F-15C radar questions

[Gloom Demon]

I am having problems understanding how the radar elevation coverage control works.

 

For example, below is an image of the default position of the radar elevation coverage in Long Range Scan and to the right I have pictured my understanding of it. The lower circle is the lowest elevation the radar can scan and the higher circle is the highest elevation. So, assumingly, we are scanning the vertical plane from 25 through to 36 degrees (or, maybe, cockpit measurement units?) or an arc of 11 degrees. I have always thought, that degrees start at zero at the top, so maybe these are the cockpit measurement units from the AOA indicator with zero being the horizon.

 

In the second picture I have tilted the elevation coverage a bit down - supposedly, we are now scanning the vertical plane from 23 to 34 degrees.

 

Now, if I tilt the elevation all the way down I get a strange situation where both of the circles show an elevation of zero. Now, surely, such a radar mode would be useless. And - an aircraft wouldn't be able to scan below itself, which is not true...

 

 

The same thing happens when I tilt the radar's elevation all the way up - both circles show zeroes - where would the radar be pointed?

 

I am pretty sure that I am not understanding something right here - maybe someone can explain this to me?

 

Thanks! :-)

Edited September 8, 2014 by Gloom Demon

[GGTharos]

60 deg deflection in all directions.

[Precog]

The numbers represent altitude at the range of the tdc cursor... in this case 10nm. This tutorial should help:

Edited September 8, 2014 by Precog

[Precog]

The radar is a cone that expands outwards. It has an upper and lower altitude limit whose values change depending on the distance from the aircraft. you can tilt this cone up and down but it doesn't close. if you tilt it all the way down it is still scanning part of the sky but at some point from the aircraft both the upper and lower limit of the cone will be at or below ground. in the last example, the tdc cursor is at 10nm. at this range the cone is below ground level as indicate by both circles being zero. if you move the tdc closer to the aircraft you will find these values eventually changing indicating the radar is scanning part of the sky at the range of the tic.... got it :)

[GGTharos]

Yep. The circles show you the altitude segment scanned by the radar at the range of the TDC. A lot of people believe that the TDC is changing something, and they are very, very wrong. The TDC in this case is only a range indexer: at this range, the radar is scanning from this altitude to that altitude.

[HiJack]

If you have altitude of angels 20 then 00-02 is still at ground level and up to 2000 feet 10 miles in front of your nose.

[VTJS17_Fire]

Here a quote from the posted YT Video, which I think is wrong. Maybe you can help me.

 

Q: I'm a bit confused, can someone please answer these questions?. You said that when you move the target designator up, you're not changing the altitude. So what are you changing?

 

A: You're not changing the altitude [with the TDC], you're changing how far your radar is looking. Notice how when he raises or lowers the TD, the range increases from 20 NMi to 40Nmi and so on. That's how far in front from your aircraft your radar will scan.

 

 

 

IMO, that isn't true.

If I scan with a Scope of 80, the TDC on the 40NM marker, this would mean, that my Radar is only scanning 40NM in front of me. Right?

 

But the contact at 60NM - which is on my VSD though - has a nail on his TEWS/ RWR Scope. Both couldn't functioning, if I scan only 40NM in front of me.

 

+ How could me Radar energy reach his RWR sensors at 60NM, if I only scan 40Nm in front of me?

+ How can I have this contact at 60NM, if I'm scanning just 40NM of my nose?

 

 

Thanks in advance,

 

regards,

Fire

[HiJack]

He is not "painted" but his nose "sniffs" your radar beam.

[Precog]

The radar scans out to infinity, although the longer the range the harder it is to resolve targets. The TDC therefore does not influence how far the radar scans, it only provides info on the upper and lower scan altitude at the range of the TDC. That's why the radar still picks up contacts at 60nm and beyond

[VTJS17_Fire]

He is not "painted" but his nose "sniffs" your radar beam.

 

The TDC therefore does not influence how far the radar scans, it only provides info on the upper and lower scan altitude at the range of the TDC. That's why the radar still picks up contacts at 60nm and beyond

 

I'm confused. If I read it correct, you both disagree youse.

Or: I didn't understand it in English. :huh:

[esb77]

Ok, explanation time.

 

The radar search volume is the area that you're basically shining a radio frequency searchlight through.

 

The numbers for high and low are not angles of deflection from the airplane's centerline even though that would be a pretty sensible system.

 

If you take those lines from your diagrams, what the numbers represent is the altitude above ground of the upper and lower edge of the radar search pattern at the range of the TDC.

 

So if you are sufficiently nose down and you haven't stabilized the radar to point at a particular altitude, or if you slew the radar search area down far enough you can get to the point where both lines intersect the ground. The vertical angle of the scan arc has not changed, it's just that the top of the arc and the bottom of the arc intersect with the ground at a range of 20 nm, so the distance above ground level is zero.

 

See the crude diagram here. The upper limit UL and lower limit LL of the scan arc both intersect the ground before reaching the range of the TDC, so their altitude at that range is displayed as zero. Hope that helps.

 

 

Summarized from page 85 of the LOMAC 1.1 manual.

 

Note:Modified diagram to better reflect how radar system probably really works.

Edited September 8, 2014 by esb77

[Exorcet]

I'm confused. If I read it correct, you both disagree youse.

Or: I didn't understand it in English. :huh:

The radar scans a fixed volume when it's set to look between certain elevations. The TDC has no impact on what the radar can see, it only impacts what the radar display looks like.

 

Example, an Il-76 might be detected at 80 nm out. The radar will detect this target regardless of radar range scale, but the radar display won't show the target if you set your scale to less than 80 nm.

[esb77]

Air to air radar systems are somewhat complex.

 

Ideally you want to know what the system is doing in terms of emitting signal and receiving useful returns AND how the computer and display try to display some (but usually not all) of that information to you in a readable and hopefully useful way.

 

In other words, it would be a VERY good idea to read the manual so that you know what's going on.

[VTJS17_Fire]

The radar scans a fixed volume when it's set to look between certain elevations. The TDC has no impact on what the radar can see, it only impacts what the radar display looks like.

 

Example, an Il-76 might be detected at 80 nm out. The radar will detect this target regardless of radar range scale, but the radar display won't show the target if you set your scale to less than 80 nm.

 

But in that quote, I read:

You're not changing the altitude [with the TDC], you're changing how far your radar is looking.

 

Or are here looking and scanning different terms? :huh:

[Exorcet]

But in that quote, I read:

You're not changing the altitude [with the TDC], you're changing how far your radar is looking.

 

Or are here looking and scanning different terms? :huh:

I think you misunderstood, the two lines you quoted are talking about different things. Your radar sees everything it can see (which is everything in its cone that reflects enough signal) at the same time. The TDC has no effect on the radar unless you're in narrow azimuth mode where the TDC can be used as a visual cue to steer the radar left and right. The TDC only exists on the radar screen (or VSD) which is a display translating radar information into human readable format. The VSD is a middle man, and it only shows you what you ask it to show you, which can be some, none, or all of the information that the radar has picked up.

Edited September 8, 2014 by Exorcet

[Ironhand]

But in that quote, I read:

You're not changing the altitude [with the TDC], you're changing how far your radar is looking.

 

Or are here looking and scanning different terms? :huh:

To amplify what Exorcet is saying, when you bump the TDC up against the top of the VSD and the range changes from, say 20nm to 40 nm, you are simply asking the VSD what the radar is picking up out to that higher distance. When you bump down from 40nm to 20nm, you are simply asking the VSD only to display what the radar is picking up out to 20nm. In both cases the radar's range hasn't changed, only what you are asking the VSD to display.

 

EDIT: I created some instructional videos some time ago on my website that you might find helpful. Just click my signature and it'll take to to the site. They're also kicking around on YouTube uploaded by other folks.

 

 

Rich

Edited September 9, 2014 by Ironhand

[Gloom Demon]

Thanks for the help everyone - now I understand where I was thinking wrong. I still don't get it what happens when the radar is pointed upwards, but that is not important, probably.

 

Another question - when the plane rolls - does the radar compensate or it rolls with the aircraft?

 

[GGTharos]

Depends on the radar mode.

[Gloom Demon]

I would presume, that in vertical mode, the radar will roll with the airplane, or vertical mode wouldn't make sense, but what about LRS or TWS?

[GGTharos]

Those should be stabilized.

[Gloom Demon]

Great! Thanks :-)

[TAW_Blaze]

Those should be stabilized.

 

Now this is particularly interesting. IIRC I've gone through some situations where from a starting position of X degree bank I'd see the bandit in RWS/TWS, then wing level he'd disappear. Then if I banked to the same side again he would reapppear on the VSD.

 

I'm quite curious how this really works in game, as far as both horizontal (bank) and vertical (pitch) stabilization goes. It is crucial to proficient radar management. However not a single word is mentioned about it in the manual.

[GGTharos]

Could be a holdover from a certain flanker limitation. Or maybe you're crazy :-)

[TAW_Blaze]

Is there a chance to have a word on it from someone who knows how it's built? It's really unnerving that some stuff in the game are a downright mistery that you can test for eternity but won't know if your theory is true or not. They should definitely include key information like this in the manual. No matter if the real thing has it it's not necessarily made in the game just because of that. In comparison in the BMS manual a lot of things that are not functional are just stated as being such instead of leaving a fog on them.

[GGTharos]

Maybe.

 

In any case there used to be something in the flanker that would cause the radar to drop lock if you rolled over 110deg (or rather past 110deg), but I don't recall the details.