Aim-120 Arm Variant

[Burncycle360]

Given the difficulty in carrying something the size of an AGM-88 and its prominent fins internally, were / are there any plans to develop an anti-radiation version of a more compact missile like the AIM-120 so aircraft like F-35 can conduct DEAD?

[Dawes]

The Joint Dual Role Air Dominance Missile explored that concept but was canceled a few years ago. DARPA's "Triple Target Terminator" (T3) seems to be an attempt at continuing that train of thought.

[Olof Larsson]

Given the difficulty in carrying something the size of an AGM-88 and its prominent fins internally, were / are there any plans to develop an anti-radiation version of a more compact missile like the AIM-120 so aircraft like F-35 can conduct DEAD?

 

The current focus seems to be on the AARGM-ER, that will have strakes along (almost) the entire length of the missile, no fins in the middle of the missile, a larger diameter rocker engine, twice the range of the AARGM and fit inside the weapons bay of at least the F-35A/C.

 

 

https://www.defence24.com/aargm-er-anti-radiation-missile-for-the-5th-generation-fighter-aircraft

[lastdingo]

A reduction of the diameter by 2/3 would greatly reduce the sensitivity and likely also the wideband capabilities of an ARM.

A clipped fins version of AGM-88E similar to clipped fins AMRAAMs might make sense, but I don't know what difference it would make in regard to internal carrying capacity of the F-35.

[DB]

Launch platform ESM plus GPS guided powered munitions is more flexible, and almost certainly cheaper.

[Chris Werb]

Launch platform ESM plus GPS guided powered munitions is more flexible, and almost certainly cheaper.

 

I think even a powered weapon with a terminal seeker, like SPEAR 3 would work out cheaper, and you can have them attack from multiple directions near simultaneously.

[Olof Larsson]

 

Launch platform ESM plus GPS guided powered munitions is more flexible, and almost certainly cheaper.

 

I think even a powered weapon with a terminal seeker, like SPEAR 3 would work out cheaper, and you can have them attack from multiple directions near simultaneously.

 

 

Well, the AARGM-ER would have the advantage of getting there quickly, forcing the enemy to shut down and relocate at once. My guess is that we will see a combination of dedicated ARM's (for larger strike packages) guided munition with terminal seekers (Brimstone, SDB II and so on), GPS/INS guided munition (JDAM, JSOW A/B and so on), loitering munition like the IAI Harop and stealthy drones. With projects like the GLSDB, GMLRS-ER, the future ATACMS-replacement we might also see groundforces taking on a area SEAD-role, in conjuction with loitering munition and drones.

[Chris Werb]

 

 

Launch platform ESM plus GPS guided powered munitions is more flexible, and almost certainly cheaper.

 

I think even a powered weapon with a terminal seeker, like SPEAR 3 would work out cheaper, and you can have them attack from multiple directions near simultaneously.

 

 

Well, the AARGM-ER would have the advantage of getting there quickly, forcing the enemy to shut down and relocate at once. My guess is that we will see a combination of dedicated ARM's (for larger strike packages) guided munition with terminal seekers (Brimstone, SDB II and so on), GPS/INS guided munition (JDAM, JSOW A/B and so on), loitering munition like the IAI Harop and stealthy drones. With projects like the GLSDB, GMLRS-ER, the future ATACMS-replacement we might also see groundforces taking on a area SEAD-role, in conjuction with loitering munition and drones.

 

 

The Israelis had ground launched Shrike and Standard ARM. Air defence suppression was a key role for ATACAMS from the outset.

[Josh]

AIM-120D has a two way datalink and GPS - wouldn't it be perfectly reasonable for something like F-35 (or a flight of F-35s) to exactly geolocate an emitter and fire a Mach 4 missile down to that location? The only modification the missile would need is fusing.

[Chris Werb]

The target wouldn't even have to have been geolocated by an F-35 - something else could give the launch aircraft the location. As the missile is proximity fused, that ought to work well against radar antennae etc. Late AGM-88 already have that capability.

[Josh]

Aim-120 I think uses a laser detection device that angles outward, not a radar proxy fuse. So depending on the angle it would detonate very low. Not sure if the frag pattern would be optimal. But you could probably work something out.

 

ETA: I'd think the standard seeker could probably be modified to work as a proximity detector, since it really wouldn't be used in this mode anyway. I'd expect the ideal angle to engage would be near vertical - exploit the AIM's high altitude speed and coast and then plunge to bypass point defenses. What modes does HARM have? I know you can just 'slap shot' a round out there and it will do it's best to fly straight to the first thing it detects, but does it have a mode to maximize terminal energy over flight time? IE, a lofted trajectory instead of a flat line one?

Edited March 19, 2019 by Josh

[Dawes]

The HARM warhead is described as a "directed fragmentation warhead using the variable charge-to-metal concept".

[Josh]

Answered my own question. HARM, depending on the version, had several different operating modes. The first is a position known mode, which is lofted trajectory for max range/energy that locks on after launch. There's also a similar/sub mode called 'equations of motion' which apparently is useful for engaging specific emitter types at range - wasn't clear how this worked. These would be the modes used by dedicated SEAD a/c with some kind of directional RWR. The next mode is 'Target of Opportunity', in which the seeker on the missile is used to sense the target and the missile is fired once it has locked on. This would typically be for a non RWR/SEAD a/c and requires the target to be inside the missile's detection envelope. Finally, there is a self protection mode which is slaved to an aircraft's RWR which will just engage whatever type of seeker the RWR specifies, down the bearing of the signal (if the RWR is capable of bearing determination).

 

These are modes associated with the earlier versions - I suspect the 88E variant has additional options based in INS/GPS guidance (previous versions were inertial guidance for LOAL) and MW radar terminal homing.

 

There apparently a real program to develop the AARGM-ER which is hoped to be fielded circa 2024 that would be an extended range variant that could be carried inside the F-35.

But in the meantime, I have to wonder if command guiding an AIM-120 into an exact GPS coordinate isn't a quick and dirty, if some what expensive, way for a fighter to engage a soft radar target. Even if you had to just rely on the impact fuse for detonation, having 20kg of warhead go off within ten meters of an emitter will probably shut it up even if most of the frags go into the ground. Just the concussion would probably induce shock damage. Hell, several hundred pounds of missile hitting the earth that close at transonic speed would probably at least force some kind of repair even without a warhead. It would allow F-35s to use AIM-120s as improvised ARMs for now, and fighter aircraft in general to have some kind of basic defense against SAMs if they had access to the exact coordinates of the attacking radar. With F-35 providing 360 degree ISR, they might realistically have this even though they would lack the sensors for it.

Edited March 20, 2019 by Josh