Aerodynamics
first rough 3D CFD:
flat bottom body design vs venturi body design
car body surface 7,12 square meters
average upper body pressure 0,8 Kpa
average bottom body pressure -2 Kpa
total down-force at 300 Km/h = 7,12 square meters x 1200 Newton per square meter = 8544 Newton is about 871 Kg down force.
a rough estimate is a 300 Pa difference due to the venturi design which results in 217 KG more down force plus the earlier 871 KG equals 1088 KG
velocity plot showing the advantage of venting the front fender
Pressure plot
blue color on bottom of car is good = down force
red yellow and green on bottom of car is bad = lift
Red yellow green on top of car is good = down force
blue on top is bad = lift
sum all the bad and the good over the entire car surface and the end result is 871 Kg down force
Flat under body versus venturi underbody
Below the venturi body (blue lines in graphs). The underside is slightly altered from flat to venturi shape the graph below in blue shows the static pressure of the venturi versus the red line of the flat under-body.
The first graph is the longitudinal section of the car on Y = 0 mm and starts at -5000 mm x axis which is in front of the car and ends at +6000 mm which is behind the car
The second graph is the transverse section of the car on x = 0 mm the right side is the middle bottom of the car on the y coordinate axis value close to zero so the graph starts at the outside of the car towards the middle of the car where the pressure underneath the car is lowest.
a rough estimate is a 300 Pa difference which results in 217 KG more down force plus the earlier 871 KG equals 1088 KG
Venturi under body
Venturi under body
sides of body are lowered by 20 mm
middle underside of body is lowered by 20 mm
flat under body
static pressure underneath the car venturi body. The right side is the front of the car. The dark blue blob is the rear diffuser.