This isn’t really surprising:

The SR-71 Black Bird is truly a wonder of engineering. You can tell that’s the case just by looking at it even if you have no prior knowledge of aviation. The way it looks just screams “radical design.”

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Designed in part by Clarence “Kelly” Johnson for Lockheed and its secret division called Skunk Works, this bird was years ahead in innovation.

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That’s the point of this article. It had to be thought through. In the early 60s no computers existed that could render or even come close to computing how this aircraft should be built. It was all done on drawing boards with pencils, rulers and protractors (if you remember what any of these are.) That’s one incredible feat if you think about it.

What’s even more incredible is that in the 2000s this design was ran through a sophisticated computer program used to design planes. You’re talking about thousands of rivets, angles of the fuselage and about a million other factors that this computer checks for.

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The end result? The computer wouldn’t do anything different. The design is as efficient as it could be. It was perfect.

I might have expected some minor redundant elements to be identified in the computer model, but not much else. The purpose of computer-aided modelling is not to give you a different design as one worked out by hand, but to make that process of working out quicker and easier to visualise. The underlying engineering principles – bending moments, second moments of area, allowable stresses, material properties, etc. – on which the manual calculations and drawings are based would have been programmed into the computer software: the computer isn’t making any decisions, it is merely performing hand calculations very quickly and in vastly greater quantities. The SR-71 engineering team would have performed all necessary calculations by hand and scrutinised the whole design to eliminate any redundancy, seeing as the design was so close to the edge in what was feasible. You’d be far more likely to find a bog-standard 1950s motorway bridge to differ from a computer-modelled version because there wouldn’t be as much pressure to optimise the design. It’s a matter of resources and time/economic priorities, not capability.

People seem to think that computers, when executing calculations, can do what humans can’t. Presumably they wouldn’t expect a result calculated by an Excel formula to differ from a hand calculation, so I’m not sure why we’d expect engineering calculations to change once the forumlae are calculated by machine instead of on a piece of paper.

(On the subject of the SR-71, this is an awesome little story.)