Aluminum vs. steel material cost ratio

So there are a lot of different designs that people fool around with. There's a reason why we can spend more money in aluminum. Anybody know, those of you that took class last semester? It's lighter, but it's also more expensive. Aluminum is about five times the expense of steel, so they're always more expensive structures, okay. You can afford to spend more time worrying about the joints, because you've got apparently more stress. Remember I talked about the value of a pound saved? In automobiles, two dollars a pound; in aircraft, $200 a pound; in spacecraft, twenty thousand dollars a pound. Aluminum structures are five times the cost per equivalent volume or size as steel, and therefore you can fool around a little more with forming or machining your edges and prepping them, and you need to.