May 11, 2004
Earthworms and Earthquakes
Don Boudreaux ( yes, yes, I know I link to him a lot. That's because it's a great blog at Cafe Hayek. ) compares and contrasts the differences between the modest incremental changes brought by market economies and the paradigm shifts that we all want to see but so rarely do. Those modest changes are compared to the activity of earthworms as they overturn the soil, as noted by Darwin ( what was, in his youth, "The Stony Field", was in his old age smooth pasture, the activities of the worms over the years burying the stones ) and the paradigm shifts to earthquakes.
Just to use this as a peg upon which to hang today's gratuitous scandium reference we have two examples in the day job, The Low Hanging Fruit Company ( motto " Scandium, It's Rocks!").
Adding scandium to aluminium alloys provides a number of benefits and you'll have seen the bike frames and baseball bats made out of this stuff ( yes, we have or do supply all of those manufacturers ) .
If you add it to the alloy that makes wings for aeroplanes, there is one little benefit. As it does not oxidise, you do not need to paint or lacquer the wing surface, thus saving 1 - 2 % of the total weight of the plane. Yes, this is aerospace, so it takes a decade to get a new alloy into the market but that 1 - 2 % fuel saving on every single flight is coming to you from both major manufacturers in the next few years. Think of this as one of those earthworm moments.
There's also another benefit, one that seems to be driven by a groups of British scientists. When you weld steel, the weld is stronger than the surrounding plate : you expect the actual piece of steel to bend or break before the weld. With aluminium, the weld is the weak spot. However, if you add scandium to both the weld wire and the plate, hey presto, the weld is stronger than the surrounding alloy. This opens up the possibility that in a decade's time we will stop using rivets in aircraft : we'll simply weld them together. That in itself would save a massive 10 % of the weight of an aircraft. Think of that as the earthquake.
The extra cost on a 160 tonne Jumbo would be around $700,000 at today's prices for scandium. Right, $ 700,000 extra on a $ 100,000,000 dollar bird, and we save 10 % of the fuel on every single flight.
Time for a little blegging : I'm looking for $ 5 million to build a new scandium extraction plant : the tip jar's over on the right somewhere.
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Strange this scandium stuff. In 40 years in the aircraft I've only heard of the stuff used in guns. There are no current commercial airplane applications using scandium/aluminum alloys. It's hard to believe that it doesn't oxidize. Can somebody give me some mechanical data for the alloy(s)? Next, we don't weld aircraft structure. Contrary to your premise, welded structure (i.e. cast, annealed structure)is far weaker (tensile and fracture toughtnes-wise) than wrought materal and it's also much harder to guarantee that the welds are perfect. Basically, aircraft will never be welded. They may be bonded however..
Best regards, Mike B
Posted by: Mike B | Sep 8, 2005 7:55:32 PM