DBEA55AED16C0C92252A6554BC1553B2 Clicky DBEA55AED16C0C92252A6554BC1553B2 Clicky
June 17, 2024
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Alcoa announced today that it is expanding its aluminum lithium (Al-Li) capacity and capabilities at three locations to meet growing aerospace demand for its newest alloys.  These alloys, introduced last year and now patented, allow OEMs to build dramatically lighter and lower-cost airplanes compared to composite alternatives.

This news is important when looking at what OEMs are doing developing ever lighter airplanes.  Airbus (A350) and Boeing (787) have selected the CRFP route whereas Bombardier has gone the Al-Li route for its CS. Alcoa believes its product offers less risk to OEMs than CFRP.  While CFRP is well known in military use, it has been used less on commercial airplanes until quite recently.

ALCOA further states that its new technologies:

  • lower the weight of an airplane by up to 10% vs. composite-intensive planes;
  • lower the cost to manufacture, operate and repair planes by up to 30% vs. composite-intensive planes, and at significantly lower production risk;
  • allow for a 12% increase in fuel efficiency, on top of the 15% from new engines; and
  • deliver passenger comfort features equivalent to composite-intensive planes, such as higher cabin pressure, large windows and higher humidity.

The last two items deserve special attention. Offering this much in fuel savings is highly significant and then being able to allow for larger windows (like on the 787) and better cabin pressure/humidity is compelling.


9 thoughts on “Al-Li an alternative to CFRP

  1. Maybe this material will work for B in it’s 777-8/9X models. Especially for the former, which would be a 772ER replacement. As I understand it, the 772ER fuselage is much heavier than the A359’s and therefore at a substantial disadvantage. B might be able to get great prices from Alcoa if they were the “launch” customer for this metal .

  2. An interesting “rerun”. In the early 1990’s, General Motors launched Saturn with a mostly plastic body (including considerable recycled plastic content) espousing the economy of being able to quickly change body styles at a fraction of the cost of steel. The steel industry responded by working with the automakers on much lower cost and quick-change die technology, and now we can count how many pastic cars vs. steel are running around. Maybe CFRP fuselages will see the same reversal after 787/350….

  3. When Boeing designed the original 777 they took a close look at Al-Li. They rejected it because the overall cost and material properties were not worth the change over traditional aluminium. The result is that today the 777 flies around with less than 400 pounds of that alloy.

    But that was more than 20 years ago. Since that time the oil price has gone up and the Al-Li alloys that are offered today are more attractive because the material is more mature in its development. Enough so for Airbus to have selected it as the primary fuselage material on the first A350 incarnation. But in the end the market pressures were so high on Airbus that they had to change the design and they selected, more or less against their will, CFRF panels for the fuselage.

    So Airbus was more or less in the same position as Boeing was when they designed the 777, and just like them they initially made the more conservative choice. Only the market forces were much different in 1990 than what they are today. The market needs a high profile application of Al-Li, but on something considerably bigger than the CSeries, in order for this exotic alloy to be perceived as a viable alternative to CFRP.

  4. Interesting analogy. If you are interested, Guy Hachey would probably have a job for you. 🙂

  5. I think everyone missed one of the biggest advantages of CFRP, it doesn’t corrode and it has much longer fatigue life. On the negative side, Boeing may have just built an airplane that eventually puts them out of bussiness.

  6. That CFRP does not corrode is a well known fact among those working in the aerospace industry. But it’s true that the longer fatigue life is not as widely recognized. Anyway, those two characteristics did not escape the airline industry and that is reflected in the huge 787 and A350XWB backlogs. It is also what was behind the pressure on Airbus to make the switch from Al-Li to CFRP.

    It may take a long while for us to find out if that was the right choice and if it was implemented the right way (panels vs barrels). It is a complex issue and we have little experience designing and manufacturing large fuselages out of CFRP. We don’t have much more experience with Al-Li either. As far as I know the CSeries will be the first application of Al-Li for the fuselage.

    In regards to CFRP it is indeed largely expected that there will be a major reduction in maintenance costs over aluminium alloys. But corrosion is only one factor, although a very important one, to consider among several others. First there is no such thing as a 100% CFRM design. There will always be some metallic structural elements incorporated into the design. Also, there is a requirement for additional lightning protection because CFRP is not naturally conductive. How easy, or difficult, will it be to maintain a safe level of conductivity over the lifetime of the aircraft? The structural repair methods are still not well developed either because we lack field experience. What will happen in the event of a tail strike, or heavy landing, or ground equipment repeated impacts? How do we asses the damages? And how do we carry inspections?

    Now, THE BIG QUESTION: What is the actual weight saving when compared to Al-Li? And its corollary: At what scale, and for what applications, is CFRP better suited, 737 capacity or 777? Medium-haul or long-haul?

    It could be that CFRP will meet all the initial expectations. In which case it would indeed be a miraculous material. That is what many airlines have bargained for from the start and they will be the first ones to tell us if it was too good to be true.

  7. @ alloycowboy

    “Boeing may have just built an airplane that eventually puts them out of business.”

    That is a major statement, to say the least. But I am afraid I cannot contradict you on that. I just hope we are both wrong.

    Regards, Normand

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