Feasibility of anti-air ARM?

[EtherealN]

This isn't really a serious proposition, but a discussion elsewhere on the forum got me thinking of whether it's remotely feasible (nevermind if it's practical):

 

Can you target an aircraft with an anti-rad missile?

 

In an old online WWII sim I once torpedoed a strategic bomber as a target-of-opportunity thing (I was flying a torp bomber, obviously, and I had run out of machinegun ammo and never found a ship to torpedo). So while it is entirely innefective practically I did manage to just use the torpedo as a gravity bomb and an insane amount of luck to get that kill.

 

In that same vein, if a strike plane is flying around and has an unused ARM, and comes across another aircraft that is beaming full power with it's radar, would it be theoretically possible to lock on and get a kill?

Edited April 20, 2009 by EtherealN

[4c Hajduk Veljko]

Jane's reports they (R-27P) are in service with Russian AF.

 

Vympel offers R-27EP anti-radar air-to-air missile, COVER

 

If ground based radars can be targeted, why not airborne radars?

[EtherealN]

Well, I would have imaginet there could be some obstacle like the sensor strength being lower etcetera.

 

My biggest practicality objection from my own gedankenexperiment though was the fact that the target would be able to just shut off his radar and be done with the threat. But well, apparently it's feasible enough that there's actually been such a missile made.

 

Thanks for the link. :)

[GGTharos]

It's potentially feasible, but not very useful. You have to meet several requirements, for example the launching radar would likely have to be in STT all the time (targeting a scanning radar is not useful since you get updates only every x amount of seconds).

 

Further, the missile is limited to flying a PN aproach, reducing its range with respect to an actual radar-guided weapon. It's a low-lethality guidance mode, which is why it isn't widespread. I mean just look at how many are expended on immobile ground targets.

[nscode]

Would it at all be possible to lock a scanning radar? With ground ARM you need to catch several sweeps in order to triangulate the position with enough precision. Here you would have a movable target that changes its position with every sweep. Maybe with a fast processor you could take more samples of one sweep. Anyhow, a really complicated task.

[Case]

It the target is not changing course much, then yes, it should be possible to extrapolate.

 

Check this though:

During the early morning of January 17, 1991 the first day of operation Desert Storm a B-52G (aircraft 0248) was fired upon by an F-4G Wild Weasel. The B-52's tail gunner locked his tail gun radar on the Wild Weasel mistaking it for an Iraqi MIG. The Wild Weasel immediately detected the B-52 tail gun radar and misidentified the radar signature as an Iraqi Anti-Aircraft Artillery (AAA) site. The F-4G Wild Weasel crew fired a single AGM-88 HARM anti-radiation missile and watched in horror as it headed not towards the non-existent Iraqi AAA site, but to one of the B-52 bombers it was tasked with protecting. Luckily the missile failed to hit the plane, but instead detonated directly behind the bomber. The shrapnel and missile debris damaged the tail section of the B-52G. It ripped off everything aft of the vertical stabilizer. This included much of the tail gun system, the aft Electronic Warfare suite, and the drag chute. The B-52G was able to return safely to the island of Diego Garcia. It was later fully repaired at Anderson Air Force Base on Guam where it was renamed "IN HARM's WAY". The tail gunner position was subsequently eliminated from the entire B-52 fleet.

http://steeljawscribe.blogspot.com/search/label/Project%20VALOUR-IT

[GGTharos]

I think even though certain fighters can do so today, good luck sticking that ESM suite on a missile - IMHO.

[Wilde]

Hm, I always thought an ARM is a passive weapon system. Taking the B-52 example I don't get how that happened. If the bomber STT'ed the F-4, then how did the ARM know where to fly?

[GGTharos]

It...flew right along that STT radar beam? Which is exactly what it should do.

[Case]

Hm, I always thought an ARM is a passive weapon system. Taking the B-52 example I don't get how that happened. If the bomber STT'ed the F-4, then how did the ARM know where to fly?

Just follow the radar beam... since it it continuously locked it just has to ride it until the proximity fuse explodes the missile.

[EtherealN]

Well, it did say the tail gunner "locked" his radar on the aircraft - I would assume that that means the AGM-88 had a steady stream of radiation to follow.

 

EDIT: Hahah, two other people posting in the short amount of time it took me to type that... :P

[Wilde]

It...flew right along that STT radar beam?

 

Yes sure, that's pretty obvious. But what are the odds, that the ARM stays inside the radar beam at any point? If the F-4 breaks in any direction after the missile launch, then the radar beam would quickly sweep too. And then the ARM wouldn't be inside the radar beam anymore. That hit from the example must have been pretty lucky, or unlucky fwiw.

[GGTharos]

I think you're overthinking the issue a little. Sidelobes help.

[EtherealN]

Pretty much, and therefore why it was noted that it's not a very effective thing.

 

What happened in the example looks to me like the plane that got locked launched the HARM as a defensive measure - as long as it maintains position and the "offender" maintains the lock, the offender will have a missile bearing down on him. Through this the plane that locked up might have to cease it's radar lock to evade the missile, thereby removing the threat to the plane that launched the HARM.

 

In the case of two aircraft that are actually enemies (as opposed to blue on blue as in the example), it would be a bit like a chicken race to see who flinches first. :P

 

Another potential gain from engaging with such a missile would be that you can release a weapon, with guidance, beyond IR range (I suppose) without having to have a radar yourself - so if you are flying masked or in stealth mode and have reason to believe that you are undetected, you could f.ex. engage an AWACS or something like that without setting off ever RWR in the neighborhood and thereby negating your stealthed or masked approach.

 

I'm not sure such a circumstance would be common enough for people to actively load up for it, but the more stealthy planes get the more important EMCON might be - and your weapon riding your target's radar beam would be a stealthish approach to engaging BVR.

 

But I'm just speculating there.

[Wilde]

Sidelobes help.

 

What does that mean? Sorry, English is not my native language.

 

 

Also I'm not overthinking it. I'm just curious. The emitting radar waves outside of the radar beam of the STT'ing radar should be rather minimal, shouldn't they?

[EtherealN]

Sidelobes is the fact that radar energy is not a laser beam. You are radiating energy (that can be detected and tracked) not only directly at the aircraft you have locked on, but also around it.

 

So even if they're minimal, they're still there and might be enough.

[GGTharos]

What does that mean? Sorry, English is not my native language.

 

That's alright, because I'm talking radar, not english ;)

All beams have sidelobes - ie. emissions which are (typically, for our discussion) weaker than the mainlobe (What we would normally call the radar beam). At close range those can be pretty powerful.

 

Also the definition of what IS a radar beam is traditionally the half-power point from center. So the center is 'full power', and then you go out until you reach half-power. This means the actual detectable beam can be wider - on the order of several degrees, depending on radar.

 

Also I'm not overthinking it. I'm just curious. The emitting radar waves outside of the radar beam of the STT'ing radar should be rather minimal, shouldn't they?

Depends. If you have an AESA antenna, or even a PESA, yes (AESA minimizes it even more AFAIK - also, quality matters. A crappy PESA/AESA won't minimize them as much as it ought)

 

If you have an MSA you'll have to live with sidelobes.

 

Edit: Some material...

 

http://en.wikipedia.org/wiki/Sidelobe (Don't try too hard to understand it, it should just give you the gist of things)

 

 

Edited April 20, 2009 by GGTharos

[EtherealN]

There are so many fighter jock acronyms I need to learn... >.<

[Wilde]

That's alright, because I'm talking radar, not english

 

Haha funny. Well, the question might have sounded stupid, but the dictionary wouldn't translate "sidelobe". In radar terms German is rather conservative about anglicisms.

 

Whatever.. As I said, the side lobes should be rather small. We're talking some -20dB compared to the main lobe here, which is what, 1% of the main lobe then? Is an ARM weapon that sensitive?

[GGTharos]

If you consider that a radar guided SARH missile can home in on the relatively puny reflections off of a target ... ;)

[4c Hajduk Veljko]

Kh-31P is antiradiation missile with a passive seeker. Some variants of the Kh-31 missile can reportedly be used against large none-maneuvering airborne radars such as AWACS platforms.

Edited April 20, 2009 by =4c= Hajduk Veljko

[59th_LeFty]

I think the answer for the main question is that an A2A ARM is quite pointless if it only has passive homing. Using the techniqe on other, but mainly (semi/) active radar homing missile should be wise. The question then, is the technical design.

 

Actually, it is hard to believe for me, that a Home On Jam missile is not capable of passive homing all the way on the target. The problem could posibly is assigning the seeker to the adequate source.

[GGTharos]

Because the missile knows its own parameters best, it allows it to do the best job it can using its own radar (or the launching aircrafts radar). When a jammer comes on, those parameters become less certain (if not downright wrong) and the missile's Pk degrades.

There's no point in a passive radar homer against aircraft: Even the HARM will employ an mmw seeker now.