Military vs. civilian gas turbine engine divergence

Until 1980s, military pushed engine technology and civilian followed. With the turbofan, civilian engines diverged — supersonic fighters can't use fans, so the dual-use technology pipeline broke. ## Cases mentioned in passing (not developed)

Now, this is a divergence between military engines and commercial engines. Through the 1970s and early 80s, military engines would push the technology, and then the civilians would come along and say, oh great, we'll just take that technology improvement and efficiency and put it on our civilian aircraft. Starting in the 80s, when General Electric and Rolls-Royce and everybody else started looking at this basic concept of, you really want to move the greatest mass of gas — you want this m to be huge, and that's what goes through the fan. The m that goes through the engine itself is a lot smaller. Before, the two m's were the same.