Rne - Range of No Escape

I'm not sure if this is a bug or if I'm just misunderstanding how this is meant to work / what it's trying to show, but there's seems to be something funny with the Rne indicator in the Hornet. If it is a bug, feel free to move it to the bug forums.

My understanding of the Rne indicator, is that it's meant to show the point at which firing a missile will reach the target even if the target does a 180 degree turn and tries to fly away (i.e. it's the point at which they can't escape).

Right now, it seems to be not indicating the correct range for that at all. I've attached two examples, but it's apparent at all altitudes and speeds (if you're very high and very fast you'll even sometimes see Rne at the same point as Rmax - which seems counterintuitive). In both examples, I fire at Rne, and the enemy evades the missile without needing to do a 180 degree turn. In the low altitude example, I actually outrun the missile before it reaches the enemy.

40kft:

2kft:

So, do the indicator parameters need to change, or have I misunderstood what Rne is trying to represent?

Rne2k.trk

Rne40k.trk

Uh, you do realize that doesn't mean he can't dodge it right?

I believe it just means he won't be able to outrun it at that range. Using chaff and evasive manuevers would be quite another thing.

Thanks for the track files, but unfortunately I can't watch them because I didn't buy the modules.

I did manage to watch a few seconds of it, where I guess it didn't need the module, but it kicked me out. From what I saw in the 40k file, it was head on, and he was flying fast enough to escape the blast. Though it was close.

Uh, you do realize that doesn't mean he can't dodge it right?

 

 

I believe it just means he won't be able to outrun it at that range. Using chaff and evasive manuevers would be quite another thing.

 

 

Thanks for the track files, but unfortunately I can't watch them because I didn't buy the modules.

 

 

I did manage to watch a few seconds of it, where I guess it didn't need the module, but it kicked me out. From what I saw in the 40k file, it was head on, and he was flying fast enough to escape the blast. Though it was close.

It really isn't that close. Missiles in both scenarios are essentially dead weight before they get anywhere near - none actually reach the target in any of the scenarios. The target also doesn't do an immediate 180, it kept flying forwards until just towards the end - so if Rne were correct the missiles should have flown right past him even if tracking was lost.

I understand tracking can be lost, but it seems like Rne has been configured at too high a range - it seems like it should be about 50% of the range it actually is. It'd be easier to test with a buddy instead of the AI - just have a friend fly towards you at a constant speed and fire when you get Rne, then get them to pull a 180 without changing their speed (and not to chaff). I would expect the missile won't get near, and actually you probably need to be about half the range Rne actually is for the missile to start reaching.

If you try with a buddy try the following: launch immediately after reaching Rne, have your friend do a 180, nothing else, and measure the missiles speed when (or if) it reaches the target. If the speed is not sufficient to hit (or at least it wouldn't be able to stand any additional maneuvers) the Rne indicator gives optimistic calculations.

I agree that the Rne does not mean you couldn't evade the missile - but that is not the point. Within Rne you should not be able to bleed the missiles energy beyond a certain amount (this amount may be defined differently by different missile manufacturers). Within Rne you might still evade the hit, but beyond Rne you can actually deny the shot ever reaching you.

That said launching within Rne doesn't yet mean a high pk shot - E.g. shooting within Rne only means your target will have to do extra work to succesfully defend, but will still quite likely survive.

Regards,

MikeMikeJuliet

Yeah, I like the F-18, but I'm not buying yet. During the free weekend trial, I got the feeling that some of the systems are still "Alpha" at best. I'm sure there will be a lot more tweeking in the future.

You can an easily do a 180 and the missile launched at Rne isn't going to come even close. Kind of defeats the purpose of Rne.

You can an easily do a 180 and the missile launched at Rne isn't going to come even close. Kind of defeats the purpose of Rne.

Yeah that's what I was thinking. It works really well in the Mirage, you know that if the target is within Rne then the missile is definitely going to reach them and they're going to have to work to evade it. Looks like they just need to tweak the calculation for it in the Hornet.

RNE is generally considered with a given G turn and a given acceleration aftewards so depending on the numbers what we see may or may not be accurate.

That said DLZ calculations have been off in every jet. I don't know if it's more broken or less in the 18 but in the other fighters you're pretty much reliant on your knowledge of how the missile is performs. But it might be down to the numbers mentioned above.

Rne is very optimistic... i was head-on with an su-25 last night, fired an AIM-7 as soon as he hit Rne, he turned about 160 degrees and just flew away from it. No evasive maneuvers, no chaff... just flew away from it. I agree, that there are standards (expected g-rate of the turning aircraft, as blaze mentioned) in the calculation that can throw off the missile performance after the shot... and that's fine, but Rne is still WAAAY off.

I agree and I think this should be moved to bugs, it's definetly way off

Know system-wide problem.

Missiles in DCS have various problems, daring back to version 1.0.

My understanding is due to reliable data (a lot of this stuff is still classified) and that they were hampered by simulation tech at the time. Therefore, the underlying code makes a great number of (inaccurate) assumptions about missiles. Namley their drag coefficients, guidance programming, thrust capabilities, etc.

I know ED has had this on their RADAR for a long time, and the drag stuff is being worked on (IASGATG did a mod a while back, and has since worked with both heatblur and ED on this issue) and we've seen in recent changelogs that they're getting to the guidance issues.

The guidance issues are the biggest factor in what you describe.

The trouble is that DCS missiles just fly straight at the target all the time.This is why you see AMRAAMs pull 40 G off the rail with a 20NM shot. In reality, missiles don't maneuver at all unless they have to, and even then it's very energy efficient.

Sounds like we're finally getting movement on that now, too.

Know system-wide problem.

Missiles in DCS have various problems, daring back to version 1.0.

My understanding is due to reliable data (a lot of this stuff is still classified) and that they were hampered by simulation tech at the time. Therefore, the underlying code makes a great number of (inaccurate) assumptions about missiles. Namley their drag coefficients, guidance programming, thrust capabilities, etc.

I know ED has had this on their RADAR for a long time, and the drag stuff is being worked on (IASGATG did a mod a while back, and has since worked with both heatblur and ED on this issue) and we've seen in recent changelogs that they're getting to the guidance issues.

The guidance issues are the biggest factor in what you describe.

The trouble is that DCS missiles just fly straight at the target all the time.This is why you see AMRAAMs pull 40 G off the rail with a 20NM shot. In reality, missiles don't maneuver at all unless they have to, and even then it's very energy efficient.

Sounds like we're finally getting movement on that now, too.

You haven't been keeping up with DCS news - they corrected the AIM-7 range and guidance in the last couple of months. Rmax is now an accurate indicator - the missile will hit a non - manoeuvring target at Rmax. Rne is not accurate though - there's nothing wrong with the missile (IASGATG has given it his seal of approval), it's the algorithm for the indicator that's wrong.

Just as a small FYI, you're talking about Rtr (range turn and run). If you execute a max performance 180, maintaining speed (so a slice-back, for example) and accelerate when you hit 180, that's the escape maneuver. If you do it at Rtr, you will barely avoid being caught up by the missile.

Rne is shorter than Rtr and you've correctly surmised that it's meaning is that there's no way to prevent the missile from physically reaching you (ie. it has the energy to reach your aircraft). As has also been said, this does not mean that the missile cannot be evaded via countermeasures (active, passive, notching, etc), last ditch maneuvers etc.

Also remember it is a term made by the missile manufacturer ;)

A lot of fancy keywords (gillette now with smooth action ;) )

Are you implying the fine men and women at Raytheon would purposefully inflate their numbers?

No, it isn't. It's made by air force studies - literally by USAF officer PhD/Master thesis on the study of BVR combat.

Also remember it is a term made by the missile manufacturer ;)

 

A lot of fancy keywords (gillette now with smooth action ;) )