Is the SEPECAT Jaguar's design aerodynamically inferior to more modern jets?
Only aerodynamics? Then the answer is simple: It lacks artificial stability.

In a paper by Ray Whitford on fighter design he published a comparison study between the conventional Jaguar and an advanced version optimised for relaxed static stability. The improved version is slightly unstable at subsonic speeds and much less stable at supersonic speeds, resulting in much less horizontal tail downforce and reduced size of all lifting surfaces.



Both configurations have the same airfield and combat performance! However, the smaller surfaces and the reduced trim drag improve performance noticeably. Note that this optimization was for the ground attack role; an optimized fighter version would had maintained a larger wing and horizontal tail for higher agility.