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the reduced part count and assembly costs. The composite parts combined with other design
efficiencies led to reduced fuel consumption- a major attraction for the airlines. Currently the
A300-600 airframe is 4.5% composites by weight.
The weight and manufacturing cost savings for the A300 vertical fin and, subsequently, a carbon
fiber epoxy/honeycomb core sandwich elevator for the A310 had proven so impressive that
Airbus used composite materials for the entire tail structure of the A320. In addition, composites
were also used in the A320’s fuselage belly skins, fin/fuselage fairings, wing fixed
leading/trailing-edge bottom access panels and deflectors, trailing edge flaps and flap track
fairings, spoilers, ailerons, nosewheel/mainwheel doors, main gear leg fairing doors, nacelles,
(SM1) 1-7
interior and carbon brakes. The floor panels were also made of glass fiber reinforced polymer
matrix composites. These composite structures in the A320 airframe, shown in Figure 7, added
up to 5.5 tons, or 28 percent of the total weight.
Figure 7. Composite Materials Applications on Airbus A320
Almost 4.5 tons of composites are used on the A340, a large-capacity, twin-aisle, medium-to-very
long range aircraft. The A340 composite horizontal stabilizer incorporates an integral, loadleveling
fuel tank that permits center of gravity control for best cruise efficiency. Although
composites constitute only about 13 percent of the aircraft’s total weight, the A340 scored a first
in triple type certification by Europe’s Joint Aviation Authorities, the US Federal Aviation
Administration and Transport Canada. The A340-500 and A340-600 prototypes are targeting
addition airframe elements for composites applications. These include the rear pressure
bulkhead, the keel beam, and the fixed leading edge of the wing, which is especially significant
since it involves the first large scale use of a thermoplastic matrix composite component on a
commercial transport. The thermoplastic leading edge offers a 20 percent weight savings with
reduced fabrication time and improved damage tolerance.
The A-3XX design under development is expected to rely on composite structures to achieve the
promised 18 to 20 percent reduction in operating costs- a main selling point for the model.
Composites are envisioned for the entire outer wing, i.e., outboard of the outboard engine, and the
fuselage skins (mainly GLARE) in addition to the tried and tested applications on the previous
models.
(SM1) 1-8
In the US, the most significant use of composites in commercial transports has been on the
Boeing 777. Composite structures make up 10 percent of the structural weight of the B-777.
Figure 8 shows the various composite structural elements used in the B-777. Corrosion and
fatigue resistance with weight savings and improved damage tolerance were the main drivers for
these applications. The composite empennage alone saves approximately 1500 lb over similar
aluminum structure. The composites usage trend for commercial and military (C-17) transports is
summarized in Figure 9. In the case of transport aircraft where cost and reliability are the
predominant factors, composite applications seem to be leveling off at 20 percent of the structural
weight a ceiling lower than for combat aircraft. The barrier in this case is set by the affordability
of the airframe since initial acquisition cost plays a major role in airlines’ selection of a particular
model.
Figure 8. Boeing 777 Composite Usage
(SM1) 1-9
11996655 11997700 11997755 11998800 11998855 11999900 11999955
Composite
% of
Structural
Weight
1100
1155
DC9
747
L1011 MD80 737-300
757 747-400 MD90
767
A300-600 MD-11
A310 777
A340 A330
A320 A321
11 22
3
4
5
A322
3355
2200
3300
DC10
In commercial
transports, cost has
kept composite
applications low
In commercial
transports, cost has
kept composite
applications low
Figure 9. Composite Usage Trends in Commercial Transports and General Aviation
Aircraft
Helicopters
The strength-to-weight advantage of composites is vital to maximizing payload in helicopter
design. Boeing used composites in rotorcraft fairings in the 1950s and manufactured the first
composite rotor blades for the CH-47 helicopter in the 1970s. Composites constitute key
structural elements of the Boeing-Sikorsky Comanche RAH-66 helicopter and the Bell-Boeing
tiltrotor V-22 Osprey. The main design driver for these composite applications is weight savings.
Stiffness tailorability and radar absorbing properties are a significant contributor to these savings.
　
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