At an early stage of the fighter's development
it became obvious that the MFI was a
lot different from the American fifth-generation
fighters. For instance, the Mikoyan fighter
had a variable ventral air intake from the
start, whereas the F-22 had non-adjustable
two-shock lateral intakes optimised for supersonic
cruise and the rival Northrop/General
Dynamics YF-23 had non-adjustable dorsal
intakes. Soviet aerodynamicists believed a
ventrally located intake offered certain
advantages during vigorous manoeuvres,
minimising the danger of an intake stall during
high-G turns and high-alpha flight. Also,
the tail-first layout maximised lift and the
canards performed a pitch damping function
at critical AoAs. By comparison, the F-22 and
YF-23 utilised a more conventional layout
with trapezoidal wings and stabilators.
