In article , miket6065 wrote:
I remember reading that the IR sensors on the Eurofighter Typhoon can pick
up icebergs against the cold of the sea!

Wouldn't that be against the warmth of the sea? Or is the sea colder (due
to salt?)

However I also remember reading that the IR sensors on the MiG29 has a very
limited range, just a very few miles maybe less than 10.

Based on these two comments a Stealth fighter can be picked up but you must
be extremely close to do so. IR sensors by themselves don't seem to be the
best way to find these aircraft.

An IR sensor on the front of a missile might have a frontal diameter of 100 mm;
if it was made bigger, it would be able to detect more incoming IR light, and
detect further out, presumably? If you double the diameter of the front lens,
can you detect aircraft twice as far out?