Also a response from DaveS (msg#3688) on the Admiralty Trilogy Yahoo Group.

 

(In the case of a pair of Litening II pod equipped AV-8B II+ dropping 2nd Gen SALH-guided GBU-12D's on a small ground target.

 

Is it true that the designator capable of effectively designating the target provided that the designating aircraft keeps the target within its 270 degree frontal arc (per 6.3.4.2.2)? i.e. the designator is not restricted to the 12/3 degree detecting/classifying field of view and theoretically the "optic" lens can "slew" side to side within the 270 degree frontal arc of the designating aircraft?

 

"In the case you are talking about, I would say yes.

 

I know that for early SALH there were some different limitations (for early

SALH, the designator plane could not be dropping the bombs) and if you were

using the Soviet/Russian aircraft listed in the rule you would have the arc

limitations listed in the rule."

 

Thanks to DaveS for responding quickly and completely to my questions, however tetious.

cross post from Admiralty Trilogy Yahoo site from Paul K. - clears a lot up.

 

"Maybe I can help clarify things a little bit. There are two different

components in this system that are the cause of some of this confusion. There

is the sensor itself and the sensor mount. When the description is talking

about the 12 / 3 degree views that is a description of the sensor. When the

description talks about 270 degree frontal arc that is the sensor mount, here's

how it works. The 12 degree / 3 degree description is the Field of View (FOV)

of the sensor. In wide FOV it can see 12 degrees (6 degrees either side of what

its pointed at). It also has a narrow FOV, a "zoom" if you will, that will see

only 3 degrees (1.5 degrees either side of what it is pointed at). This is a 4

X zoom feature. That is a great capability but if you stopped there you would

be stuck with always having to point the aircraft at the intended target. To

overcome this you bolt it to a mount that can be rotated or slewed around to

look off axis. In this particular case the mount the sensor is on can slew

through the frontal 270 degree arc (i.e. 135 degrees either side of centerline).

Okay so what does that mean? It means that you can train the sensor anywhere

within 135 degrees either side of the nose of your aircraft but you are only

going to see 12 degrees of that 270 degree arc when in wide FOV or 3 degrees of

that 270 degree arc when you are in narrow FOV.

 

There is no difference between a FLIR and a IRST in terms of the technology of

the IR sensor, it is all dependent on the design of the mount. (Third

generation IRST systems have an imaging capability because they added a camera

lens side by side with the IR sensor) One other critical design feature of the

mount, beyond the 270 degree azimuth, is the elevation limits for the sensor.

To function effectively as an Air to Air sensor it must be able to look above

and below the aircraft's flight path. (The FLIR in my S-3 could easily pick up

air contacts but could not be slewed "up" so if the air contact was above our

altitude we would have had to roll the aircraft to see it.) Without knowing

more detail about the Litening II POD's design limitations its hard to say how

effective it is as an IRST. Its FOV, even in wide FOV, is much less than the

description of a standard IRST. Although I confess I don't know enough about

IRST technology to know how it searches the +/- 60 degree arc. it would seem

that as an IRST the Litening II pod is limited by a "soda straw" effect. [in

the S-3 the FLIR could scan side to side until the operator saw an IR

significant "blob" at which point they could take over manual control - not sure

if these system do that or something else.] The other factor that needs to be

looked at when discussing pods designed for ground targeting being used for air

to air work is the pod placement on the aircraft. Anywhere you mount it on the

aircraft is going to provide significant "blind zones" where the aircraft

fuselage blocks out any hope of seeing the target.

 

For this pod I would say that it meets the requirements for: 4.6.2 Airborne

FLIR, 4.6.3 IRST (with limitations from FOV, blind zones etc.), 4.8.2 Laser

Designator and 4.8.3 LRMTS."

Pete, regarding your question about where the targeting pod might be mounted, it seems the AV-8B Harriers are mounting them underwing for now, as shown here:

 

 

Apparently the centreline pylon isn't used for much of anything except the ECM pod, and if the targeting pod were put there, then the ECM pod would have to go. Also, it seems the Harriers routinely operate in pairs and perform buddy lasing, with one Harrier carrying a couple of LGBs and the other carrying the targeting pod and a single LGB.