The Army's 30-ton ENIAC (Electronic Numerical Integrator and Computer), introduced in 1946, could solve the "basic" aerodynamic problem around designing shells in 130 hours. That seems perhaps a bit sluggish by today's standards, but when you consider that any other existing machine at the time would have needed at least a year to solve the problem, and even several lifetimes wouldn't be enough time for a human to do it, ENIAC represents a giant leap forward in computing.
Inventor John W. Mauchly realized the need for such a computer when he was slogging through mounds of geophysical data for his research. Once it was built, the data-crunching monster took up the entirety of a 30 by 50-foot room that had to be ventilated to siphon off the heat produced by its 18,000 electronic tubes.
Read the full story in Lightning Strikes Mathematics