F-15C avionics wishlist

[tflash]

http://www.dtic.mil/ndia/2001missiles/defabio.pdf

 

I figured you might enjoy this SK, and it has a 'tenative' picture of what a Link-16 display might look like as well.

 

Link 16 would definitely be an interesting option. Anything that would bring some life in the now not much used MFD below the radar display would be very welcome!

 

What would be fine also is integration of the RWR with Chaff/Flare dispensers, so that the TEWS automatically launches Chaff & flare according to a threat.

[355th_Xantris]

Should be nice, although RWR would never be able to know if heetseeker is incoming.

[D-Scythe]

So can anybody who's part of ED's V1.2 beta test team confirm whether or not anything new is going to be done for the F-15C radar in this next add-on? From Chizh's third party LOMAC 3d models thread, there seems to be already a V1.1+ version in existence, and unlike FC, I was wondering if there was going to be something in V1.2 for the NATO guys as well.

[SwingKid]

So can anybody who's part of ED's V1.2 beta test team confirm whether or not anything new is going to be done for the F-15C radar in this next add-on? From Chizh's third party LOMAC 3d models thread, there seems to be already a V1.1+ version in existence, and unlike FC, I was wondering if there was going to be something in V1.2 for the NATO guys as well.

 

Any decisions about F-15 avionics will only be made after the Ka-50 avionics are complete. Wait for screenshots. In the meantime, I think our research is still not finished.

 

-SK

[D-Scythe]

Well, how extensively do you intend to research this? I mean, are we aiming for an APG-70 radar model in Lock On done with great detail (like in Janes F-15, with all the modes/sub-modes, etc.) or are we aiming for a less detailed, but still much more accurate, model than the one we currently have in V1.1 (with maybe just the major modes, no sub-modes, etc.)?

[GGTharos]

We're keen on getting everything that we can implemented, but please keep in mind that the devs do in fact have a very large number of thigns that they would like to implement, believe it or not. :)

 

I would personally prefer to at least see SNIFF mode and in addition indicators for autopilots, little niggling things liek the flap light, AoA on HUD in gun mode, proper representation of gun reticle, etc. and a better behaved radar (it. no auto-stt on jamming contacts in TWS, just drop the contact instead, proper representation and modelling of TWS tracked contacts, and slightly more complex TTA logic for missiles.

[SwingKid]

Two things I aim for in the research are to (a) have an F-15 radar model that matches the level of the Su-27 and MiG-29 radar models, and (b) include features that allow players to employ tactics that are employed in real life.

 

So, if you need to fly at high altitude to get the improved range and resolution that RGH provides, then we should include that. If you need to pitch the aircraft up at the moment of launch to loft an AIM-120, then we should model that. If you need to direct ECM rearward at your chaff in order for it to work against a monopulse missile, we should model that too. The avionics should not be a goal in itself, but rather an avenue to better tactics.

 

I think we have accumulated a large number of interesting mode names and acronyms, but I don't think that what we have so far has led to a formulation of any verified F-15 tactics. From what I can see we have only described "switchology". What do we want to be able to do? What combat situations occur most frequently? Which avionics modes are more important than others?

 

-SK

[Skywall23]

I think we have accumulated a large number of interesting mode names and acronyms, but I don't think that what we have so far has led to a formulation of any verified F-15 tactics. From what I can see we have only described "switchology". What do we want to be able to do? What combat situations occur most frequently? Which avionics modes are more important than others?

 

-SK

 

Yup. Makes me remeber a radar mode of the russian aircraft called "search" which was used like the encounter, auto, etc modes, but this radar mode was only slightly different from the one of these modes so ED decided not to implement it. I think it was a good decision. :)

[GGTharos]

SK, jsut an FYI - from reading the F4 forums at Frugals, I got a very strong impression that any and all BVR tactics are classified at least on the US side, so we won't be seeing any of that meterial AFAIK :/

 

But I think the general facts we coud and should go with is the trends in aircraft designed and missiles: The planes are built to get up to altitude and speed in minimal time so as to get the first shot. So definitely, altitude in missile shots is important. I think missile ballistics would greatly aid in simulating this - after all a missile coming down on your aircraft will not decelerate as quckly as one going the other way around, and this would alleviate the current problem with ranges on high-low and low-high shots being very similar ... according to minizap at least, a 5k to 40k shot has 1/3rd or less the range of the same shot done the other way around, and this isn't well represented in LOMAC.

 

At the same time a missile AFM might let us explore some interesting missile properties like the R-77's ability to do very high AoA turns :)

[SwingKid]

SK, jsut an FYI - from reading the F4 forums at Frugals, I got a very strong impression that any and all BVR tactics are classified at least on the US side, so we won't be seeing any of that meterial AFAIK :/

 

Oh please. "Any and all"? What, do they think F-pole is secret?

 

One of the first tactics employed in modern warfare is to inundate the enemy IADS with air-launched decoys. This has been going on since Israel vs Syria during the cold war and is no secret. We cannot discuss the implications of this on BVR combat for ourselves?

 

-SK

[GGTharos]

My point here is that we won't find any documentation on modern BVR tactics, and in many cases I expect there to be little or no information of how radar modes are used and why for said tactics ... I'm not saying that we can't discuss them here.

[D-Scythe]

SK, while we don't have that much information, we still have enough to make things a lot better than it currently is (in terms of radar). Here's what we have so far, right?

 

1. APG-70 CAC modes IRL detects targets out to 15 nm. Not much to discuss about this - tactics are obvious.

2. VECTOR radar mode is like RWSI (i.e. HPRF and MPRF), except the radar works only half as fast to take more time to process data, and gather more information. We know that because of this, it has a higher chance of picking up small RCS targets (and probably NCTR) at longer range than standard combat modes. Again, tactics are obvious.

3. Velocity Search, we also have a great deal of information on. Displays targets in respect to speed. Pros and cons, and when and how pilot's would use it are also obvious.

4. Range Gated High: Wags stated that "it uses an intermediate between MPRF and HPRF that gives good all-aspect acquisition," and also that it uses a short pulse wave form for better target break out and that it shouldn't be used below 6000ft AGL. This one's up for grabs - I think I can get a bit more information on it, but not much.

5. TWS mode - besides having the radar automatically centre/keep the PDT within its gimbal limits (as opposed as doing it manually, which is currently the case), I don't think that it's a bad representation of the real thing.

6. HOJ/AOJ we probably can't get too much information on.

7. SNIFF mode should still be able to pick up jamming targets I think, so that the radar sorta acts like a passive sensor.

 

And that covers the all the main radar modes (although the sub-modes are a different matter). The pros and cons of each seem to be obvious enough, and even if we don't know RL tactics like GGtharos suggested, it would give us a good idea of how to use the radar. Still, I agree with GG in terms of ECM vs. ECCM in the Eagle anyway - the more advanced functions of the AGP-70 and the ALQ-135 are still probably *all* classified.

 

But there's still enough data to bring Lock On's APG-70 up to par with its Russian counterparts, I think.

[SwingKid]

I'm not trying to be obtuse, but seriously, we don't want the programmers to keep changing and fixing things forever. So let me play "ED prgorammer's advocate" for a moment and explain why I am hesitant with this data:

 

1. APG-70 CAC modes IRL detects targets out to 15 nm.

 

Range depends on cross-section. What kind of targets? You mean, the radar can detect the B-52, or the F-22, out to 15 nm? Also, can the FLOOD mode be used to get a range on a close target, without bearing information, purely for computing a gunsight solution? Some sources say yes, others say nothing - but they don't say if this is regular "FLOOD" mode, or a second "FLOOD" CAC mode for the gun vs. for AIM-7.

 

2. VECTOR radar mode is like RWSI (i.e. HPRF and MPRF), except the radar works only half as fast to take more time to process data, and gather more information. We know that because of this, it has a higher chance of picking up small RCS targets (and probably NCTR) at longer range than standard combat modes. Again, tactics are obvious.

3. Velocity Search, we also have a great deal of information on. Displays targets in respect to speed. Pros and cons, and when and how pilot's would use it are also obvious.

 

I don't think so. VECTOR and Velocity Search do not seem to co-exist on the same F-15. Rather, one seems to be an upgraded version of the other. I think Velocity Search only shows closure on an azimuth vs. speed scale, whereas VECTOR shows closure + aspect on the same scale. I don't think VECTOR uses the azimuth versus range scale like RWSI.

 

4. Range Gated High: Wags stated that "it uses an intermediate between MPRF and HPRF that gives good all-aspect acquisition," and also that it uses a short pulse wave form for better target break out and that it shouldn't be used below 6000ft AGL. This one's up for grabs - I think I can get a bit more information on it, but not much.

 

"MPRF" and "HPRF" are relative terms. By their very definitions, there should be no such thing as an "intermediate" - if there are doppler ambiguities, it's MPRF. If there are not, then it's HPRF, regardless what the exact numerical PRF may be. Why not use it below 6000ft? False targets will appear on the radar scope, or real targets will not appear on the scope? If the former, then we should model ground clutter for all radars, not just F-15.

 

5. TWS mode - besides having the radar automatically centre/keep the PDT within its gimbal limits (as opposed as doing it manually, which is currently the case), I don't think that it's a bad representation of the real thing.

6. HOJ/AOJ we probably can't get too much information on.

 

So, no changes requested..?

 

7. SNIFF mode should still be able to pick up jamming targets I think, so that the radar sorta acts like a passive sensor.

 

What about repeater ECM that does not transmit unless it is illuminated? Should not "Sniff" mode send out little pulses? More importantly, a real F-15 pilot wrote once after real combat that this mode was interesting in theory and in tests, but in real operations there are so many friendly and enemy emitters that "Sniff" mode is practically worthless and never used. We should really spend time modelling radar modes that real pilots do not use? If so, where do we stop? What about the ground radar modes of F-15C?

 

In terms of bringing it up to Russian standards - we don't even know what the roll-stabilization is for in the APG-63, or when, if ever it is turned off. Whereas for the Su-27 Lock On has modelled roll limits due to roll-stabilization. Is it fair that F-15 pilots can maintain a lock through a roll while Su-27 pilots cannot, if both radar antennas are roll-stabilized?

 

So I think, we know some things about these modes, but not enough to model them accurately. We would simply be going from one abstraction (Lock On's current APG-63 model) to a different abstraction.

 

As for tactics, none of the above suggests changes seems to relate. What does it matter if CAC detects targets at BVR ranges? I won't start turning and burning at such ranges. What is more interesting is not the range of CAC modes, but that they auto-acquire. Velocity Search was described in the Falcon 4 manual as: "the last and certainly least radar mode ... this mode was created as a joke on fighter pilots. If you think about it that way, VS is not too bad. I really have no idea how you would use it in combat." RGH description doesn't say how the improved target breakout is displayed - how can you physcially draw two targets closely separated on a scale of 50 nm per inch, without any "zooming" of the display?

 

If I were an ED programmer, I would really be scratching my head, wondering how our list of changes will make any difference to the game. So, let's discuss and see if we can answer these questions, at least for ourselves. If we can all at least agree what we want and why, that may be a big step towards compensating for lack of data about the real thing. From past experience, I think this is a good way to "stumble upon" discovering how the real systems actually work in the process - because the real systems are designed to address many of the same questions and needs that we have, only, coming from real pilots. Radar modes are not invented for the fun of it. With all that has been written about them, we should be able to figure them out.

 

We certainly have time to discuss it, while the Ka-50 is being made. :)

 

-SK

[GGTharos]

I'll interject my opinion: The F-15's CAC modes will -lock- aircraft within 15nm is what D-scythe means, not 'detect'. I'm fairly certain if the reports say they were picking up low-flying Mirages at 80 and 100nm in GF, they won't have any trouble 'locking on' to just about any aircraft modelled in LOMAC within 15. Regardless, this change isn't necessay, though it might be 'neat'.

 

I can no longer access

http://www.knovel.com/knovel2/Toc.jsp?SpaceID=132&BookID=65&NodeID=109304025&Action=Collapse&Type=null&FilterMode=false

as I'm no longer in university, but check chapter 41 IF you can ... does it help for RGH? THat is, at least with the theory - I don't understand it myself.

 

TWS Mode:

I already said what I'd liek to see in TWS mode ... also when changing azimuth to 30 degrees the scan should be centered on the TDC not just straight ahead, I think.

 

Other ideas: I don't know how far the sidelobes 'leak' enough energy for the RWR but it seems that in LOMAC it's just 180 degrees in front of the plane regardless of your scan width. It's not F-15 speciific but it'd be nice if it could be 'narrowed' unless that's not realistic.

 

SNIFF is useful in THIS GAME, unless the jammers are made to work automatically like they're supposed to from what I hear. It should be modelled if the jammer modelling doesn't change. For the game itself I think it could be of use. At the very least, people would start learning to fly without having jammers on all the time ;)

 

I also have a suggestion for RGH breakout: Maybe they don't 'draw' the targets there and they don't zoom in them, but they represent it with a 'multiples' symbol and let you cycle the targets with the 'primary designate' function, for example, or 'cycle primary' (BTW, we need a cycle primary fucntion on the F-15 for TWS, as well as an unlock function, a working one that is..currently I cannot unlock the primary in TWS)

I would also like to see TWS targets drawn with the proper delay between sweeps in TWS modes on BOTH sides, not this insta-update stuff that's going on with designated TWS targets right now.

Also ebcause of the way TWS is supposed to work, TWS designates targets should not be lost unless they're lost on the radar screen. To be more clear: If a plane changes aspect and I 'lose' the TWS lock but the blip is STILL on the screen, I shoudln't have lost the 'lock' (since it's not a real lock and jsut a software function that simply keeps a trackfile on that contact ... so if the contact's there, the trackfile's there, and the 'lock' is there). I would like TWS to automatically reject jamming targets, or put them in a 'dugout' instead of the current display method, so that targets overlayed on the jammer can be selected instead of the jammer. VERY annoying. At the same time, the TWS should NOT go to STT on a jamming target just because it started jamming (and is beyond burn through range), it should just drop that contact and make the secondary target the primary and track that instead. If the contact is within burn-through range and jamming TWS should NOT go to STT on it, since it has all the information required to track the target available. If the target goes beyond burn-through range, it should be dropped and handled as above. Personally, I think that the 'dugout' diaply method would be best for handling jamming contacts. The current mode of operation of TWS is very annoying to me. I can'tt hink why udner any circumstances this would be desired behavior on the real aircraft.

 

Another thing I'd like to see on the F-15: An X through the target square if the target is friendly.

 

Another thing I'd like to see insofar as jammers are concerned: Right now there's adifferentiation ebtween friendly and enemy jammers. This shouldn't be so, IMHO. They should all show up the same.

[SwingKid]

I'll interject my opinion: The F-15's CAC modes will -lock- aircraft within 15nm is what D-scythe means, not 'detect'. I'm fairly certain if the reports say they were picking up low-flying Mirages at 80 and 100nm in GF, they won't have any trouble 'locking on' to just about any aircraft modelled in LOMAC within 15. Regardless, this change isn't necessay, though it might be 'neat'.

 

If the radar is going to auto-select its own targets from 15 nm BVR, is it important that we model a "reject" switch among the keyboard controls? I've proposed this in the parallel discussion about the keyboard layout - 15 nm is a long distance to be locked onto the wrong target.

 

I can no longer access

http://www.knovel.com/knovel2/Toc.jsp?SpaceID=132&BookID=65&NodeID=109304025&Action=Collapse&Type=null&FilterMode=false

as I'm no longer in university, but check chapter 41 IF you can ... does it help for RGH? THat is, at least with the theory - I don't understand it myself.

 

Yes, this is where I get most of my understanding about the physics of RGH. My main concern about it is how its peculiarities are displayed in the cockpit, different from other modes.

 

TWS Mode:

I already said what I'd liek to see in TWS mode ... also when changing azimuth to 30 degrees the scan should be centered on the TDC not just straight ahead, I think.

 

Slewing with the scan knobs or slewing with the TDC - is this not just switchology? I would think the difference to tactics is negligible. Can we map the scan slew and the TDC slew to the same HOTAS control?

 

Other ideas: I don't know how far the sidelobes 'leak' enough energy for the RWR but it seems that in LOMAC it's just 180 degrees in front of the plane regardless of your scan width. It's not F-15 speciific but it'd be nice if it could be 'narrowed' unless that's not realistic.

 

Good idea. Let's check this again with v1.1, I'm not sure if it stayed the same.

 

SNIFF is useful in THIS GAME, unless the jammers are made to work automatically like they're supposed to from what I hear. It should be modelled if the jammer modelling doesn't change.

 

How would the ECM in the game look different if it were made to work only when illuminated? My impression was that that was how it was already working.

 

I also have a suggestion for RGH breakout: Maybe they don't 'draw' the targets there and they don't zoom in them, but they represent it with a 'multiples' symbol and let you cycle the targets with the 'primary designate' function, for example, or 'cycle primary' (BTW, we need a cycle primary fucntion on the F-15 for TWS, as well as an unlock function, a working one that is..currently I cannot unlock the primary in TWS)

 

You mean, draw the targets on the scope in a position where they are not, just to ensure adequate spacing from each other? That is quite a bit of programming work, figuring out where to intelligently place the secondary blips - to the left or above or diagonally - to then have to redo later if we find out how the real thing works. What if there is a second closely-spaced group right next to the first? If we are going to be making this display up, I'd prefer to base it on a zoomed display with "truer" blip positions, like in the F-16 MLU. But figuring out how the real RGH display works would be best.

 

I would also like to see TWS targets drawn with the proper delay between sweeps in TWS modes on BOTH sides, not this insta-update stuff that's going on with designated TWS targets right now.

Also ebcause of the way TWS is supposed to work, TWS designates targets should not be lost unless they're lost on the radar screen. To be more clear: If a plane changes aspect and I 'lose' the TWS lock but the blip is STILL on the screen, I shoudln't have lost the 'lock' (since it's not a real lock and jsut a software function that simply keeps a trackfile on that contact ... so if the contact's there, the trackfile's there, and the 'lock' is there). I would like TWS to automatically reject jamming targets, or put them in a 'dugout' instead of the current display method, so that targets overlayed on the jammer can be selected instead of the jammer. VERY annoying. At the same time, the TWS should NOT go to STT on a jamming target just because it started jamming (and is beyond burn through range), it should just drop that contact and make the secondary target the primary and track that instead. If the contact is within burn-through range and jamming TWS should NOT go to STT on it, since it has all the information required to track the target available. If the target goes beyond burn-through range, it should be dropped and handled as above. Personally, I think that the 'dugout' diaply method would be best for handling jamming contacts. The current mode of operation of TWS is very annoying to me. I can'tt hink why udner any circumstances this would be desired behavior on the real aircraft.

 

Ok, these suggestions have some good tactical relevance. However -

 

if a non-jamming target is on the same bearing as a jamming target, is it really realistic that you should be able to see it at all in TWS? How would the radar reject the "jamming target" but keep the true target on the same bearing? We should agree on an estimate of the radar's ability to resolve separate targets in azimuth.

 

Also -

 

How often in modern air combat should we be encountering non-ECM targets at all? I would like to optimize the systems and tactics to efficiently handle jamming targets, not non-jamming targets. Maybe we should start with the "kinematic ranging mode", that is absent in Lock On but very important in an ECM environment, before anything else. Would you agree? This would help us to do away with burn-through altogether, but it is something that affects both Russian fighters and the F-15.

 

Another thing I'd like to see on the F-15: An X through the target square if the target is friendly.

 

Hmm, an X in real life usually means a target thought to be hit by an AMRAAM, no?

 

Another thing I'd like to see insofar as jammers are concerned: Right now there's adifferentiation ebtween friendly and enemy jammers. This shouldn't be so, IMHO. They should all show up the same.

 

Agreed.

 

-SK

[GGTharos]

Tehnically, the auto-lockon mode is supposed to pick out the nearest target (or at least the one with the largest RCS) ... that should be the closest one in -most- cases, I think, or am I wrong?

 

But, a reject switch is definitely a good idea I think.

 

Some clarification on my proposal for RGH: You have no 'zoom' mode, you only display one cotnact instead of the group, since you can't visually break them out on the screen - BUT- the radar paints a symbol that indicates multiples and gives the multiple count. When you go to deisngate, the radar auto-enumerates the group, so it designates #1 first, press again and it cycles to #2 of the group, etc. This would eb a good use for a cycle button here, who operation would vary depending on what you use it with.

 

Clarification on slewimg the scan area: I don't think it's quite as simple as I think you're thinking ... it could attempt to stay centered on TDC or PDT (if you have a designated target)within gimbal limits. You could slave both controls to the tdc but this is way unoprimal with the way the radar slewing is coded in 1.02 at least.

 

Clarification on SNIFF: It would look different if the jammers behaved the way you suggest, but they do not. Under those circumstances SNIFF actually becomes very useful. It would be quite feasible to do away with SNIFF given the behaviour you describe. This here I think is purely from a gaming standpoint; LOMAC doesn't offer us the enormous amount of emitters that we'd find in RL as you described, which makes this function more useful. It is realistic within this limited contaxt - ie, a 'what if'.

 

About rejecting the jamming target: You've got a point there, but you could and SHOULD be able to reject it given different altitudes or different enough bearings. Right now this isn't possible. Also, you simply shouldn't have a contact to try and designate if the other jammer was 'masking' it. This is a LOS issue which shouldn't be too problematic to calculate I would hope.

 

 

Now, again, about jamming vs. non-jamming targets: We don't have the rich environment nor variety of jammers we normally would have, however; I agree with you, it would be very interesting to simulate this plus other techniques of defeating jammers (and at the same time, Jammers helping defeat missile accuracy by introducing range and closure errors). This would require some more advanced missile logic modelling, and I've got some big beefs with that one as well (missiles don't optimize for closure, only trajectory! This causes very big problems, namely of the 'dive that SAM intot he ground' variety). Anyway, this would kick butt.

 

About the X: I don't know what it means in real life, but in this game given the availability of IFF, I strongly believe that the IFF information MUST somehow be represented on the HUD when available against a locked target. IFF issues in online servers right now are pretty huge. I honestly can't think of any other way to represent it.

 

Another thing I wouldn't mind seeing BTW would be slightly elongated min missile ranges for all missiles ... but that's another discussion.

[D-Scythe]

The AN/APG-70 according to Steve Davies, International Airpower Review:

 

VECTOR and VS search

__"Vector (VCTR) mode provides a secondary search mode that uses all PRFs, but in a slower scan rate of 35 degrees per second in order to increase the detection range of targets with a small radar cross section...Velocity Search is more of a scope formate change than a distinct radar mode; it changes the VSD/MPD from a range/azimuth format into a velocity/azimuth one, and displays the fastest-closing contacts at the top of the scope and the slowest-closing ones at the bottom."

 

Seems to be two separate modes to me. If Mr. Davies is correct (and there's no reason to believe that he isn't), I would use VCTR to try and detect and track targets at extremely long range, or if I was engaging an F-117A or trying to pick up cruise missiles hiding in ground clutter. I would probably not use it to engage an inbound flight of Su-27s at 40 nm, especially if I know exactly where they are already, because RWS will do the same job, and twice as fast.

 

Range Gated High

__"RGH only functions when the F-15 is above 4000 ft (1220m), thus allowing acceptable levels of ground clutter returns when the radar is scanning out to a maximum range of 160 miles (257 km)."

 

I don't want to take Mr. Davies word as God's, but apparently its 4000ft, not 6000. Otherwise, I have no idea how it works, or when to use it.

 

RWSI

__"The main search mode is Interleaved (INLV - known as Range While Search/RWS in the F-15E)."

 

Would be nice to get this changed if its true, although it would be mostly cosmetic.

 

TWS

__"TWS provides much more information than any search mode, and it maintains track files and 'vector sticks' for each target...(that) give a graphical indication of both the speed and heading of the contact...target altitude and MACH are temporarily displayed next to the acquisition symbol. Data on specific TWS targets can be gained from either placing the acquistion cursor over the target using a Throttle Designator Control button on the throttle, or by locking the target up...TWS offers the most appropriate 'observation' mode where high-confidence sorts of closely formated targets are required without alerting the EW equipment of adversary aircraft."

 

Target information seems to be displayed, either with vector sticks or by placing the TDC cursor over the target, without locking it up. Obviously, TWS would be used to engage multiple targets simultaneously. I think the computer does all the work in keeping the PDT within the scan zone limits itself though, rather than having the pilot manipulate the radar and do it himself. ANd unlike GG, I don't want it to be simply centred on the PDT, but just keep it there, even at the scan zone extremes, if necessary. There may be other contacts at differing altitudes than the PDT, and I still want *some* manual control over the scan zones, instead of having it completely automated, and I'd imagine that most fighter pilots would think the same.

 

CAC modes (only BORE and VTS, the ones in Lock On)

__"For dogfighting, the APG-70 offers Automatic Acquistion options known as 'Auto Acq' modes. These are used when adversary aircraft are within 15 miles (24 km) and a quick reaction capability is required. Boresight Auto Acq (BST) provides a very fast, visual target-lock method and is a thin radar beam of around 4 degrees. Its line of sight is indicated by a synthetic circle generated in the HUD - the pilot simply needs to place the target aircraft inside this circle and the radar will automatically lock...Vertical Target search uses a vertical scan from +5 to +55 degrees and is very useful for acquiring a target that is manouvering in front and above. Vertical Search can also be slewed in the direction of a reported target, although its main application is in the dogfight."

 

IMO, having the extra range in the Lock On F-15 CAC modes would allow us to quickly react to a target within 20 nm (where manipulating the elevation limits on the radar is a pain in BVR [2] mode at such short ranges) and get off a Slammer extremely quickly, especially if the target is producing a contrail. The main point, at least the way I see it, is to get off a Slammer as quickly as possible, and at as many targets as possible, faster than a Su-27 or MiG-29 can with R-27/R-77s in BVR mode and outside of Archer range. You won't necessarily have to turn and burn.

 

Nothing on HOJ, AOJ or kinematic ranging on jamming targets, unfortunately, except:

 

HOJ, AOJ, etc.

__"Several 'special' modes are provided to counter hostile electronic warfare techniques, and the APG-70 will automatically reconfigure the radar to optimise detection and tracking characteristics when necessary. It will also automatically enter special tracking modes when it detects jamming of the radar channels."

 

It does say that it's automatic, so maybe ED would not have to model this, since the radar and computer handles it itself? At least the more complicated aspects of it, anyway.

 

And I thought the X meant that the target was too close for an AIM-9/AIM-120/AIM-7 shot (whichever one is selected). I remember seeing a similar 'X' over the HUD during HUD film from a Navy F/A-18C in a dogfight with a German MiG-29G...not entirely sure though. But I do agree with GG: there must be some type of IFF indication.

[SwingKid]

Picking and choosing what to reply here to give more information and less speculation:

 

VECTOR and VS search

__"Vector (VCTR) mode provides a secondary search mode that uses all PRFs, but in a slower scan rate of 35 degrees per second in order to increase the detection range of targets with a small radar cross section...Velocity Search is more of a scope formate change than a distinct radar mode; it changes the VSD/MPD from a range/azimuth format into a velocity/azimuth one, and displays the fastest-closing contacts at the top of the scope and the slowest-closing ones at the bottom."

 

Seems to be two separate modes to me. If Mr. Davies is correct (and there's no reason to believe that he isn't), I would use VCTR to try and detect and track targets at extremely long range, or if I was engaging an F-117A or trying to pick up cruise missiles hiding in ground clutter. I would probably not use it to engage an inbound flight of Su-27s at 40 nm, especially if I know exactly where they are already, because RWS will do the same job, and twice as fast.

 

If you check the right side of http://www.f15sim.com/images/left_console_new.jpg (from the Dash-1 of the F-15), there is reason to believe that the APG-63(v)1's "VECTOR" mode has replaced the APG-70's "VS" mode on a one-for-one basis.

 

Also, from Peter Davies and Tony Thornborough's F-15 book,

 

"Range Gated High (RGH) mode provides data purely on high- and low-closure rate targets. A High PRF Vector mode can be used and this doubles the time it takes to complete the scan, the extra data and processing time being used to pick up tiny, and possibly first-generation stealthy, targets at very long range."

 

Velocity Search is not described. The "Introduction to Airborne radar" however describes the advantage of Velocity Search as being that no FM ranging is employed. This makes the VS mode have lower electronic losses and higher sensitivity, making it suitable for long-range detection of low-RCS targets - very similar to Davies' description of Vector mode. Whereas RGH seems to be getting rid of the guard horn filter - so it is sensitive to ground clutter, but has longer-range detection. I read elsewhere that Vector mode represents targets on the scope as a vector showing their direction of motion, whereas most other modes show them simply as blips. So I think RGH and VS/VECTOR are not the most useful modes - you might use them for long-range detection if the scope is otherwise empty, but then switch to INLV/HI/MED as soon as possible. It may also be that only INLV/MED/HI are compatible with TWS.

 

-SK

[D-Scythe]

If you check the right side of http://www.f15sim.com/images/left_console_new.jpg (from the Dash-1 of the F-15), there is reason to believe that the APG-63(v)1's "VECTOR" mode has replaced the APG-70's "VS" mode on a one-for-one basis.

 

Huge picture, but it was worth it. But in terms of the modes, the APG-63(v1) is the most advanced radar available to the F-15C/E apart from the APG-63(v2), and we're aiming for the APG-70...right? In any case, I agree with you - both VS and VCTR would be used in the initial detection phase.

 

What do you mean that only INLV and its sub-modes are 'compatible' with TWS?

[GGTharos]

I think he means they're the only modes it makes sense to use TWS with. I don't see tracking being done using less reliable modes like VS/VECTOR, or maybe even RGH ... though the latter I can see a TWS mode with.

 

Actually, another gripe I have with the F-15's avionics is that if you narrow down the azimuth to get a faster target update, it goes back to full azimuth when you designate a target in TWS. Why are the two linked at all?

[SwingKid]

Huge picture, but it was worth it. But in terms of the modes, the APG-63(v1) is the most advanced radar available to the F-15C/E apart from the APG-63(v2), and we're aiming for the APG-70...right? In any case, I agree with you - both VS and VCTR would be used in the initial detection phase.

 

I think we should now aim for APG-63(v)1. Except for VECTOR replacing VS, it is not so different. The APG-70 is no longer an F-15C radar. It is practically removed from all F-15C to serve as spares for the F-15E fleet.

 

What do you mean that only INLV and its sub-modes are 'compatible' with TWS?

 

HI and MED are not really modes, but rather PRFs, and INVL just alternates between the two.

 

I'm not sure TWS can use VS or VECTOR data if those modes don't use FM range-measurement. RGH might on the other hand provide too much range data for TWS - it uses complex range gating circuitry that requires at least 4x computer memory just to display target detection - in order to use TWS with this mode, you should only be able to maintain track on 1/4 of the normal number of targets, for a given amount of computer memory, and at a cost of much more software complexity to correlate blips from adjacent range bins. From what I know of TWS and RGH I have doubts they would work well together. Davies has described a "TWS sort" sub-mode, but pilots indicate that it does not use range-gating for improved resolution. I've never heard or read anything about TWS being able to use (or not use, to be fair) VS, VECTOR or RGH, but we know it can select HI, MED or INLV on the fly, depending on the needs imposed by target aspect. VS, VECTOR and RGH on the other hand don't seem to have that much to do with target aspect. If you are detecting targets at such long ranges for these modes to be useful, your scope is probably too empty to be using TWS anyway. INLV, MED and HI should be enough for anything in AMRAAM range.

 

-SK

[tflash]

Not to interfere ... but this thread is becoming so interesting you should consider to make a compilation into a PDF file and add it to the Lockon on-line documentation. I never read such an interesting discussion on radar modes (I read most of the literature you mention though).

 

Back to the point: I would also go for APG-63(V)1

[Guest ruggbutt]

I think I'm gonna compile this stuff in notepad and discuss it w/my F16 pilot friend next time I see him. He might be able to give me some insight about real life applications for each mode rather than literature put out by the manufacturer. Sometimes the two are worlds apart.

[SwingKid]

Kinematic Ranging vs ECM targets

 

For a war game of Russia versus USA, ECM radio interference jamming should play a central role. Here is an idea for a system of kinematic ranging, based on what is documented in the MiG-29 flight manual and adapted for Lock On's F-15 avionics displays.

 

Step 1.

 

The fighter is in a heavy jamming environment. There are multiple BVR targets, all emitting ECM, and the pilot cannot determine whether the targets are in range for launching missiles, or not.

 

 

The appearance on the Heads-Down Display (HDD):

 

 

Note that even while the radar scope range is set to 10 nm, ECM targets beyond 10 nm still appear on the display as vertical strobes.

 

Step 2.

 

The pilot selects a single target and moves the radar cursor over it...

 

 

Step 3.

 

...and locks the target in the Angle-On-Jam (AOJ) tracking mode.

 

 

The AOJ mode keeps the radar antenna constantly pointed at the ECM source. Therefore, it works like Single-Target Track (STT) mode, and cannot be used with Track-While-Scan (TWS) mode.

 

At the moment of locking the target in AOJ, the fighter's radar records two vital pieces of information:

 

(a) the position of the own fighter in space, at the moment of locking the target in AOJ, and

(b) the compass heading that the radar antenna is pointing, at that moment.

 

These two pieces of information define an imaginary line, here called the "inertial reference line" (IRL).

 

 

The IRL extends to infinite distance, and passes through the initial positions of both the fighter and the target. The range to the target is not known. The IRL is used as the first reference for triangulation of the target's range.

 

At the moment of starting AOJ tracking, the kinematic ranging mode is automatically activated.

 

Step 4.

 

The pilot banks the fighter to turn away from the target, carefully keeping the bearing of the ECM strobe within the radar scan limits:

 

 

Step 5.

 

When the strobe is at about 45 degrees off to the right or left, the pilot levels out the aircraft and continues flying straight, waiting for the radar to calculate the target range.

 

 

Step 6.

 

By flying in a direction not directly towards the jamming strobe, the fighter is forever increasing its "perpendicular distance" from the initially defined IRL. This distance is shown in red:

 

 

In addition to remembering the IRL, the kinematic ranging radar now monitors two more pieces of information:

 

© the inertially-measured perpendicular distance the fighter has flown from the IRL (red line), and

(d) the compass heading that the radar antenna is pointing, to keep itself aimed at the ECM target.

 

Note that even if the fighter turns and the scan angle of the radar antenna with respect to the fighter changes, its compass heading should be unaffected by the fighter's turn.

 

What does affect the radar antenna's compass heading is the range to the target (unknown), and the perpendicular distance the fighter has flown from the IRL (red line). In general, the further the fighter moves away from the IRL, the more the radar antenna will deviate from its original compass heading when the fighter was on the IRL. The amount of deviation is dependent on the distance from the fighter to the target. If the target is far away, the radar antenna will change its compass heading very little. If the target is near, the compass heading will change a lot.

 

A small radar antenna beam is typically only a few degrees wide - let's say, 1-2 degrees from the middle of the beam to its edge. So, a 2-degree change in the radar beam's direction could move it from being "on target" to "off target", whereas a smaller change might not make such a noticeable difference in the received signal strength. So, let's say that the compass heading of the radar antenna should change by at least 2 degrees, in order that the radar can triangulate a reasonably correct range to the target. As soon as the radar antenna compass direction changes by 2 degrees, the radar measures the length of the "red line" (perpendicular distance fighter has travelled from IRL) and from that, estimates the range to the target.

 

For example. If radar antenna compass heading deviation equals 2 degrees at the moment the fighter has displaced itself (red line) 500 feet from the IRL, then the estimated range to the target is about 2.5 nm. The ECM strobe can disappear from the HDD, replaced by a normal-looking solid blip, and the HUD symbology can show a missile firing solution with a target range of about 2.5 nm. The pilot can then turn back towards the target and take the shot (or, at such short range, start looking for the target visually).

 

If the radar antenna deviation has not reached 2 degrees by the time the fighter has displaced itself 500 feet away from the IRL, then the range to the target remains unknown and the fighter continues flying in the same direction. However, the radar now knows the target is probably more than 2.5 nm away. So, the ECM strobe below 2.5 nm can be removed, to indicate this to the pilot:

 

 

As the pilot continues flying further from the IRL, the closest parts of the ECM strobe will continue to gradually disappear, until the radar antenna deviation finally reaches 2 degrees. After about 1 second, the 400-knot fighter has displaced 500 feet and the first hollow blip disappears, as shown above. After 2 seconds, the fighter is at 1000 feet and the blips below 5 nm range disappear:

 

 

After 3 seconds, the fighter is at 1500 feet and all blips below 7.5 nm disappear:

 

 

After 4 seconds, the fighter is at 2000 feet and the range scale changes to 20 nm, with all blips below 10 nm removed:

 

 

And so on. Looking back at the diagram:

 

 

...we can see that as the fighter moves away from the IRL, increasing the length of the red line, the purple rays (one of which, a or b your pick, should represent 2 degrees deviation) will creep further and further up the IRL, passing possible positions of the target (green) along the way.

 

This is the basic idea behind kinematic ranging. I don't know how accurate is the HDD symbology I have presented here, but I think it would be a good abstraction for gameplay, to help the player choose flying tactics and make decisions about when to shoot the HOJ shot. If something like this were implemented, then it would make other possible features more relevant:

 

- eliminating "burn-through"

- having missiles not loft against ECM targets

 

etc.

 

More later...

 

-SK

[GGTharos]

I think other methods of defeating ECM should be considered as well, like the ability to time-code pulses for example. It might get you a 'fuzzy' range, but it would be faster than KR. KR should be there because it's interesting - subs use very similar techniques, but given their speeds, ehh... ;)

 

In addition, a missile could still loft against its target, and in fact help itself to a range determination by vertical displacement. It should have a fairly easy way of telling when to begin its dive - LESS optimal than knowing the target's position, because you might want to make a different dive depending on target altitude, but, your seeker's deflection should give you enough of the story to cope.

 

The problem with this is that it's now hard to simulate the effects of jamming ... I make it sound liek jamming has no efect at all while this isn't what I'm trying to convey.