The U.S. Navy has solved an aircraft trainer shortage, by constructing "new" aircraft from the parts of older ones. Needing two-seat F-5F fighters to train pilots, and the current ones too old to fly anymore, navy mechanics found that by taking second hand, single seat, F-5Es they could merge enough parts from both to produce a new "Frankenfighter" that had two seats and were safe to fly for another thousand hours or so. The navy now has three of these two seat Frankenfighters. There are used to train pilots for the 40 single seat F-5Ns (refurbished F-5Es that represent the bad guys) used for fighter training.
The U.S. F-5 fighter was designed (in the late 1950s) and built (until 1972) largely to compete with the Russian MiG-21, and sold to many U.S. allies as a low cost alternative to the more expensive fighters used by the Americans. The only F-5s used by the United States were for training. F-5s had many of the same flight characteristics of Russian and Chinese aircraft. While over 2,200 were built, most have now been scrapped. Spare parts are often obtained by buying F-5s from someone who is replacing them with more modern aircraft.
The U.S. is not the only one to go Frankenfighter on the F-5. Three years ago, Iran showed off a modified American F-5 fighter and proclaimed this new "Saegheh" as similar to the American F-18 jet fighter. This is not the first time Iran has run a stunt like this. But even with a redesigned tail and better electronics, the 1960s era F-5 is still a low cost, and low performance, aircraft. The F-5E, which the Iranians had when the Islamic revolution took over in 1979, is an 11 ton aircraft, with a max speed of 1,700 kilometers an hour, and a range of some 1,400 kilometers. It was armed with two 20mm cannon, and could carry about three tons of missiles and bombs. The Iranians have taken the basic F-5 frame and rebuilt it to hold two Russian engines. The Chinese did the same thing, and produced the J-8 (a twin engine MiG-21) that turned out to be not worth the effort.