AGM-158 JASSM

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.
 
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 .....
 

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