I'm reading about the AIM-9 Sidewinder Missile again. I noticed this interesting photo:
Notice, that's a piston-engined aircraft, and a small one at that. So I'm asking myself, how did the missile lock onto it? The AIM-9 is a very early heat-seeking missile (~1956). I thought early heat-seekers could only lock onto a jet engine, which I believe has a much larger heat signature than a piston engine.
Now I know today that IR missiles can lock onto almost any heat signature, even the heat of the adiabatically compressed air at the wings' leading edge. But in 1956, I'm surprised that an IR missile could lock onto a piston engine's heat.
So I want to start with this question: What is the heat signature of a piston engine, in terms relative to a jet engine? 2x less? 3x less? Or somehow equivalent?