The charts below show the results of a CFD "virtual wind tunnel" simulation of a Kyosho Mini-Z MR03 Mazda 787b 3D Model.
The first chart shows the increase in drag force as a function of speed. The second chart shows the relationship between down force (or lift) and speed. Both charts show the data points and curves for each one of the different rear wing configurations tested in the simulations: no rear wing, flat rear wing, 15 degree rear wing, 30 degree rear wing, 45 degree rear wing, 60 degree rear wing, gurney flap, scoop wing.
Each data point on each chart represents a different simulation, conducted at a different speed: 2.5 m/s (9km/h), 5.0 m/s (18 km/h) , 7.5 m/s (27 km/h), and 10 m/s (36 km/h). This should cover practically the full range of speeds observed in a typical Mini-Z track.
The curves were interpolated using a 2nd order polynomial. In all cases the fit was almost perfect (R-squared greater than 0.98) indicating that, according to the simulation, both drag and down forces increase as a proportion of speed squared. These results are pretty much in line with basic aerodynamics laws.
For complete results of the Mini-Z MR-03 CFD "virtual wind tunnel" simulation click here.