For the S1 to achieve these often conflicting goals, The Invicta Car Company has adopted several innovative approaches in both the design and construction phases of manufacturing its first car in modern times. The overall appearance and the engineering layout of the S1 are the collaborative results of a three-way think-tank between Invicta Chairman Michael Bristow, project manager Chris Marsh and consultant designer Leigh Adams.
Design & Construction
The Invicta S1 is the world’s first car to feature a one-piece carbon-fibre bodyshell. This shell, when bonded to the steel tube spaceframe chassis, creates an immensely strong, but lightweight, structure and results in a car with high flexional and torsional rigidity (for responsive handling) and excellent impact resistance (for high levels of occupant safety).
Crucial to the successful building of the one-piece bodyshell was the decision to manufacture much of it in a new carbon fibre material from the Advanced Composites Group, called ZPREG. This revolutionary material weighs just 30% of the equivalent steel panel and is much faster and easier to work with than conventional carbon fibre. It also gives an ‘A Class’ surface to accept a top-quality paint finish, makes use of composite tooling which can be produced in under 12 weeks, and does not require the use of an autoclave or the high laminator skills typical of previous carbon fibre manufacturing in the motorsport and aerospace industries.
The spaceframe chassis is more conventional and incorporates all the ‘best practice’ features of this well established construction method. It weighs 160 kilos, but all of that weight is low down, below the car’s roll centre. Made from 2mm thick steel formed into 40mm square tubes and cross-braced for maximum strength, the chassis construction uses TIG welding to give a smooth surface in the areas that are bonded to the bodyshell.
Safety & Styling
The Invicta S1 spaceframe chassis is believed to be the strongest ever tested by UK car safety officials. The carbon composite semi-monocoque construction of the S1 bonds carbon fibre floor panels above and beneath the steel tube frame and also incorporates many safety features including: side-impact bars, rear-impact beam, seats positioned within the steel frame chassis, a full roll-over safety cage and Kevlar reinforcement of the doors, front and rear bumpers and windscreen surround.
Invicta wanted the S1’s appearance to reflect its commitment to building a no-compromise sportscar in which performance and handling take priority, but practicality and comfort are not forgotten. Engineering decisions, about dimensions, engine location and weight distribution came first and body styling followed. Designer Leigh Adams and his Automotive Design & Prototyping (ADP) studio say they regard the Invicta S1 as "an excellent opportunity to use the ‘timeless classic’ bold proportions of a high body-side and a sleek glass area, so appreciated by autophiles and designers since the lowered-roof cars of the 1950s."
continues | Part Two