# Model identification

Before start to discuss about the model we need to consider that we are not speak about any efficiency or friction: we have described the ideal curves.  First of all  we have identified the forces acting on the veichle:

In the spread sheet (named “Calcoli”) the formula of the forces are explained:

Continuing on the model identification (spread sheet “Calcoli” ) we have represented, in each line, one particular working condition.

Obviously ,for these calculation we have used some known data  or constant: Air density = 1,25Kg/m³. Gravity acceleration g = 9,8m/s² Typical friction coefficient value fv = 0,01. Wheel radius r = 0,217m information from the tyre. Veichle mass m = 350 Kg  this value consider also the pilot. The full mass value is 550Kg. Veichle Cx   = 0,34 ; this value comes out from the formula of the aerodynamic resistance (Ra). For this calculation we have considered the maximum speed (maximum speed from the Internet video of the traditional 3 wheels tuned), the weight of Ape and the frontal area. The values of the frontal area comes out from the Ape leaflet (= 1,4m²) . Slope Cp = it is percentage (consider CP= 100% is equal to 45°). Acceleration a = 1,38888…89 comes out considering that we need to reach 100Km/h (=27,78m/s) in 20s then from the formula a = v/t you have the value. With these information we have identified the performances needed. We have identified: the electric motors size, gear ratio, drives size and the batteries. Following the view of this calculation file:

If you want to learn more go in the next  page: “The Kit!”.