Solving problems of fuel consumption is similar to problems of speed, time, or distance.
Both are rate problems. The only difference is that the unit that changes over a given
amount of time is now fuel instead of distance. Again, it is a simple matter of setting up
ratios on the computer and solving for the unknown factor. The outer scale is now used as
the FUEL scale; and the solution is still a matter of transferring the ratio, or proportion, to
the outer/inner scales of the computer and reading the unknown factor (fuel consumed or
rate of consumption). Use the formula:
FUEL FL OW FUEL CO NSUMED
Since fuel is measured in pounds, the outer scale on the CR-3 becomes the FUEL (in
pounds) scale while the inner scale remains the TIME scale.
Examples of fuel consumption problems follow.
Finding amount of fuel consumed.
Given: Fuel consumption. . . . . . . . . . . . . . 1000 pounds per hour
Time flown. . . . . . . . . . . . . . . . . . . .1 hour and 45 minutes
1. Estimate the answer. Since the total time is just under 2 hours the answer should be
a little under 2000 (2 hr x 1000 # / hr), approximately 1800.
2. Place the RATE INDEX (▲) located on the TIME (inner) scale under the 10 (1000 #
/ hr) on the FUEL (outer) scale. (Figure 4.3-24)
Figure 4.3-24 Fuel Consumption 1