AGM-158 JASSM

I read that a Tomahawk was so modified as a test item, but I don’t think anyone has stated anything in open source about MSTs guidance other than some statements implying the guidance had multiple modes/sensors. I’d lean towards the MST likely having something like LRASM capability as a wild guess.
 
zjz said:
8 seconds at speeds of, say, 300m/s translate to 2.4km range, and at 2.4km, FOV of 12deg horizontally translate to 500m across the FOV, which further translate to 250m of TLE in left/right direction ..... assuming GPS is good and not jammed, it is still pretty good IMHO ....
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I think that's a tad more complicated:
- moving targets... travel a certain distance while missile closes in
- if the target move at 100kph, in 8 seconds, it would have covered 220m
- missile aims at impact point forward of the target
- with 250m lateral range of FoV, you would have to track a speeding target only with the outer ring of your sensor (representing 30m at 8 seconds from impact)

I don't think those are suitable conditions for a reliably successful target tracking. Target is supposed to move not always linearly or may take evasive action.
 

BAE Systems contracted to manufacture seekers for LRASM Lots 4/5

Lockheed Martin Missiles and Fire Control has contracted BAE Systems Electronic Systems in Nashua, New Hampshire to manufacture additional next-generation seekers for...
www.janes.com

BAE Systems awarded production contract for additional LRASM seekers

BAE Systems Electronic Systems in Nashua, New Hampshire, in early December disclosed the award from Lockheed Martin Missiles and Fire Control of a USD60 million contract...
www.janes.com
 
I think that I should point out that the descriptions I’ve posted concerning AGM-158 are likely limited to the A version and might have drifted since. One of the B upgrades was specifically a processor upgrade per a previous post, which implies the weapon puts more thought into the target acquisition process now. I have seen the stats I’ve posted in a couple places but the below link is probably the most authoritative. Note however that the F-18 was a threshold aircraft, which severely dates the source (or alternatively makes it super current, but that is not my impression).

AGM-158 Joint Air to Surface Standoff Missile (JASSM)

The JASSM is a conventionally armed, low observable cruise missile designed to destroy the enemy's high-value targets from aircraft that can be launched from outside the area defenses. The missile has
www.dyess.af.mil
 
TomcatViP said:
I think that's a tad more complicated:
- moving targets... travel a certain distance while missile closes in
- if the target move at 100kph, in 8 seconds, it would have covered 220m
- missile aims at impact point forward of the target
- with 250m lateral range of FoV, you would have to track a speeding target only with the outer ring of your sensor (representing 30m at 8 seconds from impact)

I don't think those are suitable conditions for a reliably successful target tracking. Target is supposed to move not always linearly or may take evasive action.
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Agreed, the narrow FOV is acceptable for a static target, not a moving target.
 
I'm still baffled as to how it exerts pitch control given the lack of tail-fins.
 
Pitch/roll - via elevons. Like on Snark decades before.
 
They just have to use the variable wing. Increase sweep and nose down moment increases : the bird pitch down. Decrease the sweep and the nose down moment decrease: pitch up.

You can see at release in the video above that the VG goes to high sweep while the missile increase separation with the Super Hornet and then move back to a lower sweep for to regain cruise attitude.

They probably use differentiate sweep angle for roll.

A very stealthy missile doesn't want to have to play with elevons (that are always deflected one way or the other).

;)
 
I'm not theorizing how JASSM does that, I just telling what is written in TO.
Wing is fixed in high sweep position after separation, and then finally moves to lower sweep fixed position for cruise.
You can clearly see elevons here.
 

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TomcatViP said:
They just have to use the variable wing. Increase sweep and nose down moment increases : the bird pitch down. Decrease the sweep and the nose down moment decrease: pitch up.

You can see at release in the video above that the VG goes to high sweep while the missile increase separation with the Super Hornet and then move back to a lower sweep for to regain cruise attitude.

They probably use differentiate sweep angle for roll.

A very stealthy missile doesn't want to have to play with elevons (that are always deflected one way or the other).

;)
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AGM-158D is being procured this year as part of the lot 22 JASSM buy.
AGM-158B-3 is also apparently a thing that is going to be procured in 2025, with the D model outnumbering orders of the B model.
 

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HyFonic said:
AGM-158D is being procured this year as part of the lot 22 JASSM buy.
AGM-158B-3 is also apparently a thing that is going to be procured in 2025, with the D model outnumbering orders of the B model.
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Do we know what capabilities the D version has explicitly? I was under the impression that this version would include an M code GPS receiver (SABR?), the control surfaces changes that slightly extend range of the B3, and a datalink. One source mentioned that a coating changed to reduce signature was also in the works.

In any case, good to know the D is going to production so soon.
 
HyFonic said:
I believe this is one of the only documents that really discusses it at all, it's from the FY22 budget.
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Well t he at seems to confirm the datalink, which was my biggest question. The USAF seems to deliberately be obscuring what updates are being made and which missiles get them. I cannot blame them, but in particular the rapid designation changes are frustrating. There’s so much material about the “agm-158D” that just refers to the hypothetical/undocumented “JASSM-XR” that you have to wade through some googling to find anything referencing the actual new standard, and you need to know what you are looking for. Perhaps that is intentional.
 
kqcke for you said:
So poland stole some of your JASSM production. They got themself some fine 821 AGN-158 B-2
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Yeah, I was rather surprised at the quantity. The line only produces 550 a year right now, with a ramp up to 850. That still would be a years worth of production, presumably spread out over multiple years.
 
Yeah. Makes me wanne go to them and get some for ous. They got like ~11x as mutch as we get
 
kqcke for you said:
So poland stole some of your JASSM production.
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No, they bought it;).

kqcke for you said:
They got themself some fine 821 AGN-158 B-2
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AGM-158B-2.

kqcke for you said:
They got like ~11x as mutch as we get
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Of course they did, Poland it recent years has been on a defence spending-spree which has kicked into overdrive by Russia's invasion of Eastern Ukraine (They know from bitter experience what it's like to be under the Russian/Soviet boot-heel).
 
158B-2 I *think* has a revised shape for longer range and the M-code GPS (I presume SABR or something similar).
 
These last few documents confuse me. They mention 158B-2, 158B-3 and 158D as if those are three separate missiles.
And they're recent documents, so we can't say that 158D is just the old designation for 158B-2.
Personally, I've never heard of 158B-3 until now. Nor have I heard of 158D being mentioned as something separate and different from 158B-2.

So what are those two designations? What sort of changes do they entail? How come those just appeared out of nowhere, all of a sudden?
 
I lt is rather difficult to separate out the various iterations of AGM-158. They all come off the same production line and represent incremental improvements across lot numbers. I have attempted to piece together the changes based on scattered documentation, all of which has been posted to this thread by myself or someone else at some point. To summarize my best guess:

AGM-158B / B-1: original JASSM-ER

AGM-158B-2: range extension modification apparently using aerodynamic changes.

AGM-158B3: B2 with M code anti jam GPS receiver.

AGM-158D: weapon datalink added


AGM-158C / C1: original LRASM

AGM-158C2 / “Naval JASSM: LRASM with RF detection system removed (for range extension?) but presumably retains datalink and radar altimeters

AGM-158C3: LRASM ER, unknown changes to increase LRASM range to JASSM-ER level, presumably retains RF detection system.
 
But that's still your personal guess, right? Is there any piece of government source documentation or manufacturer documentation which mentions either B-3 or D variant in any sort of detail?
 
totoro said:
But that's still your personal guess, right? Is there any piece of government source documentation or manufacturer documentation which mentions either B-3 or D variant in any sort of detail?
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There is no publicly published list of versions and features. There were docs posted previously in this thread that I used to piece together the list. Someone posted a budget doc just a dozen or two posts up the page that seemed to confirm D gets the WDL. There are lots references to the B-2 having a moderate range extension, so that is very sure (this was erroneously called the D or JASSM-XR version in some articles and USAF *might* have changed the designation after the fact). C2 was described in an Aviation Leak article also posted here, with the (I think misleading) synopsis that the USN had come full circle and rejoined the JASSM program. LRASM-ER/C3 has been mentioned in budget docs with no details given.

So the above list is very solid. I think what is not completely clear is what changes compromise the B3 configuration (I am confident that either B2 or B3 introduces M code; all GPS guidance systems are getting it) and if/when a new outer coating was introduced to reduce IR and RCS (I’ve only seen this feature mentioned once so consider it unconfirmed).
 
B-2 range extension over B-1 is usually described as being considerable, though. from 1000 km to 1900 km.
But, truthfully, all the sources listing such a range are not really quality sources.

When you mention that B-2 has a moderate range extension, you mean to imply that actual range increase of B-2 variant over B-1 variant is not, in fact 900 km but (much) less?
 
totoro said:
B-2 range extension over B-1 is usually described as being considerable, though. from 1000 km to 1900 km.
But, truthfully, all the sources listing such a range are not really quality sources.

When you mention that B-2 has a moderate range extension, you mean to imply that actual range increase of B-2 variant over B-1 variant is not, in fact 900 km but (much) less?
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There were rumors of an “extreme range”/XR version that was a stretched fuselage. I’ve seen no credible sources for such a development nor any reports since a couple years ago. B2 has been characterized as having a longer range but no description of that range increase has been printed in what I would consider a credible source. We do know that it has the same engine and largely keeps the same form factor, so barring a major decrease in warhead, it is my opinion that any range increase is quite modest.
 
Josh_TN said:
There were rumors of an “extreme range”/XR version that was a stretched fuselage. I’ve seen no credible sources for such a development nor any reports since a couple years ago. B2 has been characterized as having a longer range but no description of that range increase has been printed in what I would consider a credible source. We do know that it has the same engine and largely keeps the same form factor, so barring a major decrease in warhead, it is my opinion that any range increase is quite modest.
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Yep, this is the problem. There are several mentions of JASSM XR becoming AGM-158D and then -158B2. But those talk about a dramatic stretch (nearly double the weight) with increases in both warhead weight and range. It is obvious this is not the missile that is actually being built now as -158B2, so something changed but the program is very opaque about what and when.
 
TomS said:
Yep, this is the problem. There are several mentions of JASSM XR becoming AGM-158D and then -158B2. But those talk about a dramatic stretch (nearly double the weight) with increases in both warhead weight and range. It is obvious this is not the missile that is actually being built now as -158B2, so something changed but the program is very opaque about what and when.
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I went looking to see what the differences were yesterday. At first I was excited about the range increase but then it turns out there probably isn't one.


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