dc.description.abstract |
As all engineering works are a blend of theory and
empiricism, aircraft design, by its nature, represents a
mixture of aircraft designer's knowledge obtained from
aeronautical engineering disciplines and its usage
combined with his experience. This means not only the
application but also the integration of all the
fundamental knowledge of aerodynamics, structure,
propulsion, stability and control, operational and
economic aspects, etc., based upon the designer's
judgements and experiences.
Thus the tasks involved in designing an aircraft
configuration, without exception, show complex
characteristics, considering the fact that aircraft
configuration design means the integration of components
such as lifting surfaces ( wing ), fuselage, power-plant,
control surfaces ( tail or canard ), and undercarriage.
The discrepancies and mismatches among the aircraft
components make the configuration design iterative,
repetitive, and thus time - consuming. Such complexities
of configuration design processes often require
compromise, through trial and error, to resolve conflicts
between the major design areas.
Moreover, it takes tens of years to become a
experienced design expert whose sound judgement, based
upon experience and profound knowledge, influences
greatly the aircraft configuration design. The
differences in judgements depend upon the designers'
imagination and experience, and they are the cause of
variations in aircraft configurations.
Therefore, the efforts were made to overcome those
difficulties which hinder the aircraft designer from
making the task of configuration design more efficient,
and further to assist the aircraft designer in getting an
easy and interactive preliminary aircraft configuration
without always relying upon design experts. Hence the
current research project is directed at the development
of an expert system for aircraft design. This involves
the use of Artificial Intelligence and its programming
language called PROLOG ( PROgramming in LOGic ).
The research started from a thorough analysis of the
major component design areas and has constructed an
EXPERT SYSTEM to find out the efficient Control Mechanism which can search intensively for the solutions to design
problems for all types of aircraft; civil and military,
subsonic and supersonic, conventional and unconventional,
etc. In addition, users can have access to the
explanations of important items such as a design process,
terminology, equations, and results. The explanation
facility is one of the most important functions of
Expert Systems.
Partly due to the limit of computer capacity and partly
due to the magnitude of laborious program execution at
this stage, the system implementation has focused on
the high - subsonic, conventional and jet transport
aircraft categories. The approach taken was to find an
efficient and effective control mechanism ( i. e. an
Inference Engine ), which integrated the PARAMETRIC
STUDY, WING DESIGN, FUSELAGE DESIGN, ENGINE DESIGN, TAIL
DESIGN, UNDERCARRIAGE DESIGN, WEIGHT ANALYSIS AND COST
ANALYSIS into a whole configuration system.
The comparison between Expert System results and
existing aircraft such as Boeing 747, Airbus 300 series,
BAe 146 series, McDonnell Douglas MD series, etc., showed
the permissible ranges of error to be within about 10 %.
Such results enable the Expert System to claim that it
can act as a useful design tool for the aircraft designer
in the initial stage of aircraft configuration design.
Finally, the author believes that the control mechanism
devised for this Expert System can be used as a sound
basis for extending the Expert System to include other
types of aircraft and further to encompass spacecraft
design, as the designer wishes. |
en_UK |