Using the software, the design team was able to sort through the 20 design candidates quickly to find the one with the most optimized radar cross section.

The diamond-like look of the design was largely dictated by the limits of the computing hardware of the day. "Some of the mathematics were being done on slide rules still, and a PDP-8 and other like computers, so yeah, computer limitations really kept the shaping down," Burnett told Ars. "We were just really beginning to understand the mathematics of the physics that govern this technology."

I have a couple of pieces of a wrecked SR-71 Blackbird, [#SR-71A (61-7953 / 2004)".] They were considered pretty stealthy back in the day.

I thought someone called me.

Tiny little pieces. One servo motor, and one 4 inch square piece of hexagonal cell bodywork.

I could probably just get the blueprints from wikileaks if I wanted to.

I found the pieces in 1998, almost 30 years after it crashed. I bet the spooks thought they had cleaned the site pretty well.