Lightweight Electric/Hybrid Vehicle Design

Introduction xiii
reached the customer, which may have led engineers to be less conscious of the weight/performance
trade-off in detail design. Individual parts could well be specified on the basis of subjective
judgement, without the sobering discipline of the above trade-off analysis.
Not so, of course, for the early aeronautical design engineers whose prototypes either ‘flew or
fell out of the sky’. Aircraft structural designers effectively pioneered techniques of thin-walled
structural analysis to try to predict as far as possible the structural performance of parts ‘before
they left the drawing board’, and in so doing usually economized on any surplus mass. These
structural analysis techniques gave early warning of buckling collapse and provided a means of
idealization that allowed load paths to be traced. In the dramatic weight reduction programmes
called for by the ‘supercar’ design requirements, to be discussed in Chapters 4 and 6, these attitudes
to design could again have great value.
Design calculations, using techniques for tracing loads and determining deflections and stresses
in structures, many of which derive from pioneering aeronautical structural techniques, are also
recommended for giving design engineers a ‘feel’ for the structures at the concept stage. The
design engineer can thus make crucial styling and packaging decisions without the risk of weakening
the structure or causing undue weight gain. While familiar to civil and aeronautical engineering
graduates these ‘theory of structures’ techniques are usually absent from courses in mechanical
and electrical engineering, which may be confined to the ‘mechanics of solids’ in their structures
teaching. For students undertaking design courses, or projects, within their engineering degree
studies, these days the norm rather than the exception, the timing of the book’s publication is
within the useful period of intense decision making throughout the EV industry. It is thus valuable
in focusing on the very broad range of other factors–economic, ergonomic, aesthetic and even
political–which have to be examined alongside the engineering science ones, during the conceptual
period of engineering design.
0.2.1 FARTHER-REACHING FACTORS OF ‘TOTAL DESIGN’
Since the electric vehicle has thus far, in marketing terms, been ‘driven’ by the state rather than
the motoring public it behoves the stylist and product planner to shift the emphasis towards the
consumer and show the potential owner the appeal of the vehicle. Some vehicle owners are also
environmentalists, not because the two go together, but because car ownership is so wide that the
non-driving ‘idealist’ is a rarity. The vast majority of people voting for local and national
governments to enact antipollution regulation are vehicle owners and those who suffer urban
traffic jams, either as pedestrians or motorists, and are swinging towards increased pollution control.
The only publicized group who are against pollution control seem to be those industrialists who
have tried to thwart the enactment of antipollution codes agreed at the international 1992 Earth
Summit, fearful of their manufacturing costs rising and loss of international competitiveness.
Several governments at the Summit agreed to hold 1990 levels of CO 2 emissions by the year 2000
and so might still have to reduce emission of that gas by 35% to stabilize output if car numbers and
traffic density increase as predicted.
Electric vehicles have appeal in urban situations where governments are prepared to help cover
the cost premium over conventional vehicles. EVs have an appeal in traffic jams, even, as their
motors need not run while the vehicles are stationary, the occupant enjoying less noise pollution,
as well as the freedom from choking on exhaust fumes. There is lower noise too during vehicle
cruising and acceleration, which is becoming increasingly desired by motorists, as confirmed by
the considerable sums of money being invested by makers of conventional vehicles to raise
‘refinement’ levels. In the 1960s, despite the public appeals made by Ralph Nader and his supporters,
car safety would not sell. As traffic densities and potential maximum speed levels have increased