“The S-II stage was a nightmare the minute it was conceived, and it only got worse from there. During the course of its creation, it would grind up people and careers the way the transcontinental railway devoured laborers. Though the methods and materials used to build the S-II were reasonably well known, nobody had ever tried to apply them on such a titanic scale. Originally, it was to be somewhere around 8 stores tall with a diameter of 22 feet, but the width ballooned from there to 27 feet before the contract was even signed, then to 30, and finally to 33 feet. And all the while as the size of thing increased, NASA was trimming the allowable weight.” Harrison Storms of NAA.
What went wrong? Even years after the investigators began to sift through the wreckage of Apollo 1 piece by piece, no one could say exactly. But within weeks the general picture became clear: The fire was a disaster waiting to happen.