F/A-22 IRST?

In article ,
Bob writes:
On 3 Sep 2004 20:03:42 -0700, (WaltBJ) wrote:

Yes, I understand all that - but I maintain today, as I have in the
past, that it will not be long before turning on a radar set will be
tantamount to suicide. And, yes, I know about LPI radars. But the one
thing about a long-range radar is that it has to radiate power, and
one side can detect the other's transmitter long before they
themselves are detected. Now add space elint to the equation,
GPS/Inertial guided missiles with ecm terminal homing and blithely
boring holes with the radar on will quickly go out of fashion. Even
more so, radar ground sites in known/easily pin-pointed stations.
Boats, too, for that matter. Might as well have a huge neon sign
saying "Hit me". Even in 1960 we had missiles that could switch to ecm
home; not much of a step to homing on AI radar with our progress in
micro processors. Now bring in satellite elint and direction . . .
Walt BJ

Even in 1960 we had ecm systems that would listen to check if a
missile had switched to ecm home.G

And it would know that _how_? The missiles in question don't emit
anything, they just look for a source of RF in front of them. That
source can be (In the simplest case, a CW SARH like a Sparrow III) the
reflection of the illuminator's beam, or the jillion times more
brilliant source of teh target's jammer. The missile really would
prefer to have the Illuminator doing the job - it compares thw signal
from behind (The illuminator directly) with the reflected signal to
get closure rate inforamtion - but it's also quite happy tp get its
Az-El data from the jammer, and trust its Prox Fuze to do the job.
The shooter gets a much better picture (minus range data) of teh
target's Az-El, with the much brighter signal coming from the jammer.
(Of course, you'd have to dial the receiver gain down a bit, bit that
doesn't show) So it's not too tough to keep teh target in the
illuminator's beam, which reveals nothing wrt jammer effects.
(Dang, if I'm not careful, I'll start sounding like Kurt Plummer!)
In any case, there's no different behavior from wither the missile or
the shooter that would give anything away.


--
Pete Stickney
A strong conviction that something must be done is the parent of many
bad measures. -- Daniel Webster

On Sun, 5 Sep 2004 10:50:19 -0400, (Peter Stickney)
wrote:

In article ,
Bob writes:
On 3 Sep 2004 20:03:42 -0700, (WaltBJ) wrote:

Yes, I understand all that - but I maintain today, as I have in the
past, that it will not be long before turning on a radar set will be
tantamount to suicide. And, yes, I know about LPI radars. But the one
thing about a long-range radar is that it has to radiate power, and
one side can detect the other's transmitter long before they
themselves are detected. Now add space elint to the equation,
GPS/Inertial guided missiles with ecm terminal homing and blithely
boring holes with the radar on will quickly go out of fashion. Even
more so, radar ground sites in known/easily pin-pointed stations.
Boats, too, for that matter. Might as well have a huge neon sign
saying "Hit me". Even in 1960 we had missiles that could switch to ecm
home; not much of a step to homing on AI radar with our progress in
micro processors. Now bring in satellite elint and direction . . .
Walt BJ

Even in 1960 we had ecm systems that would listen to check if a
missile had switched to ecm home.G

And it would know that _how_?

You are right. You can't beat hoj..

The missiles in question don't emit
anything, they just look for a source of RF in front of them. That
source can be (In the simplest case, a CW SARH like a Sparrow III) the
reflection of the illuminator's beam, or the jillion times more
brilliant source of teh target's jammer. The missile really would
prefer to have the Illuminator doing the job - it compares thw signal
from behind (The illuminator directly) with the reflected signal to
get closure rate inforamtion - but it's also quite happy tp get its
Az-El data from the jammer, and trust its Prox Fuze to do the job.
The shooter gets a much better picture (minus range data) of teh
target's Az-El, with the much brighter signal coming from the jammer.
(Of course, you'd have to dial the receiver gain down a bit, bit that
doesn't show) So it's not too tough to keep teh target in the
illuminator's beam, which reveals nothing wrt jammer effects.
(Dang, if I'm not careful, I'll start sounding like Kurt Plummer!)
In any case, there's no different behavior from wither the missile or
the shooter that would give anything away.

In message , Bob
writes
You are right. You can't beat hoj..

Two words. Offboard jammer.

(Cf. GEN-X, Nulka, Sea Siren...)

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

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

On Mon, 6 Sep 2004 21:08:44 +0100, "Paul J. Adam"
wrote:

In message , Bob
writes
You are right. You can't beat hoj..

Two words. Offboard jammer.

(Cf. GEN-X, Nulka, Sea Siren...)

In 1960?

In article , "Kevin Brooks"
wrote:

"Harry Andreas" wrote in message
...
In article ,
wrote:

WaltBJ wrote:

Having used an IRSTS in the F102A for over a year and a half (and
teaching its use to other pilots) I am continually amazed at the
refusal of the USAF and USN to employ some form of IRSTS in their
fighters.

Walt, the F-14 has had an IRSTS since the earlyt '80s, and the F-14D had
both IRSTS and TCS. Modern FLIR pods can also do double duty as IRSTS,
albeit they usually will be cued by radar.

As simple and crude as the Deuce's IR system was, it still
added a whole new spectrum of attack modes to the weapons system.
Undetectable, unjammable, good against fighters in the weeds, line of
sight detection against head-on B58s at M 2.0 and picking up
afterburning 106s at 40 miles head-on. Surely a 21st century IRSTS
would be far superior to what we enjoyed back in the 60's. And the
Deuce's system weighed less than 50 pounds all told . . . the powers
that be might ask themselves why the Russians have IRSTS on all their
fighters.

Part of the reason is that they were designed to operate under tight
GCI,
and their a/c radars were/are generally much inferior to US systems as
far as performance goes. So, the ability to be vectored by GCI within
range and then use a passive system for acquisition/tracking instead of
letting the opposing pilots know their general direction (by RWR) where
they're coming from,which allows the other side to radar search for them
long before they reach their own detection range, probably plays a big
part. As long as we feel we have the BVR range advantage, we don't want
to close to IR missile range. In the case of the F-22 and even more the
F-35, both of them will be getting a lot of their info from off-board
sensors, as well passive sensors (the F-35 will have two internal FLIRS,
one forward and the other downward-looking). And then there's always
the
money issue, which Kevin mentioned -- with the F-22 costs spiraling out
of sight, I imagine they looked to cut the 'nice to have' stuff to try
and keep the cost reasonable [Sic.] and make sure it gets into
production, after which they can then load it up with all the goodies as
retrofits.

The IRST was deleted at program inception, long before the costs spiralled
out of control.
The reason? Cost. They knew well from experience that the cost of the
hardware, cost of the software, and cost of integration and flight test
were going to be too high to support it's functionality.
I can only imagine how bad it would be now if they had decided to keep it.
(BTW, I worked the ATF program and early parts of F-22)

At inception? I thought the decision to axe the IRST came well into the
nineties? The folks at Arnold were doing wind model testing of LMCO's AIRST
as mounted in the then-F-22 as late as 96-97 (see:
http://www.arnold.af.mil/aedc/testhi.../trisonics.pdf ). And
the AFA noted it was still being developed in 97 as well
(www.afa.org/magazine/nov1997/1197airborn.asp).

Sorry if I wasn't clear: the IRST was deleted at the beginning of the F-22
program. It was there for ATF.
Room was left for it in both the airframe and in the CIP in case they decided
to put it back.
Test does not mean implementation. Including it during flight test is a
smart decision IMO, whether you're going to implement it or not, as the
cost of re-flight testing the aircraft is sooooo high, and would really
make addition of it later cost prohibitive.

--
Harry Andreas
Engineering raconteur

In article ,
wrote:

Harry Andreas wrote:

In article ,
wrote:

WaltBJ wrote:

Having used an IRSTS in the F102A for over a year and a half (and
teaching its use to other pilots) I am continually amazed at the
refusal of the USAF and USN to employ some form of IRSTS in their
fighters.

Walt, the F-14 has had an IRSTS since the earlyt '80s, and the F-14D had
both IRSTS and TCS. Modern FLIR pods can also do double duty as IRSTS,
albeit they usually will be cued by radar.

As simple and crude as the Deuce's IR system was, it still
added a whole new spectrum of attack modes to the weapons system.
Undetectable, unjammable, good against fighters in the weeds, line of
sight detection against head-on B58s at M 2.0 and picking up
afterburning 106s at 40 miles head-on. Surely a 21st century IRSTS
would be far superior to what we enjoyed back in the 60's. And the
Deuce's system weighed less than 50 pounds all told . . . the powers
that be might ask themselves why the Russians have IRSTS on all their
fighters.

Part of the reason is that they were designed to operate under tight GCI,
and their a/c radars were/are generally much inferior to US systems as
far as performance goes. So, the ability to be vectored by GCI within
range and then use a passive system for acquisition/tracking instead of
letting the opposing pilots know their general direction (by RWR) where
they're coming from,which allows the other side to radar search for them
long before they reach their own detection range, probably plays a big
part. As long as we feel we have the BVR range advantage, we don't want
to close to IR missile range. In the case of the F-22 and even more the
F-35, both of them will be getting a lot of their info from off-board
sensors, as well passive sensors (the F-35 will have two internal FLIRS,
one forward and the other downward-looking). And then there's always the
money issue, which Kevin mentioned -- with the F-22 costs spiraling out
of sight, I imagine they looked to cut the 'nice to have' stuff to try
and keep the cost reasonable [Sic.] and make sure it gets into
production, after which they can then load it up with all the goodies as
retrofits.

The IRST was deleted at program inception, long before the costs spiralled
out of control.
The reason? Cost. They knew well from experience that the cost of the
hardware, cost of the software, and cost of integration and flight test
were going to be too high to support it's functionality.
I can only imagine how bad it would be now if they had decided to keep it.
(BTW, I worked the ATF program and early parts of F-22)

One wonders then why the F-35 will have two of them, and why the F-16
Block 60s
are also getting an internal FLIR.

F-35 has a different mission. IR is useful for ground attack, and is not as
range limited in that mission as in A/A missions.

As to Block 60...you'll have to ask the UAE.
AIUI, they set the requirements for that aircraft.

--
Harry Andreas
Engineering raconteur

In article , "Paul F Austin"
wrote:

"WaltBJ" wrote
Yes, I understand all that - but I maintain today, as I have in the
past, that it will not be long before turning on a radar set will be
tantamount to suicide. And, yes, I know about LPI radars. But the one
thing about a long-range radar is that it has to radiate power, and
one side can detect the other's transmitter long before they
themselves are detected. Now add space elint to the equation,
GPS/Inertial guided missiles with ecm terminal homing and blithely
boring holes with the radar on will quickly go out of fashion. Even
more so, radar ground sites in known/easily pin-pointed stations.
Boats, too, for that matter. Might as well have a huge neon sign
saying "Hit me". Even in 1960 we had missiles that could switch to ecm
home; not much of a step to homing on AI radar with our progress in
micro processors. Now bring in satellite elint and direction . . .

Fortunately, F22s or F35s in operation won't do that. Both aircraft have
intraflight datalinks for cross-linking data among aircraft as well as other
links for e.g. downloading the take from RJs and satellite sensors. The
IFDLs allow a flight of F22s to share the radar duty cycle across multiple
aircraft in whatever strategy most suits the occasion, meaning that any ESM
location data on a particular emitter ages fast, especially if it's cruising
at M1.5. All the GPS in the world does you no good if you lose location
awareness on the target .

It's good to see that Lockheed is catching up to Sweden.


As an aside, F35s will have not two but seven IR cameras. The FLIR EOTS
sensor is augmented by a six-camera Distributed Aperature System of IR
sensors that gives the pilot a 4pi steradian field of view, including places
where aircraft structure gets in the way.

Very cool system BTW.

--
Harry Andreas
Engineering raconteur