Su 27 Radar elavation scan

@IvanK wouldn't it be wiser to keep the expected range lower than 60km so that you can cover higher altitude with lower "bars" (elevation adjustments), for example setting it to 20-30km and doing a 3 bar scan is going to cover complete spectrum of altitude a bandit may be flying at (12km+ range is not covered by your proposed 4 bar @ 60km expected)

Yes this is what I was trying to get at by having the expected range at 10km. A 4bar scan, with expected range at 10km, should cover a greater amount of sky without gaps between bars.

The reason I'm looking for confirmation of this, is that with targets just outside WVR (say 12km) it is very very difficult to pick them up with BVR mode. In the gunzo servers everything is very congested and I want to be sure I'm covering the most amount of sky without leaving gaps.

Nate

Ty soviet

As to expected tgt range at a lower value I don't see the point. When I say 4 Bar scan I am not referring to manual antenna adjustments the Scan is (I believe a programmed L to R and up and down pattern that covers the full block of airspace that is 10degrees. In other words you get the whole 10,000m block in one hit at 60Km without any adjustment, the radar does this for you. (now in FC2 its all emulated as I don't think the antenna actually steps up a bar on each alternate sweep as it does in a real jet but the effect is the same). When you make a Delta H adjustment you raise or lower this entire 4Bar scan volume. Delta H just varies the angle of the centre point of the whole 4 Bar scan pattern.

All you are doing with Delta H is changing the centre of that scan. at 60Km expected range each Delta H click changes the antenna tilt (and the entire scan volume centre point) by 1 degree. Now if you step the expected range back to say 10Km then exactly what change in tilt do you get then get for each Delta H click ? I have no idea. If you don't know this then how can you say you know you are covering the entire scan area without gaps ?

If someone can figure out the precise algorithm that determines antenna tilt as a function of Delta H and expected target range the question could be answered. Here lies the problem. The only indication you have of antenna tilt is the elevation scale on the MFD. However there are no values associated with it and Antenna tilt at various expected range values is non linear. At 60Km expected target range it is linear and 1 degree per Delta H click.

Either way the radar antenna has fixed Gimbal limits. So whether you set the expected target range to 10km or 100Km the antenna can only elevate or depress a fixed angular amount. You have the same antenna tilt range regardless of expected target range setting.... its just try to figure out where the antenna is pointing.

""Yes this is what I was trying to get at by having the expected range at 10km. A 4bar scan, with expected range at 10km, should cover a greater amount of sky without gaps between bars."

Why ? You get 10degrees of scan volume regardless of expected target range all you are changing is the size of the antenna tilt increments by reducing expected target range. In other words for each Delta H click you might be getting a 3 degree change in antenna tilt but who knows exactly how much you are getting ?Another way of thinking about is that expected target range is like an antenna tilt rheostat as you play with expected target range you are varying the amount of antenna tilt per Delta H click .... but by an unkown amount.

Now when you are in close a larger tilt per click might be advantageous but we are talking about the general unassisted search or Fighter sweep scenario.

Having a little play in the Su27 Quick action set up. 2 targets at around 70Km range unknown altitude.

With Expected target range at 10nm I can find the paints. However 1 click in Delta H each way and I loose the paint. With Expected target range set to 60Km it took 3 or so delta H clicks to loose the paints. Therfore antenna tilt control is more precise. So this to me shows that antenna tilt (scan volume tilt) is in bigger (and unpredictable) amounts the lower you set the expected target range. That then implies the possibility of gaps in a meduim to long range search scenario.

As to expected tgt range at a lower value I don't see the point. When I say 4 Bar scan I am not referring to manual antenna adjustments the Scan is (I believe a programmed L to R and up and down pattern that covers the full block of airspace that is 10degrees. In other words you get the whole 10,000m block in one hit at 60Km without any adjustment, the radar does this for you. (now in FC2 its all emulated as I don't think the antenna actually steps up a bar on each alternate sweep as it does in a real jet but the effect is the same). When you make a Delta H adjustment you raise or lower this entire 4Bar scan volume. Delta H just varies the angle of the centre point of the whole 4 Bar scan pattern.

 

All you are doing with Delta H is changing the centre of that scan. at 60Km expected range each Delta H click changes the antenna tilt (and the entire scan volume centre point) by 1 degree.

Understood. I initially misunderstood what you meant by 4-bar. I get you now.

Now if you step the expected range back to say 10Km then exactly what change in tilt do you get then get for each Delta H click ? I have no idea. If you don't know this then how can you say you know you are covering the entire scan area without gaps ?

I don't know :) I'd like to know though.

If someone can figure out the precise algorithm that determines antenna tilt as a function of Delta H and expected target range the question could be answered. Here lies the problem. The only indication you have of antenna tilt is the elevation scale on the MFD. However there are no values associated with it and Antenna tilt at various expected range values is non linear. At 60Km expected target range it is linear and 1 degree per Delta H click.

Ah, I didn't realise it was non-linear, that's a spanner in the works.

Either way the radar antenna has fixed Gimbal limits. So whether you set the expected target range to 10km or 100Km the antenna can only elevate or depress a fixed angular amount. You have the same antenna tilt range regardless of expected target range setting.... its just try to figure out where the antenna is pointing.

 

""Yes this is what I was trying to get at by having the expected range at 10km. A 4bar scan, with expected range at 10km, should cover a greater amount of sky without gaps between bars."

 

Why ? You get 10degrees of scan volume regardless of expected target range all you are changing is the size of the antenna tilt increments by reducing expected target range. In other words for each Delta H click you might be getting a 3 degree change in antenna tilt but who knows exactly how much you are getting ?Another way of thinking about is that expected target range is like an antenna tilt rheostat as you play with expected target range you are varying the amount of antenna tilt per Delta H click .... but by an unkown amount.

Again this was me misunderstanding the term 4-bar, sorry. I'll just use the entire 10deg zone from now on.

Ideally I'd want the 10 degree scan volume to increment in 10deg intervals with each Delta H Click. If it is possible to work out which expected range setting could achieve, or be close to this, I'd be happy, but the non-linear increments make this very difficult.

Nate

I think the main factor IvanK are notching bandits and mountains, in an environment with multiple bandits coming from different directions and different altitudes its very realsitic for a bandit to get within 20km of you without being seen by a good continuous scan. Therefore the less movement required on the elevation the better, getting quick scans close and at distance are paramount in these environments. The problem with having your range set so far is that you need to elevate to a much higher Delta H value to see close bandits high or low than you would with a shorter range set. Which means it takes longer and is more laborious to scan.

Remember Delta H at +1 is 1000metres altitude above yours at 60km range as opposed to default setting of 1000m altitude at 10km range. Each click is a 1000metres at the set range.

In close I agree its always going to be fraught. However unlike conventional tilt adjustments we are not tilting by a known angular value but some hybrid Range/Alt value. That imo leaves you open to gaps. I guess with a bunch more number crunching you could produce a comparison chart of both sides of the argument....Off to find my Trig calculator :)

The KGB should have stolen the US algorithms from the US that allow you to set your TDC at any given range then tilt with continuous readout of altitude covered by the scan at that range (as in F15/18) much more usable system.

Nate Said:

"Ideally I'd want the 10 degree scan volume to increment in 10deg intervals with each Delta H Click. If it is possible to work out which expected range setting could achieve, or be close to this, I'd be happy, but the non-linear increments make this very difficult."

That or something like that is a good idea Nate... You have sowed a seed :). Though 10degrees I reckon is a bit too much. Hopefully some number crunching might give us something usable like that. Combining your idea the 60km idea and Frosties point about the close in problem might allow a generic "Best setting to cover all bets" ... off to crunch numbers .. my head hurts :)

Really quick dirty Trig says:

Expected target range 5.67Km each Delta H click raises varies the Antenna tilt by 10degrees (entire Scan Volume)

Expected target range 6.3Km each Delta H click raises varies the Antenna tilt by 9 degrees.

Expected target range 11.4Km each Delta H click varies the Antenna tilt by 5 degrees (Half scan volume)

So If I am thinking straight given the Scan Volume is a total of 10degrees and lets say you want to ensure at least 1 degree Overlap between Delta H clicks you want to move the antenna by 9 degrees per delta H click. That works out with an expected target range value of 6.3 Km.

Many thanks for taking the time to work that out Ivan, however as you mentioned earlier these increments are not Linear, so when scanning the extremes I'd say you'd have to assume gaps in coverage.

I suspect however that it'd be a rare case where you'd need to scan near the gimbal limits.

Nate

You don't need any complicated math to move the scan zone. You only have to look closer to the scan coverage bar on the HUD.

Note the bar length represents the vertical scan coverage, 10 degrees. In this example, you can read the scan elevation coverage is from about 20 to 30 degrees and the HUD view coverage is from about -7 to 13 degrees. Yes, the radar is scanning the area above the HUD.

When you move the elevation angle to scan broader volume, memorize the last bar coverage first, then increase/decrease the height offset so that the new coverage has some overlap with the last coverage. By this method, you can scan broader volume easily and efficiently without any gaps.

The symbology is understood, but by your example above, it takes 4 clicks of delta H to move to each scan zone, I want it to take 1 click.

With a target at 12 km, for example, you don't have the time to be thinking about where the scan zone is and by how much you have to elevate to cover the next area of sky. It should take one click. This is possible with the correct Estimated range setting, which Ivan has kindly worked out above.

Nate

The symbology is understood, but by your example above, it takes 4 clicks of delta H to move to each scan zone, I want it to take 1 click.

 

With a target at 12 km, for example, you don't have the time to be thinking about where the scan zone is and by how much you have to elevate to cover the next area of sky. It should take one click. This is possible with the correct Estimated range setting, which Ivan has kindly worked out above.

 

Nate

OK, I see what you mean now.

Well, at larger delta H, 1 click angle increment will be smaller. This means you will have more overlap when scanning the extremes. So you don't have to worry about the gaps.

I reckon 6kms range will cover the sky in front with no overlap. Try it.

Nice pics DoctorK! Thing to remember as well is the info shown in the HUD you described is dependent on the expected range setting.

The symbology is understood, but by your example above, it takes 4 clicks of delta H to move to each scan zone, I want it to take 1 click.

 

With a target at 12 km, for example, you don't have the time to be thinking about where the scan zone is and by how much you have to elevate to cover the next area of sky. It should take one click. This is possible with the correct Estimated range setting, which Ivan has kindly worked out above.

 

Nate

If you got a target 12 Km in front of you and haven't got a missile of yet you should reconsider your BVR tactics. Anyway, on that range you should be in dogfight mode, looking out, punching out flares and trying to get a visual instead of fiddling with your radar.

If you got a target 12 Km in front of you and haven't got a missile of yet you should reconsider your BVR tactics. Anyway, on that range you should be in dogfight mode, looking out, punching out flares and trying to get a visual instead of fiddling with your radar.

As I said, for me, this was for gunzo servers. But even so it's not uncommon to find bandits after a protracted fight at 11-20km (for example) you can't get a visual at these ranges and WVR modes won't pick up a target over 10ikm. So between 10 -20 km you are really at a limbo. What I'm trying to do is effectively fight targets in this range.

Nate

I never ever use this stuff jeje need to go back to school

I have been testing away and tinkering with basic Maths to determine exactly how this Antenna elevation works on the Russian types. Its a complex thing as the Expected Target range and Delta H setting are interlinked in what appears a non linear way. In addition at certain expected target range settings you cannot get maximum antenna elevation.

The basis of this is the Total beam coverage per scan is 10degrees in Elevation. The angular amount the antenna elevates per Delta H click is a function of Expected Target range. The angular value varies. You only have 15 clicks of elevation, with each click representing a change of 1000M above your altitude at the expected target range.

The aim is to come up with a standard expected Target range setting for all altitudes that:

Maximises the full 10 degree of beam coverage per scan

Minimises the number of Delta H changes

Provide a Beam coverage overlap between Delta H sweeps.... i.e. leave no gaps.

Exp Tgt Range (Km)......... Deg elev per Delta H Click......... Max elev possible

2 ..................................20deg....................................Full +60deg

4 ..................................10deg....................................Full +60deg

5...................................7.5deg...................................Full +60deg

6...................................6.7deg...................................Full +60deg

10.................................4.0deg..................................Full +60deg

12..................................3.6deg..................................Only to +50deg

15..................................3.0deg..................................Only to +45deg

20..................................2.0deg..................................Only to +30deg

30..................................1.3deg..................................Only to +20deg

60..................................1.0deg...................................Only to +12deg

It seems to me that a Basic Target range setting of 10Km is optimum.

This ensures you can still get your full +60 degrees of antenna elevation.

It also provides 6 degrees of overlap Per AH click, though in desperate or in close searches you can use 2 Delta H clicks and still get 2 degrees of overlap (no gaps)

At low level a datum Delta H start point should +1. This gives coverage from 1 degree below your level to +9 degrees above your level. You are not wasting a large amount of your scan below the horizon.

On the MFD Each Tick of antenna elevation is approximately 20degrees.

Good work IvanK, I came to the same conclusion based solely on game experience, and now you back up my findings with solid math and science. :) Rep inbound!

Excellent work there Ivan, many thanks for find all that out.

Nate

It seems to me that a Basic Target range setting of 10Km is optimum.

But what you must also realise by going right upto the maximum elevation of +15 at 10km range your looking at the airspace 10km in front of you, 15000m above your altitude. Pretty much an empty void.

So while the longer the range chosen, over 10, that you use creates a tighter angle (less than 60deg), the need for that angle hardly ever arises.

:huh: ................. > :D

Could you expand on that please?:music_whistling:

And your point AS is ?

Online would be better ;) :D

The Oracles speak !

Online would be better ;) :D

correct :D

You both realise that he is not talking about radar scan range but Exp. Target Range setting? ....There is a difference.