Barthélemy note: impact of a 5 cm front track variation on weight (vehicle L, March 1971)

In this document

This document is a printed technical sheet from the Société Anonyme André Citroën, bearing the handwritten title "VEHICULE L" and signed "BARTHELEMY Mars 71" p. 156.

I - Influence of a 0.05 m front track variation on weight

The note details, piece by piece, the calculation of the additional weight induced by a 5 cm widening of the front track. Each line follows a formula (dimension x thickness x density) resulting in a weight in kilos, for structural elements: front bumper, trim panel, hood, hood lining, axle crossmember, rack, rack housing, transmission, apron, dashboard, floor, body crossmembers, windshield and roof p. 156.

The "Structure" total (the word is uncertain in the transcription) reaches 3.930 kg.

A second calculation evaluates the weight of the associated trim (dashboard, roof, apron, floor), for a total of 0.250 kg.

The General TOTAL of this first part amounts to 4.180 kg.

II - Order of magnitude of the weight of a 0.150 m section in front of the front wheels

A second section quantifies, according to the same principle, the weight of a 15 cm section in front of the front wheels: hood and fenders, hood lining, hollow fender body, trim panel, front cradle side members, for a TOTAL of 6.150 kg p. 156.

The document also includes two line sketches (top view of the bodywork and plan view of the front of the vehicle) as well as an administrative box "VALABLE POUR / LANCÉ PAR NOTE N°" which remained without usable mention p. 156.

Context

The "vehicle L" evokes, in the internal Citroën nomenclature of the time, a project or a platform under development — the exact acronym cannot be specified without another source. This type of weight calculation note falls under the classic methods of automotive design offices of the 1960s-1970s, where each dimensional modification (here the front track) had to be translated into mass impact to anticipate its effects on dynamics and material costs.

Archivist's perspective

This document differs from Paul Magès' notes devoted to suspension or hydraulics: it is a classic mechanical costing work, probably produced by a design office collaborator (Barthélemy) rather than by Magès himself. It nevertheless illustrates the quantitative rigor that surrounded every geometric evolution of a vehicle at Citroën during this period.

Its interest for the Magès collection is probably documentary rather than inventive: it testifies to the technical environment and calculation methods in use within the design office at the beginning of the 1970s, in continuity with older work on suspension and structure architectures, as mentioned in Paul Magès' note on the AP suspension (22 February 1963).