Propulsion Systems Major US Airline Year 2000 Operating Costs Cost per ASM = 9.75 ￠ Aircraft Fuel Engine Maint. Material & OSR 2% Engine Ownership Salaries 3% 40% Airframe Ownership 10% Airframe Maint. Material &OSR 2% Landing fees and other rents 5% Passenger service 3% Other 13% 13% Selling expenses 9% "Other" includes contracted services, asset write-downs, other non-recurring items -20% -15% -10% -5% 0% 5% 10% 15% 20% 25% 30% -15% -10% -5% 0% 5% 10% 15% 20% 25% 30% 35% 40% 45% Relative Cash DOC per Trip Relative Cash DOC per Seat Airplane Operating Cost Comparison Three Class Seating 3000 nm Trip Se a t s = C o n s t a n t GOAL - 1 0 % Current State-of-Art I n c r e a s i n g S e a t s Typical Engine-Related Airline Cost Breakdown 33% 13% 54% Initial Cost (List) Maintenance Cost Fuel Cost 777-200ER/PW4090 $0.75/gal Fuel Price Thrust Sizing Requirements Y Limit TOGW T/W W/S X Limit ? Number of Engines ? Aircraft Max Take Off Gross Weight ? Take Off Field Length ? Time to Climb ? Cruise Altitude and Mach Number ? Lift to Drag of Wing ? Aircraft Potential Growth Basic engine relationships Thrust = (Velocity of exhaust - velocity of aircraft) Mass Overall engine efficiency = K thermal X K propulsive Overall Engine Efficiency Includes Two Processes: Energy Conversion and Thrust Production Gas Generator Available Propulsion Energy Fuel Input K overall = Kthermal X Kpropulsive Thermal efficiency measures the process of converting chemical energy of the fuel into energy available for propulsion - Function of overall pressure ratio and component efficiencies - h s Current engines at 40:1 overall pressure ratio Future engines at 60:1 overall pressure ratio Propulsive efficiency measures the process of converting energy available for propulsion into useful propulsive power Gas Generator Gas Generator Turbofan or Turboprop Gas Generator Kpropulsive 100% as Vexhaust Vo Lower specific thrust is fundamental to improving fuel economy goodness Fuel economy Drag/thrust Engine efficiency Weight/thrust Specific thrust (lb /lb mass) Increasing bypass ratio Commercial Turbofan