2.7 Table 1.2 gives weights of the New Efficient Aircraft. The reserve fuel, approximated as 4% of take-off weight, may effectively be added to the empty weight. The mass of fuel actually burned over the entire flight, the block fuel, with maximum payload and maximum take-off weight is mivel = 27.6 tonne. As reasonable approximations, the fuel burned during take-off and climb is 2% of take-off weight, and during climb the aircraft travels 160 nm. Likewise during descent, it may be assumed that fuel equivalent to 0.2% of take-off weight is burned and the aircraft travels 130 nm. a Find the aircraft mass at beginning and end of cruise for maximum payload and maximum take-off weight (i.e. conditions to give range R1). (Ans: 171.5 tonne; 147.8 tonne) b Use the Breguet equation to estimate the range R1 for the cruise sector of the flight of the NEA for maximum payload with maximum take-off weight. Then find the total distance travelled. (Ans: 2896 nm; 3186 nm) Part 1: Design of Engines for a New Efficient Aircraft . 30 rose the Breguet equation again to estimate the cruise range of the NEA if payload is reduced so that no freight is carried but only the maximum number of passengers, 280, each estimated with baggage to weigh 95 kg. (First find the fuel available to be burned and thence the ratio of mass at beginning and (Ans: 4801 nm; 5091 nm) d Estimate the fuel-burn metric, kg-fuel/ATK (.e. kg-fuel/tonne-kilometre) for cases b and c. (Note: The range calculated here for the NEA is some 6% higher than was deduced from the Stanford il (Ans: b. 0.116 kg/ATK; c. 0.165 kg/ATK) University code pass used to design the NEA. Breguet is an idealisation which will always overesti- mate range if His correct, so this is not altogether surprising. Applying the same Breguet approach to the 787-8 gives a range of 6082 nm, including distance travelled in climb and descent, about an 11% 12 Part 1: Design of Engines ru. overestimate.) Table 1.2 A comparison of the New Efficient Aircraft with two modern large, two-engine aircraft Boeing 787-8 Airt A350 NEA 2011 Entry into service 242 2014 315 5900 47 268 13: 6 Normal max. passengers Range at max. payload, R1 (nm) Max. payload Max. take-off weight Empty weight Fuel burn at R1 Fuel burn per nm at R1 Cruise Mach no. Cruise L/D Engine sfc (kgh-'kg-1) Wing span (m) Wing area (m) 2020? 280 3000 40.2 175 100 27.8 9.2 0.78 21.6 0.50 60 304 25 1 5500 40.2 228 122e 60 10.9 0.85 21e 0.52e 60 325 32 21 44 32 Wing sweep Weights in tonne (103 kg), range in nm; 'e' indicates estimate. R1 is maximum range at maximum payload, 2.7 Table 1.2 gives weights of the New Efficient Aircraft. The reserve fuel, approximated as 4% of take-off weight, may effectively be added to the empty weight. The mass of fuel actually burned over the entire flight, the block fuel, with maximum payload and maximum take-off weight is mivel = 27.6 tonne. As reasonable approximations, the fuel burned during take-off and climb is 2% of take-off weight, and during climb the aircraft travels 160 nm. Likewise during descent, it may be assumed that fuel equivalent to 0.2% of take-off weight is burned and the aircraft travels 130 nm. a Find the aircraft mass at beginning and end of cruise for maximum payload and maximum take-off weight (i.e. conditions to give range R1). (Ans: 171.5 tonne; 147.8 tonne) b Use the Breguet equation to estimate the range R1 for the cruise sector of the flight of the NEA for maximum payload with maximum take-off weight. Then find the total distance travelled. (Ans: 2896 nm; 3186 nm) Part 1: Design of Engines for a New Efficient Aircraft . 30 rose the Breguet equation again to estimate the cruise range of the NEA if payload is reduced so that no freight is carried but only the maximum number of passengers, 280, each estimated with baggage to weigh 95 kg. (First find the fuel available to be burned and thence the ratio of mass at beginning and (Ans: 4801 nm; 5091 nm) d Estimate the fuel-burn metric, kg-fuel/ATK (.e. kg-fuel/tonne-kilometre) for cases b and c. (Note: The range calculated here for the NEA is some 6% higher than was deduced from the Stanford il (Ans: b. 0.116 kg/ATK; c. 0.165 kg/ATK) University code pass used to design the NEA. Breguet is an idealisation which will always overesti- mate range if His correct, so this is not altogether surprising. Applying the same Breguet approach to the 787-8 gives a range of 6082 nm, including distance travelled in climb and descent, about an 11% 12 Part 1: Design of Engines ru. overestimate.) Table 1.2 A comparison of the New Efficient Aircraft with two modern large, two-engine aircraft Boeing 787-8 Airt A350 NEA 2011 Entry into service 242 2014 315 5900 47 268 13: 6 Normal max. passengers Range at max. payload, R1 (nm) Max. payload Max. take-off weight Empty weight Fuel burn at R1 Fuel burn per nm at R1 Cruise Mach no. Cruise L/D Engine sfc (kgh-'kg-1) Wing span (m) Wing area (m) 2020? 280 3000 40.2 175 100 27.8 9.2 0.78 21.6 0.50 60 304 25 1 5500 40.2 228 122e 60 10.9 0.85 21e 0.52e 60 325 32 21 44 32 Wing sweep Weights in tonne (103 kg), range in nm; 'e' indicates estimate. R1 is maximum range at maximum payload