Aircraft Performance
Fuel flow is the rate of fuel consumption by the engine, measured in pounds per hour (PPH)
1.7.98 Relationship between fuel flow, thrust available, thrust required and velocity for a turbojet airplane in straight and level flight
- Thrust curves represent fuel flow
- The fuel consumed is proportional to its thrust available
- To maintain equilibrium flight, thrust available must equal thrust required
- Minimum fuel flow for a turbojet is found on the thrust required curve
- We look at the thrust required or power required curve to determine the velocity that would give us the max endurance or range that we need
1.7.99 Relationship between fuel flow, power available, power required, and velocity for a turboprop airplane in straight and level flight
- Power Curves represent fuel flow
- The thrust provided by a propeller is not produced directly by the engine (no relationship between thrust and fuel flow)
- The fuel flow varies directly with the power output of the engine
- Minimum fuel flow for equilibrium flight will be found on the power required curve
1.7.100 Define Maximum Range and Maximum Endurance
1.7.101 and 1.7.102 State the angel of attack and velocity , compared to L/D max at which turbojet and turboprops achieve maximum endurance and range
- Maximum Endurance is the maximum amount of time that an airplane can remain airborne on a given amount of fuel. Minimum fuel flow occurs at minimum Tr for a turbojet and minimum Pr for a turboprop. Maximum Endurance is found at L/DmaxAOA and velocity for a turbojet and at velocity less than L/Dmax, and an angle of attack greater than L/DmaxAOA for a turboprop
- The T-34C max endurance is achieved at 420 ft-lbs of torque
- Maximum Range – the maximum distance traveled over the ground for a given amount of fuel. TO maximize range, you must minimize fuel flow per unit of velocity. Maximum Range for a turbojet is found at velocity greater than L/Dmax and an angle of attack less than L/DmaxAOA. Maximum range for a turboprop is found at L/DmaxAOA and velocity
- The T-34C max range is at 580 fl-lbs of torque