composite mass in 20% of structural mass A320 A340 A310/300 10% A300/600 A A concorde300310 vautour 6% (3.3 tons) 1970 1980 1990 Figure 7.2 Evolution of Mass of Composites in Aircraft composite in of aerodynamic 767 surface 30% 747 757 0 20% 737 10% 727 0 707 0 1960 1970 1980 1990 Figure 7.3 Use of Composite in Boeing Aircraft How to evaluate the gains: In theory:For example,a study was made by Lockheed Company (USA)for the design of a large carrier having the following principal characteristics:payload 68 tons,range 8300 km.This study gives the following significant results: for an aircraft made using conventional metallic construction: total mass at take-off:363 tons mass of the structure:175 tons ■for an aircraft made using“maximum”composite construction: total mass at take-off:245 tons mass of the structure:96 tons. Such a difference can be explained by the cascading consequences that can be illustrated as in Figure 7.4. In practice:In reality,introduction of composites in the aircrafts is limited to certain parts of the structures.It is done case by case and in a progressive manner during the life of the aircraft (re-evaluation operation).One is then led to consider the different notions: 2003 by CRC Press LLC
How to evaluate the gains: In theory: For example, a study was made by Lockheed Company (USA) for the design of a large carrier having the following principal characteristics: payload 68 tons, range 8300 km. This study gives the following significant results: for an aircraft made using conventional metallic construction: total mass at take-off: 363 tons mass of the structure: 175 tons for an aircraft made using “maximum” composite construction: total mass at take-off: 245 tons mass of the structure: 96 tons. Such a difference can be explained by the cascading consequences that can be illustrated as in Figure 7.4. In practice: In reality, introduction of composites in the aircrafts is limited to certain parts of the structures. It is done case by case and in a progressive manner during the life of the aircraft (re-evaluation operation). One is then led to consider the different notions: Figure 7.2 Evolution of Mass of Composites in Aircraft Figure 7.3 Use of Composite in Boeing Aircraft TX846_Frame_C07 Page 140 Monday, November 18, 2002 12:17 PM © 2003 by CRC Press LLC
decrease of empty mass decrease in motor-mass decrease in consumed fuel (minus 33%for the same mission)】 decrease in total mass Figure 7.4 Cascading Effect in Mass Reduction Notion of the exchange rate is the cost for a kilogram saved when one substitutes a classical metallic piece with a piece made mainly with com- posite.For the substitution light alloy-carbon/epoxy-this cost is on the order of $160 (1984)per kilogram when the piece is calculated in terms of rigidity (similar deformation for the same load).It is amortized over a period of at least one year for the gain in "paying passenger." Notion of gain in paying passenger is the gain in terms of the number of passengers,of freight,or in fuel cost;for example,for a large carrier: An aircraft of 150 tons,with 250 passengers consists of 60 tons of structure.A progressive introduction of 1600 kg of high performance composite materials leads to a gain of 16 more passengers along with their luggage. A reduction of 1 kg mass leads to the reduction of fuel consumption of around 120 liters per year. Why are the reductions of mass (average about 20%)not more spectacular? Consider the example of a vertical stabilizer.The distribution of mass of a composite vertical stabilizer can be presented as follows: Facings in carbon/epoxy:30%of total mass Honeycombs,adhesives:35%of total mass Attachments:25%of total mass Connections between carbon/epoxy components and attachments:over- layers of carbon/epoxy Allowance for the aging of the carbon/epoxy:overdimensions of the facings (the stresses are magnified about 10%more for a subsonic aircraft and 13%for a supersonic aircraft) In consequence,the global gain of mass in comparison with a classical metallic construction for the vertical stabilizer is not more than an order of about 15%. Example:European aircraft Airbus A-310-300 (Figure 7.5). 2003 by CRC Press LLC
Notion of the exchange rate is the cost for a kilogram saved when one substitutes a classical metallic piece with a piece made mainly with composite. For the substitution light alloy—carbon/epoxy—this cost is on the order of $160 (1984) per kilogram when the piece is calculated in terms of rigidity (similar deformation for the same load). It is amortized over a period of at least one year for the gain in “paying passenger.” Notion of gain in paying passenger is the gain in terms of the number of passengers, of freight, or in fuel cost; for example, for a large carrier: An aircraft of 150 tons, with 250 passengers consists of 60 tons of structure. A progressive introduction of 1600 kg of high performance composite materials leads to a gain of 16 more passengers along with their luggage. A reduction of 1 kg mass leads to the reduction of fuel consumption of around 120 liters per year. Why are the reductions of mass (average about 20%) not more spectacular? Consider the example of a vertical stabilizer. The distribution of mass of a composite vertical stabilizer can be presented as follows: Facings in carbon/epoxy: 30% of total mass Honeycombs, adhesives: 35% of total mass Attachments: 25% of total mass Connections between carbon/epoxy components and attachments: overlayers of carbon/epoxy Allowance for the aging of the carbon/epoxy: overdimensions of the facings (the stresses are magnified about 10% more for a subsonic aircraft and 13% for a supersonic aircraft) In consequence, the global gain of mass in comparison with a classical metallic construction for the vertical stabilizer is not more than an order of about 15%. Example: European aircraft Airbus A-310–300 (Figure 7.5). Figure 7.4 Cascading Effect in Mass Reduction TX846_Frame_C07 Page 141 Monday, November 18, 2002 12:17 PM © 2003 by CRC Press LLC
vertical stabilizer:Kevlar/carbon/glass number of metal components divided by 20 rudder: Kevlar/carbon flap fairing horizontal stabilizer Kevlar motor mast reinforcement:Kevlar (19 kg instead of 26 kg of metal) air conditioning components:Kevlar. flaps,ailerons,spoilers 29 kg instead of 43 kg in metal main landing gear hatch and fairing disk brakes front landing gear hatch carbon/carbon karman:Kevlar 1.8 kg/m2 radome:glass top of vertical stabilizer(Kevlar/glass) top of the rudder (no carbon to avoid lightning strike) (Kevlar) floors leading edge of vertical stabilizer (Kevlar/carbon /glass) vertical stabilizer edge trusses: (Kevlar/carbon/glass) rudder light alloy:2 kg carbon:800 g (Kevlar/carbon/glass) Karman vertical stabilizer (Kevlar) trailing edge:Kevlar Airbus A-310 vertical stabilizer:the number of components and rivets is divided by 20 in comparison with the classical solution Figure 7.5 Composite Components in an Airbus A-310 ■Total mass:180tons Mass of structure:44.7 tons Mass of composites:6.2 tons Mass of high performance composites:1.1 tons Reduction of mass of structure:1.4 tons ■ Percentage of composites:13.8%of mass of structure.A reduction of mass of the structure of 1 kg augments the range of the aircraft by 1 nautical mile. 2003 by CRC Press LLC
Total mass: 180 tons Mass of structure: 44.7 tons Mass of composites: 6.2 tons Mass of high performance composites: 1.1 tons Reduction of mass of structure: 1.4 tons Percentage of composites: 13.8% of mass of structure. A reduction of mass of the structure of 1 kg augments the range of the aircraft by 1 nautical mile. Figure 7.5 Composite Components in an Airbus A-310 TX846_Frame_C07 Page 142 Monday, November 18, 2002 12:17 PM © 2003 by CRC Press LLC
leading and trailing edge extemal ailerons of vertical stabilizer external spoilers horizontal rudder stabilizer flap rails and covers fairing intemal spoilers floors cabin compartment motor case karman brake disks radome carbon/carbon hatch of landing gear hatch and cover of main landing gear Figure 7.6 Composite Components in an Airbus A-320 Example:European aircraft Airbus A-320 (Figure 7.6). ■Total mass:72tons ■Empty mass:40tons Mass of structure:21 tons Mass of composite materials:4.5 tons,corresponding to a reduction of mass of the structure of 1.1 tons.The percent of composite mass is 21.5% of the mass of the structure. A few other characteristics:Length:37.6 m;breadth:34 m;150 to 176 passengers transported from 3,500 to 5,500 km;maximum cruising speed: 868 km/h Example:European aircraft Airbus A-340 Total mass:253.5 tons Mass of structure:76 tons Mass of composites:11 tons,corresponding to a reduction of structure mass of 3 tons Percentage of composites:14.5%of the mass of the structure Example:Future supersonic aircraft ATSF (Figure 7.7),Aerospatiale (FRA)and Britisb Aerospace (UK).Principal characteristics defined at the stage before the project Transport of 200 passengers over a distance of 12,000 km Cruising speed between Mach 2(2,200 km/hr)and Mach 2.4(2,600 km/hr) 2003 by CRC Press LLC
Example: European aircraft Airbus A-320 (Figure 7.6). Total mass: 72 tons Empty mass: 40 tons Mass of structure: 21 tons Mass of composite materials: 4.5 tons, corresponding to a reduction of mass of the structure of 1.1 tons. The percent of composite mass is 21.5% of the mass of the structure. A few other characteristics: Length: 37.6 m; breadth: 34 m; 150 to 176 passengers transported from 3,500 to 5,500 km; maximum cruising speed: 868 km/h Example: European aircraft Airbus A-340 Total mass: 253.5 tons Mass of structure: 76 tons Mass of composites: 11 tons, corresponding to a reduction of structure mass of 3 tons Percentage of composites: 14.5% of the mass of the structure Example: Future supersonic aircraft ATSF (Figure 7.7), Aerospatiale (FRA) and British Aerospace (UK). Principal characteristics defined at the stage before the project Transport of 200 passengers over a distance of 12,000 km Cruising speed between Mach 2 (2,200 km/hr) and Mach 2.4 (2,600 km/hr) Figure 7.6 Composite Components in an Airbus A-320 TX846_Frame_C07 Page 143 Monday, November 18, 2002 12:17 PM © 2003 by CRC Press LLC
radome temperature:130°C (mach2,05) front cone auxiliary gear hatch main landing gear hatch leading flaps temperature 130C(mach2.05) flaps extemal flap rudder Figure 7.7 Composite Components in a Future Supersonic Aircraft Economically viable for a single type of aircraft on the market (enlarged international cooperation) 7.1.6 Regional Jets Example:Regional transport aircraft ATR 72,ATR (FRA-ITA)(Figure 7.8): ■Total mass:20tons Percentage of composite materials more than 25%of the mass of the structure ■ Transports 66 passengers over a distance of 2,600 kilometers Interior equipment:Facings of panels for portholes and ceiling,baggage compartment,bulkheads,toilets,storing armors in glass-carbon/phenolic resins/NOMEX honeycomb;decoration by a film of "TEDLAR" 2003 by CRC Press LLC
Economically viable for a single type of aircraft on the market (enlarged international cooperation) 7.1.6 Regional Jets Example: Regional transport aircraft ATR 72, ATR (FRA–ITA) (Figure 7.8): Total mass: 20 tons Percentage of composite materials more than 25% of the mass of the structure Transports 66 passengers over a distance of 2,600 kilometers Interior equipment: Facings of panels for portholes and ceiling, baggage compartment, bulkheads, toilets, storing armors in glass-carbon/phenolic resins/NOMEX honeycomb; decoration by a film of “TEDLAR” Figure 7.7 Composite Components in a Future Supersonic Aircraft TX846_Frame_C07 Page 144 Monday, November 18, 2002 12:17 PM © 2003 by CRC Press LLC