I am not sure if this question is appropriate for this SE - Ideally this should be posted in Engineering SE but as far as I'm aware it does not exist! (I can only assume that the scope of engineering is far too broad for one sub-domain.)
In the 1960s and 70s computers such as the CDC-6600, and its successor the CRAY-1, were considered the pinnacle of computing power. Now, in my understanding of computers and FEA/CFD etc., the power of these computers (60-80MHz-ish) would be nowhere near powerful enough to perform FEA/CFD calculations within realistic time frames and to a reasonable degree of accuracy.
So what tools did NASA, and other entities with similar requirements (be it in construction, automotive, aerospace industries), use to perform their stress analysis, aerodynamics, engine fluid flows, pressures etc. before constructing and indeed launching their vehicles (, implementing their designs in general)?
As an engineer I can appreciate the importance of these steps in a design process so I'm truly stumped.