First lets discount the remark concerning the last 30 years. The Tornado, F16, F18, F18 etc were all initially designed back in the 70s - if not the late 60s.
Early jet engines were weak so a single engined fighter (Vampire, Sea Hawk, A-4 etc) had to be relatively small, light weight and short range. No real problem for short-range agile IDF or FBA aircraft, but longer range aircraft needed 2 engines.
Early engines were also unreliable so single engined aircraft were lost a far higher rate, the expense of having and running 2 engines was offset by not losing so many. It also helped that, over the ocean, you tended to get the crew back - which is why the RN and USN liked them. Which explains the Buccaneer, F-4, F-14, A-6, A-5 etc.
Engine power improved, as did reliability. The F-16/F-18 fly-off probably marked the point where the improvement made the loss rate etc acceptable - at least over land. Hence the USAF going for the F-16 and the USN for the F-18.
At the top end where you want high performance the thrust of two engines still win. Which is why the Typhoon, Rafale, F-22, SU-30 etc have two. For bomb trucks where, apart from TO and landing, you want low fuel burn, a single engine will probably now win out, though I don't know anyone building one apart from the Gripen.
I say that because the F-35 design is driven by the STOVL requirement which pretty much ruled out two engines from the start.
I am surprised the Russians haven't built a NG Mig-23/27 replacement. There must be a market for it.
Last edited by ORAC; 31st Jan 2008 at 11:03.