Burn Rate

Gallos Per Hour (GPH) = Gallons Used / Hours Flown

Example:

Duration of Flight = 2 hours

Gallons Used = 18 gallons

18 / 2 = 9 GPH

Rule of Thumb

The fuel consumption of an aircraft engine is equal to one half the horsepower divided by 10.

Example:

Lycoming IO-360 = 180 horsepower

180 / 2 = 90

90 / 10 = 9 GPH

Rule of Thumb

A small single engine aircraft with a 180 Hp engine will burn approximately 1 gallon of fuel every 5 minutes. The lower the altitude the better the endurance (not range) for normally aspirated engines. (Recommendation: Check the actual fuel burn of your aircraft  with the POH to see how they compare)

Fuel Burned

Fuel burned = Time x Burn Rate

Endurance

Endurance = Usable Fuel / Fuel Burn Rate

Example:

Usable Fuel = 40 gallons

Fuel Burn Rate = 10 GPH

40 / 10 = 4 hours