aknowledged Addressing the Inaccuracies of the AGM-122 Sidearm

[Scorch00]

I know Razbam did what they could with it before control of weapons went to ED, but it seems to just have been thrown in a closet and forgotten about since the Harrier is the only aircraft that currently carries the AGM-122. A number of us have been discussing it in the AV-8B discord for some time, and came to the realization the reason the AGM-122 has never been fixed, is because nobody has reported just how inaccurate the current version of the missile is compared to the real missile. So I gathered a bit of things that had been mentioned in our conversations to post here. Hopefully more knowledgeable people can chime in on some of these that I list off. Although it may be unpopular to fix the missile. Based on how people currently use it, in a sense of it being a tiny HARM it needs to be properly fixed in comparison to all the other work done on other missiles in the sim. The AGM-122 is based off the very unsuccessful AIM-9C Sidewinder. The AGM-122 has a very limited range, limited usage window, and unique features that are missing from the missile even currently. The issues that should be addressed are some of the following;  
 
1) Range: Currently the AGM-122 in DCS can be lofted to ranges of 20+nm. This is entirely inaccurate for this missile by a significant margin.  This is based off the missile specifications as well as documentation of the missile being far less capable than it's being used currently.
 
2) Missing features of the missile. Self lofting feature of the missile is also missing. The AGM-122 was designed to be fired at very low altitudes. When the missile is fired at a certain altitude, it will, loft itself for a top down attack onto the targeted radar emitter. Also, a lesser documented option mode the Sidearm had, which allegedly was not used much if at all, was an automatic launch feature. 
 
3) Limited Bandwith usage. I cannot speak to the this in great detail as I am not fully aware as to this specific limitation and how it’s put forward in DCS, but the AGM-122 has specific bandwith windows that have to be selected prior to take off for it to scan for in-mission. I know this feature isn’t available, but the scan range on what the 122 can engage I don’t believe is implemented either. It simply can be fired at any surface radar site, which is also allegedly inaccurate to the missile.  
 
Addressing the range issue which arguably is the largest issue with the missile currently. It is vastly out performing the real missile. Which is a short range, self defense ARM. The AGM-122 shares the entirety of the AIM-9C, except the seeker. The AGM-122/AIM-9C is equipped with a thermal battery that is powered off the exhaust gases when the missile is launched. Which stores heat to the battery and provides at a maximum, of 60 seconds of guidance time and a maximum range cited on paper of 18,044 yards, or about 9 nautical miles (8.9 and change). This is because of the thermal battery limitation. Once the 60 seconds is up, the missile is dead, as there is no longer guidance power. No more guidance, no more control surface control or detonation ability, it’s dead as a door nail. Therefore, lofting it 20+ nautical miles onto SAM sites is not possible with this missile. In numerous documents of use of the AGM-122 the paper cited range of 9nm is in best case scenario launched at high altitude. In typical launch at low altitude from helicopters or the Harrier, ranges were much lower, around 5-6nm at most.  Again, it was a short range ARM.
 
Documentation of the thermal battery guidance limit is noted in the NAVWEPS OP 3353 Declassified Document on the AIM-9C/Parent platform of the AGM-122. (which I wont link here for obvious reasons). It is publicly available.  
 
This article also cites the limited range of the AGM-122 being much lower than a cited 9nm.  

 
https://www.thedrive.com/the-war-zone/12009/the-agm-122-sidearm-came-to-be-from-a-novel-missile-recycling-scheme 
 
Addressing the missing pop up feature. The missile was entirely designed to be launched from low altitudes aboard helicopters primarily and therefore, a “pop up” program was input into the programing of the Sidearm that if it was fired below a certain altitude it would pop up and attack the radar emitter in a top down attack. Similar to the Javelin missile. Currently the missile in DCS does not do this. If fired at low altitude the missile will nearly in all situations hit the ground or trees. This is precisely the reason why the missile was given the pop up feature in real life. The article cited above also describes this feature. As for the self launch feature. This I think “could” be left out given there’s not much documentation on it other than some tertiary sources from interviews talking about how pilots didn’t like that mode (link to an interview about that mode below), but it had it. But in this mode, if the missile picked up a threat on one of it’s 7 bands it would be set to prior to take off, if a threat passed in front of the seeker in range when the missiles were armed, the missile would automatically leave the aircraft and engage the site on it’s own.  
 

 
 
Addressing the limited bandwith the seeker could see. Coupling it with a considerably shorter range, the bandwith receiver on the missile had to be set on the ground prior to launch. Now we don’t have this feature in DCS. However, the limitations in what types of sites it can see I think should be implemented based on what bands it can see. The missile can detect and engage things like the ZSU-23 and other fixed site type emitting dishes/signals. However, given it's limited seeker, it had problems with rotating dishes, as anytime the radar beam pointed in a direction not in the cone of detection, the 122 would lose track of it. The missile based on sources is stated to be most effective against the ZSU-23 style radar and SA-8 sites. This has been discussed in detail in the discord by people that have a much better understanding of the restrictions in this category than I, but I wanted to at least mention it and anyone else who sees this can chime in on more detailed knowledge on the matter.  The only other thing addressing the seeker on the 122 would be the fact of the limited seeker it was easily fooled by countermeasures.

Edited May 23, 2023 by Scorch00
range correction

[JackHammer89]

I wonder if it would be possible to select the "seeker band" from kneeboard in a similar fashion with which we set laser codes from GBUs and APKWS?

Restricting it to somewhere like the ME would be really annoying for MP servers, dynamic missions etc. 

EDIT:

Great work on putting together this report, I hope it gets picked!

Edited May 16, 2023 by JackHammer89

[Scorch00]

8 hours ago, JackHammer89 said:

I wonder if it would be possible to select the "seeker band" from kneeboard in a similar fashion with which we set laser codes from GBUs and APKWS?

Restricting it to somewhere like the ME would be really annoying for MP servers, dynamic missions etc. 

EDIT:

Great work on putting together this report, I hope it gets picked!

 

It would make the ability more useful if it were possible I"m sure. if it were put there like a lot of the codes as you mentioned are. I'm sure that would fall on Razbam to implement in the Harrier. Say mission briefing Intel says you may encounter certain threats in an area and those threats operate on "x" band, you have to put that into your Sidearm before launch. But I guess in the meantime restricting what all it can actually be used against would at least be helpful in keeping the missile more in line with how it was/could be used. There's not a whole lot of info that I could find, but the limitations of using it against rotating dishes was one thing the missile had problems with. But certain fixed antenna or dish type systems it could work against. The ZSU-23, SA-8, and I think early S-300 were things I've seen mentioned. Not sure where that falls into with other sites. I'm sure someone knows specifically the bandwith limitations of the missile and what sites emit what frequencies.  These 3 things I feel are what most of us had talked about in the use of it.

And thank you. I hope so too.

[Flappie]

I found various sources mentioning both the short range (about 9 nm) and the lofting.

I'll test then ask for these changes as soon as I get back to my PC.

I found nothing about a selectable bandwidth window. If you have unclassified documents compatible with rule 1.16, please share them with BIGNEWY in a private message.

[Scorch00]

6 hours ago, Flappie said:

I found various sources mentioning both the short range (about 9 nm) and the lofting.

I'll test then ask for these changes as soon as I get back to my PC.

I found nothing about a selectable bandwidth window. If you have unclassified documents compatible with rule 1.16, please share them with BIGNEWY in a private message.

Thank you. Much appreciated. I will look and try and locate them and PM them if/when found.

[Chizh]

В 16.05.2023 в 00:07, Scorch00 сказал:

I know Razbam did what they could with it before control of weapons went to ED, but it seems to just have been thrown in a closet and forgotten about since the Harrier is the only aircraft that currently carries the AGM-122. A number of us have been discussing it in the AV-8B discord for some time, and came to the realization the reason the AGM-122 has never been fixed, is because nobody has reported just how inaccurate the current version of the missile is compared to the real missile. So I gathered a bit of things that had been mentioned in our conversations to post here. Hopefully more knowledgeable people can chime in on some of these that I list off. Although it may be unpopular to fix the missile. Based on how people currently use it, in a sense of it being a tiny HARM it needs to be properly fixed in comparison to all the other work done on other missiles in the sim. The AGM-122 is based off the very unsuccessful AIM-9C Sidewinder. The AGM-122 has a very limited range, limited usage window, and unique features that are missing from the missile even currently. The issues that should be addressed are some of the following;  
 
1) Range: Currently the AGM-122 in DCS can be lofted to ranges of 20+nm. This is entirely inaccurate for this missile by a significant margin.  This is based off the missile specifications as well as documentation of the missile being far less capable than it's being used currently.
 
2) Missing features of the missile. Self lofting feature of the missile is also missing. The AGM-122 was designed to be fired at very low altitudes. When the missile is fired at a certain altitude, it will, loft itself for a top down attack onto the targeted radar emitter. Also, a lesser documented option mode the Sidearm had, which allegedly was not used much if at all, was an automatic launch feature. 
 
3) Limited Bandwith usage. I cannot speak to the this in great detail as I am not fully aware as to this specific limitation and how it’s put forward in DCS, but the AGM-122 has specific bandwith windows that have to be selected prior to take off for it to scan for in-mission. I know this feature isn’t available, but the scan range on what the 122 can engage I don’t believe is implemented either. It simply can be fired at any surface radar site, which is also allegedly inaccurate to the missile.  
 

Thanks for documents
The range of the AGM-122 close to the original in DCS. But you are right, there is no pop-up and loft at low altitude. I put it on my wish list.
As for the choice of frequencies, you are also right. All anti-radar missiles of those years had very narrow operating freq bands, so before the flight it was necessary to select a frequency band or change the entire seeker, as was the case on Soviet missiles. We will think about how to implement it.

[Dragon1-1]

This will be big deal when HB implements Shrikes on the Phantom, those had dedicated seekers tuned to various threats, much like the Soviet ARMs. HARM was nice because it was AFAIK the first to have a big threat database to pick from in flight.

[Scorch00]

 

1 hour ago, Chizh said:

Thanks for documents
The range of the AGM-122 close to the original in DCS. But you are right, there is no pop-up and loft at low altitude. I put it on my wish list.
As for the choice of frequencies, you are also right. All anti-radar missiles of those years had very narrow operating freq bands, so before the flight it was necessary to select a frequency band or change the entire seeker, as was the case on Soviet missiles. We will think about how to implement it.

I'm not 100% sure what the max range is currently, but there are plenty of videos on youtube of gents lofting them 20+ nm. And well, the missile is capable of 9nm at 10,000 feet, Down low, it's like 5-6 nm. And really being employed low like they should be that missing loft features is kind of paramount. I know the frequency tuning is probably the most complicated part to implement. And not sure how all and how close replication is even allowed considering it's in that EW field of knowledge. But the lofting and range/guidance battery limitation are the biggest thing I thing about it. Regardless, I appreciate the work you all are doing and for taking a look at this.

Edited May 18, 2023 by Scorch00

[Northstar98]

1 hour ago, Chizh said:

We will think about how to implement it.

May I suggest the new fusing window - at least in terms of selection? It seems like it would be a fairly conevnient place to put them.

Also, the same thing would apply to the Shrike for variants other than the AGM-45A/B-10.

Edited May 18, 2023 by Northstar98

[Scorch00]

4 minutes ago, Northstar98 said:

May I suggest the new fusing window - at least in terms of selection? It seems like it would be a fairly conevnient place to put them.

Also, the same thing would apply to the Shrike for variants other than the AGM-45A/B-10.

 

That's a good idea I feel, especially with other early ARM missiles like the Shrike coming.

I know there's the mention of the new fuse customization for weapons that's coming down the road, I feel this seeker tuning feature would likely fit better into that feature if and/when that gets here. As it's more in that same realm as setting up a weapon prior to taking off with it.

[Chizh]

11 часов назад, Northstar98 сказал:

May I suggest the new fusing window - at least in terms of selection? It seems like it would be a fairly conevnient place to put them.

Also, the same thing would apply to the Shrike for variants other than the AGM-45A/B-10.

 

Yes, it is good idea

[Harlikwin]

On 5/18/2023 at 10:06 AM, Chizh said:

Thanks for documents
The range of the AGM-122 close to the original in DCS. But you are right, there is no pop-up and loft at low altitude. I put it on my wish list.
As for the choice of frequencies, you are also right. All anti-radar missiles of those years had very narrow operating freq bands, so before the flight it was necessary to select a frequency band or change the entire seeker, as was the case on Soviet missiles. We will think about how to implement it.

With regard to the seeker settings. I'm pretty sure this had to be set on the ground, which could be set via knee-board stuff. You guys are doing the shrike, which this is more or less a miniaturized version of that  last seeker with some improvements, albeit with a much smaller antenna which isn't going to couple well to lower frequency radars. It is a bit of an assumption but the 7 "bands" are likely pre-sets for various soviet systems in use at that time, or at least portions of a given band that would contain one or more threats that would be differentiated by things like freqency/prf etc. Given that the operating frequencies/prfs of most of these radars are known (and I assume you or HB have them in the new RWR model) if not I can point you to them. The key distinctions here would be that its very likely this missile can only engage "track" radars rather than search radars that are of course much lower in frequency. 

Given that, the most likely systems its going to be looking for on 1980's battlefield are going to be primarily on the SHORAD side of the equation, so stuff like ZSU-23, SA-8, sa-15 as likely its primary threats (which also both conveniently operate at around 14Ghz). I'd also assume systems like Sa-6, and Sa-11 would also be of interest, and then possibly Sa-2/3 with the various sub-variants of this likely eating up different bands it could pick up. 

I very much doubt it could/would target stuff like the SA-4/5/10 etc. 

[Chizh]

Please share information: how many interchangeable seekers did the missile have and at what frequencies did they operate?

[Silver_Dragon]

On 12/21/2023 at 3:35 AM, Harlikwin said:

With regard to the seeker settings. I'm pretty sure this had to be set on the ground, which could be set via knee-board stuff. You guys are doing the shrike, which this is more or less a miniaturized version of that  last seeker with some improvements, albeit with a much smaller antenna which isn't going to couple well to lower frequency radars. It is a bit of an assumption but the 7 "bands" are likely pre-sets for various soviet systems in use at that time, or at least portions of a given band that would contain one or more threats that would be differentiated by things like freqency/prf etc. Given that the operating frequencies/prfs of most of these radars are known (and I assume you or HB have them in the new RWR model) if not I can point you to them. The key distinctions here would be that its very likely this missile can only engage "track" radars rather than search radars that are of course much lower in frequency. 

Given that, the most likely systems its going to be looking for on 1980's battlefield are going to be primarily on the SHORAD side of the equation, so stuff like ZSU-23, SA-8, sa-15 as likely its primary threats (which also both conveniently operate at around 14Ghz). I'd also assume systems like Sa-6, and Sa-11 would also be of interest, and then possibly Sa-2/3 with the various sub-variants of this likely eating up different bands it could pick up. 

I very much doubt it could/would target stuff like the SA-4/5/10 etc. 

The AGM-122 was builded on a "boadband sekker", but not info available about a "interchangeable" sekker.

http://www.designation-systems.info/dusrm/m-122.html

Other font:
https://www.forecastinternational.com/archive/disp_old_pdf.cfm?ARC_ID=1060

[Chizh]

1 hour ago, Silver_Dragon said:

The AGM-122 was builded on a "boadband sekker", but not info available about a "interchangeable" sekker.

http://www.designation-systems.info/dusrm/m-122.html

Other font:
https://www.forecastinternational.com/archive/disp_old_pdf.cfm?ARC_ID=1060

Thank you @Silver_Dragon

We need frequency boundaries or frequency band of Sidearm seeker.

[Harlikwin]

14 hours ago, Silver_Dragon said:

The AGM-122 was builded on a "boadband sekker", but not info available about a "interchangeable" sekker.

http://www.designation-systems.info/dusrm/m-122.html

Other font:
https://www.forecastinternational.com/archive/disp_old_pdf.cfm?ARC_ID=1060

There wasn't an interchangeable seeker. I think however it had to be set for certain bands, most likely on the ground. IIRC there were 7 bands it could use or be set to (or combinations therof), but I'll have to look that up. Also, the more I think about the limitations of late 70's electronics I wouldn't be surprised in the least if it was 7 pre-programmed "threats". Most likely SHORAD and AAA radars. ZSU-23, SA-8, SA-6 etc. 

"The receiver subassembly shall provide the capability to scan the entire frequency band of A to G in a sawtooth" (this is where the 7 bands comes from, A-G, and its also pretty clear it doesn't mean Radar band "A" or "G" its just a generic designation. Probably refering to 7 different slices of spectrum, which likely correspond to "threat" radars. My further guess is stuff like PRF etc is either pre-programmed or has to be set on the ground if you want a different "threat library" as the harrier tac man never mentions any sort of in-cockpit programming.  Its also entirely possible the library is just fixed.

 

Also the guidance life of the missile and or seeker sensitivity needs revisiting. People are using these like HARMS and hitting stuff 10s of miles away by firing them at 30k feet etc.

Here we go. Dokumints. Original Credit to Beamscanner. MY COMMENTS IN BOLD

@Chizh

Most of the following information was found via MIL-G-85742

 

AGM-122 Receiver Info:

-Made 1984

-Uses a Local Oscillator/mixer to down convert the received signals to IF

-Can detect PRF, PW and Amplitude

--This correlates to a superheterodyne Receiver--

 

-Scans between frequencies "A through G"(likely a unique band code, not referencing NATO band codes as a seeker that small wouldn't be able to track such low frequencies)

-We know it can detect an SA-8 and a ZSU-23 radar, thus we know it can at least see signals roughly between 7 and 15 GHz.

-Generates a tone for the pilot to hear that matches the signals PRF.

 

 

"WGU-15(XCL-1)/B" Seeker info:

-Conically scanned. 'Gyro speed.. between 7-20Hz'

-'Unambiguous FOV>15 degrees'

-"The system gain in each of the four quadrants" Implies a 4 quadrant array

---Of note, the seeker must be able to detect linearly polarized signals from any angle (given the missiles chance of spin), but also must be cheap given its purpose. Knowing this, the tracking technique, the rough size of the seeker, and the time of IOC, the missile likely used a small 4 spiral antenna array
 

---Spiral antennas are cheap, have wide bandwidths, and can see nearly all polarizations. The band width these antennas provide would indeed allow the seeker to see the SA-8 and the ZSU-23 from such a small aperture.

---Spiral antennas have wide beam widths, making for poor tracking. Though, using the sum of 4 spiral antennas can narrow your beam width and increase your tracking performance.

It does not use a 4 spiral antenna, its a parabolic dish like the 9C used but not exactly the same (picture included)

null

 

Other:

-Uses PN guidance

-"The AGM-122 was less capable than newer antiradiation missiles like the AGM-88 HARM, but also substantially cheaper, and its lighter weight enabled it to be carried by combat helicopters as well as fighter aircraft and fighter bombers."

-"While Sidearm is less capable than modern anti-radiation missiles (like AGM-88 HARM), it is still a cost-effective alternative against low-tech threats."

Likely can't deal with more modern russian radar threats i.e. SA-10/11 etc

-"it was proposed to build new missiles as improved AGM-122B. The AGM-122B was to receive a new guidance and control system using re-programmable EEPROM memory boards."

supports the idea of a small fixed set of radars it could detect/target

--The above implies that there were some short falls with the AGM-122 guidance against modern systems. This would make sense if the missile used a conical scan tracking system like I hypothesized, as multipath effects, jammers, decoys, and amplitude modulation could cause to seeker to guide off target.

 

Based on the following

-PN guidance

-no INS unit

-no target plotting

-the use of conical scan tracking (also called 'lobe on receive')

The missile was probably very ineffective against radars with a scanning antenna. I imagine shots were only made on radars who's beams were fixated (locked) on to the launching aircraft. Reason being that the seeker would lose the radar every time the beam spun around to the other direction, in which case it might home in on a reflection off an illuminated object (think of a flashlight spinning around).

Broadly agree, its entirely possible it would only target actual tracking radars, though possibly it could use sidelobes. 

 

References:

 

http://guidedmissilecomponents.emilspec.com/MIL-G-85742-2/page2.html

http://guidedmissilecomponents.emilspec.com/MIL-G-85742-3/index.html

http://guidedmissilecomponents.emilspec.com/MIL-G-85742-4/index.html

http://guidedmissilecomponents.emilspec.com/MIL-G-85742-5/index.html

http://guidedmissilecomponents.emilspec.com/MIL-G-85742/index.html

http://www.designation-systems.net/dusrm/m-122.html

https://www.onwar.com/weapons/rocket/missiles/USA_AGM122.html

Edited March 7 by Harlikwin

[Harlikwin]

Also, its very likely you cannot use the Jammer and the Sidearm at the same time, for obvious reasons. 

[Floydii]

On 5/19/2023 at 1:36 AM, Chizh said:

Thanks for documents
The range of the AGM-122 close to the original in DCS.

Im not sure this is correct.

The main issue here is that the AGM-122 can currently reach 100% further (at least) than the stated range (at speed and altitude) of 9nm. Can any of the L-M model AIM-9s in DCS go 20 NM and stay controllable?

[Hobel]

vor 7 Stunden schrieb Floydii:

Im not sure this is correct.

The main issue here is that the AGM-122 can currently reach 100% further (at least) than the stated range (at speed and altitude) of 9nm. Can any of the L-M model AIM-9s in DCS go 20 NM and stay controllable?

is it confirmed that the lifetime of the AGM-122 should be 60 seconds?
if it is more than 60 seconds, what would be the limiting factor?

[Floydii]

I'd suggest it would be the missile running out of energy (and therefore lift) before the 20nm mark.

[Hobel]

vor 2 Stunden schrieb Floydii:

I'd suggest it would be the missile running out of energy (and therefore lift) before the 20nm mark.

Aim9m has similar aerodynamics as the agm-122 and could also reach about 20nm without self-destruction.  Energy would not be a problem.