The Navigation Computer: Fuel Consumption

Fuel consumption problems work exactly like distance/speed/time calculations. We normally get a fuel consumption per hour, use base 60, and read the answer in minutes. If it comes to more than 60 minutes we use the yellow scale to read the answer in hours and minutes.

Example. Your fuel consumption is 2300 kg/hour. Your time to destination is 1 hour 37 minutes. How much fuel will you use?

Remember - minutes are always on the inner scale.

Set the black triangle against 2300. Align the cursor with 1 hour 37 minutes (97 minutes). Read off the answer - 37.2. The correct answer is obviously 3720 kg.

Using a calculator gives you the answer 3718.33 kg. This should reassure you that the navigation computer is very accurate - in fact, probably considerably more accurate than your fuel gauges.

Example Your fuel flow is 130 imperial gallons per hour. You have 380 gallons left above your reserves. What is your Safe Endurance?

Set the black triangle against 130.

Align the cursor with 380 (outer scale).

Read off the answer - 175.5 (inner scale). Use the yellow ring to see that this is 2 hours and 55.5 minutes.

Example You have used 3700 litres of fuel in the last 1 hour 45 minutes. What is your fuel consumption rate?

Find 3700 on the outer scale and align the cursor.

Bring 1 hour 45 minutes (105 minutes) on the minutes scale into alignment with the cursor. Use the yellow scale to convert hours and minutes to minutes if necessary.

Read off the consumption against the black ‘60’ triangle.

The answer is 21.1. A common-sense check shows that this must be 2110 kg/hour. The electronic calculator solution is 2114.29.

Next: Distance Conversions

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