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Originally Posted by Bring_Back_Shantz
I wouldn't be too sure about that, especially on an industrial scale.
Carbon fiber is a lot easier to transport than aluminum, so you instantly get a savings on transoprtation of raw materials. Plus no matter what shape you are making the process is basically the same. The more complex of a shape you start to make with aluminum, the more steps you need and the more it costs to produce the part.
Plus, aircraft grade aluminum, isn't exactly the cheapest material around either.
I'd be willing to bet that a company using the ammount of material that Boeing would, can get some pretty good cost reductions.
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I'm pretty sure the use of carbon fibre in such an immense application would be more expensive than aluminum. One of the biggest issues in the aerospace industry is safety testing and validation. After using aluminum for decades the aerospace safety codes are well established and the methods of manufacturing aircraft are very sound. To use ANYTHING in the aerospace industry requires a lot of testing and validation, which was one of the stumbling blocks for carbon fibre being used in passenger aircraft.
As for total cost - for simple shapes I imagine aluminum would be immensely cheaper to use than carbon fibre. Carbon fibre is much more complicated to use due to requirements of multiple layers, directionality of fibres, stress concentrations, and requirements of resin impregnation into the weave. One of the issues one of my composites professors emphasized during his lectures is the complexity of removing the windows from a solid carbon fibre fusalage. If you have the entire body of a jet made of wrapped carbon fiber, cutting the windows out will be more complex.
The use of carbon fibre is driven by weight reduction, which decreases fuel consumption and allows for greater efficiency. I would be willing to bet that the carbon fibre construction is more expensive than traditional aerospace aluminum. Plus.. the fatigue properties and behaviours of carbon fibre are not nearly as well understood as aluminum.
As a side note - we used carbon fibre to make body panels, cooling ducts, and the seat for our Formula SAE car at the University of Waterloo, and the cost of the carbon cloth itself went up considerably in price and was much harder to get due to, what our distributor described as "a global shortage due to skyrocketing use by the aerospace industry". I'm pretty sure the costs to make these jets are extremely high.