> Revolutionary jets like the SR-71 or the 747 took months to design. Yes, and without computer assisted modelling, when they wanted to try out something - say

> Revolutionary jets like the SR-71 or the 747 took months to design. Yes, and without computer assisted modelling, when they wanted to try out something - say, reducing trim drag by moving the center of gravity further aft - they had to just try it out in the field. That experiment killed one pilot, and it's a miracle the other survived. What caused that death? Engine unstart. Why was unstart a problem on the SR-71? Because its analogue computers couldn't always keep up. All in all a spectacularly bad example, CAD would have saved lives, and despite his ranting it DID have a computer on board, and when that was replaced with a digital computer system it increased the reliability and safety of the plane. Here's the story from the survivor if anyone's interested: http://www.alexisparkinn.com/sr-71_break-up.htm http://www.alexisparkinn.com/sr-71_break-up.htm