Chapter 3 - Chassis & Body
Section 1 - Mass Calculations
Glider Mass
The glider (a vehicle without a drive-train) mass will either be determined by weighing the glider or by looking the weight up in a table. If the glider is weighed, then the mass can be found by dividing the weight by the acceleration of gravity and converting the results to metric.
Glider weight in pounds/2.205 = vehicle mass in kg
If a metric scale is used then the kilogram reading is already the mass for the glider. The glider mass will be added to the mass of the other components to determine total vehicle mass in order to calculate the acceleration rates and tire drag.
- Sample Glider Masses -
Glider Weight Mass
1964 VW Beetle 1,100 pounds 499 kg
1994 Ford Ranger 2,500 pounds 1133 kg
Component Masses
The mass of the batteries, motor, controller, cables, transmission and other added components will be determined as described above. Add components and glider masses to determine total vehicle mass.
Note: Masses of selected batteries, motors, and controllers are listed in their appropriate chapters.
Vehicle Mass
The vehicle mass is either determined by adding all of the components' and glider's masses, or by dividing the finished vehicle weight by the acceleration of gravity. On the following page is a list of selected vehicle weights and masses which can be used for comparisons.
Vehicle Weight Mass
GM Impact 2,200 lb. 998 kg
G-Van, EPRI 7,672 lb. 3,481 kg
Festiva - Solar Car 2,250 lb. 1,020 kg
Force - Solectria 2,142 lb. 972 kg
Vehicle Clearance
If a chassis is modified with the additional weight of batteries, it may effect the ground clearance. This figure illustrates the SAE recommended practice for vehicle curb, approach, departure and ramp clearances.
A = Approach angle = 16° min.
B = Ramp breakover = 10° min.
C = Departure angle = 10° min.
D = Curb height = 203 mm (8 in)
