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does the jeff/klj-7 comes with a rotating radar or radar mount?


witness_me

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Can someone from the DEKA team or someone who knows the particular airplane/radar very well please confirm if it has 2 or 3 dof?

 

 

I'm facing various problems when I'm using the a/a radar and I'm wondering if my understanding of the airplane is lacking/I'm using the wrong tactics for it's capabilities, there's something wrong with my installation or if i'm hitting some obscure bug?

 

 

 

Thanks in advance!

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Just like you see on most modern pulse Doppler plane, two gimbaled axis. Represented on display by the green marks on the white scales on bottom and left side. What’s your issue? Elevation?

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Edited by AeriaGloria

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Just like you see on most modern pulse Doppler plane, two gimbaled axis. Represented on display by the green marks on the white scales on bottom and left side. What’s your issue? Elevation?

 

 

Hey - thanks for helping - i don't think i know of any fighter jets that came out in the past 20 years that have 2 axis :S - do you know that this is the case for sure?

 

 

if you have 5 mins to spare/help, can you try some instant mission and test a couple of things:

- lock something in stt, point straight at it and then do a roll and let me know if you dropped the contact at around 70 degrees

- lock the target again, then do a flat left (bank and start pointing away from it - same horizontal plane though), pull some g's while doing it, do you drop the contact say when your nose is pointing say at around 30-40 degrees from your target (but not at 60 degrees)?

 

 

if don't have time no worries - much appreciated anyway :)

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I'm facing various problems when I'm using the a/a radar and I'm wondering if my understanding of the airplane is lacking/I'm using the wrong tactics for it's capabilities, there's something wrong with my installation or if i'm hitting some obscure bug?

The main thing I've noticed is that the KLJ-7 is modelled with +/-30° Elevation Limits, while most western aircraft have +/-60° Elevation Limits (i.e. they have similar horizontal and vertical limits).

 

This means if I do a 50° crank in the JF-17 and want to turn into the target, I'm careful in how fast I roll/turn, as it's easier to exceed the radar's gimbal limits and break target lock i.e. if a target is more than 30° off the nose and I roll 80°

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Someone correct me if I’m wrong but 2 axis gimbals seem pretty standard for non ASEA modern PD, whole teen series, MiG-23+, the PD Eurocanard radars like Grifo PS-05/A. Maybe I’m missing something and rolling a PD beam does do something, but I always though all these are two axis only. I know modern ones have rotating filters, for example Su-27/MiG-29 has a fixed ground clutter filter that forces a lock to be lost if you roll too far.

 

I’m trying to find the thread where Deka said the exact elevation limits it was a Satarosa thread, but IIRC it was 60 in both directions. Could be your problem Ramsay has to do with the elevation weirdness some people have seen. It also seems the display logic was changed. I thought it seemed to be if I turned away from a target so that the radar is pointing down at them until I reach maximum crank, the target stays in the center of the display until I rolled level then it moved to the side(this made it hard to judge how far to crank). It seems with the new update the target on your B scope will move to the side if you turn away regardless of your roll, making it easier to achieve maximum crank by just turning until the target is at the side of the display. Anyone else notice this or am I crazy?

 

Edit, found the thread, you are right, +30/-30 degrees for elevation, surprising https://forums.eagle.ru/showthread.php?t=258188. Says F-15 has same elevation limit

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Edited by AeriaGloria

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yeah if you have the same limits up/down with left/right then you can still maneuver at least, unfortunately the jeff has 30 degrees on the vertical and 60 on the horizontal afaik

 

sorry i wasn't talking about aesa's, i shouuld have clarified that

 

my comment didn't make much sense if taken literally - i doubt anyone is still making this type of radars these days - they're not in use for some time now. The airplanes you mention are pretty old - i guess i was expecting a modern fighter to fly in a certain way, but maybe that wasn't a concern for the manufacturer etc or they simply didn't want to pay for this capability

 

the "problem" i'm having is that if the radar scan zone is a rectangle and you can't rotate your antenna then when the airplane rolls the limits change (horizontal limits are now vertical and vice versa), not allowing you to perform some types of manoeuvres. It's getting pretty late for me i'll try to post some drawing tomorrow and hopefully explain this better - thanks for trying to help though!

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I get you, it’s weakness, probably a compromise just like Eagle radar. It’s much lighter then Grifo PS-05/A by over 30kg, so that might be a factor. I only mentioned MiG-23 because AFAIK it was the first gimballed Soviet fighter radar as well as PD. As far as I know the Grifo PS-05/A is KLJ-7s closest comparison

 

People will try to exploit it by getting us into a turn right where we don’t have a HMD and can’t slew our radar far up even with vertical scan. Hope someday the logic can be changed so that vertical scan is as fast as it’s supposed to be. And even with the small bar size and spacing, we are going to have to get really precise to make the most of it


Edited by AeriaGloria

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i reported this on day one. It's 100% wrong. Devs said they acknowledged it.

 

 

Better description: the radar does not ground stabilise during rolling, so radar contacts appear to move in azimuth when you are not wings level. Which affects greatly any ability to keep a track on gimbals, a primary part of lengthening the bandits F-pole.

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@Pikey - if you're referring to a problem similar to the one i was reporting here: https://forums.eagle.ru/showthread.php?t=259790 -- I think it's now fixed

 

@Aeria - first of all my comment about the radars with 2dof in the last 20yrs was a brainfart - it was late and all that :) I meant, the latest radars with a rectangular scan area (before advances in electronics made possible the increase in the number of modules / being able to have a square or square-ish scan area), before they were all obsoleted by aesa's (a good couple of decades ago or so), were using 3dof gimbals to overcome issues with the scan area becoming very narrow when an airplane is banked and/or for noise related reasons etc - chronologically this is more of a 70's / 80's issue rather than 20 years ago

 

e.g. 384976007_rotatingthingy1.JPG.a6fafad29cf665f0916f5a95ffd151e7.JPG and 521487703_rotatingthingy2.JPG.5b10ea6109d6b36982ed527cd9144cae.JPG - the f15 was using the same arrangement so the 30 degrees limitation on the vertical wasn't so much of a problem unless someone would do a barrel roll :P

 

the jeff was to use this originally i think: https://www.leonardocompany.com/documents/20142/3149726/GRIFO_S_Fire_Control_Radar_LQ_mm07799_.pdf?t=1538987501858

 

maybe PAF didn't want to pay for a larger antenna for whatever reason :S I have no idea :S I know very little about the company that makes the radar and/or the history behind the jeff and about how "non western" airforces use their aircrafts/tactics involved etc, maybe somehow it's a non issue for them?

 

As far as the game is concerned though, the radar is behaving erratically:

- sometimes if i roll more than 50 degrees, i might lose a track, even if i'm pointing straight at the target (wtf!?)

- sometimes the radar tracks 60 degrees on the vertical, sometimes it doesn't

- there's all sorts of visual glitches (i can swap modes and that takes care of them)

- it's not losing tracks when it should do

- picking a target is all over the place, sometimes i click on an old return and the radar locks on to a target 20 degrees apart !?

 

I'm not sure if it's my computer, if it's a general issue but nobody's doing any a2a and people haven't noticed, if the radar has some weird specs regarding rates of changes in attitude and/or angle when tracking etc

 

i recorded all sorts of issues with the help of a mate:

 

i'll try to raise a bug report, but considering that this post took me almost half an hour to type, i'll probably get to it sometime in the week :)


Edited by witness_me
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Where in that brochure shows the Grifo has a roll axis? While those F-15 pictures do look like the rotate, I’m still not convinced. I have been doing nothing but AA since the last patch, but I will do some tests on my own to see if I experience your issues.

 

Not fighting you, just sometimes radar can be black magic to me, it’s hard to figure everything out. Biggest thing for me versus our Soviet planes is the information overload we have

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Edited by AeriaGloria

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Where in that brochure shows the Grifo has a roll axis? While those F-15 pictures do look like the rotate, I’m still not convinced. I have been doing nothing but AA since the last patch, but I will do some tests on my own to see if I experience your issues.

 

Not fighting you, just sometimes radar can be black magic to me, it’s hard to figure everything out. Biggest thing for me versus our Soviet planes is the information overload we have

 

the grifo i linked does +- 60 degrees on both axis - i linked it here just because it seemed to me that in the early days of the project the spec was for a different setup but they (PAF) altered their specs later on (different tactics? cost? who knows)

 

the 2nd photo is from an early f15, the other one is from another airplane/it's there just as another example of what they used to do back in the day (the 1st one is still in use)

 

no worries, i didn't get such an impression, all good here :) we're all just trying to figure stuff out :beer:


Edited by witness_me
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@Beamscanner we need you

 

I see the +60/-60 now thanks. In the beginning JF-17 was to have western avionics. Not just Grifo radar but Indra ALR-400 RWR(some sources say it still uses this, but I believe they are using a Chinese unit on all units but I forget the name it’s in my saved documents somewhere...)

 

There are many theories of why they went all Chinese on the avionics. Some people think it’s cost only, some people seem to think PAF found the KLJ-7 to be just as good as the Grifo. And others say tightening down proposals to truly make it a sanction free jet also played a part

 

EDIT: forgot you can still see the legacy of their European sources avionics plan in the R&S M3AR radio that is still used. There is also the Martin Baker seat, but that is a PAF standard to have Martin Baker seats in all of their airplanes. I think they switched to only Martin Baker after accidents from other ejection seats, I’m sure there’s a whole article on that issue somewhere


Edited by AeriaGloria

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there's no doubt in my mind that a top tier radar manufacturer from china would be able to come up with a similar or better radar than the griffo s (or a radar with similar specs from any western manufacturer) at a lower price, i think that much is a given - if PAF went with lower specs it would either be because they wanted to produce it domestically/there was some IP transfer or they were looking at drivign the cost even lower or maybe they just use different air to air tactics?

 

 

p.s. please take a look at my youtube video and let me know if you get the same problems - it's driving me nuts, i can't do air to air since the last patch :P

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Saw your video definitely some weird stuff in the beginning. Is it only happening in RWS/TWS vs STT? Could be inaccuracies of predicting the RWS/TWS track through violent maneuvers? Also your video makes it clear you can notch to the side in a almost 90 degree angle bank until the contact is on the edge of the display. For example when you pull a hard almost 90 degree level turn in TWS lock the antenna elevation scale and caret don’t change only the azimuth scale/caret. So does it automatically display the limit of rectangular coverage, or like you first thought in this thread it does rotate on a gimbaled roll axis.....

 

But hey I never flew western planes with MFD radar that much maybe that’s how they work and I’m just ignorant

 

EDIT: yeah it has to roll stabilized. Don’t know why i was so against it before because now I remember things like the 120 degree roll stabilization on MiG-29/Su-27. Makes me wonder how the F-16 and it’s oval radar dish squashed down for size roll stabilizes.... I kept searching before also for “radar roll axis” but I see now it’s almost always referred to as “roll stabilized” and I know have of search results. Time for me to eat some humble pie


Edited by AeriaGloria

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Pure speculation but I see no reason why roll stabalization couldn't be handled in software. I'm not aware of any physics reason why it would need to physically roll if it is pointing at a single target; two-axis would be sufficient for that.

 

There may be some physical roll stabilization, but +/- 120 degrees seems excessive.

 

Also, no aircraft would be able to use their RADAR inverted. Wouldn't make sense. ;)


Edited by Tiger-II

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Hey it’s true Su-27/MiG-29 have that roll stabilization. While radar isn’t suppossed to be used inverted, the rotating filter on the American planes allow them to roll and turn violently without the target being covered by the ground cluster filter, so I think it is a slight advantage.

 

As seen on this thread I at first thought roll stabilization is not needed until I realized how some planes have different elevation limits then horizontal like our Jeff, F-15, F-14 I think. I’m sure I’ve seen videos of it on a startup running BIT with nosecone opened. When the roll axis is supporting the pitch and yaw axis in between the roll and the radar dish, I think it would be an advantage to maintain the maximum horizontal coverage on the horizontal. Also even if it was 60 degree by 60 degree coverage the coverage is probably square and wouldn’t rotate perfectly


Edited by AeriaGloria

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