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Author Topic: USAF plans F-15 modernization  (Read 73617 times)

Offline sferrin

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Re: USAF plans F-15 modernization
« Reply #15 on: September 19, 2014, 07:15:25 am »
I guess I just don't understand why, if Japan can do it right, why can't we?

It's not all roses for Japan in that area. Look at the ongoing (AFAIK) RF-15 [not to be confused with SNEAK PEAK] dispute. Long story short, a previous government cancelled a contract with Toshiba to convert 8 MSIP F-15DJs to RF-15 standard with podded SAR, along with optical and infrared capability. (The Government at the time had social programs to pay for after all.) Unfortunately for them, they used the old saw of unilaterally changing the contract specs, and then while the contractor was trying to meet the changed specs, declared default & Cancelled for Cause, with a ¥1.2 billion yen damages claim on the side. I say unfortunately, because Toshiba refused to play along and sued for ¥9.3 billion in damages. Tricks that work in Western style contract law tend not work so well in Japanese style contract law (which is probably why there have been recent attempts by 'reformers' to supplant the latter with the former in Japanese contracts).

How does this relate to the IRST on the F-15J?
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Offline F-14D

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Re: USAF plans F-15 modernization
« Reply #16 on: September 19, 2014, 10:14:07 am »
I guess I just don't understand why, if Japan can do it right, why can't we?

I suspect it's that until fairly recently, USAF has not been a fan of IRST  capability and so never wanted it.   

Offline John21

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Re: USAF plans F-15 modernization
« Reply #17 on: September 21, 2014, 03:42:24 am »
We used to have IRST on the F-101,102,106,4,8,14. Why did we suddenly seem to lose interest in the past 20-30 years? It's seems to be a pretty simple capability we could have kept around for only a fairly small investment in time and money.

Could pods such as ATFLIR, Litening, SNIPER-XP...etc be used in a similar way, maybe fusing what they see to the radar display? Although it probably would not be as accurate as a dedicated IRST sensor.
« Last Edit: September 21, 2014, 03:48:01 am by John21 »

Offline F-14D

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Re: USAF plans F-15 modernization
« Reply #18 on: September 24, 2014, 07:04:01 pm »
 

We used to have IRST on the F-101,102,106,4,8,14. Why did we suddenly seem to lose interest in the past 20-30 years? It's seems to be a pretty simple capability we could have kept around for only a fairly small investment in time and money.
 
Could pods such as ATFLIR, Litening, SNIPER-XP...etc be used in a similar way, maybe fusing what they see to the radar display? Although it probably would not be as accurate as a dedicated IRST sensor.
 

 Probably more than anyone cares to read, but...

The IR on those earlier a/c (note that in the case of those three USAF aircraft they were all interceptors), IR was mostly detection and not really intended to supply a usable track, mostly just search and detect.  Plus, an image was not formed, just a detection.  Also, they were add-ons not designed in from the start.  In the case of the F-4, the USN from the beginning planned for the F-4B to have a more advanced IR sensor with limited track  capability, but it proved to be maintenance intensive and not worth the trouble in the real work environment in which the F-4 was operating, so it was removed. 
 
 
The F-14A (originally) had a more advanced IR scanning sensor.  It could scan independently of the radar or be slaved to it.  In the latter case it was useful to compensate for the problem beam width error.  For example, if Maverick and Goose's F-14 had had that sensor, the" MiG-28s" would not have been able to sneak up on them at the beginning of the movie before they were exposed as multiples.  They would have seen the single radar returns, but collocated would have been two distinct heat sources which would have given the game away. It worked, but again there were maintainability issues with this more advanced piece of equipment, so it was discontinued.
 
The F-14D used the AN/AAS-42, a much more advanced type.  It had full search and track capability operating in conjunction with the radar, TCS or independently.  Reportedly it could track, "...at Phoenix ranges", which could probably be translated as "beyond AIM-120 range".   Full sensor fusion was planned for the F-14D, although offhand I can't remember how much actually got implemented after Cheney killed the aircraft.  On the tactical display the computer generated imagery could be synthesized from a combination of the APG-71 radar and the AAS-42.  If one sensor lost track through countermeasures or whatever, the go other could bring it back on target.  The IRST imagery was slated to also be displayed on the HUD and could be correlated with the TCS as well.   Again, how much of that actually got done I don't know. Imagery from the AAS-42 and it's remarkable, looks like a decent black and white movie, images fully formed.  Detects curvature and the like and can identify aircraft types when combined with the right database processor.    I imagine the latest PIRATE may have  similar capabilities   

Until recently USAF hasn't been much interested in IR/IRST /optical systems for fighters, preferring  to hang their hat mostly on radar.  Lately, though, their own work with stealth technology has convinced them they need another arrow in the quiver. 



Although ATFLIR and Sniper have been played with in the air-to-air mode, they really aren't that effective.  Their resolution (like you said) and scan is slower (modern IRSTs can scan faster than an AESA), because for what they are intended to do it's not needed.  OTOH, they are designed to operate longer.  One of the improvements to the AAS-42 planned back in the '90s was to have a seeker head that would go more than 50 hours before having to be rebuilt.   This life was acceptable because an IRST doesn't have to operate on a mission for as long a period as a FLIR.  Still, the longer the better. 



Besides there's no need to go to the trouble of adapting those devices.  You can just buy the An/AAS-42.  It was on the F-14D, a  version is on export Strike Eagles, USAF uses it on Aggressor F-16s and a later version is going to go into a centerline fuel tank on the Hornet E/F (Hey! I thought they said one of the Super Bug's benefits was that it would have so much more internal space for new systems!) and on USAF F-15s it's going to be in a multipurpose centerline pod.   Why spend the bucks to adapt something not as good (in this role) when you can buy the AN/AAS-42 , I mean "IRST21" as it's now marketed, off the shelf. 

 
« Last Edit: September 25, 2014, 11:18:43 am by F-14D »

Online marauder2048

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Re: USAF plans F-15 modernization
« Reply #19 on: September 24, 2014, 10:08:35 pm »


AN/AAS-42 IRST footage at 19 seconds in.

Offline F-14D

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Re: USAF plans F-15 modernization
« Reply #20 on: September 25, 2014, 11:22:34 am »
AN/AAS-42 IRST footage at 19 seconds in.

...and it's been significantly improved since that early marketing-level video was made.

Offline LowObservable

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Re: USAF plans F-15 modernization
« Reply #21 on: September 25, 2014, 11:57:50 am »
F-14D - Thanx. Good background - and note attached LM graphic showing that range exceeds radar.


I was never quite sure what got IRST thrown off ATF (or consigned to the future-upgrade list) but the basic line was "it didn't earn its way on board" - which may have meant that, at the time, the other sensors (LPI radar, EW and offboard) were considered enough to enable detection/track/ID without the attacker being detected. However, adversary RCS reduction and EW improvements will have moved those goalposts.



As for Selex (Pirate and Skyward-G), the story I hear is that processing has done a very good job of reducing false alarm rates in a cluttered environment (Europe). Multiplatform, fusion and dynamic ranging (weave and measure the bearing change) help provide a range measurement. And it is of course independent of RCS and EW.


As for the Bug integration, it's a little harder when you need a window looking forward.




Offline F-14D

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Re: USAF plans F-15 modernization
« Reply #22 on: September 26, 2014, 11:31:09 am »
F-14D - Thanx. Good background - and note attached LM graphic showing that range exceeds radar.


I was never quite sure what got IRST thrown off ATF (or consigned to the future-upgrade list) but the basic line was "it didn't earn its way on board" - which may have meant that, at the time, the other sensors (LPI radar, EW and offboard) were considered enough to enable detection/track/ID without the attacker being detected. However, adversary RCS reduction and EW improvements will have moved those goalposts.



As for Selex (Pirate and Skyward-G), the story I hear is that processing has done a very good job of reducing false alarm rates in a cluttered environment (Europe). Multiplatform, fusion and dynamic ranging (weave and measure the bearing change) help provide a range measurement. And it is of course independent of RCS and EW.


As for the Bug integration, it's a little harder when you need a window looking forward.

I suspect IRST got removed from the F-22 because at the time USAF had a history and culture of not being a fan of non-radar  issues r on fighters.  Both Northrop and Lockheed's proposals envisioned IRST on production versions (I believe the F-22 would use an enhanced system developed from the AAS-42), and for NATF it was an absolute requirement.  After the award, as development began, USAF decided it didn't want IRST that badly and so offered it up as a cost reduction measure.  It shouldn't be forgotten that USAF also wanted to remove AIM-9 capability, arguing that since no one would get close enough to an F-22 where an AIM-9 would be relevant, they could reduce cots and complexity by just getting rid of it (Interestingly, though, they still would keep the gun). 

Regarding the Super Bug, it's just about as big as the F-14D, yet somehow there's not room on the "more room for new systems" nose for the AN/AAS-42. 

Offline sferrin

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Re: USAF plans F-15 modernization
« Reply #23 on: September 26, 2014, 11:40:15 am »
Regarding the Super Bug, it's just about as big as the F-14D, yet somehow there's not room on the "more room for new systems" nose for the AN/AAS-42.

Pretty sure the Tomcat's forward fuselage has a lot more volume.
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Offline F-14D

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Re: USAF plans F-15 modernization
« Reply #24 on: September 26, 2014, 08:43:22 pm »
Regarding the Super Bug, it's just about as big as the F-14D, yet somehow there's not room on the "more room for new systems" nose for the AN/AAS-42.

Pretty sure the Tomcat's forward fuselage has a lot more volume.

Of course it does, a byproduct of accommodating that enormous antenna.  I was just being snarky because back when the Super Bug was being pushed one of the things emphasized was how much more internal volume it had to accommodate future systems.   

Getting back on topic,  my previous post shows it fits quite nicely in a pylon,  Low Observable's graphic show sit on the port intake station of an F-16 and this pic from the Aviationist shows it on an Aggressor F-16 on the starboard one.  It's not that big,  the reason USAF is putting "IRST21" in a centerline pod on the F-15C  is  because it enables them to carry other equipment they want to carry as well, not because they have to, as on the Super Hornet.   These two pics show the difference in the size of the installation on the two aircraft, the Eagle carrying the IRST and other systems, the SH carrying the IRST and fuel. 
« Last Edit: September 26, 2014, 08:48:44 pm by F-14D »

Online bring_it_on

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Re: USAF plans F-15 modernization
« Reply #25 on: December 15, 2014, 06:46:03 am »


From an F-15C perspective, I feel if the Talon Hate pods were going to be a permanent fixture anyways then it makes a lot of sense to save the money on integration and strap on an IRST 21/SpectIR onto them
« Last Edit: December 15, 2014, 06:49:52 am by bring_it_on »
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Offline fightingirish

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Re: USAF plans F-15 modernization
« Reply #26 on: February 12, 2015, 01:35:27 pm »

Just found via Twitter, that Lockheed Martin has unveiled the Legion Pod. It is shown on F-15Cs and F-15Es so far, so it might me the LM's IRST- and Network upgrade proposal for the F-15 family.
Quote
Sensing and Networking for Targeting
Legion Pod is a multi-function sensor system that supports collaborative targeting operations in radar-denied environments. Flexible by design and production-ready, Legion Pod is set to serve as the next sensor system of choice for fixed-wing aircraft.
Using Lockheed Martin’s IRST21 sensor, networking and advanced processing technology, Legion Pod provides high-fidelity detection and tracking of air-to-air targets. Its plug-and-play architecture also makes it easily transportable across numerous platforms, including fighter and non-fighter aircraft.
Designed for flexibility, Legion Pod accommodates additional sensors within its current structure, acting as a multi-function sensor suite without costly aircraft or system modifications. This ensures it can meet both current and emerging customer requirements.
Housed in a 16-inch diameter structure, Legion Pod’s baseline configuration includes an advanced processor and datalink capability in addition to its infrared search and track technology. With capabilities unmatched by other targeting systems and the ability to accommodate additional sensors at low cost, Legion Pod fulfills warfighters’ critical needs and sets itself apart from the competition.
Link: Lockheed Martin - Legion Pod
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Offline pathology_doc

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Re: USAF plans F-15 modernization
« Reply #27 on: February 13, 2015, 05:57:40 am »
Why would you put your IR sensor into an external tank that you may need to dump for speed, agility and reduced weight?

Offline Bill Walker

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Re: USAF plans F-15 modernization
« Reply #28 on: February 13, 2015, 06:10:20 am »
Why would you put your IR sensor into an external tank that you may need to dump for speed, agility and reduced weight?

1. Dumping a pod this small is going to make very little difference in speed, agility or weight.

2.  IRST in a pod is better than no IRST.
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Offline TomS

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Re: USAF plans F-15 modernization
« Reply #29 on: February 13, 2015, 06:22:54 am »
Legion isn't that small (16 inches diameter, 98 inches long, roughly 550 pounds).  But it's not just an ISRT either -- it's got a bunch of datalinks and room for other unspecified sensors (perhaps a next-gen HARM Targeting system, for example).
 
Putting expensive sensors in pods isn't exactly new -- Pave Tack ring a bell, anyone?  You don't dump them unless it's that or losing the aircraft.