Fuel Weight and Performance | FP&P

Question 1

How many litres is 1 USG?

Answer 1

3,785 Litres

Question 2

Kilogram to Pounds?

Answer 2

2.205 Ibs

Question 3

Convert 1 Imperial gallon to litre

Answer 3

4,54 litres

Question 4

Convert 1 imperial gallon to 1 USG

Answer 4

1,2 USG

Question 5

Define specific gravity

Answer 5

Very simply, Specific Gravity(SG) is a ratio. It compares the weight of a volume of liquid with an equal volume of water.

Question 6

How do we find the weight of 45 USG in pounds, with a SG of 0.74?

Answer 6

Specific gravity utilises the metric system, so first we must convert:

1. 45 USG x 3,785 = 170 Litres

The liquid weighs 0.74 kg per litre, so:

2. 0.74 x 170 = 126kg
3. 126 x 2.205 = 277.8 Ibs

Question 7

Define specific air range

Answer 7

Specific air range refers to still air conditions, zero wind, and is a measure of TAS divided by fuel flow, or vice versa. The distance is expressed in air nautical miles

Question 8

Define specific ground range

Answer 8

Specific ground range takes into account wind and is a measure of groundspeed divided by fuel flow, or vice versa. The distance is expressed in ground nautical miles.

Question 9

Express the 3 important points to note regarding specific range

Answer 9

1. Speed is either true airspeed or groundspeed. The units used may be knots, kilometres per hour or statute miles per hours.
2. Fuel flow can be expressed as litres per hour/minute, kilograms per hour/minute, gallons per hours/minute or pounds per hour/minute.
3. One formula is the inverse of the other:

FF 80 / TAS 300 = 0,26
TAS 300 / FF 80 = 3,75