IRST mounts discussion

Dear Guys:

It has always intrigued me why IRST's (infra-red search and track system) particularly Soviet-style systems are mounted on the outside of the pilots canopy.

Isn't it possible to integrate the IRST bulb with the front portion of the pilots windscreen? Then the IRST bulb itself would serve as the forward portion of the canopies' bubble. That way there doesn't have to be a separate fairing mounted on the nose.

Wouldn't that be more compact and create less drag and radar returns? To service the unit it could be pulled straight up and out. Of course there would be issues of sealing the device to the canopy but that should not present insurmountable problems.

Are there issues of poisonous gases being emitted or something similar? Usually infra-red detectors are actively cooled for greater sensitivity. Are the refrigerants used toxic? Does the cooling apparatus preclude mounting the unit in this position?

What would prevent this from being done? Is it impossible to mount the detector in any other way? This way it's move unobtrusive and would not obstruct a portion of the pilots forward field of vision.

The position even has the advantage of being immediately below the field of vision of the HUD meaning it would not even be visible.

Your input would be appreciated.

Thanx.

If you look closely, the fairing is actually connected to the front canopy.

And no, you need a separate fairing. Based on the scheme you described, if you have to access and repair the unit, you would have to remove the entire canopy and part of the dashboard.

can IR guide AAM be use as IRST?

Potentially, as long as the missile is still under the wing, yes if you can wire and program it to be that way. This must assume that this missile is also one of those with digital IIR (Infrared Imaging).