AGM-158 JASSM

NMaude said:
What I'd like to know is how does the missile control its pitch and roll axes? It clearly has a moveable tail fin yet where you'd expect the elevators to be there are what appear to be fixed tabs.
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JASSM uses "elevons", combine elevator + aileron

A lot of details of the JASSM can be found here :

www.scribd.com

T.O. 1B-52H-34-2-8 - Aircrew Weapons Delivery Manual (Nonnuclear) - AGM-158 JASSM (01-06-2006) PDF | PDF | Boeing B 52 Stratofortress | Aviation

Scribd is the world's largest social reading and publishing site.
www.scribd.com www.scribd.com
 
As a taxpayer it blows my mind / infuriates me that this stuff is out there.
 
sferrin said:
As a taxpayer it blows my mind / infuriates me that this stuff is out there.
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It's basically a consequence of the absolutely shitty service intranets. People don't have anywhere to store the docs they need access to for their promotion exams, so they throw it up on Scribd, etc. Add the fact that this stuff is not properly marked -- at bare minimum, this doc should be For Official Use Only.
 
The question that needs to be asked does the JASSM manual have any confidential, secret or top-secret material in it?
 
So AGM-158D will use a satellite datalink, a revised wing arrangement for more range, and M code? Is it to have the new external coating as well? Was a range figure released?
 
NMaude said:
The question that needs to be asked does the JASSM manual have any confidential, secret or top-secret material in it?
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Not one that matters here, but in general the stuff we are interested in, assuming it was classified at all, would likely be the lowest classifications. The higher the classification, the more into the weeds about something you get. I remember one worksheet that was C, but TS when filled in.
 
zjz said:
Any idea what is the NiMH & Li-Ion battery for? This is the first time I see such batteries mentioned for missile use.
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To power the seeker I imagine and possibly a Tx for communicating back to base or maybe an ECM unit of some kind. Don't know why it needs a Nickel Metal Hydride battery though, that's generally used for rechargeable applications, which would seem kind of pointless here. The way it uses the terms JASSM-ER and AGM-158D separately is also kind of confusing. They're the same missile AFAIK.
 
Forest Green said:
zjz said:
Any idea what is the NiMH & Li-Ion battery for? This is the first time I see such batteries mentioned for missile use.
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To power the seeker I imagine and possibly a Tx for communicating back to base or maybe an ECM unit of some kind. Don't know why it needs a Nickel Metal Hydride battery though, that's generally used for rechargeable applications, which would seem kind of pointless here. The way it uses the terms JASSM-ER and AGM-158D separately is also kind of confusing. They're the same missile AFAIK.
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If you end up not firing the missile you'd want to be able to recharge your batteries instead of replacing them.
 
AGM-158B = JASSM ER

After that the nomenclature gets confusing. I’ve heard the terms AGM-158B2/B3/C3/D and JASSM XR thrown around with various new features like wing alteration, weapon datalink, new coating, and large range increase said to be the changes but with no clear map between those two sets and no indication what is coming off the line when.
 
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Josh_TN said:
AGM-158B = JASSM ER

After that the nomenclature gets confusing. I’ve heard the terms AGM-158B2/B3/C3/D and JASSM XR thrown around with various new features like wing alteration, weapon datalink, new coating, and large range increase said to be the changes but with no clear map between those two sets and no indication what is coming off the line when.
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I meant to say that the AGM-158D is the JASSM-XR AFAIK, at least according to wiki. That seems to have been renamed AGM-158B-2 now though. Who the hell numbers these things? Seems it was renamed twice:

en.wikipedia.org

AGM-158 JASSM - Wikipedia

en.wikipedia.org en.wikipedia.org

In March 2016, Lockheed Martin began analysis on an enhanced wing design to further increase range.[53] In September 2018, the corporation was awarded a contract to develop an "Extreme Range" variant of the AGM-158. The weapon would weigh about 5,000 lb (2,300 kg) and deliver a 2,000 lb (910 kg) warhead out to a range of 1,900 km (1,200 mi; 1,000 nmi).[54][55] Originally called the JASSM-XR and later designated the AGM-158D, it features a new missile control unit, changes to the wings, a different paint coating, an Electronic Safe and Arm Fuze, secure GPS receiver, and program protection requirements at a unit cost of $1.5 million. Low-rate initial production began in 2021 as part of Lot 19 with deliveries beginning in January 2024 at a rate of five per month for the first 40 missiles.[56] The designation was later changed again to the AGM-158B-2.[57][58]
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Forest Green said:
I meant to say that the AGM-158D is the JASSM-XR AFAIK, at least according to wiki. That seems to have been renamed AGM-158B-2 now though. Who the hell numbers these things? Seems it was renamed twice:
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There was a rumor that the "XR" was going to be a version with extremely long range extension - like, Tomahawk range. Some accounts of this indicated it was going to involve a stretch of the airframe (presumably becoming more AGM-86 sized). I haven't heard any mention of this ever since. The other way you might get that range extension is by cutting the warhead in half - you could use the AGM-84H as an off the shelf solution (EDIT: actually WDU-40 isn’t much lighter; maybe JSMs warhead). But again, not heard anything about this in a couple years.

I've seen mentions of the other changes fairly frequently and seen them variously associated with the other letter designations - B2 (range extension?), B3 (two way datalink added?), C3 (whatever the hell the USN is buying...2 way datalink but sans the RF seeker of the "real" LRASM), and D (all of the previous changes plus a new external coating?). Somewhere in there you can throw in the M code upgrade as well; I've no idea where. But in all cases I've seen exactly one document that mentions the change and the designation and in some cases they contradict each other, so no idea. It does seem to be the case that regular production line items will get the weapon datalink and M code update in the next couple years (or rather prep for receiving M code, as GPSIII's ground segment seems to have been a shit show).

The million dollar question for me would be which versions of the weapon have any capability, even a limited one, against ship targets. I found a news clip that mentioned a 2way datalink being tested back in 2012 and implying this was all that was necessary. That might have just been the LRASM. But again, who knows: it almost seems like the USAF is deliberately muddying the waters at this point.
 
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When I worked at Williams, there was a lot of chatter about the JASSM XR using an uprated F107 variant. That being said, the missile is likely is using a smaller more efficient warhead to make room for more fuel.
 
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Josh_TN said:
There was a rumor that the "XR" was going to be a version with extremely long range extension - like, Tomahawk range. Some accounts of this indicated it was going to involve a stretch of the airframe (presumably becoming more AGM-86 sized). I haven't heard any mention of this ever since. The other way you might get that range extension is by cutting the warhead in half - you could use the AGM-84H as an off the shelf solution (EDIT: actually WDU-40 isn’t much lighter; maybe JSMs warhead). But again, not heard anything about this in a couple years.

I've seen mentions of the other changes fairly frequently and seen them variously associated with the other letter designations - B2 (range extension?), B3 (two way datalink added?), C3 (whatever the hell the USN is buying...2 way datalink but sans the RF seeker of the "real" LRASM), and D (all of the previous changes plus a new external coating?). Somewhere in there you can throw in the M code upgrade as well; I've no idea where. But in all cases I've seen exactly one document that mentions the change and the designation and in some cases they contradict each other, so no idea. It does seem to be the case that regular production line items will get the weapon datalink and M code update in the next couple years (or rather prep for receiving M code, as GPSIII's ground segment seems to have been a shit show).

The million dollar question for me would be which versions of the weapon have any capability, even a limited one, against ship targets. I found a news clip that mentioned a 2way datalink being tested back in 2012 and implying this was all that was necessary. That might have just been the LRASM. But again, who knows: it almost seems like the USAF is deliberately muddying the waters at this point.
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Yes, I understood JASSM-XR to be the AGM-86 CALCM replacement, with a separate LRSO missile for the nuclear option.
 
Found this doc:


There's a table inside of it that has a line item "LRASM-ER (AGM-158C-3)"

Wasn't there a budget doc that described the 158C3 as ditching the RF guidance system but retaining the other features? I seem to recall something to that effect. If so, it seems the reason that is being undertaken is not to save money or even increase productivity - it is to increase endurance. Purchase numbers are still anemic though.

The AGM-158C1 (what I guess you would call the baseline) is projected to be purchased at a hundred a year for five years - still seems awfully low.
 
Josh_TN said:
Found this doc:


There's a table inside of it that has a line item "LRASM-ER (AGM-158C-3)"

Wasn't there a budget doc that described the 158C3 as ditching the RF guidance system but retaining the other features? I seem to recall something to that effect. If so, it seems the reason that is being undertaken is not to save money or even increase productivity - it is to increase endurance. Purchase numbers are still anemic though.

The AGM-158C1 (what I guess you would call the baseline) is projected to be purchased at a hundred a year for five years - still seems awfully low.
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AGM-158C-2 has been described as a Navy JASSM, with parts related to LRASM but no RF seeker.


Seems like C-3 is probably an extended-range version with the RF seeker (hence LRASM, not JASSM)
 
TomS said:
AGM-158C-2 has been described as a Navy JASSM, with parts related to LRASM but no RF seeker.


Seems like C-3 is probably an extended-range version with the RF seeker (hence LRASM, not JASSM)
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Thanks. I cannot keep up with the AGM-158 designations. So it *seems* like C3 is probably an effort to miniaturize electronics and add on any changes to the B3 model that extend range, where as C2 just deletes equipment to gain range as a short term solution.
 
Josh_TN said:
I would have thought the center pair of fuselage stations would be more optimal but maybe that creates separation issues.
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In the early 2010s when ROKAF was trying to procure JASSM for their F-15Ks, there was a known problem regarding a possible inteference between JASSM's tail folding mechanism and the pylon when the missile was mounted on the left wing. Sources reported that it was a F-15K specific problem due to beefier pylons, but I'm not really sure if the K variant actually has a wider pylon that'd casue an interference issue that is not present on the E variant. Anyways, they went with the KEPD 350 in the end instead so problems solved.

Fast forward now, as shown in the foto, it seems like those "possible interference issues" were quite overblown. It has JASSM mounted both on the centre pylon as well as the left wing pylon, so I guess there actually are no issues regarding mounting the JASSM on F-15E.
 
I was referring to the pair of missiles mounted on the back corners - there are three sets of hard points wired for PGMs on the corners of the airframe. I'd have thought the central set would center the mass of those heavy stores better, putting all five missiles roughly in a band around the center of the aircraft. But there must have been some issue with placing them there.

Has the USAF tested actually *releasing* the weapons from the aircraft this way? I was under the impression that the 2021 test was less about flying a mission with five missiles and more about using the aircraft to lift weapons to a forward austere base as part of the ACE program.
 
Josh_TN said:
I was referring to the pair of missiles mounted on the back corners - there are three sets of hard points wired for PGMs on the corners of the airframe. I'd have thought the central set would center the mass of those heavy stores better, putting all five missiles roughly in a band around the center of the aircraft. But there must have been some issue with placing them there.
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That's what you mean. Well, yes, it seems like there could be an issue concerning interference with the rear-end of the LANTIRN.
 
sferrin said:
I've often wondered what the ramifications of getting heavy weapon, like JASSM or a 2,000lb bomb, hung up on one of those aft positions. Does that mean you can't drop other weapons without moving the CG too far aft?
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I guess it depends what the stability margins are and what the FCS can handle.
 
I had thought this happened once before to an Echo, but actually it was a left-right imbalance not a foward-rear imbalance when I reviewed a wiki list of all losses:

22 March 2011: F-15E-51-MC, 91-0304, c/n 1211/E169, of the 492nd FS "Bolars", 48th FW, USAF, from RAF Lakenheath crashed near Benghazi, Libya in Operation Odyssey Dawn. Both crewmen ejected safely and were recovered by friendly forces. Equipment problems with weapons interface software and the right external fuel tank led to a strong right-wing weight imbalance, which caused the aircraft to enter a flat spin during a low-speed, high altitude, 100-degree bank-angle right turn. The mishap investigation board found the cause of the crash to be lack of published knowledge on F-15E maneuvering with large external store weight imbalances at high altitude.[73]
 
Keep in mind when the F-15E was designed, the placement of pylons on the CFTs probably consider only dumb bombs, which eventually extend to JDAMS and LGBs .....

The payload the size and shape of a GW like JASSM or even JSOW is a after thought. So they just select the best, and most suitable pylon to carry the JASSM .....
 
Josh_TN said:
I was referring to the pair of missiles mounted on the back corners - there are three sets of hard points wired for PGMs on the corners of the airframe. I'd have thought the central set would center the mass of those heavy stores better, putting all five missiles roughly in a band around the center of the aircraft. But there must have been some issue with placing them there.

Has the USAF tested actually *releasing* the weapons from the aircraft this way? I was under the impression that the 2021 test was less about flying a mission with five missiles and more about using the aircraft to lift weapons to a forward austere base as part of the ACE program.
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I've seen footage of the USAF dropping a 2000lb JDAM from an aft station like that before, but not a JASSM.
 
I think a bigger problem would come if you dropped the wing loads first as that would shift the CoG rearwards, potentially behind the CoP. But I'm not sure about that.
 

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