A 1960s lift-fan fighter would need intensive pilot control

Could 1960s technology have produced an early F-35-style lift system for a supersonic Harrier successor?

The propulsion idea was theoretically possible, but limited control electronics would demand heavy pilot intervention and make the aircraft unlike a normal Harrier.

A lift-fan arrangement resembling the F-35's was theoretically possible with 1960s machinery. The harder problem was control, because contemporary electronics lacked the processing power used to coordinate a modern vertical-landing system. A pilot would have to manage much more of the transition directly. The Soviet Yak-38 Forger shows that separate lift engines were feasible in that period, although the resulting aircraft would not behave like a Harrier. Supersonic performance would therefore require a difficult propulsion and control program rather than a simple change to the historical Harrier.