Su 27 Radar elavation scan - Page 2 - ED Forums


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Old 06-10-2010, 12:06 AM   #11
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I've no idea what 150deg mode is.
Originally Posted by luza View Post
Could someone with alot of experience explain the su 27 radar in detail? The ingame tutorial is quite vague
What I do know is that the radar is displayed in the HUD of the Su-27,

Elevation angle scale,
is the scale to the right, it starts at 0 and goes up and down in increments of 1(eg. +1 or -1) to +15 or -15. These are increments of 1000's of metres, +3 = +3000m, set this for the targets expected altitude above or below you at the point of Range estimation.

Range estimation,
is the scale below the radar at the bottom, this is the targets expected range and defaults at 10km but can be adjusted from 1 to 150 km. Combine this with the Elevation angle scale to find your target.
You must remember that your radar always uses its max range, range and elevation estimations are just intercept and central points along the radars scan cone.

Range scale,
is to the top left of the radar, below your speed, it displays the max. range at which your radar screen displays (not scans) eg. 100 =100km at the top of the radar the bottom obviously being you.

Expected target aspect,
is directly beneath the range scale, it is the radars PRF (pulse rep. freq) mode. Select the correct mode which you believe will suit your target. There are 3 modes,

HI (ППС, in Russian HUD) for approaching tgts has the longest range
MED (ЗПС ) for running tgts has the shortest range
ILV (АВТ) default uses both HI and MED with a slight reduction in range than HI.

Below this still on the left are 4 symbols going down which don't always appear, the top is radar lock and is shown with a letter A (A in russian hud), 2nd down is EOS on which is shown by a letter T (T), 3rd one down signifies radar on and is shown as a letter I (и), 4th is for IFF and is displayed as an F (C), if lit you have a friendly locked.

Below this at the bottom left of the hud you have your radar mode, ther are three modes,
SCAN BVR, normal mode for all PRF modes
ATTACK BVR, STT mode when you have a target locked with full radar.
SCAN TWS, allows you to display a visual aspect in the MFD of multiple bandits but only avaliable with HI and MED - PRF modes.

When all displayed they will look like this:

500....................... 6000

T ................................... 0

SCAN BVR..... 10 ............

Last edited by Frostie; 06-10-2010 at 01:09 AM.
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Old 06-10-2010, 12:19 AM   #12
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Wow, thanks alot for all the input guys! +rep to all, keep it coming!
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Old 06-10-2010, 12:45 AM   #13
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Guys I said to expand the radar scan zone to full and as it shows 150 on the HUD I said it just so that he might understand quickly.
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Old 06-10-2010, 12:51 AM   #14
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This is from the manual:


So the distance (bottom of hud) is in Km from your aircraft and the elevation (right side of the hud) is in Km relative to your angels.

Again if you're flying 4 Km up and you expect the enemy to be 60 km out flying angels 8 you set the range to 60 and the elevation to 4(cuz you're 4 Km up so you just need 4 more to reach 8 Km). This setting should also pick up targets flying angels 12, 120 Km out, since the angle is the same. No messin around with degrees, just read the numbers..

Finaly: remember! -the distances in russian birds are in Km.


Last edited by Svend_Dellepude; 06-10-2010 at 12:59 AM. Reason: Forgot something
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Old 06-10-2010, 01:17 AM   #15
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Originally Posted by combatace View Post
Guys I said to expand the radar scan zone to full and as it shows 150 on the HUD I said it just so that he might understand quickly.
Sorry friend but I believe this is bad practice, at 150 range when you elevate up your going up at 1000m 150km away for every +1 (a very small elevation). You'd need to move all the way upto +15 just to see a bandit something like 30km away 3000m above your altitude.

A good standard to use is at the 20 to 30 range.
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Old 06-10-2010, 01:19 AM   #16
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Originally Posted by RIPTIDE View Post
In my humble opinion, yes. Watch the Marker on the right of the HUD as it travels up and down. Now. Turn down range to 2. Slew up and down, and watch the marker jump leaving big gaps. At range 10 there is overlap for example.
Range 10 is the default IIRC, I'd agree with your analysis but I'd like to see it confirmed.

Can I scan all off the sky in front of me, without gaps, by slewing, in the extreme example, -15 to +15 on the elevation with the range set to 10?

Does each increment overlap at all ranges, when the range is set to 10? Again I suspect they do, but I'd like it confirmed.

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Old 06-10-2010, 02:22 AM   #17
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You can scan the entire sky in front of you using the method I suggested.
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Old 06-10-2010, 03:47 AM   #18
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IvanK, I am pretty sure all radars in FC are 4 bar scan at 2.5 degrees = 10 degrees. Either way, very nice detail!

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Old 06-10-2010, 04:04 AM   #19
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Could well be 10 degrees. If that is the case it provides a little more overlap/coverage to the method.

The real curse of the Russian system (when used without GCI) is that 1 click of tilt doesn't always result in the same angular displacement of the antenna. As you vary the expected target range the angular value per click also changes to fit the expected target range Delta H setup ! This is the reason you need to use a constant Expected Target range value so you have a firm datum to search the entire scan area ahead of you. Then you know that 1 click up or down will cover XX block of airspace at YY range and you wont leave any gaps.

Here it is reworked on 10degrees total angular coverage.

MIG29/SU27/SU33 Radar Elevation coverage.

This assumes the Lockon FC2 Antenna elevation scan covers a total 10 degrees.
(This is a 4 bar scan, Beam width is 2.5deg, there is some overlap sidelobes ?

Range Km Altitude covered Metres
10Km............... 1,749Metres
20Km .............. 3,499Metres
30Km .............. 5,249Metres
40Km............... 6,999Metres
50Km .............. 8,748Metres
60Km............... 10,498Metres
70Km............... 12,248Metres
80Km .............. 13,998Metres
90Km .............. 15,747Metres
100Km ............ 17,497Metres
110Km ............ 19,247Metres
120Km ............ 20,997Metres

So Broad brush at 5000m Altitude if you set the expected Target range to 60Km and Delta H to 0 you should be covering Surface to 10,498m altitude. Remember this is 4 bar
So it takes some time (about 6 seconds) to cover the altitude block. At 30Km you cover
5,249metre block or from 2375m to 7625m in altitude.

General Radar search.
Initial system set up for general search. Radar range (HUD) set to 100Km. Set Delta H to 0. Set Expected Target range to 60Km. Position TDC at 0 azimuth at 60Km.

Since we are using 60Km expected target range as the base line and Delta H is at 1000m intervals it follows that for each 1000m Delta H adjustment you are tilting the antenna 1 degree (1in 60 rule). So if roaring around in the weeds there is little point irradiating the centre of the earth. Since the 4Bar scan is 10 degrees then all we need to do is tilt the scan up by 5 degrees. This will put the bottom of the scan at your level. So if in the weeds set 60Km expected target range and Delta H to +5

In general the same sort of thing can be used for minor adjustments of the scan if your altitude is > or < 5000m. So say for instance you are 6000m, if you want to cover the same 0-10,000m block you would set the AH to -1. If at 3000m you would set Delta H to +2

Remember these are initial search settings. Once the action starts and target range starts reducing you will need to adjust Delta H to keep the target painting. As range reduces the scan volume reduces dramatically so antenna setting becomes super critical and requires quicker adjustment.

No matter what it is super important to be patient and consistent, random desperate slewing of the antenna elevation serves no purpose. As the paint starts to fade a single Delta H adjustment in the right direction will usually “freshen” the target paint. If it disappears it probably means you went the wrong way (or the target dramatically changed his altitude) so give it 2 Delta H clicks the other way.

Remember as soon as you take a lock Your Delta H and expected tgt range values are reset so when you return to search you need to re set the 60Km expected target range and Delta H value.

With respect to Azimuth scan don't forget with the Russian radars you can offset the whole Scan Left, Centre and Right. For a serious scan and to cover the full left to full right you need to scan the entire elevation volume in each Azimuth scan. Again it requires a strict practised routine to ensure no gaps and it requires time. If flying with a Wingman then some co ordination can be used with each guy responsible for a specific bit of airspace both in Azimuth and elevation...... but that and sorting is a Volume in itself.

Unless under GCI/AWACS control ALWAYS set Expected Target range to 60Km.

Last edited by IvanK; 06-10-2010 at 04:48 AM.
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Old 06-10-2010, 07:44 AM   #20
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Nice job Ivank on these numbers. Very helpful!
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