AeSK, P.O.BOX 758-00517, NAIROBI, KENYA 17 May 2013 Kenya Aeronautical College Nairobi AeSK LECTURE on AIRCRAFT DESIGN AIRCRAFT DESIGNby Dr. Faustin Ondore.

AeSK, P.O.BOX 758-00517, NAIROBI, KENYAAeSK, P.O.BOX 758-00517, NAIROBI, KENYA

17 May 201317 May 2013Kenya Aeronautical College Kenya Aeronautical College

NairobiNairobi

AeSK LECTUREAeSK LECTURE

onon

AIRCRAFT DESIGNAIRCRAFT DESIGNbyby

Dr. Faustin OndoreDr. Faustin OndoreChartered Engineer, MAeSK, MRAeS, MIMechE, Chartered Engineer, MAeSK, MRAeS, MIMechE,

© FA Ondore 2

AIRCRAFT TYPES

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AIRCRAFT DESIGNAIRCRAFT DESIGN

I Introduction – Objective, Definitions, Stake-holder map.I Introduction – Objective, Definitions, Stake-holder map.

II Systems Engineering V-Diagram Model – concept, requirementsII Systems Engineering V-Diagram Model – concept, requirements capture, architecture, design, implementation, to service acceptancecapture, architecture, design, implementation, to service acceptance

III Aircraft Design Procedures- Safety V-diagram, constraints, III Aircraft Design Procedures- Safety V-diagram, constraints, processes, certification specifications (airworthiness code & processes, certification specifications (airworthiness code & acceptable means of compliance)acceptable means of compliance)

IV Problems (Airbus 380, Boeing 787, etc)IV Problems (Airbus 380, Boeing 787, etc)

V ConclusionV Conclusion

VI Discussion - Question and Answer Session VI Discussion - Question and Answer Session

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AIRCRAFT DESIGNAIRCRAFT DESIGNI Introduction –I Introduction –

purpose of lecturepurpose of lecture

• Generate the understand the key features of design and theirGenerate the understand the key features of design and their impact on performance;impact on performance;• Gain an insight into links between design and other life cycleGain an insight into links between design and other life cycle characteristics (e.g. in-service reliability);characteristics (e.g. in-service reliability);• Acquire more complete multi-dimensional knowledge aboutAcquire more complete multi-dimensional knowledge about aircraft;aircraft;• Appreciate the need to link all life cycle activities (e.g. Appreciate the need to link all life cycle activities (e.g. maintenance and operations) ;maintenance and operations) ;• Hopefully, support the production of Kenyan Aircraft Designers Hopefully, support the production of Kenyan Aircraft Designers (& Manufacturers)(& Manufacturers)

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I Introduction - definitionI Introduction - definition

Design is the process of creating a plan or convention for the construction of an Design is the process of creating a plan or convention for the construction of an object or a system object or a system

• Presentation examples – calculations, experimental reports, engineering Presentation examples – calculations, experimental reports, engineering drawings, architectural blueprints, project process, graphics etc. )drawings, architectural blueprints, project process, graphics etc. )

• A Rational Design model was developed:A Rational Design model was developed:

- designers attempt to optimize a design candidate for known constraints and - designers attempt to optimize a design candidate for known constraints and objectives;objectives;

- the design process is plan-driven;- the design process is plan-driven;

- the design process is understood in terms of a discrete sequence of stages.- the design process is understood in terms of a discrete sequence of stages.

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I Introduction -I Introduction -Stake-holder mapStake-holder map

AIRCRAFTAIRCRAFT

Air travelers- tourists; Air travelers- tourists; business people; business people;

farmers; enthusiasts; farmers; enthusiasts; sports;sports;

recreationrecreation

People -safety &

environment

Aviation Aviation business – business –

airlines; airlines; MROs; MROs;

lessors;lessors;

Regulators – ICAO; national

airworthiness authorities;

Banks & other financialfinancial institutions;

GovernmentGovernments – defense & s – defense & security; security; police; police; wildlife wildlife protection;protection;

ProducersProducersDesign and Design and Production Production

OrganisationsOrganisations

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II System Engineering V-Diagram modelII System Engineering V-Diagram model(ISO/IEC 15288: 2008) (ISO/IEC 15288: 2008)

forforProduct Life Cycle AnalysisProduct Life Cycle Analysis

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II Systems Engineering V-Diagram Model – Requirements CaptureII Systems Engineering V-Diagram Model – Requirements Capture

• Detailed analysis and documentation of all requirements – tool (DOORS) – Design Object Orientation Requirements System;• Use of Customer Focus Groups (CFGs) to solicit requirements(manufacturers/airlines with NAAs);• Customer Requirements Document (CRD) – documents all customer and other stake-holder requirements;• Systems Requirements Document (SRD) – documents all systems requirements

CRDCRD SRDSRD

AIRCRAFT AIRCRAFT DESIGN DESIGN

IMPLEMENTATIONIMPLEMENTATION

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III Aircraft Design Procedures- Safety V-diagramIII Aircraft Design Procedures- Safety V-diagram

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III Aircraft Design Procedures - constraintsIII Aircraft Design Procedures - constraints

• Purpose

The design process starts with the documentation of aircraft's intended purpose.

-Commercial airliners are designed for carrying a passenger or cargo payload, long range and greater fuel efficiency;

-Fighter jets are designed to perform high speed manoeuvres and provide close support to ground troops

•Aircraft regulations – airworthiness, safety & operational aspects;

• The market and financial factors – projections of market demands and hence project viability

• Environmental factors – noise, carbon emissions & hence need for fuel efficiency

•Safety- high speeds, fuel tanks, atmospheric conditions at cruise altitudes, natural hazards (thunderstorms, hail and bird strikes) and human error are some of the many hazards that pose a threat to air travel

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III Aircraft Design Procedures- III Aircraft Design Procedures- processprocess

Conceptual Design

• First design step, entails the sketching a variety of possible configurations that meet the First design step, entails the sketching a variety of possible configurations that meet the required design specifications. required design specifications.

•Determines the design configuration that meets all requirements and is aligned to factors such as Determines the design configuration that meets all requirements and is aligned to factors such as aerodynamics, propulsion, flight performance, structural and control systems.aerodynamics, propulsion, flight performance, structural and control systems.

• Also called Design Optimization

•Fundamental aspects such as fuselage shape, wing configuration and location, engine size and type are all determined at this stage.

•Constraints to design like those discussed earlier are all taken into account at this stage as well.

The final product is a layout of the aircraft configuration on paper or computer screen, ready for review other by engineers and designers.

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III Aircraft Design Procedures- conceptIII Aircraft Design Procedures- concept

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III Aircraft Design Procedures- process III Aircraft Design Procedures- process

Preliminary designPreliminary design

•The design configuration arrived at in the conceptual design phase is then tweaked and The design configuration arrived at in the conceptual design phase is then tweaked and remodelled to fit into the design parameters. remodelled to fit into the design parameters.

•Wind tunnel testing and computational fluid dynamics (cfd) calculations of the flow field Wind tunnel testing and computational fluid dynamics (cfd) calculations of the flow field around the aircraft are accomplished at this stage. around the aircraft are accomplished at this stage.

•Major structural and control analysis is also carried out in this phase. Aerodynamic flaws Major structural and control analysis is also carried out in this phase. Aerodynamic flaws and structural instabilities if any are corrected and the final design is drawn and finalized. and structural instabilities if any are corrected and the final design is drawn and finalized.

•Then after the finalization of the design lies the key decision with the manufacturer or Then after the finalization of the design lies the key decision with the manufacturer or individual designing it whether to actually go ahead with the production of the aircraft.individual designing it whether to actually go ahead with the production of the aircraft.

•Several designs, though perfectly capable of flight and performance, have been opted out of Several designs, though perfectly capable of flight and performance, have been opted out of production if economically unviableproduction if economically unviable

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III Aircraft Design Procedures - processIII Aircraft Design Procedures - process

Detail designDetail design

Deals with the fabrication aspect of the aircraft to be manufactured. It determines Deals with the fabrication aspect of the aircraft to be manufactured. It determines the number, design and location of frames, formers, spars, ribs and skin sections the number, design and location of frames, formers, spars, ribs and skin sections and other structural elements.and other structural elements.

All aerodynamic, structural, propulsion, control and performance aspects have All aerodynamic, structural, propulsion, control and performance aspects have already been covered in the preliminary design phase and only the already been covered in the preliminary design phase and only the manufacturing remains. Flight simulation strategies are implemented at this manufacturing remains. Flight simulation strategies are implemented at this stage.stage.

Computer Aided Design (CAD)Computer Aided Design (CAD)

The use of numerical methods tools – Computational Fluid Dynamics (CFD) and The use of numerical methods tools – Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA)- to experimental testing methods to achieve cost Finite Element Analysis (FEA)- to experimental testing methods to achieve cost efficient design in shorter time scales. efficient design in shorter time scales.

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III Aircraft Design Procedures - processIII Aircraft Design Procedures - process

DESIGN TOOLS DESIGN TOOLS • Experimental : wind tunnel tests - for aerodynamicsExperimental : wind tunnel tests - for aerodynamics- Numerical: cfd, finite element analysis- Numerical: cfd, finite element analysis- CAD - CAD

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III Aircraft Design Procedures – processIII Aircraft Design Procedures – process

--Major elements Major elements

Aerodynamics; Propulsion; Controls; Mass; Structure; Systems ; AvionicsAerodynamics; Propulsion; Controls; Mass; Structure; Systems ; Avionics

1.1.Wing design Wing design - The wing design depends on many parameters such as selection of aspect - The wing design depends on many parameters such as selection of aspect ratio, taper ratio, sweepback angle, thickness ratio, section profile, washout and dihedral;ratio, taper ratio, sweepback angle, thickness ratio, section profile, washout and dihedral;2.2.Fuselage Fuselage - the part of the aircraft that contains the cockpit, passenger cabin or cargo hold; - - the part of the aircraft that contains the cockpit, passenger cabin or cargo hold; - ultimate safe loads, wing/engine integration, emergency configuration/equipment;ultimate safe loads, wing/engine integration, emergency configuration/equipment;3.3.PropulsionPropulsion - Maximum engine thrust available; fuel consumption; engine mass; engine - Maximum engine thrust available; fuel consumption; engine mass; engine geometry; single engine operation; effects on take-off and stalling speeds;geometry; single engine operation; effects on take-off and stalling speeds;4.4.WeightWeight

-weight of the aircraft is the common factor that links all aspects of aircraft design such weight of the aircraft is the common factor that links all aspects of aircraft design such as aerodynamics, structure, propulsion together. as aerodynamics, structure, propulsion together. - derived from various factors such as empty weight, payload, useful load, etc. derived from various factors such as empty weight, payload, useful load, etc. - the various weights are used to then calculate the centre of mass of the entire aircraft.the various weights are used to then calculate the centre of mass of the entire aircraft.- The centre of mass must fit within the established limits set by requirements;The centre of mass must fit within the established limits set by requirements;

5.5.StructureStructure - focuses not only on strength, but also on fatigue, fail-safety, corrosion, - focuses not only on strength, but also on fatigue, fail-safety, corrosion, maintainability and ease of manufacturing. Must be able to withstand the stresses caused by maintainability and ease of manufacturing. Must be able to withstand the stresses caused by cabin pressurization system (if fitted), turbulence and engine or rotor vibrations;cabin pressurization system (if fitted), turbulence and engine or rotor vibrations;6.6.Systems and AvionicsSystems and Avionics – general systems, communication and navigation systems. – general systems, communication and navigation systems.

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III Aircraft Design Procedures- Certification Specifications (airworthiness III Aircraft Design Procedures- Certification Specifications (airworthiness code & amc) code & amc)

Example: Example:

EASA - AMC-20 (General Acceptable Means of Compliance for Airworthiness EASA - AMC-20 (General Acceptable Means of Compliance for Airworthiness of Products, Parts and Appliancesof Products, Parts and Appliances

• Acceptable Means of Compliance (AMC) with design & other requirements;Acceptable Means of Compliance (AMC) with design & other requirements;• Based on – FAA (FARs), EASA (Certification Specification Based on – FAA (FARs), EASA (Certification Specification Documents – CS-23; CS – 25 ; CS – E; etcDocuments – CS-23; CS – 25 ; CS – E; etc• Basis of Aircraft Certification (and issue of Certificate of Airworthiness)Basis of Aircraft Certification (and issue of Certificate of Airworthiness)• Driver for Aircraft Maintenance Programme Driver for Aircraft Maintenance Programme

Examples:Examples:

- Structural : materials processes, strength, fatigue resistance;Structural : materials processes, strength, fatigue resistance;

- Systems: designed to comply with structural and mission Systems: designed to comply with structural and mission requirements;requirements;

- Performance: system performance must exceed the mission Performance: system performance must exceed the mission mandates;mandates;

- Environmental Protection Requirements (especially for EASA)Environmental Protection Requirements (especially for EASA)

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• A380 delayA380 delay - different French vs German wiring codes;- different French vs German wiring codes; - electric cables too short to connect across- electric cables too short to connect across fuselage sections;fuselage sections; - production and connection of new - production and connection of new - Production delayed for over 1 year + millions - Production delayed for over 1 year + millions lostlost

• B787 battery overheating (causing fire) B787 battery overheating (causing fire) problems (a/c grounded)problems (a/c grounded) - - - - - - - -

IV Problems (Airbus 380, Boeing 787, IV Problems (Airbus 380, Boeing 787, etc)etc)

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V ConclusionsV Conclusions

Design flaws mainly originate with:-Design flaws mainly originate with:-

1.1.Poor requirements capture (especially Poor requirements capture (especially failure to fully accommodate all stake-failure to fully accommodate all stake-holder concerns) holder concerns)

2.2. Inadequate system integration Inadequate system integration

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VI Discussion - Question and Answer Session VI Discussion - Question and Answer Session

1.1. What is the certification procedure ?What is the certification procedure ?2.2.3.3.4.4.5.5.