Aircraft Systems Integration
Week 1: system design (H11)
Goal: introduce some system descriptions and concepts, introduce design approaches.
What is a system
According to the dictionary:
- System – a set of connected things or parts forming a complex whole, in particular.
- A set of connected things or devices that operate together.
- Something which has been set up in a coherent or organized way.
- Purposely ordened set of items and subparts that belong together.
What are the recurring themes?
- Connected, operating together – various parts work together.
- Coherent or organized – some sort of organization can be identified.
Also: “An assembly of electronic, electrical or mechanical components with interdependent functions,
usually forming a self-contained unit.”
Systems are everywhere
Eco-system or solar system, national health service (ziekenfonds), building and construction industry,
integrated transportation systems (openbaar Vervoer), manufacturing systems, public utilities
(electricity, gas, water, telephony, internet, television).
Regulatory systems, air transport management (ATM), air traffic control (ATC), international aircraft
companies (IAE, Airbus), aircraft systems integration (landing gear on A380).
A380 landing gear
Airbus (UK) coordinates with:
- Messier-Bugattie-Dowty (NG)
- Goodrich (MLG)
- Honeywell (wheel & brake)
- Bridgestone (tyre)
- GE (hydraulics, valves)
Overview:
- Gears
- Extension/ retraction
- Braking control
- Steering control (NG & MLG)
- Wheels, brakes, tyres
- Monitoring systems
,Basic system form
Feedback is both a form of input and a means for a system to check and correct its own output.
Systems don’t drop out of the sky
Many of the large systems mentioned have evolved and have grown into their current form. For
example, regulations did not emerge until a clear need was identified:
- 1903: Wright Brothers
- 1919: Paris Convention
- 1944: Chicago Convention
- 1970: JAA
- 2003: EASA
As most examples have the classical properties of a system, they conform to the definition. When
creating new, complex systems, waiting until they have evolved is not always possible.
System levels
Level 1, system-of-systems level.
Level 2, system level: ATA level within aircraft.
Level 3, subsystem level: for example, hydraulic power generation or fuel indication.
Level 4, component level.
Level 5, part level
Level 1 up to and including
level 5 goes from complete
aircraft to parts.
The top level can be used
to describe the entire
aircraft. This has become a
system itself, consisting of
many different
(interconnected) systems.
Requirements on many
levels
As systems are no longer
independent of each other, each system creates dependencies and requirements that influence other
,systems. Both parent systems and various
systems on other levels impose requirements on
the (sub)system.
Subsystem design
With the model (see figure on the right), we
need to define the nature of the interfaces
across the boundary to effectively define the
subsystem itself. Standardized interfaces would be ideal! All these interfaces work both ways, creating
requirements for all connected systems.
Design approaches
Many design approaches are variations on a theme, with direct links to System Engineering. A system
engineering approach to design is shown in the figure below, which sees the whole process as a
lifecycle. In this cycle a product goes from a need, to a reality, to disposal. Utilization and disposal are
aspects which may need to be taken into account during design!
Figure 1: Design Process
System engineering
There are various definitions:
- “Systems Engineering is an interdisciplinary approach and means to enable the realization of
successful systems. It focuses on defining customer needs and required functionality early in
the development cycle...” (INCOSE)
- “Systems Engineering involves design and management of a total system which includes
hardware and software, as well as other system life-cycle elements.” (US DoD)
- “A robust approach to design, creation and operation of systems...” (NASA)
Clearly defining needs, required functionality and thus requirements is a key element of any design
approach. The integration of both hardware and software is just one example of the overall
integration that is present in aerospace, this needs to be addressed in the development process.
System engineering and design
As shown the design process
features three steps:
1. Conceptual
2. Preliminary
3. Detail
The feedback loop shown here is used to verify the design against the requirements after each step.
System engineering vs design process
Generally, the same phases are present:
1. Conceptual
2. Preliminary
3. Detail
, This process can be carried out on a subsystem or component, or on a higher system level. When used
on a system (or higher) level we generally talk about ‘system engineering’, on lower levels it is a
general engineering process.
Phase I: orientation → Phase II: analysis → Phase III: design → Phase IV: detail design → Phase V:
realization.
Phase I and II (phase 1. Conceptual), Phase III (Phase 2. Preliminary), Phase IV (Phase 3. Detail).
Design process on a complete project
As the project matures the focus shifts more to
conventional engineering practices. The first
steps in the project are research and studies to
create the high-level system architecture and
specifications.
Level 1 – 3: systems and subsystems.
Conceptual design
The first phase is used to create high level
(level 1, 2 then 3) layouts. Various steps are
used to verify whether the best option has
been chosen. This relates to Phases I to III
from the design process.
Royal academy of engineering V-diagram
System development process