This is an excerpt from Honda's NSX-R Overview. For the complete document, please view http://world.honda.com/NSX/   Improved aerodynamics to significantly increase vehicle stability and cornering performance at high speeds In order to endow the new NSX-R with outstanding high-speed performance, we turned our attention to aerodynamics and their effect on high-speed cornering power, braking, turn-in, and other aspects affecting vehicle controllability. This led us to a new technical approach called "aerodynamically-induced stability". In addition to increasing high-speed cornering power, we have also striven to improve vehicle control quality - the ease with which the driver can control the car, and thus exploit its full potential. This enabled the chassis to be tuned for reduced understeer at low to medium speeds. The resultant improved handling at both low and high speeds endows the New NSX-R with outstanding speed on all types of circuits.   Fundamentals behind downforce and aerodynamic stability for improved high-speed vehicle handling In order to endow the new NSX-R with outstanding high-speed performance, we turned our attention to aerodynamics and their effect on high-speed cornering power, braking, turn-in, and other aspects affecting vehicle controllability. This led us to a new technical approach called "aerodynamically-induced stability". In addition to increasing high-speed cornering power, we have also striven to improve vehicle control quality - the ease with which the driver can control the car, and thus exploit its full potential. This enabled the chassis to be tuned for reduced understeer at low to medium speeds. The resultant improved handling at both low and high speeds endows the New NSX-R with outstanding speed on all types of circuits. The third advantage of downforce is that it helps reduce body roll as well as body pitch. This in turn helps reduce sudden variations in vertical forces applied to the tires at the limit, increasing vehicle stability in the wake of driver input. Vehicle behavior is also more linear near the limit of adhesion, contributing to increased driver control. In other words, creating downforce to press the vehicle onto the road as speed increases not only contributes to increased absolute cornering speed and thus absolute dynamic performance, but also significantly improves vehicle control quality as measured by response to driver inputs and vehicle stability at the limit. These are the fundamentals behind downforce and aerodynamic stability as a means to improved high-speed vehicle handling. Relationship between vertical force and cornering force As the vertical force applied to the tire increases, cornering force also increases. In other words, increasing the vertical force applied to the tire has the same effect as using larger tires. How downforce helps control changes in attitude Downforce helps reduce body roll while cornering and body pitch during braking or acceleration. This also helps reduce sudden variations in vertical forces applied to the tires at the limit, for increased vehicle stability. Downforce not only increases dynamic performance, but also creates a more stable vehicle behavior environment for steering, throttle, and braking inputs. Extensive circuit testing to determine the optimum equilibrium between downforce and front-to-rear balance In order to endow the new NSX-R with outstanding high-speed performance, we turned our attention to aerodynamics and their effect on high-speed cornering power, braking, turn-in, and other aspects affecting vehicle controllability. This led us to a new technical approach called "aerodynamically-induced stability". In addition to increasing high-speed cornering power, we have also striven to improve vehicle control quality - the ease with which the driver can control the car, and thus exploit its full potential. This enabled the chassis to be tuned for reduced understeer at low to medium speeds. The resultant improved handling at both low and high speeds endows the New NSX-R with outstanding speed on all types of circuits. The third advantage of downforce is that it helps reduce body roll as well as body pitch. This in turn helps reduce sudden variations in vertical forces applied to the tires at the limit, increasing vehicle stability in the wake of driver input. Vehicle behavior is also more linear near the limit of adhesion, contributing to increased driver control. In other words, creating downforce to press the vehicle onto the road as speed increases not only contributes to increased absolute cornering speed and thus absolute dynamic performance, but also significantly improves vehicle control quality as measured by response to driver inputs and vehicle stability at the limit. These are the fundamentals behind downforce and aerodynamic stability as a means to improved high-speed vehicle handling. Downforce balance front to rear (Straight-line driving at constant speed) By creating a downforce with the same front-to-rear balance as vehicle weight, changes in steering characteristics from low to high speeds remain well under control. At higher speeds this translates into a more linear response. More precise control of the vehicle helps the driver delve further into the car's potential. Testing at Honda's proving grounds in Takasu, Hokkaido   A front hood air duct: the aerodynamic mechanism for creating downforce At the rear, downforce is easily obtained using a wing-type spoiler. At the front, though, adding too big an aerodynamic device can negatively affect minimum ground clearance and/or the approach angle. Increased aerodynamic resistance resulting in reduced acceleration is also another example of the many problems associated with obtaining appropriate downforce in a road-going car. The solution we chose was to design the underbody of the car as flat as possible to encourage smooth airflow under the car, maintaining airflow speed to create downforce. This method not only provides for adequate ground clearance and approach angle but also does not unduly increase the forward-protruding surface of the body. However, this led to a new problem: how to extract the airflow through the front radiator that had previously been channeled underneath the car? Taking advantage of the car's mid-ship layout, an air duct was added in the front hood to provide the necessary extraction route. Longitudinal fins were also added to the outer left and right sides of the front under-cover tray to prevent the air passing under the car from entering the front wheel wells. Similarly, spats have been added to both sides of the air ducts to channel air passing through the ducts away from the wheel wells. The opening ratio under the front bumper has also been reduced to limit as much as possible the actual amount of air flowing through. All these innovations result in a smoother airflow both under the body and through the front hood, achieving the desired downforce. No large aerodynamic appendage was required, helping maintain the original NSX's overall design and ensure a relatively low aerodynamic drag. Downforce was thus achieved without sacrificing top speed. Wind tunnel tests have shown that when the car is at an angle relative to wind direction, the longitudinal fins of the front under-cover tray function in the same way as the chin spoiler, effectively reducing body lift and improving transient characteristics. Wind tunnel testing View of the underbody Cd (Drag coefficient): 0.32 Cl (Lift coefficient/overall): -0.100 Clf (Lift coefficient/ front): -0.040 Clr (Lift coefficient/rear): -0.060 Compared to the original NSX-R, this translates into an increase in vertical force acting on the front tires of 36.2kgf, and of 25.0kgf on the rear tires (test results measured at 180 km/h in both cases). Lift reduction measures (effect measured piece-by-piece) Extensive circuit testing to determine the optimum equilibrium between downforce and front-to-rear balance The air duct in the front hood could have been made simply by cutting an opening and trimming the edges with plastic. But because we wanted to maintain the beauty of the original design including the simplicity of line worthy of a car cut for speed like the NSX-R, and to reach the weight reduction target we had set for ourselves, we chose carbon fiber instead. The rear spoiler is similarly a single piece of carbon fiber designed to achieve the required downforce while maintaining a low drag coefficient in a simple shape embodying functionality and beauty. Both parts are formed using an autoclave, a method more often seen in aircraft manufacture. Multiple layers of pre-pregs made of resin-impregnated carbon fibers are cured in a high-pressure oven to form the parts. The front hood is made of carbon Aramid fibers for added resistance to tearing. In the event of an accident, it is designed not to shatter into small pieces. During the laminating process, fibers are offset by 45 degrees, with each layer above and below being symmetrically angled to provide equal strength in all directions. Nine to ten hours are required to complete the laminating process of each single part. After lamination, the whole lay-up is wrapped in a baking film, and a vacuum is applied to consolidate the laminate prior to curing for 2-3 hours in the autoclave at a pressure of two to three atmospheres. Once in the autoclave, it takes one hour to bring the part to temperature, while some five hours are required for the cooling down process. Air released from the resin when liquefying at high temperature is carefully bled off to form a strong CFRP (Carbon-Fiber Reinforced Plastic). The front hood's outer skin is formed separately from the inner frame before being glued together. Glue thickness is strictly maintained at less than 0.5mm. The resultant strength is superior to that of the base materials. The rear spoiler is a hollow, one-piece molding made using a proprietary process developed in cooperation with a parts supplier. Durability, a matter not normally emphasized in aerodynamic carbon fiber parts manufacture, has been pursued to the utmost. In all aspects of the product, durability on par with steel is achieved. The painting process has also been the object of painstaking attention, especially regarding the undercoating, with both parts undergoing a "5 coat/5 bake" process. For the front hood in particular, paint has been applied so as to let the roughness of the carbon fiber surface show through ever so slightly. In order to endow the new NSX-R with outstanding high-speed performance, we turned our attention to aerodynamics and their effect on high-speed cornering power, braking, turn-in, and other aspects affecting vehicle controllability. This led us to a new technical approach called "aerodynamically-induced stability". In addition to increasing high-speed cornering power, we have also striven to improve vehicle control quality - the ease with which the driver can control the car, and thus exploit its full potential. This enabled the chassis to be tuned for reduced understeer at low to medium speeds. The resultant improved handling at both low and high speeds endows the New NSX-R with outstanding speed on all types of circuits. The third advantage of downforce is that it helps reduce body roll as well as body pitch. This in turn helps reduce sudden variations in vertical forces applied to the tires at the limit, increasing vehicle stability in the wake of driver input. Vehicle behavior is also more linear near the limit of adhesion, contributing to increased driver control. In other words, creating downforce to press the vehicle onto the road as speed increases not only contributes to increased absolute cornering speed and thus absolute dynamic performance, but also significantly improves vehicle control quality as measured by response to driver inputs and vehicle stability at the limit. These are the fundamentals behind downforce and aerodynamic stability as a means to improved high-speed vehicle handling. Downforce balance front to rear (Straight-line driving at constant speed) By creating a downforce with the same front-to-rear balance as vehicle weight, changes in steering characteristics from low to high speeds remain well under control. At higher speeds this translates into a more linear response. More precise control of the vehicle helps the driver delve further into the car?s potential. Testing at Honda's proving grounds in Takasu, Hokkaido   Outstanding cornering speeds achieved under all conditions from high to low speeds For ultimate speed on the circuit, a specially designed tire with an asymmetrical tread pattern was selected. At the same time, roll rigidity, performance envelope and response were all increased in the pursuit of further improved cornering speeds. The newly gained aerodynamic stability leads to improved high-speed stability, allowing the understeer setting previously adopted for low to medium cornering speeds to be reduced. Front turn-in response has also been increased toward a more controllable setting for the driver. To supplement the added speed, braking capacity has also been increased, particularly in the area of fade resistance on circuit runs. The anti-lock brake system has also been fine-tuned for even greater stability when braking hard at high speeds.   Combining high-speed stability with low-speed cornering performance By contributing to increased high-speed stability, the aerodynamically induced downforce achieved in the New NSX-R has allowed the selection of a harder suspension setting to further increase cornering performance and overall dynamic performance. Overall, the suspension is tuned to promote higher cornering limits and improved handling response. The first issue we addressed was roll rigidity, equipping the NSX-R with heavier-duty springs, new spring material for reduced weight, increased damping rates, larger stabilizer bars, reinforced damper mount and rear control arm bushings for a sharper, more responsive drive. The stabilizer bar bushing is now self-lubricating for increased rigidity, enhancing the stabilizer bar's effect. Compared to the rear, the front suspension is tuned to increase road holding. Reduced understeer contributes to improved cornering behavior around tight bends, while aerodynamically-improved stability delivers superior performance at higher speeds, for further enhanced performance under all circuit conditions. LSD (limited-slip differential) pre-loading has been tuned to take into account the increased cornering performance provided by aerodynamic downforce, for improved traction. Body rigidity has also been fine-tuned, with the adoption once again of front and rear tower bars. Although the front tower bar is the same as that of the original NSX-R, the rear one has been thickened from t1.0mm to t2.3mm over the original setting, for increased rear roll rigidity. The dampers have also seen their damping rate increased, although particular attention has been paid this time to damping characteristics for minor inputs at very low speeds, with the objective of further smoothing out minor vibrations. The pistons used in the dampers are now polished to minimize production tolerances and reduce differences from damper to damper.