effectiveness of infra red sensors at detecting aircraft

How effective are infra-red sensors, such as those on some anti aircraft
missiles, at detecting aircraft? Stealth aircraft are, I imagine, harder
to detect, but by how much?

Also, is there a simple rule-of-thumb relationship between how fast an
aircraft is travelling and how much air friction heats it up (and therefore
how much infra red radiation it gives off)?

I remember reading that the IR sensors on the Eurofighter Typhoon can pick
up icebergs against the cold of the sea!

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.

MikeT

Fe wrote:

snip
Also, is there a simple rule-of-thumb relationship between how fast an
aircraft is travelling and how much air friction heats it up (and
therefore how much infra red radiation it gives off)?

IIRC Speed in hundreds of mph squared=degrees C temp rise thus for Concorde
14(00)^2=196C temp rise from a -50 base gives ~150C.

Dont know whether this applies at subsonic speed
--

regards

jc

LEGAL - I don't believe what I wrote and neither should you. Sobriety and/or
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addresses. news2x at perentie is valid for a while.

"miket6065" wrote in message ...
I remember reading that the IR sensors on the Eurofighter Typhoon can pick
up icebergs against the cold of the sea!

Did you mean the colder iceberg against the warmer artic sea?


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.

MikeT

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?