If composite propellants are so much better, how come guys in the 1950s and 60s didn use them?
Simple. They did not know about them as the composite propellant formulations were classified by the U.S. Government. During that time period, the United States was locked into a “Cold War” with the Soviet Union. A race was on to develop ICBM’s on both sides with the United States using composite solid rocket propellants. In the 1970’s and 1980’s, information about formulating composite propellants was declassified and published in various textbooks. Once amateurs had access to this knowledge, they switched to the composite propellants for safety and higher performance.
