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SPECIAL

Ford Territory

SPECIAL

Ford Territory

Australian International Motor Show: Ford GT Showcases Passion, Innovation and New Technologies

Staff, Thursday October 7, 2004.

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By May 2002, Coletti had assembled the best engineers at Ford Motor Company ? dubbed the ?Dream Team.? In conjunction with many key suppliers, the Ford GT engineering team used unique technologies and processes to bring the car to market in record-breaking time.

The team applied computer-modelling techniques to prove out chassis and body development. Even initial crash testing was performed using computers to help better predict actual crash tests and shorten the development timeframe. These intensive computer studies ultimately cut the team?s physical prototype requirements by 90 percent, helping compress the typical four-year development program into less than two.

?Engineers generally want to prove out computer models with physical prototypes,? Coletti said.

?Instead, we relied on advanced engineering and computer tools to cut prototype builds and save time and money. The advanced technology that is driving the Ford GT program today could very well be the industry standard for future vehicle programs.?

The Ford GT team also looked at new ways to do business internally and with suppliers. Ford engineers and key suppliers are all co-located in one building. This office structure encourages ad-hoc meetings to resolve issues immediately. Meanwhile, mechanics build prototype models in an adjacent garage, allowing another point of instant collaboration.

The Fast Track

Since official program approval in May 2002, the Ford GT has been on the fast track for product development timing. The build process of the first three production cars kicked off on March 10, 2003. Internally, these vehicles are known as ?Jobs One, Two and Three,? referring to Ford?s term for the beginning of vehicle production, ?Job One.?

Regular production of the Ford GT began in the second quarter of 2004.

?Developing the Ford GT from approval to driveable production models in less than a year was quite a challenge,? said Neil Hannemann, Ford GT Chief Program Engineer.

?But these three cars serve as a testament to the passion and expertise of Ford engineering.?

Stiff Aluminium Space Frame

Usually a new vehicle is designed from the inside out, meaning that the chassis and suspension points are set before the exterior body is designed around those dimensions. The exact opposite is true of the Ford GT. To preserve the design of the Ford GT40 concept car shown at the 2002 North American International Auto Show, the Ford GT engineering team did most of its work ?under the skin?.

?The first step in creating a world-class supercar is creating a stiff structure,? said Huibert Mees, Chassis Supervisor on the Ford GT program.

Mees set contradictory targets for the chassis: extremely high torsional stiffness for unparalleled body control, yet efficient use of materials so as to create a lightweight chassis that could reach performance and handling targets.

The team developed an all-aluminium space frame, comprising 35 extrusions, seven complex castings, two semi-solid formed castings and various stamped aluminium panels. The structure has two unique features: a large centre tunnel to house the mid-mounted fuel tank and cut-out roof sections for the cantilevered doors.

?Using CAD/CAM and finite-element analysis, we were able to design and test several iterations of the fuel tunnel and roof structure. That process enabled us to add significant stiffness to the overall structure,? Mees said.

Another contributor to chassis rigidity is the automotive industry's first application of friction-stir welding, used to construct the multi-piece central aluminium tunnel (housing the fuel tank). With this technique, a tool rotating at 10,000 rpm applies pressure to a seam and actually blends the metal there, forming a smooth consistent seam.

Compared to automated MIG welding, friction-stir welding improves the dimensional accuracy of the assembly and produces a 30 per cent increase in joint strength. The technique effectively isolates the fuel tank from the passenger compartment, as the seam is continuous. A patent application is pending on this new friction-stir welding process.

Once the structure of the hybrid-aluminium design was approved, Mees' team addressed each component to maximise strength and minimise weight. As a result, larger extrusions such as the primary frame rails have a different thickness on each wall. Portholes or windows in the complex castings, which support the suspension and powertrain, decrease unnecessary mass. Even the small castings that join the A-pillars to the roof have been fine-tuned for utmost rigidity and lightness.

?In our tests, the Ford GT chassis is stiffer and more rigid than the current competitive set. Indeed, we predict it will be better than upcoming competitors as well,? Mees said.

Extensive use of computer-aided crash modelling during the design phase helped the Ford GT program team cut cost and time in the early stages of development. The crash analyses were used to predict the forces generated during impacts and the resulting shapes of the crushed structures, without the costly and time-consuming destruction of hand-built prototypes.

As a result of these analyses, the front and rear bumpers are connected to the frame via extruded aluminium ?crush rails? that accordion during impact. These rails are designed to absorb most of the damage during low-speed impacts and are bolted to the frame for easy removal and replacement.

Fuel system

Crash modelling also verified that the centre tunnel is the preferred location for the Ford GT fuel tank because it helps reduce risks, most notably in collisions. As an added benefit, the location keeps overall weight distribution and the centre of gravity relatively consistent at differing fuel levels.

The ?ship-in-a-bottle? design of the fuel tank is an industry first. The mechanical components, including the fuel pumps, level sensors and vapor control valves, are first mounted on a steel rail. Then the single-piece tank is blow-moulded around the rail. This method maximises fuel volume and reduces the number of connections to the fuel system.

In another industry first, the Ford GT features a capless fuel filler neck under an aluminium cover. The aperture automatically opens as the fuel nozzle is inserted and seals the fuel system when the nozzle is removed.

High-tech Body

Most aluminium space frame vehicles use nut inserts paired with shims or washers to tailor the fitment of each body panel. However, the Ford GT team developed a novel new method, called a ?plus-nut,? to efficiently join the body and frame, as well as to locate the body panels in the proper position relative to the space frame.

These fasteners are essentially aluminium nut inserts, with additional machining stock on the mating surface. While machining the suspension and engine mounts, Computer Numeric Controlled (CNC) milling accurately trims each aluminium plus-nut for precise body positioning. The patent-pending fasteners eliminate the need for shimming the body, reducing assembly costs and improving panel fit.

The aluminium body panels themselves are also quite advanced, as they've been manufactured using super-plastic forming (SPF).

?Super-plastic forming is fairly new for the industry,? said Bill Clarke, Ford GT Body Structure Supervisor.

?It was a critical factor in producing the large sections, complex shapes and delicate accent lines of the concept vehicle. Large, intricate panels like the cantilevered doors simply would not have been feasible with traditional stampings.?

Rather than using a matched metal die to stamp the body panels, super-plastic forming works by heating an aluminium panel to temperatures approaching 500 degrees Celsius, then using high-pressure air to plastically form the aluminium panel over a single-sided die. This process produces complex shapes not possible with conventional stamping and reduces tooling costs, as only a single-sided die is required.

According to Clarke, the super-plastic forming also reduced production complexity.

?As an example, with super-plastic forming we were able to make the exterior of the rear clamshell in one piece. The same panel with traditional manufacturing would require five or six separate stampings joined together on the assembly line,? Clarke said.

The rear clamshell engine cover also represents another industry first. It features an aluminium shell hemmed to a carbon-fibre inner panel. The carbon-fibre piece is lightweight and extremely rigid, which helps stabilise the clamshell. In addition, the inner panel houses an air duct into the engine air box, from the exterior intake just below the C-pillar.

Aerodynamic Development

Like the concept car, every air intake and heat extractor on the production Ford GT is functional. According to Kent Harrison, Ford GT Performance Development Supervisor, preliminary wind-tunnel testing showed the concept car had remarkably good internal air flow.

?We first tested a fibreglass replica of the concept car in the wind tunnel and because the design was so close to that of the Ford GT race cars, the intakes and diffusers were all in the right place. We only needed minor changes to improve air flow through the car,? Harrison said.

The heat extractors in the front cowl were modified to pull more heat from the front-mounted radiators. The side intakes under the B-pillar were slightly enlarged, driving more cooling air into the engine bay and transmission cooler. Finally, an additional set of vents were added on either side of the rear glass to help diffuse heat from the engine compartment.

However, improving the aerodynamic stability was not such an easy task. The team also tested an original Ford GT race car, both in the wind tunnel and with computer simulations, to measure drag, lift, and downforce. To their surprise, the original car exhibited very high frontal lift at speed.

?The whole team had an even greater respect for the drivers who took the original car down the Mulsanne Straight at over 200 mph ? at night ? in the rain,? Harrison said.

?Because the new design and the original design were similar, the new aero model exhibited similar lift. We had to do something to generate more downforce.?

To preserve the design of the concept car, Harrison had to concentrate on the underside of the vehicle. His team added a front splitter, which creates a high-pressure area for front downforce and limits the volume of air travelling under the vehicle. They also added side splitters to prevent air from sliding under the rocker panels, while a smooth, enclosed belly pan reduces underbody turbulence.

Finally, venturi tunnels accelerate exiting air, creating a vacuum that literally sucks the car to the road. The cumulative result is significant downforce at speed and one of the most efficient lift/drag values on a production car.

Double-wishbone Suspension

A double-wishbone suspension design with unequal-length aluminium control arms, coil-over monotube shocks and stabiliser bars is used front and rear. The upper control arms are the same at each corner. They are made with an advanced rheo-cast process, which allows the complexity of form associated with casting while retaining the strength of forging.

The metal, heated to just below its melting point, is the consistency of butter when it is injected into a mould at high pressure. Pressure is maintained as the part cures, preventing porosity in the final product for exceptional strength.

?We knew from the beginning that the new Ford GT was going to be a road car, not a race car, so that helped us quickly design the suspension,? said Tom Reichenbach, Ford GT Vehicle Engineering Manager.

Tapping into his personal racing experience and the lessons he learnt working with Ford?s Formula One team, Reichenbach knew the obstacles and opportunities ahead of him.

?We?ve managed to build a world-class supercar on a race team schedule,? he said

Brembo one-piece, four-piston brake calipers each grab cross-drilled, vented discs at all four wheels. The discs are a massive 355mm at the front and 335mm at the rear, delivering fade-free stopping power. Anti-lock control and electronic brake force distribution help provide consistent, straight braking even from high speeds.

One-piece BBS wheels are wrapped by Goodyear Eagle F1 Supercar tyres, with 18" wheels and 235/45 ZR18 tyres at the front and 19" wheels and 315/40 ZR19 tyres at the rear.

Supercharged 5.4-litre V8

The Ford GT is driven by an all-new, mid-engined powertrain producing 410 kW of power and 678Nm of torque.

The engine architecture comes from Ford?s MOD engine family, which includes performance powertrains like the 290kW 4.6-litre DOHC supercharged V8 in the SVT Mustang Cobra, as well as the 260kW 5.4-litre quad-cam Boss V8 in the Falcon XR8 and the 290kW 5.4-litre quad-cam Boss V8 in the FPV GT, GT-P and Pursuit models.

?We're just starting to tap the performance potential of Ford's modular engine architecture,? said Curt Hill, Ford GT Powertrain Engineering Supervisor.

?This application really demonstrates its awesome potential. The 5.4-litre engine easily produces 410kW of power and 678Nm of torque, while meeting all the current emissions and durability standards. Those numbers are comparable to the race-prepared, blue-printed 427 (7.0-litre) big-blocks in the Ford GT40 race cars.?

The Ford GT engine features an all-new aluminium block fitted with high-flow, four-valve cylinder heads and dual overhead camshafts. To bear the stresses necessary to produce 410kW, a forged-steel crankshaft, shot-peened H-beam connecting rods and forged aluminium pistons are used.

?In total, 85 percent of the reciprocating parts are unique to the Ford GT,? Hill said.

Fuel is delivered via dual fuel injectors per cylinder, while a modified screw-type supercharger ? blowing through a water-to-air intercooler ? supplies sufficient airflow for engine output.

Hill's team specified two race-inspired powertrain components; a dry-sump oil system and a twin-plate clutch. The high-capacity, dry-sump oil system provides consistent lubrication, even during high-speed cornering. The twin-plate clutch delivers low pedal efforts, while still providing the clamp loads necessary to handle 678Nm of torque.

More significantly, these two features allow the powertrain to sit more than 100mm lower in the frame when compared with the front-engined SVT Mustang Cobra. This helped maintain the low design profile, as well as keeping the car?s centre of gravity low for optimal handling.

Backing the clutch is an all-new, six-speed transaxle from Ricardo. The clean-sheet design enabled Ford engineers to tailor the individual ratios to their specifications, without being forced to select from an existing assortment. The transmission is fully synchronised and features an integral, torque-sensing, limited-slip differential.

Digitally-mastered Interior

To maximise passenger comfort, Ford GT Chief Designer Camilo Pardo and the engineering team made extensive use of a virtual-reality computer-modelling device called the digital occupant buck.

The device is a revolutionary step in CAD/CAM technology, enabling a virtual re-creation of the interior surfaces to be translated from the CAD data. With this 'immersive' tool the engineer can 'virtually' sit inside an interior buck.

A test engineer, wearing a video headset and fitted with magnetic target sensors on his body, can sit in any seat in a virtual car and experience the environment. Everything else ? buttons, controls, pedals ? is generated electronically as part of the virtual environment.

?The real advantage of the digital occupant tool is that it allows engineers to develop a comfortable interior for a wide range of statures,? said Kip Ewing, Ford GT Package, Prototype and Launch Supervisor.

?As an example, I could sit in the Ford GT seats as a fifth-percentile female and evaluate her reach to major controls. Five minutes later, I could sit in the car as a 95th-percentile male and evaluate his outward visibility.?

As a result of this testing, Ewing tweaked the occupant package for the maximum range of accommodation. This included obvious improvements, such as maximising seat travel and headroom. But he also made other subtle improvements, like centring the pedal package relative to the driver's seat and slanting the shift lever toward the driver.

For Coletti, technology like the digital occupant buck and patented body fasteners are what make the Ford GT stand out.

?Any company can take a concept car and turn it into a crude, limited-edition production car. But the craftsmanship and technology of the Ford GT make it a world-class supercar. It's a testament to the engineering expertise and technological resources that are taking Ford Motor Company into the future,? he said.

In the spirit of the company?s 100th anniversary, these ?Centennial Supercars? capture the excitement of the original Ford GT, while showcasing the modern engineering and technology that will help lead the company into the next 100 years.

For further information, please contact:
Ford Australia Public Affairs
Phone: 03-9359 8491
Fax: 03-9359 8900

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