Mulsanne's Corner NEWS

Mulsanne's Corner NEWS isn't meant to be THE source for up to date news items.  Instead what we are doing is providing an archive for information collected through out the Net related to new car developments.  Occasionally we do post first hand gathered items, but most of the time it is news from secondary sources such as Daily or Autosport (they are much better at it than we are!).  We will provide all sources for any news item shown here.

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May 2002

>>Cadillac in trouble?  Rumors have persisted since the Le Mans test days about about aero. issues and lack of engine power.  Courtesy of Markus Eberhardt, the German magazine "Motorsport aktuell" reports the anemic top speeds hit by the Cadillac at the Le Mans test day as 315 km/h (195.3 mph).  Compare that with 327 km/h (202.7 mph) for the Ascari and 330 km/h (204.6 mph) for Audi.  Sure, top speed isn't everything, but couple that with slow lap times and you end up with a car that clearly has high drag and low hp.  So they are probably sacrificing what downforce they are carrying for whatever speed they can get (hence the slow laps times).  The silence surrounding the Cadillac effort is sounding very loud.
>>Released by the FIA last week, the implications are yet to be known.  This document can be simply described as alarmist and ill-timed.  Perhaps there is a hidden agenda?  Flat bottomed sports cars have been running since 1994 and this condition has existed since then.  The FIA's research doesn't change this fact. 

Aerodynamic Instability of Sportscars at Abnormal Yaw Angles

New research commissioned by the FIA has revealed that the current design of cars running under sportscar and ‘sport prototype’ regulations exhibit characteristics that can cause them to leave the ground and possibly invert, when they run at yaw angles greater than approximately 30 degrees, even at speeds well below their maximum. 

Exceeding the critical yaw attitude is only likely if a driver has lost control of a car. Adverse pitch and roll attitudes, resulting from mechanical failure or external disturbance, accentuate these characteristics and lower the speed at which take off can occur. 

When a car leaves the ground, it is unable to engage effectively with the circuit safety features such as run-off areas and barriers. If a car lands inverted, the safety of the driver depends on the ability of the roll-over protection to withstand the forces involved. 

Further research is being conducted in order to reduce or eliminate this phenomenon. Pending the outcome of this research and possible new technical regulations, the FIA recommends that all competitors and organisers involved with sportscar, ‘sport prototype’ and similar competition cars take the following minimum precautions. 

1. Organisers should ensure that all spectators are sufficiently far from the circuit at any given point to be in no danger from an airborne car, having regard to the speeds of the cars at the relevant part of the circuit. 

2. In collaboration with the constructors of their cars, competitors should reinforce the car’s roll-over structure so that it least meets the latest proposals which have been issued as a draft regulation for 1.1.2003. 

3. Organisers should ensure that all marshals and other race personnel working in close proximity to cars traveling at speeds greater than 150 kph are suitably protected. 

4. Organisers should take measures to slow the cars at any part of a circuit which would be particularly dangerous for competitors, track workers or members of the public in the event of a car becoming airborne.

Editors’ Note:

Sportscars normally run at yaw angles of less than ±10º. The yaw angle is the angle of the airflow relative to the heading (direction of travel) of the car. The problem that has been identified occurs once the driver has lost control of the car and starts to spin. It is different to the problem experienced by Mercedes at Le Mans in 1999, in which the cars took-off while running under normal conditions. Following those incidents, the FIA instigated circuit modifications and made changes to the Sportscar Technical Regulations. The 1999 problem has not reoccurred.

Funding for the new research was provided by the FIA Foundation.

>>Note that the FIA is clear to distance their yaw angle research findings with the phenomenon encountered by the Mercedes CLR at Le Mans in 1999.  It is important to understand that these are two separate issues.  Though it is interesting to note that the FIA feels that sports cars haven't flipped end-over-end Mercedes CLR style since 1999.  I think Bill Auberlen would disagree (BMW LMR, Petit Le Mans 2000).

>>Something for the analytical minds today.  Wing endplates act as span increase aerodynamically.  That is, in general terms, a wing with an endplate is equal to a wider wing with out one. 

>>Using this formula:

Aspect Ratio (AR) = span/chord

We can calculate the AR for wings of 165 cm and 200 cm widths given a chord of 40 cm for both:

165 cm wing AR = 4.125
200 cm wing AR = 5

>>Next, using this formula:

Effective Aspect Ratio (Ea/r) = Actual Aspect Ratio (Aa/r) * (1 + 1.9 * (endplate depth/span))

We can calculate the Ea/r for wings of 165 cm and 200 cm widths given a chord of 40 cm for both, and endplate depths of 15 cm and 60 cm:

165 cm wide wing:
15 cm deep endplate, Ea/r = 4.837
60 cm deep endpalte, Ea/r = 6.97

200 cm wide wing:
15 cm deep endplate, Ea/r = 5.7125
60 cm deep endplate, Ea/r = 7.85

>>And finally, going back the original Aspect Ratio formula and using Algebra to work backwards we can then determine the Effective Span, that is, the endplate's impact on aerodynamic span:

The Effective span of a 165 cm wide wing given the endplate depth as such:
15 cm deep endplate = 193.5 cm
60 cm deep endplate = 278 cm

The Effective Span of a 200 cm wide wing given the endplate depth as such:
15 cm deep endplates = 228 cm
60 cm deep endplates = 314 cm

Formulas out of Joseph Katz's New Directions in Race Car Aerodynamics 

>>Audi R8 2002
>>Audi has created some what of a stir with their new endplate interpretations.  ACO rules limit endplate area to a 15 cm x 40 cm square.   But Audi has created a plate just below the standard 15 x 40 cm endplate that attaches all the way to the body work, but isn't itself attached the the endplate.  Audi is surely calling this an "aero device" and not an endplate. Perhaps that's the simple work-around?

Note where the endplate attaches to the bodywork, the actual attachment point is a wing sectioned piece of body work.  The rule stating that no bodywork is allowed a wing shaped profile only applies to body work that is below the front and rear wheel centerlines.  This section appears just above the rear wheel centerline, so presumably is allowed to be wing profiled. 

Though one wonders what has taken so long for Audi to come up with this new aero piece as it seems the obvious answer to the solution.  Perhaps it was the new De Cortanze Courage C60 Evo. that spurred this development?

>>Back from our hiatus.  With the Le Mans test days occurring this weekend, that topic will understandably dominate as we catch up.  Many of the cars are sporting their Le Mans bodywork for the first time and there are some interesting new rule interpretations.  We'll be showing you these new updates as things get back to normal.
>>Bentley EXP Speed 8 2001, Early testing variant:
Image flipped for comparative purposes.
>>Bentley EXP Speed 8 2002, Le Mans Test Days:
Most striking difference is the modified rear bodywork that is tighter to the rear wheel.
©Copyright 2002, Michael J. Fuller