To add-on to what other members had stated.
The F-20 was actually a 'by-product' of the Carter administration's
policy of not arming friendly nations that are not cleared to
receive top-of-the-line US fighters (esp F-16s). This is part of
the reson why the F-5 series is so successful in sales.
And given the large no. of F-5 users wordwide, Northrop had
calculated that the F-20 (given its superior performance over the
original F-5 series, it was decided to tag the much-improved F-5
the 'F-20' rather than upped it as another F-5G/H++) would easily
scooped up by these users as a natural F-5 replacement.
Reasons why the F-20
failed (internationally):
a) The Reagan Adminstration do not share the same qualms with the
Carter Adminstration over the restriction of the export of top-of
the-line fighters (F-16) to US-friendly nations and naturally gave
the 'green light' for these nations to receive standard US fighters
rather than lower-end fighters (but this doesn't mean this fighters
are not good).
b) The home user (USAF) was not a user of the F-20 (nations tend to
see what the US itself uses. This equally meant that any aircraft
that is used by the US itself, could meant that the aircraft is not
good. Who would want to buy that?).
Therefore realising this non-US use handicap, Northrop submitted
the F-20 to a USAF fly-off competition (in the mid/late 1980s)
against the F-16 for a follow-on order (to add on to an earlier
order of the F-16).
Reasons why the F-20 lost
to the F-16 in the fly-off:
a) While acknowledging the F-20's performance, the USAF is not
ready to introduce another air-to-air fighter whose role are
fulfilled by the F-16 already.
Alternative
Nevertheless, the F-20 was shown off to some nations:
a) South Korea: The F-20 was shown to the South Korean top brass
but the F-20 crashed during the demonstration!
b) Bahrain : Ordered 8 x F-20s. But the number is too small to
justify/start the production line.
c) Taiwan: Northrop had thus tried to sell F-20 tools to the ROCAF.
Reasons failed I'm not too sure but could be that time, the
Taiwanese is either interested in the F-16 or thinking of
developing a indegenious figher ( the Ching-Kuo?)
Subsequently, some F-20 parts did find it's way into some these
nations. Noticeably the shark-nose radome of the F-20 onto the
original F-5 radomes.
Look around if you don't believe me.
This is what I know, hope it helps.
