Shopping Tools


Technical Analysis: Anatomy of a Supercar - Road Test Data

The road to 250 mph is a technically fascinating one.

By Gordon Murray / Photos by Stephane Foulon

The Bugatti Veyron 16.4 is no doubt the result of many thousands of engineering hours, and certain elements of the car are indeed cutting-edge concept and design. The two main areas that demonstrate new technology are the engine and the transmission.

The engine itself is an engineering wonder and includes some interesting new anti-knock sensing. The gearbox and gear-change system are right up to date utilizing dual-wet clutches and twin layshafts. In my opinion, this is the only way to go to attain quick, smooth gearchanges for a vehicle without a manual clutch. Most semiautomatic systems are violent in their application and not very satisfying from a driver's point of view. The Veyron gearchange is fast and extremely well applied. The complete powertrain is a great showcase for the parent company, Volkswagen AG. Another area where the car is pushing boundaries is with its electronic control systems and, in particular, their application. I drove the Bugatti on the road and on the track, which demonstrated just how seamlessly the chassis and powertrain functions have been sewn together.

The chassis/body structure is hybrid like the last Bugatti (EB110) with carbon fiber used for the primary structure and aluminum alloy for the body and front crash structure. In this respect, the all-carbon McLaren F1 and the RTM (Resin Transfer Molding) carbon Mercedes-Benz SLR McLaren are, in fact, more advanced. Carbon-ceramic brakes are used as with the Porsche GT and the SLR.

The aerodynamics is interesting and complex. The design and development have been directed at problem-solving in the areas of cooling and vehicle stability. At such high speeds, the basic shape of the Veyron will generate a lot of lift. Add to this a large frontal area and 10 radiators and heat exchangers, and suddenly here's where the 1001 hp [metric horsepower] dissipates at 250 mph! The CDA figure [drag coefficient x frontal area] is at the high end of the scale for rear-engine sports cars. At these sorts of speeds, a massive amount (often three or four times the net figure) of downforce has to be generated to overcome the basic lift in order to achieve the target figure for net downforce. The Veyron is a full ground-effect vehicle like the McLaren F1 and Ferrari Enzo. The downforce increases as a square of the speed, so there are large forces to design for at speeds approaching Vmax [top speed] — these forces eat into available suspension travel and can cause high-speed stability problems.

Compounding this problem is that ground-effect cars are notoriously sensitive to ride height and pitch changes. I solved these problems on the F1 by having just enough downforce for high-speed stability and by giving the driver a manual control over the rear wing for a 50-percent increase in downforce at lower speeds. The F1 is also designed with an automatic "air brake," which deploys when the chassis ECU detects a certain combination of speed and deceleration. The air brake increases the CD but more important, interacts with the ground-effect forces by increasing the tail vortex and base suction, which results in an increase in downforce of 100 percent and a rearward movement of the aerodynamic center of pressure of about 4 ft., which helps negate the pitch problem. The Veyron uses the McLaren air brake system but also has a hydraulic ride-height control system, which optimizes the ride heights and chassis incidence for different speeds and loads. The F1 goes a little further with automatic brake cooling and fan-assisted boundary control for the rear diffuser.


Pages: 1 2 3 4

  • Stumble It
  • Yahoo! Buzz