Searching for proof of underperforming AN/APG-73 radar

[Harlikwin]

3 hours ago, tflash said:

Anyway something is just clearly wrong with the latest patch: Against AI Mig-23's at 20K altitude I have relatively useful detection range when I narrow my sweep, but I loose lock continuously (in whatever mode). The AI Migs can engage me first 100% of the time. They are actually not really manoeuvring as they are AI. 

It is only when I boresight the radar when the bandits are within 10 NM that I can lock and engage. 

 

I mean in HPRF it only works if the target is hot, its very easy to drop locks at long range vs someone using HPRF. Once you get into MPRF ranges is where you should be trying to get locks and shots as its less aspect dependent. 

[tflash]

3 hours ago, Harlikwin said:

 

I mean in HPRF it only works if the target is hot, its very easy to drop locks at long range vs someone using HPRF. Once you get into MPRF ranges is where you should be trying to get locks and shots as its less aspect dependent. 

 

Makes sense! I have to withdraw what I said: I made a new mission, same distance, height, but other map and better weather, and now things worked normal, I could get stable TWS lock on two tracks from around 20 NM, not 10 as I posted before. I still do not understand what goes wrong in the other mission, but anyway so I have no reason to claim something is wrong with the patch. 

[Harlikwin]

34 minutes ago, tflash said:

 

Makes sense! I have to withdraw what I said: I made a new mission, same distance, height, but other map and better weather, and now things worked normal, I could get stable TWS lock on two tracks from around 20 NM, not 10 as I posted before. I still do not understand what goes wrong in the other mission, but anyway so I have no reason to claim something is wrong with the patch. 

 

While I doubt ED's radar code does it, weather can degrade performance as well IRL. The problem we have is that we don't know what ED models or not, and HOW they model it.

[tflash]

PS I think what was happening, when Mig-23's are coming straight unto you, and go wings swept back, they just disappear from the radar between about 25 miles and 10 miles, no possibility to get them back in TWS, whatever frequency / scan volume. 

So this must have to do with the RCS of the Mig-23 model in game. 

[jojo]

4 hours ago, tflash said:

PS I think what was happening, when Mig-23's are coming straight unto you, and go wings swept back, they just disappear from the radar between about 25 miles and 10 miles, no possibility to get them back in TWS, whatever frequency / scan volume. 

So this must have to do with the RCS of the Mig-23 model in game. 

I don’t think that in DCS the RCS would change depending on wing sweep !

Are you sure they didn’t got out of scan elevation ?

[GumidekCZ]

Guys, please, lets stick with topic.

We are searching for evidence outside of DCS (real world) to compare it with APG-73 performance in DCS.

Not to solve, why somebody cant lock MiG-23. If needed, create another topic or bug report with track and acmi attached.

Thanks.

Sadly as I spend couple of days searching any real world evidence, Im slowly loosing ideas, where else I can search for any valuable information. Not even single RCS value (or airframe type) detected at certain range was found   . I really hope, that others like you, will be more lucky in that.

[Beamscanner]

A 1983 defense case study prepared for the U.S. DoD, determined (utilizing the Radar Range equation; not a performance review) that the maximum detection range for the APG-65 (pre-cursor to the APG-73) against a "medium size target" (ie ~5 sm) to be about 45 nmi in look-up HPRF conditions. (implied 50% probability of detection or Pd, western norm in radar community)

 

Above are the best known facts. One could use the radar range equation, plot the most likely values that lead to 45 nmi, and extrapolate the detection range against 1 sm and 15 sm targets. 

 

Best guess/assumption: APG-73 upgrade improves detection range between 10-25%, putting its detection range

(HPRF / Look-Up / Head-On / 50% Pd / ~5 sm target) between 50-57 nmi.

 

Reference: https://apps.dtic.mil/dtic/tr/fulltext/u2/a142071.pdf

 

Edited August 13, 2021 by Beamscanner

[Beamscanner]

I believe the DCS APG-73 is currently slightly underperforming against large RCS targets.

 

Spudknocker's recent test video indicates that the DCS APG-73 is detecting the SU-27 at 48 nmi and the Mig-21 at 38 nmi in optimal conditions.

 

As my previous post estimates, a 5 m2 target should be detected under optimal conditions between 50-57 nmi. The SU-27 has an estimated forward RCS of 10-15 m2... So I do believe the detection range on it should be between 60-70 nmi, and not 48nmi.

 

Mig-21 RCS is roughly 3 m2. So it should be detected around the mid-40s or so.

 

 

[Harlikwin]

2 hours ago, Beamscanner said:

I believe the DCS APG-73 is currently slightly underperforming against large RCS targets.

 

Spudknocker's recent test video indicates that the DCS APG-73 is detecting the SU-27 at 48 nmi and the Mig-21 at 38 nmi in optimal conditions.

 

As my previous post estimates, a 5 m2 target should be detected under optimal conditions between 50-57 nmi. The SU-27 has an estimated forward RCS of 10-15 m2... So I do believe the detection range on it should be between 60-70 nmi, and not 48nmi.

 

Mig-21 RCS is roughly 3 m2. So it should be detected around the mid-40s or so.

 

 

 

Su-27 is a 5m2 target in DCS so thats probably a large part of the issue. Might be worth it to test it with a 21 which is 3m2 tgt in dcs too. 

Edited August 14, 2021 by Harlikwin

[gonk]

I get "LOST" at lot (30%) when in TWS at the instant of launch a AIM120... Is the AIM120 masking the radar ?  This is in Multiplayer mode.. don't play single player much at all.  Synch issue ? or Radar ?  

[Hammer1-1]

Most of the time its not lost, especially when you still have the contact L&S'ed and it hasnt disappeared from the scope yet.

[Jak525]

On 8/15/2021 at 8:47 PM, gonk said:

I get "LOST" at lot (30%) when in TWS at the instant of launch a AIM120... Is the AIM120 masking the radar ?  This is in Multiplayer mode.. don't play single player much at all.  Synch issue ? or Radar ?  

LOST wouldn't even tell you if the datalink to the AMRAAM isn't getting there, because it's one way. However, yes there is a gigantic problem with the LOST cue. Basically it is representative of live parameters between the aircraft and the target, whereas it needs to be a simulation of how the missile is predicted to perform based on the instant it was launched. Basically after launching an AMRAAM, if you turn sharply, it will say LOST. But the AMRAAM was already fired so ownship maneuvers are totally irrelevant. For example, if I shoot a gun and then point the gun toward the floor, the bullet is still flying straight, cause I've already fired it. The LOST cueing however is not properly accounting for this.

 

As for the LOST immediately at launch there may be an additional issue in multiplayer, I'm not sure though.

Edited August 17, 2021 by Jak525

[Svend_Dellepude]

WIP I guess. Once LOST is there it doesn't go away. I guess it's on the list of things.

[S. Low]

Is it possible for a fuel tanker within 10nm to notch the 18s radar? I was trying night time AAR a few days ago. I was approaching tankwr using the bugged out A/A tacan thing but then I wanted to lock him up to close the final distance. He was co Alt with me and I think flying left to right or right to left. I couldn’t get him to pop up on radar or SA for more than a split second. I got a soft lock on him once in Tws but it disappeared immediately.

 

Radar scan elevation had him in between the values. Scan width was down to like 60 deg. I believe it was at 4B. I’m not proficient in radar use yet but I didn’t think it would take much messing around to pick up a giant fuel tanker under 10nm at co Alt?

[Hulkbust44]

Is it possible for a fuel tanker within 10nm to notch the 18s radar? I was trying night time AAR a few days ago. I was approaching tankwr using the bugged out A/A tacan thing but then I wanted to lock him up to close the final distance. He was co Alt with me and I think flying left to right or right to left. I couldn’t get him to pop up on radar or SA for more than a split second. I got a soft lock on him once in Tws but it disappeared immediately.
 
Radar scan elevation had him in between the values. Scan width was down to like 60 deg. I believe it was at 4B. I’m not proficient in radar use yet but I didn’t think it would take much messing around to pick up a giant fuel tanker under 10nm at co Alt?

Did you adjust the brick timeout from the default of 4?

Mobius708

[MARLAN_]

On 8/17/2021 at 12:02 PM, Jak525 said:

LOST wouldn't even tell you if the datalink to the AMRAAM isn't getting there, because it's one way. However, yes there is a gigantic problem with the LOST cue. Basically it is representative of live parameters between the aircraft and the target, whereas it needs to be a simulation of how the missile is predicted to perform based on the instant it was launched. Basically after launching an AMRAAM, if you turn sharply, it will say LOST. But the AMRAAM was already fired so ownship maneuvers are totally irrelevant. For example, if I shoot a gun and then point the gun toward the floor, the bullet is still flying straight, cause I've already fired it. The LOST cueing however is not properly accounting for this.

 

As for the LOST immediately at launch there may be an additional issue in multiplayer, I'm not sure though.

 

There is also an additional issue that the NIRD/Launch Parameters are out of date ever since the AMRAAM was improved awhile ago (last year?) thus a perfectly capable shot will display LOST off the rail.

 

I just ignore and tell everyone else in my squadron to ignore the LOST indication right now until it's fixed, because it's totally useless (and confusing for those who don't know) in its current state.

[Jak525]

1 hour ago, MARLAN_ said:

There is also an additional issue that the NIRD/Launch Parameters are out of date ever since the AMRAAM was improved awhile ago (last year?) thus a perfectly capable shot will display LOST off the rail.

 

I just ignore and tell everyone else in my squadron to ignore the LOST indication right now until it's fixed, because it's totally useless (and confusing for those who don't know) in its current state.

Correct, that's another issue; the actual performance assumptions are from before the AMRAAM was reworked, I don't think they've been updated. Regardless they don't work as they should even with the out of date assumptions.

[DGC338]

I have a question about bar scan and scan Volume in the F/A-18 v F-16. 

Conditions. Scope range 80, Radar cursor set at 40NM. I get the following altitude volumes scanned by the aircraft 

 

F/A-18:

1 Bar 14K'

2 Bar 20K'

4 Bar 32k'

6 Bar 44k'

 

F-16:

1 Bar 20K' vertical scan volume

2 Bar 29K' 

4 Bar 46K' 

 

It seems odd that 4 Bar scan on F-16 is scanning more vertical Volume than a 6 Bar scan on F/A-18. It certainly may not be wrong given different radars, does anyone have any insight into this? Radar beam width differences?

 

 

Edited September 18, 2021 by DGC338

[DGC338]

I have been informed that the above is correct as per the aircraft radar specifications.

[Beamscanner]

16 hours ago, DGC338 said:

I have a question about bar scan and scan Volume in the F/A-18 v F-16. 

Conditions. Scope range 80, Radar cursor set at 40NM. I get the following altitude volumes scanned by the aircraft 

 

F/A-18:

1 Bar 14K'

2 Bar 20K'

4 Bar 32k'

6 Bar 44k'

 

F-16:

1 Bar 20K' vertical scan volume

2 Bar 29K' 

4 Bar 46K' 

 

It seems odd that 4 Bar scan on F-16 is scanning more vertical Volume than a 6 Bar scan on F/A-18. It certainly may not be wrong given different radars, does anyone have any insight into this? Radar beam width differences?

 

 

 

 

 

 

 

not odd at all. 

 

Look at the two antennas. 

 

 

 

 

 

 

 

 

 

Antenna theory: The larger the antenna (given a fixed freq) the smaller its beam width.

 

The APG-73 has a circular antenna. Meaning its beam width is angularly uniform (a uniform cone of emitted light). 

 

The APG-68 has an oval antenna. Meaning that the beam width is narrow in azimuth, but wide in elevation. Because the vertical diameter of the antenna is smaller, the beam it emits is wider in elevation. This means it can scan more vertical volume of space, but it also means that it concentrates less energy into a tight beam, greatly reducing its max detection range. 

Edited September 18, 2021 by Beamscanner

[hein22]

On 8/14/2021 at 9:40 PM, Beamscanner said:

I believe the DCS APG-73 is currently slightly underperforming against large RCS targets.

 

Spudknocker's recent test video indicates that the DCS APG-73 is detecting the SU-27 at 48 nmi and the Mig-21 at 38 nmi in optimal conditions.

 

As my previous post estimates, a 5 m2 target should be detected under optimal conditions between 50-57 nmi. The SU-27 has an estimated forward RCS of 10-15 m2... So I do believe the detection range on it should be between 60-70 nmi, and not 48nmi.

 

Mig-21 RCS is roughly 3 m2. So it should be detected around the mid-40s or so.

 

 

So the performance of last year was closer to the real thing?

Did ED say when they're planning to correct this?

[Harker]

So the performance of last year was closer to the real thing?
Did ED say when they're planning to correct this?

This seems to be more of a problem of RCS values for different aircraft instead of something specific to the Hornet. The RCS values in DCS are very different from IRL. It'd be better if ED fixed that first and then adjusted the radars based on known radar equations.

[hein22]

I just noticed that this really screwed AWACS efficiency as well. That's why I was getting constant drop outs despite very close AO.

Just now, Harker said:

5 minutes ago, hein22 said:

So the performance of last year was closer to the real thing?
Did ED say when they're planning to correct this?

This seems to be more of a problem of RCS values for different aircraft instead of something specific to the Hornet. The RCS values in DCS are very different from IRL. It'd be better if ED fixed that first and then adjusted the radars based on known radar equations.

I think ED would have corrected those before breaking the whole game. Are we even sure that the values we see in the LUA are in square meters?

I'm afraid we're stuck with this performance forever.

[The RDN]

I all, 

When ED do the corrections to the detection range of hornet's radar, I was also a little bit skeptical.. but luckily I work on Swiss Air Force, and I know a Hornet test pilot, So I asked him the question. And according to him, beyond 40 nm they can only detect large aircrafts. 

He can't give me a precise figure, but when I asked him if it seemed credible to him to detect a mig23 or an f4 only from 40 nautical miles (hot aspect with PRF high), he answered that it seemed more or less correct.

[hein22]

 

9 hours ago, The RDN said:

I all, 

When ED do the corrections to the detection range of hornet's radar, I was also a little bit skeptical.. but luckily I work on Swiss Air Force, and I know a Hornet test pilot, So I asked him the question. And according to him, beyond 40 nm they can only detect large aircrafts. 

He can't give me a precise figure, but when I asked him if it seemed credible to him to detect a mig23 or an f4 only from 40 nautical miles (hot aspect with PRF high), he answered that it seemed more or less correct.

Right now an AWACS, with its gigantic dish, is losing a contact that's cold at 25nm (in relation to the AWACS itself). That doesn't sound right at all. So Hornet accurate or not, the radar detection thing is officially broken IMHO.

It's no way possible that an AWACS has the same low aspect PD of a Hornet.

Is the F16 similar to the 18 now? Or is it still detecting targets like an F15?

Edited October 28, 2021 by hein22