[Alastor Mobius Toth]

F-16 is physically smaller than F-14/15. So it *can't* be a heavy. It's logic.

As for TSF lifespan, it depends on how you look at it.

Operation-wise, TSF models seem to have less than 5 or so, given the technical advances. For example, MiG-27 was already outdated when it was produced, and Type-94 was getting outdated (by Japan's criteria anyway) by 2001 (which gives it around 7 years of operational life).

That said, most American and Soviet designs are generally pretty accepting or retrofits, meaning that F-15 get to live on as Strike Eagle, Silent Eagle and Active Eagle, all of which are superior to F-15C.

To summarize, most individual models will, generally, not last past the decade. However, the frames themselves can remain in use for longer, if they can be modified.