AGM-158 JASSM

TomcatViP said:
They release first from the aft station already.
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And if the weapon is hung? Does that mean they can't drop anything else? Saw a picture from Desert Storm where an F-15E had four 2000lb bombs loaded on the CFTs and had always wondered about it.
 
Can the F-35 eject its pylons? I could see using a mission to launch stand off weapons followed by using internal ordnance for another role.
 
Josh_TN said:
Can the F-35 eject its pylons?
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I imagine that they would be ejected as once the store they've been carrying has been ejected/released they're just draggy deadweight that increases the F-35's RCS.
 
NMaude said:
I imagine that they would be ejected as once the store they've been carrying has been ejected/released they're just draggy deadweight that increases the F-35's RCS.
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Ideally. However the only aircraft ever ascribed with that feature in my reading is F-22. And apparently fitting and ejecting pylons still has an RCS penalty such that an improved system was being developed along with an F-22 specific low signature drop tank.

It would make sense on F-35 but I’ve never seen it listed as a feature.
 
I imagine it would probably be a rarity anyway, much like the dropping of drop tanks is. Has a US aircraft ever done that in combat since the Vietnam War?
 
Forest Green said:
https://twitter.com/x/status/1708226434442076605
View: https://twitter.com/AirPowerNEW1/status/1708226434442076605?s=20
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Given that image along with the new designation and goal of engaging moving targets, I think it is very likely that the AGM-158D variant will use an IIR sensor with a wider field of view to increase the capability against moving targets. I believe the D version is also going to incorporate the M code upgrade, new RCS reduction coating, and a weapon datalink, though I think these measures are being introduced slowly to the B series weapons before the D version enters production. It continues to be difficult to sort out what improvements are being introduced in which production lots and what their official designation is, but clearly capabilities will continue to grow along with the added production capacity.
 
Scott Kenny said:
Moving targets suggests something like the SDB2 seeker, though apparently the JASSM already uses IIR.
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JASSM does have an IIR sensor but its field of view is reportedly 12 degrees (at least in the early models). It also apparently only activates in the last seconds (reportedly 8) to get a view of the target and select the exact aimpoint. Increases in processor power and changes to software probably can make this more flexible - activating earlier, maneuvering to pan the sensor across a wider field - but the better solution would be an IIR sensor with a wider arc, like that of NSM or SLAM-ER. That would probably allow/better enable an automated target recognition mode.
 
Josh_TN said:
JASSM does have an IIR sensor but its field of view is reportedly 12 degrees (at least in the early models). It also apparently only activates in the last seconds (reportedly 8) to get a view of the target and select the exact aimpoint. Increases in processor power and changes to software probably can make this more flexible - activating earlier, maneuvering to pan the sensor across a wider field - but the better solution would be an IIR sensor with a wider arc, like that of NSM or SLAM-ER. That would probably allow/better enable an automated target recognition mode.
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Agreed. 12deg FOV is like looking through a soda straw...
 
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 ....
 
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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Easy enough for a static target probably even degraded or forced into an INS only mode. Difficult to hit a moving target without near constant updates or some other mid course guidance mode. It makes me wonder if LRASM uses all the same IIR hardware as JASSM or uses modified terminal seeker hardware.
 
I think LRASM has passive RF, and the IIR is for terminal, aim-point hit .....

Makes me wonder, is JASSM IIR gimbaled or strapdown? Cooled or un-cooled?
 
zjz said:
I think LRASM has passive RF, and the IIR is for terminal, aim-point hit .....

Makes me wonder, is JASSM IIR gimbaled or strapdown? Cooled or un-cooled?
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Definitely not gimbaled given that tiny window and FoV. Can’t speak to the cooling, but I recall the uncooled Stormbreaker IIR was something of a breakthrough when it came out, so I’d lean towards a cartridge cooled seeker on JASSM given its vintage and short visual acquisition time.

The RF guidance would have to geolocate really accurately to compensate for a lack of GPS guidance, but that is possible. I’ve always wondered if the LRASM actually used DToA and relies on multiple missiles sharing data rather than individual units having a precise RF location mechanism. It seems to me the latter would be incredibly hard to package on a missile body with high bearing/azimuth accuracy even if money was no object.
 
On a related note, I recall reading that Tomahawk MST uses a BAE passive RF seeker. Came across one obscure article that mentioned it has 8 or 16 receivers! ( interferometer??) My memory may have failed me on the details though .....
 
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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