No Escape Zone logic is incorrect

Hello,

Since the release of the F/A-18, the NEZ has been a mystery to me. So I've done some testing and I'm really struggling to see what use it has at the moment. If I understood well the concept of a NEZ, it is to inform the pilot that the target, if it keeps the same parameters (speed and altitude) will not be able to outrun the missile by turning at exactly 180° away from the launcher, if it goes defensive, missile is trashed, if it speeds up, missile is trashed.

So in theory, Rne should be equal to Rmax when the target has turned 180° cold, and this distance (Rne) should not change with target aspect.

Though this is not the behavior observed in game and I don't know what the Rne currently indicates. Please feel free to correct me if i'm wrong about how this logic should work but currently, the way I understand it, the Rne cue is bugged on the F/A-18C.

Track attached, first missile fired is to test how the Rne changes if the target turns cold, and second missile launch is to see if the Rne indicator was correct when the target was already cold. In both cases the Rne provided incorrect information to the pilot as in the first case, it was very far away from catching the target and second case the missile was still burning by the time it hit.

Regards,

Rex.

server-20181228-220807.trk

Hello,

 

 

 

Since the release of the F/A-18, the NEZ has been a mystery to me. So I've done some testing and I'm really struggling to see what use it has at the moment. If I understood well the concept of a NEZ, it is to inform the pilot that the target, if it keeps the same parameters (speed and altitude) will not be able to outrun the missile by turning at exactly 180° away from the launcher, if it goes defensive, missile is trashed, if it speeds up, missile is trashed.

 

So in theory, Rne should be equal to Rmax when the target has turned 180° cold, and this distance (Rne) should not change with target aspect.

 

 

 

Though this is not the behavior observed in game and I don't know what the Rne currently indicates. Please feel free to correct me if i'm wrong about how this logic should work but currently, the way I understand it, the Rne cue is bugged on the F/A-18C.

 

 

 

Track attached, first missile fired is to test how the Rne changes if the target turns cold, and second missile launch is to see if the Rne indicator was correct when the target was already cold. In both cases the Rne provided incorrect information to the pilot as in the first case, it was very far away from catching the target and second case the missile was still burning by the time it hit.

 

 

 

Regards,

 

Rex.

This bit is wrong as when head on and during the targets break turn the velocity of closure of the missile is greater than if he is heading cold so RNE is greater than the of a purely cold target. RNE will always change with a change in target aspect.

The RNE is a factor of the missiles VC throughout it's time of flight, combined with the fact that any target turn will change the missile target intercept point so loss of energy due to maneuver must also be taken into account. ( Hence the use of pre shot crank or double crank in a semi active fight)

Unfortunately its just not that simple. I am unable to look at your track right now but hopefully my explanation helped in some form.

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So in theory, Rne should be equal to Rmax when the target has turned 180° cold, and this distance (Rne) should not change with target aspect.

 

This bit is wrong as when head on and during the targets break turn the velocity of closure of the missile is greater than if he is heading cold so RNE is greater than the of a purely cold target. RNE will always change with a change in target aspect.

 

The RNE is a factor of the missiles VC throughout it's time of flight, combined with the fact that any target turn will change the missile target intercept point so loss of energy due to maneuver must also be taken into account. ( Hence the use of pre shot crank or double crank in a semi active fight)

 

Unfortunately its just not that simple. I am unable to look at your track right now but hopefully my explanation helped in some form.

 

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I don't see why it would be much more complicated actually. If the launcher and the target are closing, Rmax will increase as closure speed increases, and Rmax decreases as closure speed decreases, which makes perfect sense. The point of the Rne is to inform the pilot that if the target goes from hot to cold without changing speed or altitude (very drastic change in closure speed), the missile will have enough energy to reach the target. This value shouldn't change if target or launcher speed do not change as it's predicting the range at which the missile will still hit based on the lowest closure speed possible with current target and launcher parameters. It's predicting the "worse case" scenario.

I also don't see why it would take into account energy losses from a target going defensive as that is not predictable, a % of the Rne might be substracted as a margin if the target does any maneuvers.

Lets take a launcher at a constant speed. Rmax, if it's not limited by the maximum range at which the selected missile can lock onto a painted target, is the maximum range at which the missile will be able to hit if the target does not change speed, it's altitude or change aspect. This increases or decreases with changes in closure speed (which is directly affected by target aspect), so if a target is hot Rmax is greater then Rne and even more so if the target is closing fast as the Rne decreases and Rmax increases if the target accelerates.

Now when a target is cold, the closure speed is low, Rmax decreases as the target accelerates and so does Rne because this "worse case scenario" is acheived. Both should be equal in the case where the target's relative heading is 180° since the maximum range at which the missile can hit is also the Rne if no margin is subtracted. In that scenario if the target accelerates, Rmax decreases and Rne decreases as the closure speed decreases and vice versa if the target deccelerates.

In short, Rmax increases if the target speed or launcher speed increases, Rne decreases if target speed increases. Rmax decreases if the target speed or launcher speed decreases, Rne increases if target speed decreases. If Launcher speed increases, Rne and Rmax increases. The higher altitude the better for Rne and Rmax.

This I find makes alot of sense, it's not a max PK indicator, which would be alot less confusing and would vary alot with target aspect as it is observed in game. Although it's a little counter intuitive.

EDIT : While indeed you could add some range to the Rne when the target is hot to anticipate the time it will take that aircraft to turn at 180° relative heading, you can't be sure how long it will take him to break, so this added distance could vary alot and potentially be missleading in some cases.

Most of what you said is absolutely correct but that last part.

RNE is a guide it assume a certain amount of g, maybe 4g but when you are dealing with a fighter target and his turn and the fact that RNE's are relative low maybe as low as 5 miles for some missiles the time it takes for a target to turn from Hot to cold adds a considerable percentage to the RNE.

A supersonic target doing M1.1 may have a turn radius as high as 5 nm depending on available g at altitude this, will add a lot to the RNE.

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Most of what you said is absolutely correct but that last part.

 

RNE is a guide it assume a certain amount of g, maybe 4g but when you are dealing with a fighter target and his turn and the fact that RNE's are relative low maybe as low as 5 miles for some missiles the time it takes for a target to turn from Hot to cold adds a considerable percentage to the RNE.

 

A supersonic target doing M1.1 may have a turn radius as high as 5 nm depending on available g at altitude this, will add a lot to the RNE.

 

 

 

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Yes absolutely, missleading was not a very wise choice of words ^^. But how would you identify the target type ? NCTR could be used but at relatively close range with the target being hot, but that's exactly what we want anyways so maybe it's used for that purpose. You'd also need some data on these airframes to estimate their turn rate and then calculate the Rne.

That or some general numbers are used for turn radius as a function of g load and speed along with the set size of the target set in the stores page to estimate max g of the target at that particular altitude.

At this point though It's only speculations, only someone with proper documentation (I hope ED does because this needs some work) could answer this question, though there is definitely something wrong with the NEZ in game because the behavior described in this thread is not what is observable in game.

It uses an assumed g for the target which is specified for a particular missile and you are given the detail when you convert to the Jet. Speed is automatically taken into account as target g and speed gives turn radius which gives you RNE for a missile. The target type is irelavant to the dispslayed RNE.

I will have a look on Monday and see what it's doing in the F18 as you have got me curious.

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It uses an assumed g for the target which is specified for a particular missile and you are given the detail when you convert to the Jet. Speed is automatically taken into account as target g and speed gives turn radius which gives you RNE for a missile. The target type is irelavant to the dispslayed RNE.

 

I will have a look on Monday and see what it's doing in the F18 as you have got me curious.

 

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Makes a lot more sense then trying to identify the target to estimate it's turn radius using NCTR and data on that particular airframe, then using it to calculate Rne. Thank you for the information.

I'm three OP YouTube described Rtr, note Rne. When inside Rne, there it is not possible to prevent the missile from reaching your aircraft. It does not mean it will hit, but it will always have the energy to reach you. This Rne vs Rtr.

I'm three OP YouTube described Rtr, note Rne. When inside Rne, there it is not possible to prevent the missile from reaching your aircraft. It does not mean it will hit, but it will always have the energy to reach you. This Rne vs Rtr.

What does Rtr mean and what's the logic behind it ? I don't think that indication is present on the Hornet's HUD or ATTACK RDR page.

Rtr is 'range turn and run' ie. max perfomance 180 and best acceleration away. Now, whether that 180 is a sliceback and at how many g's etc gets redefined often enough AFAIK so the deails can be whatever you want them to be.

And no, AFAIK it isn't not on part of the Hornet's DLZ.

Rtr is 'range turn and run' ie. max perfomance 180 and best acceleration away. Now, whether that 180 is a sliceback and at how many g's etc gets redefined often enough AFAIK so the deails can be whatever you want them to be.

And no, AFAIK it isn't not on part of the Hornet's DLZ.

Ok so Rtr takes into account the turn radius of the target and Rne doesn't if I understood correctly ? Does Rne work in a different way then what was described ?

I don't know about taking turn radius into account, I'm not convinced you need to account for anything other than time to target.

Rne is calculated as a range at which it is not at all possible to kinetically escape the missile, regardless of maneuver. And that's all I know about it - I'm sure they have a whole bunch of simulation runs to compute this sort of thing.

I know what the no escape shot was on the Tornado F3 and it definitely took target turn into account. Problem is that the actual RNE of any missile tells you a lot about it's performance and so it is not easily obtained as it is classified. I am sure ED has a good model for their RNE, just not sure what it is, maybe they would care to comment.

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I know what the no escape shot was on the Tornado F3 and it definitely took target turn into account. Problem is that the actual RNE of any missile tells you a lot about it's performance and so it is not easily obtained as it is classified. I am sure ED has a good model for their RNE, just not sure what it is, maybe they would care to comment.

 

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You can use the current in game missile performance to get a correct Rne though.

I'd also like to see the devs or ED comment on what the current Rne calculation takes into account.

I'm a really bad narrator but hopefully this showcases the problem ^^.

One correction i'd like to add is that I said that the Rne was using a worse case scenario closure rate (when the target is exactly 180°, relative heading), what I meant is that the range given by using the worse closure rate possible and other parameters used to calculate Rmax except the current closure rate would be somewhat equal to the Rne (if Rne doesn't take into account target turn radius).

Although what I described is Rtr (Range turn and run, explained above by GGTharos). Rne, if it is purely to inform the pilot that whatever maneuver the target does the missile will have the energy to reach the target, should be even smaller the Rtr. In either cases, Rtr or Rne, they should be much smaller then what the Rne cue indicates in game.

This looks more than off to me. If the target's parameters don't change at all when hes getting launched at while being as cold as possible, Rne should equal Rmax (=Raero +- the distance the target will travel until the missile will get there depending on it's vector) as to my understanding.

Dlzs should be based on time to target very broadly speaking. This can be represented as missile flight distance (not distance to target) as well since they're basically the same thing. Dinner additional parameters would certainly be useful but those are the basics IMHO.

It's complicated and different jets have different implementations (with varying quality/utility) as I understand it. There's probably no way we'll see something very 'realistic' in DCS imho. Even the 'realistic' implementation for a particular jet may not be worth much at all... I recommend you ignore the DLZ and determine your own engagement guidelines in the meantime...

One question I have: is the F18C supposed to display an estimate of 'no escape' or should it be an estimate of 'turn and run' in the Lot 20 hornet dlz?

I refer to the answer I gave earlier

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It's complicated and different jets have different implementations (with varying quality/utility) as I understand it. There's probably no way we'll see something very 'realistic' in DCS imho. Even the 'realistic' implementation for a particular jet may not be worth much at all... I recommend you ignore the DLZ and determine your own engagement guidelines in the meantime...

 

One question I have: is the F18C supposed to display an estimate of 'no escape' or should it be an estimate of 'turn and run' in the Lot 20 hornet dlz?

ED might as well remove the Rne indicator then, it's entirely possible to use the missile performance in game and a very simple definition of the Rne cue to get a correct indication (if you're within Rne, the missile can't be defeated kinetically, you can't "outrun" it even if that term would be better suited for Rtr). Though it is of course easier said then developped. It's still one very important and usefull cue for Air to Air.

I have an idea, it's only an idea and is very likely wrong but, for Rtr, lets say you have multiple sets of two graphs which you could get by doing tests in game, first one with Missile speed as a function of time and the second range travelled as a function of time, each set would correspond to data taken at different altitudes (lets say 0, 5000, 10000, 15000,... all the way to 45k feet), what you'd need to know is at what range will the missile be at the same speed as your target for a given altitude. You select the set of graphs closest to the given target altitude, you get the target speed, get the time after launch at which the missile will be at the same speed as the target, then run the time through your range(t) function and you'd get Rtr, crude Rtr, no turn radius taken into account, nothing else except pure target parameters and missile parameters, the graphs would also need an offset to take in account launcher speed, altitude difference is also an important factor,...

As for what other parameters Rne takes into account I don't know, but if Rne tells you at what range the missile cannot be kinetically defeated then it should be smaller then Rtr in most scenarios, if not all.

Please feel free to add to this discussion, I'm not claiming the idea I shared is correct or practical but with the Hornet becoming more and more intresting (Thank you ED :) ) I'd really like for A/A to not suffer from this problem.

I refer to the answer I gave earlier

 

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Exact missile performance is indeed likely to be classified, but I'd argue that's not actually that relevant. The DLZ doesn't need to match the real missile, it needs to match the peformance of the missile that's modelled in DCS. ED know how their representation is modelled, so they should be able to do this. Hopefully that makes sense.

That was a British joke Squirrel.

You are correct all we really need is the parameters that ED are using for their RNE.

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ED is working on improvements for A/A and with them there might be some improvements to the ranges we get in the cockpit.

But why adjust something now that is about to change anyway?