock rather thanthe need for long lead-time specialised shapes or performs.Thus metallic developments may well revolve around the useof rapid deposition techniques that will enable complex three

dimensional components to be built precisely-to-form andthe use of developing techniques for welded or adhesivelybonded attachments and joints. Advances in compositemanufacture will continue to focus on the rapid and reliabledeposition and consolidation of material attempting tominimise jigging and lay-up inefficiencies.

Parallel development of real-time on-line process controland inspection systems will also be required to provide theProduct assurances. Intelligent automated systems withmultiple degrees of freedom and high levels of precision andrepeatable performance can be seen as key enablers for theabove.

With rising energy prices, energy consumption willincreasingly become a major concern for the future OEM.Demands for lower energy processes will drive materialsdevelopment, for example microwave curable compositesor structural adhesives, low energy laser treatments or othertechnologies not yet recognized today.

As discussed previously jigging and tooling are a significant

cost in the production of aircraft. One possibility is that‘fly-away’ jigs become a feasible in the future i.e. jiggingis designed and built-in as an integral part of the aircraft’sstructure.


Looking at parallel engineering developments for example forthe automobile, it can be seen that vehicles are now offeredwith whole life warranties or zero planned maintenance. Itwould seem that within a twenty year timescale such veryhigh levels of reliability might be achievable in aerospace.The use of structural health monitoring and advancednon-destructive evaluation techniques linked to designanalysis tools could potentially provide sufficient data to giveprediction of component safe life, which in turn could be usedto give operators a more directed maintenance programmefor each of their aircraft, significantly reducing unscheduledmaintenance and time out of service. This data could also befed back to the design organization and be used to improve

subsequent derivatives design.Future military operations are foreseen that will continue torequire the deployment of rotorcraft for transport of personneland equipment, for surveillance, ground attack and maritimedefence. It maybe that an improved heavy lift capabilitywill become a major issue requiring new designs to begenerated.

It would seem that improvements in the ruggedness ofrotorcraft deployed in very adverse military conditions willbe a driving force for equipment and system improvements.Equipment and engines obviously feature strongly in thematter of maintenance. Also simple issues such as theperformance of seals and sealants figure here just as much

as more traditional areas for concern such as corrosion inmetals or environmental degradation in composite.

Irrespective of the source of design and manufacturingcapability, it is predicted that the UK will maintain a healthybusiness in the operation, maintenance and improvement ofrotorcraft operated in civilian markets.

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Requirements Perceived for Materials andStructures Research and Development

6.1 Safety

• Development of new tougher composite materials and ofcomposites with improved thermal and electrical properties

• Full scale modeling and testing of crashworthy structures

• Development of improved, damage tolerant, wear, erosion,corrosion and fatigue resistant structures

• Developments of understanding and control of frettinginduced corrosion

• Development of sensor systems for inspection, corrosionand damage detection to be integrated within structuralhealth monitoring capabilities

• Modeling of included defects and damage events includinghigh strain and high strain rate loading and high frequency,multi-modal loads

• Structural techniques or materials to enhance ballisticsurvivability

6.2 Reliability

• Development of dynamic structural modeling includingcoupled modelling of whole rotorcraft

• Modelling of long term performance of materials andstructures to reduce certification testing.

• Development of adaptability in design better to enableenhancements, upgrades and modifications

• Improved prediction of residual life including modelling offatigue loads specifically for rotorcraft

• Modelling and development of techniques to suppressfretting and corrosion/fatigue damage

• Development of life extension processes and theirmodelling

• Advanced in-service inspection & evaluation tools includingenhanced analysis methods for damage identification, theinterpretation of its significance and self sentencing

• Integrated structural health sensing and conditionmonitoring

• NDE Techniques for metallic and composite structuresparticularly addressing rapid inspection of complexgeometries

• Repair process developments:

○ Repair of composites including in-situ repair techniques

○ Reliability, self-healing material

○ Friction stir welding

○ Repair process assurance techniques (process control,non-destructive evaluation)

6.3 Efficiency

• Enhanced performance modeling for rotorcraft specificallyincluding development of more advanced rotor models

• Development of novel concepts for whole rotorcraft, theirstructural and rotor design

• Optimisation of combinations of material, manufacturingand assembly techniques that meet performance,environmental and cost requirements over the full life cycleof the product

• Material developments in conjunction with othermanufacturers for Thermoset and Thermoplasticcomposite that concentrate on high strength and stiffness,preforms, fillers, alternative manufacturing routes and lowtemperature curing systems.

• Composites with improved 3D properties and improvedcoatings with enhanced abilities for damage detection,repair and disposal/recovery.

• Possible long term development of morphing materials andstructures especially for active rotorblades.

• Assessment of the impact of an increasing use of novellightweight metal alloys including aluminium-lithium alloysand metal-composite hybrids

• Assessment of developments for titanium alloys andsupporting processes and treatments

These requirements are addressed by separating them, non-exclusively, in terms of the principal research drivers previouslyidentified.


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• Assessment and development of multi-functional materialswith additional property attributes e.g. Electrical andthermal performance of composites

• Assessment and demonstration of the potential benefitsand opportunities to insert nano-technologies into materialsand process developments

• Structural optimisation and and analysis including

asymmetric lay-up in composites

6.4 Affordability

• Strengthened virtual design and test techniques to enablemore rapid evaluation of options, more rapid detaileddesign, reduced levels of testing, strengthen procurementadvice. Develop virtual structural test capability, decreasestime to market

• Lower cost composite manufacturing developmentsincluding woven fabrics with enhanced performance andprocessability

• Material developments for metals that address the high costand restricted availability of titanium, possibly alternativemanufacturing methods such as laser processing.

• Assessment of the vulnerabilities introduced by use ofmaterials in critical supply and identification of alternatives

• Assessment of alternative materials, materials options andinterchangeability of materials

• Development of tools to enable composite materialsinterchangeability at low cost without expensive re-qualification.

• Continual development of metallic and composite

fabrication techniques, particularly to deliver net shapeproduct and thereby negate post-processing:

○ Joining technologies e.g. Welding, Adhesive bondingand Laser processing

○ Thermoplastic welding and techniques to build upstiffened thin panelled structure

○ Advanced casting or resin transfer moulding – materials+ techniques

○ Additive Manufacture - metallic or composite

○ Ultra low cost tooling - recoverable and flyaway tooling

○

Surface engineering/coatings techniques○ 3D woven composites

○ Automated lay-up and fibre placement, toroidal winding

○ Process simulation for fast resin transfer moulding

○ Low energy, high speed product processing

○ Out-of-autoclave manufacturing techniques

○ Microwaveable curing

○ Composite to metal joints

○ Low energy laser treatments

• Performance and process development for adhesivebonded joints, composite to composite, composite to metal

and metal to metal.

• High performance/quick assembly joints for CFRP/hybridstructure

• High performance/quick assembly joints for CFRP/hybridstructure real-time quality assurance methods

• Further development of automated manufacture andassembly systems including intelligent systems foraccurate measurement and inspection, feature recognition,process control, and tight tolerance performance.

• Jigless assembly and forming including ‘fly-away’ tooling

• Machine/human interface technologies

6.5 Environmental Impact

• Technology watching and its evaluation

• Further design and development of noise/ vibration controltechnology for rotorcraft

• Alternative materials and surface engineering processesto meet future environmental legislation requirementsor diminishing availability especially noting heavy metalissues.

• Development of Environmental impact models

• Strengthening of virtual design, test and evaluationtechniques to include assessment of potentialenvironmental impacts including noise thereby enablingmore rapid evaluation of options and reduced testing

• Studying the implications of non-national design and lifeingtechniques including design philosophies, for examplediffering international attitudes to chromium and cadmiumbased protection systems

• Strong contribution to support rapid insertion of newtechnology into existing designs to obviate environmentalimpact (e.g. loss of use of cadmium.)

• Low consumption cleaning and protection systems• Materials recovery, re-cycling and/or re-use technologies

• Assessment of development of natural fibres forcomposites or advanced fibres providing alternatives forcarbon.

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Research Collaboration

7.1 National Strategies for Collaboration

National collaborative programmes for industrially ledaerospace research and development can be identified underthe umbrella of the Aerospace and Defence KnowledgeTransfer Network as the National Aerospace TechnologyStrategy wherein lies a strong element of advancedmaterials and structures research including SMARTstructures, Advanced Materials and Health Managementand Prognostics. Aligned subject matter such as advanced

design and manufacture, modeling and simulation are alsoextensively accommodated. Technology developed underthis umbrella is fed into major demonstration programmeswhich include future composite wing init iatives for example.

Other initiatives such as Greener by Design or OMEGA focusmore upon the environmental issues and challenges facingthe aerospace industry and growth within it.

Open, competitively won, Government funding supportsthese and of course yet further programmes via a raft ofmechanisms such as the UK Technology Strategy Boardopen competitions, the Research Councils responsiveresearch modes and specific focused support from

the Regional Development Agencies and Devolved Administrations.

The Technology Strategy Board places a clear emphasis onthe need for research in advanced materials and structuresalbeit encompassing a far broader field than aerospaceper se taking Transport and Intelligent Transport Systemsas themes for investment for example. The TSB, along with

Advantage West Midlands and East Midlands Development Agency are supporting the creation of the Manufacturing

Technology Centre (MTC). This centre will address the gap incapability in the UK of translating research and developmentfindings into useful production solutions for, among others,airframe manufacture. Ministry of Defence, with its own clearcut requirements, funds its own programmes including thosein materials, structures and health management for examplebut taking cognizance of the content of these nationalinitiatives described above.

A key element in all these programmes is the involvement,leadership, investment and up-take provided by UKaerospace industry which is very substantial.

A parallel Network in Materials, Materials UK , accommodatesissues more pertinent to the materials supply industry on abroader basis than aerospace.

7.2 International Collaboration

International collaboration is perhaps best exemplified byparticipation in European Framework programmes althoughthe opportunities for international collaboration beyondEurope continue to mount.

Current FP7 developments are focusing on very largeprogrammes set at a strategic level for example by theinclusion of aerospace within more general transportationthemes. Whilst there is an inevitable dilution of the aerospacetechnical focus within these large multi-national initiatives, amyriad of individual opportunities exist within these structuresfor individual participation. Frameworks beyond the closingFP7 are perhaps now becoming more significant for researchconsidered within the 20 year timescale of this Review.

Research is increasingly done via national and international collaborationto minimize cost, broaden perspectives and enhance capabilities.


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Summary

This review has been produced under the auspices of theMaterials and Structures National Technical Committee, anintegral part of the Knowledge Transfer Network in Aerospaceand Defence. The central requirement for the review to isto provide informed opinion on the foreseen needs andopportunities for capability in materials and structures for UKair vehicles.

The recent history and current trends in application ofstructural technology and advanced materials for militaryand civil rotorcraft have been reviewed and possible futuredevelopments over two decades identified speculatively.This leads to the identification of possible new research anddevelopment projects in structures and materials set againstrequirements for safety, reliability, efficiency, affordability andenvironmental impact.

Principal Authors

C J Peel

OBE, FREng, FRAeSProf Chris Peel

Advise Air LtdTel: +44 (0) 1252 694 791,Email: [email protected]

Michael Overd

Head of Structures Design & DevelopmentTel: +39 033171 1779Tel: +44 1935 702452Email: [email protected]

Designer

Daniel Jones

Network & Communications Manager Aerospace, Aviation & Defence KTN

Tel: +44 (0) 207 091 1123Fax: +44 (0) 207 091 4545Email: [email protected]

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Materials & Structures National Technical Committee

Members

Mike Hicks (Chairman) Rolls-Royce plc

Geoff Armstrong Goodrich

David Bond Messier-Dowty

Andrew Clarke QinetiQ Group plc

Andrew Clements Cytec Engineered Materials

John Cornforth GKN

Paul Curtis DSTLRichard Freeman TWI Ltd

Mark French QinetiQ Group plc

Patrick Grant Oxford Materials

Ian Gurnell Advanced Composites Group

John Haddock BAE Systems plc

Simon Harris

Keith Harrison

Phil Harrison

Messier Dowty

Independent

Airbus UK Ltd

Terry Hirst Goodrich

Richard Jones DSTL

Ajay Kapadia National Composites Network

Nigel Keen Materials KTN

Dan Kells BAE Systems plc

Peter Morgan Corus Ltd

John Morlidge Technology Strategy Board

Michael Overd AgustaWestland

Pete Murray Aerospace, Aviation & Defence KTN

Chris Peel IndependentRichard Pitman BIS

Ken Poston Bombardier Aerospace

Malcolm Robb BAE Systems plc

Kam Sagoo BAE Systems plc

Colin Small Rolls-Royce plc

Iain Smith TWI Ltd

Roger Thomas TIMET

Geoff Tomlinson University of Sheffield

Paul Weaver University of BristolDavid Wilkes Ministry of Defence

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Images reproduced with the kind permission of: AgustaWestland.

About the Aerospace, Aviation & Defence Knowledge Transfer Network

The Aerospace, Aviation & Defence KTN is the single overarching network of Business, Government and Academia fostering collaborative research and development across the sector furthering wealth creation inthe UK. The KTN is funded solely by the Technology Strategy Board and is hosted by A|D|S Group, the UK’s

premier trade association across Aerospace, Defence and Security.

To connect with the Aerospace, Aviation & Defence KTN you can register for freeat www.aadktn.co.uk to access services, networks and to receive the weeklynewsletter. Email the KTN at [email protected] for further information.

The views and judgments expressed in this report reflect the consensus reached by the authors and contributors

and do not necessarily reflect those of the organisation to which they are affiliated. Whilst every care has beentaken in compiling the information in this report, neither the authors nor the Aerospace, Aviation and Defence

KTN Materials and Structures National Technical Committee can be held responsible for any errors, omissions or

subsequent use of this information.

Documents

Rotorcraft and Rotary Wing Materials & Structures Review V1.0.0