How many pounds of fuel represent CNAF's 20 minute flight at maximum endurance airspeed at 10,000 feet?

How many pounds of fuel represent CNAF's 20 minute flight at maximum endurance airspeed at 10,000 feet?

• A. 100 pounds
• B. 125 pounds
• C. 150 pounds
• D. 200 pounds

Answer: (B)

Fuels planning for a given flight relies on the rate at which the engine burns fuel at the chosen endurance condition. At maximum endurance airspeed, the aircraft is flown at the speed that minimizes fuel burn per hour, maximizing time aloft for a set fuel load. To find how much fuel a 20-minute flight at 10,000 feet requires, first convert the time to hours (20 minutes = 0.333 hours). Then use the fuel flow rate for maximum endurance at 10,000 feet from the CNAF performance data. Multiply the hourly burn by the time: 0.333 hours × about 375 pounds per hour gives roughly 125 pounds of fuel. So the fuel on board for that 20-minute leg at that altitude and speed is about 125 pounds.

Fuels planning for a given flight relies on the rate at which the engine burns fuel at the chosen endurance condition. At maximum endurance airspeed, the aircraft is flown at the speed that minimizes fuel burn per hour, maximizing time aloft for a set fuel load. To find how much fuel a 20-minute flight at 10,000 feet requires, first convert the time to hours (20 minutes = 0.333 hours). Then use the fuel flow rate for maximum endurance at 10,000 feet from the CNAF performance data. Multiply the hourly burn by the time: 0.333 hours × about 375 pounds per hour gives roughly 125 pounds of fuel. So the fuel on board for that 20-minute leg at that altitude and speed is about 125 pounds.