In message , Alan Minyard
writes
AIM 9s at recips?? I doubt if you would ever get a tone.

Certainly would. Even the original seeker (uncooled lead sulphide,
really basic) would track a flashlight or a lit cigarette, and the
exhausts and propellers of 900hp recips are *hot*. By the time you're up
to AIM-9L or thereabouts, you should be able to get a workable
acquisition on a reciprocating engine unless the background clutter's
hateful (and this would be over ocean, in good weather, with the
attacker choosing altitude and aspect at leisure)

--
He thinks too much: such men are dangerous.
Julius Caesar I:2

Paul J. Adam MainBoxatjrwlynch[dot]demon{dot}co(.)uk