The latest American warplanes, the F-22 and F-35, are often called "5th generation" fighters. This leaves many readers wondering what the other generations were. The first generation of jet fighters were developed during and right after World War II (German Me-262, British Meteor, U.S. F-80, Russian MiG-15.) These aircraft were, even by the standards of the time, difficult to fly and unreliable (especially the engines). The 2nd generation (1950s) included more reliable, but still dangerous to operate, aircraft like the F-104 and MiG-21. The 3rd generation (1960s) included F-4 and MiG-23. The 4th generation (1970s) included F-16 and MiG-29. Each generation has been about twice as expensive (on average, in constant dollars) as the previous one. But each generation is also about twice as safe to fly and cheaper to operate. Naturally, each generation is more than twice as effective as the previous one. The Russians are still working on their 5th generation, although some of the derivatives of their Su-27 are at least generation 4.5. One of the reasons the Soviet Union collapsed was the realization that they could not afford to develop 5th generation warplanes to stay competitive with America. The Russians had a lot of interesting stuff on the drawing board and in development, but the bankruptcy of most of their military aviation industry during the 1990s has left them scrambling to put it back together ever since. At the moment, the Russians are thinking of making a run for the 6th generation warplanes, while will likely be unmanned and largely robotic.