Four short months separate each Formula One season, a tour that takes this year's 14 teams to Grand Prix events on five continents. At peak season-the European "summer campaign"-a mere two weeks separates individual events. It's said that Formula One drivers race against each other, but F-1 engineers race against the clock.
George Ryton, chief designer with the Tyrrell Racing Organization, agrees: "Between some Grand Prix stops, we literally have to re-draw parts of the car, manufacture the modifications, and have the car up and racing in less than a fortnight." To help him do this, Tyrrell uses AutoCAD Release 12 from Autodesk, a supplier it first used in 1990. The drawing office, Ryton says, was completely converted to CAD operation within a year of introduction. Now there are eight seats used for every aspect of the car's design, except the engine.
While Ryton's team works primarily in 2D, he claims solid modeling in 3D is also critical. Variations to the fuel tank, for example, can be evaluated for mass and center of gravity. "The gradual emptying of the tank as fuel is used during the course of a race," he points out, "can significantly change the car's handling. A different shape can mitigate these effects, but the optimum shape and size only can be discovered through the rapid processing of alternative designs with CAD."
Similarly, Jordan Grand Prix uses Hewlett-Packard's Precision Engineering/ME10 for 2D design. The company's Solid Designer, based on object-oriented solid modeling technology, handles 3D tasks. Such tools not only enable team engineers to turn around new or modified designs during the period between championship races, but they speed complete redesign during the off season.
Robert Stubbings, a design engineer with Jordan, cites this year's Jordan-Hart 195, which has much in common with its predecessor, the Jordan-Hart 194. All data from the 194 was accessible at the touch of a button when design commenced last fall on the new car. "Rather than redrawing one sketch after another," Stubbings notes, "we now have a much more structured approach to the individual design."
Integrated manufacturing. Williams Grand Prix first started with CAD ten years ago, but only recently adapted a fully integrated package of computer-aided engineering. Chris Wheatley, Williams R&D engineering manager, claims this approach greatly facilitates the fabrication of body parts from composite materials.
Engineering starts with Autodesk's AutoCAD products, supplied by CADlogic Ltd., to convert the design concept into a computer model of the part. This model runs on a computerized fluid dynamics (CFD) package where a whole range of parameters can be specified, including flow patterns, speed, angle of attack, air temperature, and surface roughness.
Structural details, such as material thickness and weight, are added using finite element analysis (FEA). Optimization routines determine the most suitable combination of shape and material, with data directly downloaded to CNC manufacturing centers. Tool instructions based on the model create molds for the composite parts, while the software generates a net of prepreg patterns on a Misomex plotter/cutter programmed for depth of cut.
These shapes are then cut, laid up, and cured in an autoclave before moving to the assembly shop; master software specifies prepreg angles of orientation. Wheatley says Williams uses about 10 different types of prepreg. "Effectiveness of the nesting designs for cutting the prepreg is so high," he adds, "that scrap is now history. All we have left are bits of "spaghetti' and tiny corners."
In this fashion, Williams can complete a part from design to final inspection without a single drawing. The entire process takes about six days.
Adding analysis. In Formula One racing, the use of aluminum honeycomb structures and materials, such as carbon and DuPont's "Kevlar," are now commonplace. Composites cut total weight 20 to 25%, while improving aerodynamics and body stiffness. Energy absorbing nose modules for frontal impact protection, and body shell survival modules-developed from molded composite parts-help shield the driver.
To get the most from its composite structures, team Ligier uses COMPOSIC(R), a composite structure analysis tool from Framasoft + CSI. Applied to a car's body shell, the software lets Ligier's design team perform such analysis functions as:
Static push tests on the sides and shell undersurface, and on the integrated roll-over bar.
Crash tests representing a frontal shock at an impact speed of 11 m/sec, after which the shell must not show any trace of damage.
Part behaviour predictions, ranging from aerodynamic fairings to the gearbox to components in the front or rear axle assembly.
Composite materials, says Christophe Sauvan, analysis engineer at Ligier, are particularly demanding of structure optimization tools. Parameters, such as ply thickness, fiber type, ply angle, reinforcement material, and the number of layers-combined with a multitude of model variables-present F-1 design teams with an almost infinite variety of possible combinations for achieving a wide range of mechanical properties.
These considerations must also be weighed against cost and response time. "The Formula One scene," Sauvan explains, "is in a state of constant evolution, where delivery dates-whether for design, testing or manufacture-must be reduced to the minimum. COMPOSIC helps us achieve test cost savings and manufacturing cost economics by lowering the number of tests, and by optimizing the utilization of materials. In certain cases, simulation enables us to select cheaper, less-sophisticated materials, but ultimately attain better performance."
As an example, Sauvan cites the team's cockpit and rear fin support plate. By optimizing the direction of plys, Ligier can incorporate a less-rigid, less-expensive material, without sacrificing strength.
Concurrent synergy. Critical to maintaining the demanding product cycles of F-1 racing is the ability to work concurrently, both in-house and with suppliers. Last year's campaign by the McLaren team provides a good example. With a new engine configuration, and the 1994 rule changes facing them, the team turned to Computervision's CADDS 5 software to make the January deadline.
"We had confirmation in early October that we would be competing for the 1994 championship with a new Peugeot V10 engine," explains Chief Designer Neil Oatley. Because McLaren designed the car concurrently with the engine, which was developed in France, the team met its timetable. Peugeot transmitted its CADDS data electronically as the engine was built, allowing the McLaren team to incorporate the new data simultaneously into the models.
"This particular engine had an integrated heat exchanger in the "V' to cool the oil, which demands a new cooling system to be designed around it," says Oatley. "Laying out that system impacts on other components, so there's a constant knock-on effect."
Making space for the new cooling system involved altering the rear of the carbon-fiber monocoque, whose complex 3D surfaces would be next to impossible to alter by hand. Changes to the model, however, were simply transferred by modem for machining by McLaren's subcontractors. The monocoque tooling, moreover, is machined from a solid tooling block, which would again be impossible without CAD input.
As for the 1994 regulation changes, Oatley points out the rule that allows refueling during the race, which stipulated a minimum fuel-tank limit of 200 liters. The smaller size left more room for cooling system ducting and other components. Again, McLaren used CV's CADDS Physical Properties package to work out the volumes for the new tank's fuel capacity, and NURBS surface design and solid modeling to create the new component and CVNC manufacture it.
During the Formula One season, one race may end when the last car crosses the finish line, but another is just beginning: the race against the clock. Without the help of CAD, CAM and CAE, a team may as well go home.
|1995 FORMULA ONE STATS|
|1) BENNETON FORMULA LTD.||RENAULT RS7 V10 EDS||UNIGRAPHICS|
|2) FERRARI S.P.A.||FERRARI V12||CATIA|
|3) ARROWS GRAND PRIX INTERNATIONAL LTD.||HART V8||CATIA|
|4) McLAREN INTERNATIONAL LTD.||MERCEDES ILMOR F0 110||COMPUTERVISION|
|5) LARROUSSE SA||FORD ED||NA|
|6) LIGIER SPORTS MUGEN||HONDA V10||COMPUTERVISION|
|7) MINARDI TEAM S.P.A.||FORD ED V8||CIMATRON|
|8) JORDAN GRAND PRIX LTD.||PEUGEOT V10 A10/E||HEWLETT PACKARD|
|9) TYRRELL RACING
|YAMAHA OX 10 C V10||AUTODESK|
|10) PP SAUBER AG||FORD ZETEC R 95 V8||CATIA|
|11) WILLIAMS GRAND PRIX ENGINEERING LTD.||RENAULT RS 7 V10||AUTODESK|
|12) SIMTEK GRAND PRIX LTD.||FORD ED||COMPUTERVISION|
|13) PACIFIC GRAND PRIX LTD.||FORD ED V8||HEWLETT PACKARD|
|14) FORTI CORSE S.R.L.||FORD ED V8||NA|
Rule changes drive design
Federation Internationale de Sport Automobile (FISA) is the organization controlling Formula One racing. Here are the rule changes it promulgated for 1995:
Banning of electronic and computer-aided hydraulic systems so that drivers have to exercise greater vehicle control.
Revisions of aerodynamic rules so that the ride height is increased with a stepped longitudinal underbody and a 50% reduction in diffuser length that dramatically changes the down pressure at the rear of the car.
Engine size limited to 3 liters, normally aspirated (no turbocharger).
Increase in minimum weight and a side impact test.
Further reductions in front and rear wing size over those introduced in mid-1994.
"These changes are probably the most comprehensive since the move from ground-effect cars to flat bottoms in 1983," says Alan Jenkins, technical director of the Arrows Grand Prix team. "The individual elements of the regulations are themselves not especially difficult," Jenkins points out. "The problem is the amount of design effort required, with the changes affecting almost every area of the car."