Question regarding Su-27 Radar

[Lino_Germany]

My question is regarding the radar range scale and the deeper sense of the ability to change manualy the expected radar-range to the target.

 

What does the changing of the range scale by the [+] and [-] keys (german keyboard layout [ß] and [´] keys) really cause?

In the past I thought that this function infuenced my radar emission. So if the radar scale is set to 25 km, there should not be radar emission at the range of 50 km!?

 

However, now appears this situation:

 

 

 

 

As you can see, although the radar range scale is set to 25 km, an enemy thread is displayed at the top the HUD, range is 50 km.

 

So my conclusion is, that the radar works at any time with full power.

 

If this conclusion is true, what is the sense behind the manualy change of the radar range onto an expected target?

 

I quote from the DCS Su-27 Flight Manual:

 

The expected (manual) range to target (often derived from AWACS and GCI data), as set by [RCtrl-+] and [RCtrl--] keys and is indicated at the bottom of the HUD under the azimuth coverage bar. The elevation coverage of the radar scan pattern is calculated from this parameter.

 

In my opinion this radar-feature has zero effect in the sim. Can someone confirm this assumption?

[Weta43]

It's doing what it's supposed to...

The strength doesn't differ, you're just telling it where to point - for a given height difference, the angle from your nose will be different at different distances.

 

If you dial in 10 km away, and 10 km higher than you, the radar will point up at 45 degrees and scan around that area. 10 km higher and 20 km away, ~ 23 degrees

[Lino_Germany]

So the radar range scaling ist just some possibility to adjust the radar cone alignment (in degrees) smoother (with wide range setting) or rougher (with short range setting)?

Edited March 3, 2015 by Lino_Germany

[Mar]

This is display range. As Weta said, the only things you can do with the Su-27 radar are point it up/down/left/right and change the pulse frequency mode. You can't increase or decrease the range of the radar.

 

The radar will always show contacts at the very top of the screen if your display range is lower than the contacts' actual range, and I believe vice versa.

[Lino_Germany]

Thanks for your replies. I think I got it.

[Azrayen]

So the radar range scaling ist just some possibility to adjust the radar cone alignment (in degrees) smoother (with wide range setting) or rougher (with short range setting)?

 

Exactly, Lino. :)

And I may add that, despite your initial assumption, it always did that (and that only) even on previous versions of the simulator (at last back to FC1, can't remember if this feature was available before that).

 

Cheers,

Az'

[IonicRipper]

While we're on the subject, can anyone tell me why exactly the Sukhoi engeneers decided that we needed the hud pointed in the same direction as the radar in order to see the radar's targets? Example, if I have the radar pointed 5 clicks up, i need to point my nose up just in order to see if there are any targets there. Why couldnt the hud always show what the radar saw regardless of the antenna elevation setting?

[karambiatos]

While we're on the subject, can anyone tell me why exactly the Sukhoi engeneers decided that we needed the hud pointed in the same direction as the radar in order to see the radar's targets? Example, if I have the radar pointed 5 clicks up, i need to point my nose up just in order to see if there are any targets there. Why couldnt the hud always show what the radar saw regardless of the antenna elevation setting?

You don't need to point your hud where the plane is, you are using it wrong, if you leave the distance marker at the default 10km, putting the radar 5 times up will only detect targets almost completely above you.

 

The correct elevation only applies for a target at the correct distance, if you aren't using the distance setting, then it won't work correctly.

[Ironhand]

While we're on the subject, can anyone tell me why exactly the Sukhoi engeneers decided that we needed the hud pointed in the same direction as the radar in order to see the radar's targets? Example, if I have the radar pointed 5 clicks up, i need to point my nose up just in order to see if there are any targets there. Why couldnt the hud always show what the radar saw regardless of the antenna elevation setting?

They didn't, as Karambiatos has already noted. FWIW (not much), I almost never change the range scale myself and just leave it at 10. That being said, I don't recall ever needing more than 3 clicks up and, then, it was only because I was keeping an eye on a very high flyer from a low altitude. Most of the time I'm within 1 or 2 clicks of "0".

[IonicRipper]

5 was just as an example, i dont ever recall using 5 clicks. What i wanted to know is if there was a better way to scan high targets when flying low. 2 clicks up is apparently not visible on the hud anymore according to the hud view tick marks. I guess more testing in the mission builder is in order.

[karambiatos]

the HUD doesnt show altitude, when in radar mode but the distance, so if a contact shows near the top of the hud he is farther away than a contact near the middle.

 

Unless you mean the contacts are going outside of the frame of the hud and you need to move your head down to see the rest of them which wouldn't be strange, it's not the first time the 27s had things going outside of the HUDs frame.

[Ironhand]

5 was just as an example, i dont ever recall using 5 clicks. What i wanted to know is if there was a better way to scan high targets when flying low. 2 clicks up is apparently not visible on the hud anymore according to the hud view tick marks. I guess more testing in the mission builder is in order.

The HUD view tick marks indicate the portion of the sky you can see with your eyes through the HUD, don't they? If the elevation bar is above or below those marks, you are scanning a portion of the sky you cannot physically see in the HUD. It doesn't mean that you can't scan [EDIT]and have it displayed on the HUD[/EDIT]. It just means that what you are scanning won't be physically visible through the HUD. Or am I not understanding the concern?

Edited April 3, 2015 by Ironhand

[mvsgas]

the HUD doesnt show altitude, when in radar mode but the distance, so if a contact shows near the top of the hud he is farther away than a contact near the middle.

 

Unless you mean the contacts are going outside of the frame of the hud and you need to move your head down to see the rest of them which wouldn't be strange, it's not the first time the 27s had things going outside of the HUDs frame.

 

The HUD shows altitude, it actually show a lot of information. How to tell the target altitude? Change antenna elevation. This should give you an idea of target elevation when compared to you height.

See this at 3:25

 

 

additionally,

http://cdn.akamai.steamstatic.com/steam/apps/250310/manuals/DCS_Su-27_Flight_Manual_EN.pdf?t=1417046009

 

See page 52

 

Similarly like a F-15.

Edited April 3, 2015 by mvsgas

[karambiatos]

The HUD shows altitude, it actually show a lot of information. How to tell the target altitude? Change antenna elevation. This should give you an idea of target elevation when compared to you height.

 

What I meant is the contacts them selves don't represent altitude but distance, when in radar mode.

 

if the contact is near the top its farther away rather than higher up, if its at the bottom its close rather than below.

 

Don't get all semantic on me please.

[mvsgas]

Ok, thanks

[IonicRipper]

What I meant is the contacts them selves don't represent altitude but distance, when in radar mode.

 

if the contact is near the top its farther away rather than higher up, if its at the bottom its close rather than below.

 

Don't get all semantic on me please.

That, I know. It might just be as Ironhand wrote, though. I was always under the impression that in order to see a target high or lower then you, you had to match the hud view mark to the elevation scale. Like I said, I will conduct some tests in the mission editor this evening.

[Ironhand]

That, I know. It might just be as Ironhand wrote, though. I was always under the impression that in order to see a target high or lower then you, you had to match the hud view mark to the elevation scale. Like I said, I will conduct some tests in the mission editor this evening.

What you should find is that those two outward facing tic marks are there to help you know where (how far above or below the HUD) to look in order to visually acquire a closing target that has moved into visual range (which you have not yet locked). Otherwise, when you think about it, there's no other reason for it to exist...unless you use it to gauge how far above or below the horizon you are actually pointing your radar.

 

[EDIT] I've paid so little attention to those tic marks myself that I'm not sure whether they shift or not. I don't think they do. If that's the case, then their usefulness assumes more or less level flight. Otherwise they would indicate nothing very useful.

Edited April 3, 2015 by Ironhand

[Weta43]

They do - they show you the angle the radar is pointing, and the expected altitude relative to your aircraft - if the expected distance to the target (as set on the bottom of the hud) is short, and the altitude high, the radar will be pointing up fairly sharply. if the expected distance is longer, but the relative altitude the same, it will not be pointing up as sharply ...

 

As you can see in this image, the relative altitude is set to +10km, and as the expected distance is changed from 10km to 140km the scan marker moves up and down the hud.

 

This explains why Ironhand never has to move the expected altitude more than a few clicks - as long as he keeps the expected range vey short..

 

 

 

If you're getting instructions from GCI, this is crucial to allow you to point your radar at the appropriate target ...

Edited April 3, 2015 by Weta43

[Robin_Hood]

By the way, there seems to have been some confusion between different things on this thread. There are two very different things:

 

The Display range, or radar scale is what the OP was talking about in the first place, and has no effect whatsoever on the radar setting (be it the signal or the antenna position). It only scales the display.

 

The Expected range to target, or search range, is what most have been talking about afterwards, and has been thoroughly explained by everyone (ie. sets the antenna elevation angle in conjunction with the search altitude). Note that if the search altitude is set to 0, changing the search range has no effect at all (untill you change the search altitude).

 

Also, as have been said already, the radar does not require you to point up or down in order to detect or display contacts. In fact, since it is gyro-stabilized, pointing up or down has no effect (other than changing your altitude, which may in turn make a contact appear).

 

Note that the EOS does work that way, though. Not only does it require you to point up or down to see contacts, but the plots on the HUD do represent elevation angle and not distance (so if you see a contact at the top of the HUD, it is high, and if you pull up, the plot will move down the HUD).

[steve65]

I agree with Robin Hood and that is the best overall explanation for me to understand.i think I found an error in lino's original post.he states that since the radar range is set at 25km that the contact at the top of the hud is at 50km which I think is incorrect.you don't know that contact is at 50km because the radar range scale is not set that high you just know that the contact is 25 km or greater.is that correct?FYI I dont fly the su-27 but I found this thread very informative because I do fly the mig -29 and it's radar works the same way.

Edited April 4, 2015 by steve65

[Robin_Hood]

Yes, in that first screenshot, the radar is saying there is a contact at 25 km or somewhere beyond. Top of the hud is 25 km (as indicated by the scale on the left), although contacts that are farther are displayed at the top (so as to improve SA).

 

Correct me if I'm wrong, but I believe that is something the F-15C display doesn't do, ie. it will not display any contact farther than the set range scale.

[escaner]

Correct me if I'm wrong, but I believe that is something the F-15C display doesn't do, ie. it will not display any contact farther than the set range scale.

 

That is correct.

[karambiatos]

Yes, in that first screenshot, the radar is saying there is a contact at 25 km or somewhere beyond. Top of the hud is 25 km (as indicated by the scale on the left), although contacts that are farther are displayed at the top (so as to improve SA).

 

Correct me if I'm wrong, but I believe that is something the F-15C display doesn't do, ie. it will not display any contact farther than the set range scale.

 

the range scale in the Su-27 and F-15 works differently.

 

In the su-27 at which you want the contacts displayed accurately is set by zooming the TAD in and out, if you lets say zoom the TAD at 8 km distance, contacts farther than that will all pack them selves up at the top of the HUD, indicating that they are farther out than the range you've set.

 

If it's already been mentioned sorry, i didn't read all the replies.

 

I can't remember if the F-15 packed the contacts that are farther than the set range.

Edited April 4, 2015 by karambiatos

[WildBillKelsoe]

Am I right in assuming this is how radar is represented?

[steve65]

the range scale in the Su-27 and F-15 works differently.

 

In the su-27 at which you want the contacts displayed accurately is set by zooming the TAD in and out, if you lets say zoom the TAD at 8 km distance, contacts farther than that will all pack them selves up at the top of the HUD, indicating that they are farther out than the range you've set.

 

If it's already been mentioned sorry, i didn't read all the replies.

 

I can't remember if the F-15 packed the contacts that are farther than the set range.

 

 

 

So if you increase the range scale the contacts will still be packed together just in the middle of the hud instead of the top until you increase the target distance scale to show them as separate contacts?