Boeing's 787 Dreamliner has attracted a lot of attention. Although much of it has been negative, there is often a price to pay in innovation. From delayed delivery to faulty batteries, the launch of the Dreamliner has not been flawless. Regardless, they are getting orders and other manufacturers are taking notes.
That is where a host of alloys based on aluminum and titanium have helped, but they are still relatively dense. Composites seem to be the go-to materials for high strength and low weight. Boeing is on board with that. They've constructed half the 787 from carbon fiber.
Composites have their downsides too. They are typically not as tough under impact and can be difficult to repair. That consideration made it into the design.
Boeing says, "In addition to using a robust structural design in damage-prone areas, the 787 has been designed with the capability to be repaired in exactly the same manner that airlines would repair an airplane today — with bolted repairs. These can be just as permanent and damage tolerant as they are on a metal structure."
Alternatively, airlines have the option to use, "bonded composite repairs, which offer improved aerodynamic and aesthetic finish." These repairs can take significantly longer (~24hr), but the overall maintenance schedule versus metallic components is touted as being lower.
Carbon fiber construction leads to reduced routine and nonroutine maintenance through two major factors: corrosion and fatigue. Corrosion of ceramic and polymeric materials tends to be less rapid than metallics, and catastrophic failure by cyclic stressing (fatigue) of components is also less of a risk.
As described by Boeing, "Airline operators are aware of the fatigue cracking and corrosion difficulties experienced with traditional aluminum floor beams. The 777 model has been flying for more than 10 years with more than 565 airplanes in the fleet and to date has not replaced a single composite floor beam."
Another benefit is the reduction in assembly. Boeing states that the single-piece carbon fiber structure of the fuselage, "eliminated 1,500 aluminum sheets and 40,000 - 50,000 fasteners per section."
With these sorts of benefits, it is understandable the companies like BMW want to partner with Boeing on carbon fiber development. This scale of carbon fiber construction is not without its hiccups though. For instance, the delivery of the jets was delayed multiple times because of concerns about structural flaws. In October, there was an incident of a panel falling from the fuselage during flight.
More efficient and more reliable travel is being made possible through a growing depth of composite research. Applying new technology on a grand scale is never perfect. Despite the barriers they had to overcome, Boeing is pushing aviation engineering to new heights.
To help envision the scale of the manufacturer used in the Dreamliner, below is a short video showing the carbon fiber construction process.
Images courtesy of Boeing