Colombo he had the drawings with him and an agreement was quickly reached. There was no shortage of controversy in the press for this choice, but Columbus, on more than one occasion, was able to say that this was not the first option, they had arrived there due to the various difficulties that had been raised internally for a possible construction in headquarters. From the theoretical point of view, the monocoque, i.e. the shell construction according to an aeronautical terminology, is in clear advantage compared to the tubular trellis because it arranges the resistant material in the most peripheral position possible (skin). However, it is essential to guarantee the stability of the shapes in order to be able to exploit the maximum stresses allowed by the material. In aeronautics shell constructions took over with metal constructions. For the stability of the shapes of the fuselages, light reinforcements were immediately used, both longitudinal, called currents, and transversal, called frames; for concentrated loads, reinforced frames were used. In F1 a similar approach was followed, but considering the small dimensions and the often rounded shapes, the currents had a minimal diffusion, while the frames were used to stiffen, connect the lateral tubular structures and distribute the concentrated loads. In Ferrari, the tubular steel frames had never been completely abandoned: they had been heavily lightened (sections and thicknesses) because they were reinforced with riveted light alloy sheets. The greatest contribution to the rigidity was provided by the sheets, the rest by the underlying tubes which also stabilized the shapes, the riveting was tear-off. A technique called semi-monocoque, which ensured greater simplicity in construction and maintenance, paying (at least theoretically) a slight loss of torsional stiffness for the same weight. The regulation of the72 and then of ’73, forcing the use of metal sheets with a minimum thickness of 1.5mm, protective sandwiches and more, facilitated shape stability. The group led by Colombo believed that the right moment to give up the series of tubes in the central part and therefore launched the project of the monocoque. Let’s see it in detail. Just to facilitate the construction as much as possible, he had a simple design: the 2 lateral tubular structures were parallel, with a rectangular cross section with rounded corners, with a marked bevel to widen the passenger compartment; the tapering towards the front was related only to the height of the sections. The sheets used were in light alloy, whose trade name is Avional. The interior of these structures were designed to contain the 4 tanks safety bag with rubber bag. Perhaps due to the choice not to place a fifth central tank behind the driver and still remain contained in height, it was decided for a body width around the 900-950mm (estimated), not a little even if the tendency to enlargement was widespread. To reach the maximum stiffness, the 2 tubular structures were widely connected: naturally from the bottom, by a central box structure that supported the steering wheel, by a cover plate for the pedal unit and by 2 head frames, only these in steel to cope with concentrated loads.
The front frame was developed on 2 levels with the central one more protruding to accommodate the pedal, the rear one on a level, both built by shaping and bending sheets to obtain open shapes and leave room for riveting by beating (the technique used in aeronautics) . Front the structure was complete from 2 mergers, one on each side, which in addition to acting as a second support for the rocker arm pin, supported the steering box, the anti-roll bar, the lower connection of the spring-shock absorber and the rear joint of the triangle. Definitely interesting, so much so that this idea of multifunctional parts made in fusion, to be inserted into the frame, removable or not, was also adopted later, until the advent of carbon. A small trellis made of small steel tubes, which can be dismantled, completed the front structure and acted as a support both for the front joints of the suspension traiangles and for the nose. Behind the trim closed the bodyshell, and had the engine attachment points, mounted with carrier function. The flat engine did not facilitate this type of assembly, so 2 interconnection castings were made with the aim of spacing the fixing points in height. The (double) bracing of the rollbar had been designed to increase overall rigidity. The flat carrier engine was not really new in Ferrari, they had a similar scheme already made on 158 from ’64, perhaps first in F1.
In this project it is evident great attention to detail, both in the conception and implementation phase. One example is the arrangement of the motor attachment points. There were 6, so 3 for each merger, and placed at the vertices of a triangle. This arrangement involved a greater stress for the single upper point: by choosing to align it and connect it with the reinforcements for fixing the front bracing of the rollbar, it was not necessary to add anything else. Observing the rear frame, it can be seen that the central band of the monocoque was lower, this to obtain perfect coplanarity with the side protections (10mm thick) which also extended to the bottom. It is also noted that the side is flat with no constrictions to increase the space for the side radiators. A choice made to simplify the construction phase but limiting the cooling system, we’ll talk about it again. Moving on to suspensions, remained in line with the schemes used in Ferrari in that period. Front, upper rocker and lower triangle with a wide base. The rocker arm is remarkable for its shape and finish: made with thin, shaped and welded steel sheets, it had an original “fork” at the point of attachment to the spring-shock absorber group; a system to increase the suspension travel. Behind, lower trapezoid with a wide base bound to the transmission box and with an adjustable side to intervene on the convergence; above, connecting rod with reaction strut-tie connected to the base of the rollbar (type Tyrrell 002) which in turn is fixed on the engine-frame interconnection castings. The intent was of course to exploit attachment points with maximum rigidity. For this car a 2500mm pitch, long compared to the usual Ferrari which had been around 2400mm for years. The tendency to lengthen the pace was starting to spread, even if marked differences remained: in ’73 Stewart won the World Championship with the Tyrrell 005-6 which had a wheelbase of 2386 mm while in ’74 Fittipaldi won it with the McLaren M23 he had a wheelbase of 2642 mm.
templateStk #: B3, anno: 1973;
chassis numbers: 010, 011, 012;
designers: Sandro Colombo, Giorgio Ferrari, Giacomo Caliri and Franco Rocchi;
frame type: light alloy monocoque, Avional®, with supporting engine;
tanks: 4 rubber containers, capacity about 230-240 L.;
suspension ant.: final quadrilateral, balance wheel and spring-amm .;
suspension post.: Quad. def., upper link strut, trapezoid and spring-amm. on the diag;
uprights: light alloy castings, ant. with fixed hub;
circles: magnesium alloy, ant. and post. 13 ″;
brakes: ventilated discs and Lockheed calipers;
step: 2500 mm; carreggiata ant.: 1625 mm; carr. post.: 1605 mm ;
tires: GoodYear 9.2/20.0-13″, 14.0/26.0-13″;
car body: glass fiber composite;
total mass: 578 Kg, (575 kg. Min.r.);
engine: Ferrari; type: 01/11; year: 1973;
displacement: 2991.8 cc; number c. : 12 at 180 °; bore x stroke: 80mm x 49.6mm;
Compression ratio: 11,5:1 ;
power: 485 cv a 12500 R.P.M.;
distribution: 4 valves for c. with double overhead camshaft, gear cascade;
basement: light alloy, wet rods with Nikasil coating; 4 bench supports;
lubrication: dry sump;
supply: Lucas indirect mechanical injection;
power on: Magneti Marelli electronic Dinoplex, 1 spark plug per cylinder.
During the Colombo management, that is, for the first 5 GPs of the season, neither the chassis nor the suspensions were modified. It was in the subsequent management of Forghieri that targeted changes were made especially with a view to ’74. None of the 3 original frames were left in the initial configuration, which is also the reason for the scarce photographic documentation available. In the next episode we will deepen the aerodynamic look with a mention also to the sporting results.
Historic F1 technique: Ferrari 312 B3 (1973) – First part