Weight and Climbing

F

a (in pounds) F a (in pounds) F a (in pounds) a (in mph/sec) a'= a/21.95 Ci = 1.06 Ci = 1.1 Ci = 1.2

1 0.046 48.3 50.1 54.7

2 3 4 5 6 0.091 0.137 0.182 0.228 0.273 96.6 144.8 193.1 241.4 289.7 100.2 150.3 200.4 250.5 300.6 109.3 164.0 218.6 273.3 328.0

7 8 9 10 0.319 0.364 0.410 0.455 338.0 386.3 434.5 482.8 350.7 400.8 450.9 501.0 382.6 437.3 491.9 546.6

Table 5-1 Acceleration Force, Fa (in pounds), for Different Values of C

i

To use Table 5-1 with your EV, multiply by the ratio of your vehicle weight and use the Ci 5 1.06 column for lighter vehicles and Ci 5 1.2 column for heavier ones. For example, the 3,800-lb. Ford Ranger pickup truck of Chapter 10 would require 5 mph/ sec 5 3.8 3 273.3 5 1038.5 lbs.

Weight and Climbing

When you go hill climbing, you add another force:

Fh

5 Wsin f where Fh is hill-climbing force, W is vehicle weight in pounds, and f is angle of incline as shown in Figure 5-2. The degree of the incline—the way hills or inclines are commonly referred to—is different from the angle of the incline, but Figure 5-2 should clear up any confusion for you. Notice that sin f varies from 0 at no incline (no effect) to 1 at 90 degrees; in other words, the full weight of the vehicle is trying to pull it back down the incline. Again, weight is directly involved, acted upon this time by the steepness of the hill.

Degree of incline 5 1% 5 1 foot 5 Rise 100 feet Run

Angle of incline, O 5 Arc tan Rise 5 Arc tan 0.01 5 about 0 degrees 34 minutesRun

Figure 5-2 Angle of incline defined.