Issue: Jan 2016


Under the skin of Jaguar’s new SUV



by Nick Palmen

Jaguar is turning heads with its entry into the sports utility segment of the market in the form of the F-PACE – a SUV which, according to the company, “has the DNA of a sports car”.

Automotive Industries (AI) asked Andrew Whyman, Jaguar F-PACE Vehicle Program Director, why the company decided to add a SUV to its line-up.

Whyman: We received such an overwhelmingly positive response to the C-X17 concept car which made its debut in Frankfurt in 2013 that we just had to make it a reality. We also expect this market segment to grow to around 20 million cars by 2020, so F-PACE is an exciting opportunity for us.

AI: What does the new vehicle offer to the driver?

Whyman: This is a performance crossover with outstanding dynamics, yet also delivers a smooth, quiet ride. The F-TYPE-inspired design combines dramatic looks with a spacious interior and an exceptionally large luggage compartment. Together with our all-new infotainment system, our most advanced all-wheel drive system and an outstanding range of active safety technologies, the all-new F-PACE makes every journey a better, more rewarding experience.

AI: How does Jaguar’s lightweight aluminum architecture help the new F-PACE to deliver precision and control without sacrificing ride comfort?

Whyman: Everything about the all-new F-PACE has been engineered from the outset to deliver the driving experience which sets all Jaguars apart from the competition. The philosophy was not one of adapting the core DNA to suit expectations of how a sports crossover could ride and handle. Quite the opposite: Jaguar took everything that gives its saloons and sports cars class-leading dynamics and applied them to the all-new F-PACE.

This uncompromising approach drove demanding targets for the body’s weight, weight distribution, torsional rigidity, and aerodynamics - only with these fundamentals in place can chassis systems truly deliver. Given the ideal starting point by the high stiffness of the lightweight aluminum architecture, the all-new F-PACE also has a long 2,874mm wheelbase, which benefits not only ride but also dynamics because it helps to put the center of mass right between the axles.

Add double-wishbone front and Integral Link rear suspension – the most advanced of their type – and a sophisticated Electric Power Assisted Steering (EPAS) system, the result is a performance crossover which delivers an unmatched breadth of dynamic capability on all surfaces and in all conditions.

Proven on F-TYPE, the double-wishbone front suspension designed for the all-new F-PACE was chosen for the same reasons: it out-performs all other systems. Extremely stiff in camber, double-wishbone suspension allows the front tires to develop lateral force more quickly. This makes the vehicle more agile because turn-in is sharper and response to the driver’s input at the steering wheel is felt immediately.

The other key benefit is superior roll camber gain characteristics: the tire is better able to maintain its contact patch throughout the suspension’s full range of travel, enabling it to generate more grip, and also maintain steering feel. Aluminum is used almost exclusively to make the suspension as light as possible, most notably the front knuckles. The intricate, ribbed design is achieved by forging the components from cast blanks: this enables maximum stiffness for minimum weight. Among the other enhancements are bonded bushes for the tubular anti-roll bar: as well as better NVH properties these also prevent dirt ingress, improving robustness.

The result of years of advanced research and development, Integral Link is the most sophisticated and most capable rear suspension system available and provides unequalled ride, handling and refinement attributes. Integral Link separates lateral and longitudinal stiffnesses, enabling the suspension to provide the best possible comfort without compromising dynamics.

Bushes which manage longitudinal loads can be made much softer than would otherwise be possible with conventional multilink suspensions, enabling excellent energy absorption and therefore a smoother, quieter ride. At the same time, lateral stiffness can be far higher, making the vehicle more responsive. Caster stiffness can be increased too, which is felt by the driver as improved stability when braking.

The upper links are aluminum forgings, while the lower arm is hollow-cast aluminum – the optimum lightweight solution for this complex part. The springs and dampers are mounted separately, allowing each to be ideally positioned for the forces acting on the suspension and contributing even more to the all-new F-PACE’s benchmark dynamics and refinement. This design is also highly space-efficient, minimizing intrusion into the luggage compartment.

AI: How do the F-TYPE derived technologies, and in particular Torque Vectoring, enhance the agility of the vehicle?

Whyman: The Torque Vectoring system can apply finely-metered braking to the inner wheels to mitigate understeer during corner entry, helping the driver to keep the vehicle on the ideal line through the turn. The system works predominantly on the inside rear wheel to avoid any corruption of steering feel, and as a result system intervention is virtually transparent to the driver. To preserve Jaguar dynamics DNA and make the system as effective as possible, the calibration was done in-house, the controller is bespoke, and development was done in parallel with the base chassis handling balance. And because the system enables such fine levels of wheel control it can also deliver benefits at slower speeds too, such as when driving on mud or snow.”

AI: How is the electric power-assisted steering system optimized in the new F-PACE?

Whyman: The Electric Power Assisted Steering (EPAS) system has evolved. As well as software tuned with all of the learning taken from F-TYPE, XE and XF, the F-PACE system benefits from the addition of closed-loop control. Specially-developed algorithms calculate the forces coming back from the road and use this information to further refine the level of assistance, making the steering even more intuitive.

The EPAS system also benefits from a variable steering ratio - as standard. This is achieved using variable pitch gears on the rack bar and fixed pitch gears on the pinion. The more the driver turns the wheel, the more responsive the steering becomes as the system changes the contact point with the rack’s gear teeth from the valleys on-center to the peaks at full lock. But EPAS doesn’t just improve the driving experience: it also improves fuel efficiency because the motor only draws current when the driver turns the steering wheel. This helps to cut consumption and emissions on the European combined cycle by as much as 3%.



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