Aircraft Familiarity, Aircraft Design Process, Market Study
2.6 Four Phases of Aircraft Design
k k
Aircraft Familiarity, Aircraft Design Process, Market Study 57
However, the aerospace market differs from the consumer market. There are limitations in applying the QFD/HOQ method in high-technology with very high investment and with low production volume of high cost aerospace products. The main customers in aerospace industries are the (airline) operators and general public feedback to manufacturing industries comes through operators. The (airline) operators have in-house engineers, some with design experience from industries and are knowledgeable about their requirements.
Aircraft manufacturers are in constant dialogue with the operators to explore what kind of new advanced technologies can be introduced to stay ahead of competition, these serving as the drivers to lay down the new aircraft specifications meeting the mission requirements, not overlooking public opinion. Here, the HOQ analyses may prove useful by the marketing department of aircraft manufacturers to incorporate some of the user requests. Military aircraft design office starts with the specifications laid by the MoD in their RFP. A technology demonstrator will refine the advanced technology to be incorporated in the new design.
The aircraft design office is supplied by the new aircraft project requirements/specifications. It is sug- gested that a mock survey in a classroom exercise may avoid HOQ analyses. Once specifications are finalised, the search is constrained with little scope for the aircraft design bureau to apply the QFD/HOQ tool. Each requirement is of importance in the competitive high investment endeavours, setting relative importance may be counterproductive in a fiercely competitive environment. Industry management may take an interest in QFD/HOQ, primarily aimed at production planning but the design office have their set procedure developed over time. It is for this reason that this book bypasses dealing with QFD/HOQ in new aircraft project design phases as described in Section 2.6. (Applying QFD/HOQ in aircraft design phases may have limitations but it is by no means a flawed system as the consumer market has shown uniform gains by adopting it. Readers are recommended to explore related publications in the public domain [27, 28].)
After the market demand and manufacturer’s capabilities are established, the new aircraft design starts to progress with the following considerations.
1. Candidates’ aircraft configurations are presented for management review to cater for the diverse range customer requirements that can be combined into a family of designs retaining component commonality as a cost reduction measure, each variant catering for the needs of the customer for their mission require- ments. The technology level to be adopted in all areas of the project has to be established, both for design and manufacture.
2. The most suited configuration from the candidates’ designs is taken up with a view towards obtaining the go-ahead for the project. After the go-ahead, it then goes through detailed analyses to ensure aircraft performance, handling criteria, structural and systems integrity complying with airworthiness standards.
A family of variant designs are also offered to cover the wider market at a lower cost.
3. Establish the human interface for both the crew and customer for ease of operation of the bought-out items offering best value for money as well as being low weight.
4. Management strategies to keep cost low and remain competitive. Efforts are made to make the product right first time at every stage of progress. Extensive risk analyses are made.
5. Establish the manufacturing philosophy and ensure quality.
6. Ensure maintainability, training, support for customers and disposal at the end of aircraft life.
k k configuration and performance capabilities at a credible accuracy level, sufficient to guarantee the
operators what to expect, to the management to decide to give a go-ahead or not. Naturally, budget allocation at this stage is kept low due to the uncertainty in advancing the project. This is the subject matter of this book.
Design analyses. This consists of two phases (Phases II and III) as described next.
i) Project Development Phase (Preliminary Design) – Phase II
This starts after go-ahead for the new aircraft project is obtained when management commits with extended budgetary provision to make detailed analyses. The project is now committed as a point of no return with an expectation of aninvestment return. This has two stages as follows. In this phase, the prediction of aircraft capability is fine-tuned to high accuracy with detailed computer-aided engineering (CAE) analyses and extensive aerodynamic, structure and system tests. Detailed structural design starts now (details in Sections 2.6 and 2.7).
ii) Detailed Design Phase (Full-Scale Product Development) – Phase III
In this phase, for civil aviation, the preproduction or prototype, and for combat aircraft scaled down tech- nology demonstrator building, is accelerated (details in Sections 2.6 and 2.7).
Certification/verification(Phase IV). This is the final phase to get preproduction fight tested and certified for operation (details in Sections 2.6 and 2.7).
Aircraft manufacturers conduct year-round exploratory work on research, design and technology develop- ment as well as market analysis to search for a product. A new project is formally initiated in the four phases shown in Chart 2.4, which is applicable for both civil and military projects.
Among organisations, the terminology of the phases varies. Chart 2.4 offers a typical, generic pattern pre- vailing in the industry. The differences among terminologies are trivial because the task breakdown covered in various phases is approximately the same. For example, some may see the market study, specifications and requirements as Phase I and the conceptual study as Phase II; others may define the project definition phase (Phase II) and detailed design phase (Phase III) as the preliminary design and full-scale development phases, respectively. Some prefer to invest early in the risk analysis in Phase I to get more information and delay go-ahead; however, the general trend is to make risk analyses in Phase II when the design is better defined, thereby saving the Phase I budgetary provisions in case the project fails to obtain the go-ahead. A military programme may require early risk analysis because it would be incorporating technologies not yet proven in operation. Some may define disposal of aircraft at the end as a design phase of a project.
Adhering to the general pattern, companies conduct the design phases as evolved over time and became ingrained to their practices. It is for this reason, the topic is not elaborated on any further. A new employee should be able to sense the pulse of organisational strategies and practices as soon joining a company.
Company management establishes a dedicated Design-Build-Team (DBT) to meet at regular intervals to conduct design reviews and make decisions on the best compromises through multidisciplinary analyses (MDA) and multidisciplinary optimisation (MDO), as shown in Chart 2.5; this is what is meant by an IPPD (i.e. concurrent engineering) environment.
The conceptual phase of aircraft design is now conducted using a multidisciplinary approach (i.e. concurrent engineering), which must include manufacturing engineering and an appreciation for the cost implications of early decisions in IPPD environment. As mentioned in Chapter 1, the chief designer’s role has changed fromtellingtolistening; he or she synthesises information and takes full command if and when differences of opinion arise. Margins of error have shrunk to the so-called zero tolerance so that tasks are done right the first time; the Six-Sigma approach is one management tool used to achieve this end.
2.6.1 Understanding Optimisation
Specialist areas may optimise design goals, but in an IPPD environment, compromise must be sought. It is emphasised frequently that optimisation of individual goals through separate design considerations may prove counterproductive and usually prevents the overall (i.e. global) optimisation of ownership cost. MDO offers
k k
Aircraft Familiarity, Aircraft Design Process, Market Study 59
Marked Study Project Indentification
INPUT
Decision ? (accept or not)
Yes Go Ahead refine
(iterate) No
abandone or
Phase 1 Conceptual Design Phase
Phase 2 Development Phase
Phase 3 Detailed Design Phase
Phase 4 Project Final Phase
No
Yes
Production, delivery, support till end of life Verification
(requirements met or not?)
Iterations
modify/refine (iterate)
Task 1: Project Definition
Task: Project Development
Task: Detailed parts design finished, parts fabrication, test completed, design review, customer dialogue, standards established, etc.
Task: Aircraft assembled, first flight and tests completed, compliance of standards, etc.
Aircraft sizing, engine matching, airworthiness, resource and budget appropriation, set manufacturing philosophy, weight, performance and DOC estimates, etc.
Task 2: Project Finalisation
Generate aircraft specifications from customer requirements, assess competition, set technology level,
Analyses and test, performance guarantees, structural layout and stressing, system architecture, risk analyses, jigs and tool design, equipment supplier and outsourcing partners selected, wind tunnel and ground tests, etc.
Chart 2.4 Four phases of the aircraft design and development process.
k k
Aerodynamics (CFD/wind tunnel tests) Optimise: maximise range,
other performance criteria Chapters: 3, 4, 6, 9, 11, 12, 13
Structures (FEM) Optimise: minimise weight ensure strength and safety Chapters: 4, 6, 8, 9, 16
Reliability and maintainability Optimise: minimise operating cost Chapters: 16
Systems (bought-out item) Optimise: minimise cost and weight Chapters: 7, 15
Production
Optimise: minimise production cost Chapters: 17
Verification (iteration) Final Aircraft Configuration Optimise: minimise DOC/LCC (global optimisation) Chapters: 3, 4, 6, 10, 15
Engine (bought-out item) Optimise: minimise fuel burn other criteria: noise, pollution Chapters: 10
Chart 2.5 Multidisciplinary analysis (MDA) and optimisation (MDO) flow chart.
good potential but it is not easy to obtain global optimisation; it is still evolving. In a way, global MDO involv- ing many variables is still an academic pursuit. Industries are in a position to use sophisticated algorithms in some proven areas. An example is reducing manufacturing costs by reshaping component geometry as a compromise – such as minimising complex component curvature. The compromises are evident in offering a family of variant aircraft because none of the individuals in the family is optimised, whereas together, they offer the best value. In other words the aim is to have a ‘satisfied’ rather than an ‘optimised’ design.
Industry is aware of the importance of optimisation but in the design practice, simple parametric optimisa- tion taking one variable at a time yields a satisfactory result. It is for this reason this book does not deal with any optimisation process unless it is supported by worked-out examples substantiated with existing designs.
2.6.2 Typical Resources Deployment
All phases do not work under uniform manpower loading; naturally, Phase I starts with light manpower during the conceptual study and reaches peak manpower (100%) at Phase III; it decreases again when flight testing starts, by then the design work is virtually done and support work continues.
Figure 2.5 is a typical distribution of cost and manpower loading (an average percentage is shown); the manpower loading forecast must be finalised during the Phase I study. The figure also shows the cumulative deployment. At the end of a project, it is expected that the actual figure should be close to the projected figure. Project costs consist primarily of salaries (most of the cost), bought-out items, and relatively smaller miscellaneous amounts (e.g. advertising, travel and logistics). Chain lines in Figure 2.5 illustrate the cost-frame outlay.
k k
Aircraft Familiarity, Aircraft Design Process, Market Study 61
go-ahead
manpower cost frame
customer support
customer support
Phasewise deployment Cumulative outlay
Start Phase 1 Phase 2 Phase 3 Phase 4 Start
100% manpower deployment Phase 1 Phase 2 Phase 3 Phase 4
Figure 2.5 Resource deployments (manpower and finance).
2.6.3 Typical Cost Frame
A crude development cost, up to certification (in the year 2015 in US Dollars), is shown in Table 2.1. Typical unit aircraft costs by class are also given (there is variation among companies). A substantial part of the budget is committed to Phase I.
2.6.4 Typical Time Frame
Typical time frames for the phases of different types of projects are shown in Chart 2.6. All figures are the approximate number of months. Exploratory work continues year-round to examine the viability of incorpo- rating new technologies and to push the boundaries of company capabilities – which is implied rather than explicit in Chart 2.6.
When an aircraft has been delivered to the operators (i.e. customers), a manufacturer is not free from obli- gation. Manufacturers continue to provide support with maintenance, design improvements and attention to operational queries until the end of an aircraft’s life. Modern designs are expected to last for three to four decades of operation. Manufacturers may even face litigation if customers find cause to sue. Compensation payments have crippled some well-known general aviation (GA) companies. Fortunately, the 1990s saw a relax- ation of litigation laws in GA for a certain period after a design is established, a manufacturer’s liabilities are reduced; this resulted in a revitalisation of the GA market. Military programmes involve support from ‘cradle to grave’.
This emphasises that the product must be done right the first time. Midcourse changes add unnecessary costs that could be detrimental to a project – a major change may not prove sustainable. Procedural method- ologies such as the Six-Sigma approach have been devised to ensure that changes are minimised.
Table 2.1 Development costs up to certification included (cost at 2015 prices).
Aircraft class (turbofan) Development cost (US$a)) Unit cost (US$* ) 6-passenger general aviation aircraft 7–12 million ≈±2 million 10-passenger business aircraft 25–40 million 5–10 million 50-passenger regional aircraft 60–100 million 25–30 million 150-passenger midsized aircraft 200–500 million 50–70 million 500+- passenger large aircraft 2–10 billion? 200–300 million Military combat aircraft (high end) 5–15 billion? 100+million?
a) Does not include production launch cost.
k k
Exploratory work round the year
Civil
Military
Phase 1
4 - 6 General
Aviation
Business Aircraft
Regional Aircraft
Mid-size Aircraft
Wide-body large aircraft
Advanced Jet Trainer
Combat Aircraft
Military aircraft projects have large variations.
If technology demonstrator time is included then it could take a decade.
Flight testing time would be about twice tha of large civil aircraft because of weapons and systems integration of many new technologies.
10 - 12
12 - 14
12 - 16 20 - 24 18 - 24
12 - 16
12 - 16 12 - 18
12 - 18
20 - 24
10 - 12
12 - 16 8 - 10
12 - 14 6 - 8
6 - 9
9 - 12
12
24
8 - 10
Phase 2
approximately 24 to 30 months after go-ahead
approximately 32 to 36 months after go-ahead
approximately 36 to 42 months after go-ahead
approximately 48 months after go-ahead
Airbus 380 took nearly 5 years
should complete in less than 54 months Phase 3
FIRST FLIGHT CERTIFICATION
GO AHEAD
Phase 4
Chart 2.6 Typical project time frame.