2004 Nasamax DM139

Images copyright and courtesy Bob Chapman @ Autosport Image, Ben Michell, and Team Nasamax
Text copyright Michael J. Fuller

The new regulations initially altered the front to rear aero balance putting a premium on the generation of rear grip.  The rear wing is now closer to the center of the car (even at the maximum allowable 750 mm rear overhang) than under the previous LMP900 regulations and it is subsequently operating in a less optimum airflow field.  Additionally the rear wing is of shorter chord and therefore is less efficient in its own right.  "Initially the effect of the smaller rear wing and small overhang made a big difference and it was very difficult to generate enough rear aero to balance the front.  It was possible to balance the car to an acceptable level but the overall downforce was down by as much as 25% as a result", said Salter.
Salter:  "For the early part of the season the (rear) bodywork and diffuser stopped short of the full overhang by 150mm...as we developed the car we went from a high wing (Monza)..."
"...to a low wing for Le Mans (and Silverstone) which actually helped generate more rear...as the car and aero was developed the overall length and front overhang did change...we had suffered a lot of over steer in the car and in order to make it driveable (i.e. under steer) we had to take a lot of downforce out...
"At Spa the rear bodywork was at full overhang and the front suitably extended also. 

We didn't have a wind tunnel model or time to build one so we did all our development full size which meant we had to get it right pretty much first time.  We couldn't test lots of configurations quickly so the car evolved more slowly.  We knew this was a  fairly safe way to proceed for 2004 since there wasn't going to be much competition but there is lots more to come by doing a model programme.  Our testing was conducted with straight-line aero mapping and coast downs and track testing.  The most important thing was to be always measuring pushrod loads and have a  repeatable procedure for the straight-line work.  Coast downs were less important as we had power so weren't too worried about drag, therefore we were primarily looking for downforce

Significant gains could be made over where the Nasamax is now.  Clearly it is going to be difficult to generate as much rear downforce as with the old regs since the wing is 70% smaller and a lot further forward.  But with good design a proper LMP1 car should be a lot more competitive than the current hybrids".

The DM139's rear undertray.  Compare with the Courage C65's.  The underfloor's +/- tolerance really is minuscule and thus there are precious few differences between competitors in this area.  It is a spec (controlled) part when one only considers volume and shape, though the way it interfaces with the car will naturally be different (different inner fenders, mountings, mounting methods, etc.).

ęCopyright 2004, Michael J. Fuller