Maximum Laser Range (discussion)

[raelias]

So, I'm just beeing curious here first of all

 

 

I was reading trough the bugs and someone reported a known "issue" with laser with DCS, which have a range of 8NM where the spot floats, the issue was marked as "not bug", which brings to my curiosity, in real life, optimal/semi-optimal conditions, from how far away can you actually guide a bomb/Mav to a target using the laser of the TPOD (Ligheting/ATFLIR if there is a difference?) Sounds a little short to me on a clear day, but then again I'm just guessing I'm sure someone has better info to give.

 

 

Thanks!

[silverdevil]

I do not know the limits in the sim. however the pod laser range should be more that 8 NM. however like a bullet which can go miles, there is a limit to sighting. in the pod you can see objects from far away and can zoom. if you see a target as a little dot the accuracy would obviously be harder. a quick search of public documents have this as actual capabilities of the modeled pod

 

- AN/AAQ-28 [Laser Designator] - Laser Designator, Laser Target Designator & Ranger (LTD/R), Max range: 27.8 km

- AN/AAQ-28 [FLIR] - Infrared, Infrared, Attack FLIR, Max range: 55.6 km

- AN/AAQ-28 [FLIR, Air-to-Air Tracking] - Infrared, Infrared, Navigation / Attack FLIR & Air-to-Air Tracking, Max range: 185.2 km

[Harlikwin]

Its hard to really say IRL there a bunch of factors and caveats to effective range mainly dealing with the atmospheric parameters, as well as "spot jitter" (cuz your plane isn't static) and laser dispersion. So that 27.8km might be on a house sized target under ideal conditions (at night). DCS more or less models nothing of this, they just have a "range" which for all units is about 8nm (15km) which doesn't seem too absurd given that it can paint a man sized target.

 

They don't really model any of the other atmospheric issues when dealing with the TPOD, or TPOD inaccuracies either.

[Ramsay]

I was reading trough the bugs and someone reported a known "issue" with laser with DCS, which have a range of 8NM where the spot floats, the issue was marked as "not bug", which brings to my curiosity, in real life, optimal/semi-optimal conditions, from how far away can you actually guide a bomb/Mav to a target using the laser of the TPOD (Ligheting/ATFLIR if there is a difference?) Sounds a little short to me on a clear day, but then again I'm just guessing I'm sure someone has better info to give.

 

IIRC charts for the AGM-65E show a range a little over 9 NM in best visibility with a laser designator fairly close to the target (max range fell to ~3 NM in humid conditions).

 

The max range for self/buddy lase in best visibility was ~7 NM i.e. it's similar to the range in DCS but obviously there isn't a floating laser spot when the spot is too dim to detect.

 

IIRC a set of GBU tests had a laser designator out at 28 km (15 NM) for a GBU detection at ~2 NM in best visibility.

 

I don't think I can be more specific due to 1.16

 

I hope the "not a bug" mark is for the AGM-65E loosing lock and ED will look to fix the floating laser spot ?

 

I guess the minimum I'd like to see is the laser spot turn off if it doesn't intercept an object before the ~8 NM (15km) max range (while keeping the pencil beam for the NVG laser marker).

[Harlikwin]

IIRC charts for the AGM-65E show a range a little over 9 NM in best visibility with a laser designator fairly close to the target (max range fell to ~3 NM in humid conditions).

 

The max range for self/buddy lase in best visibility was ~7 NM i.e. it's similar to the range in DCS but obviously there isn't a floating laser spot when the spot is too dim to detect.

 

IIRC a set of GBU tests had a laser designator out at 28 km (15 NM) for a GBU detection at ~2 NM in best visibility.

 

I don't think I can be more specific due to 1.16

 

I hope the "not a bug" mark is for the AGM-65E loosing lock and ED will look to fix the floating laser spot ?

 

I guess the minimum I'd like to see is the laser spot turn off if it doesn't intercept an object before the ~8 NM (15km) max range (while keeping the pencil beam for the NVG laser marker).

 

Guess that atmospheric/humidity modeling they are doing might be useful for more than FM's. :music_whistling:

 

If I were them I'd at least model laser power, then the attenuation and divergence factors are generally known from other "non military" fields plus whatever guess they have for how much of a dB SNR the seeker actually needs to guide. And if they want to be mean, then spot bounce/jitter just to make everyone's life a lil harder and bombs a bit less "precise".

[Eldur]

The

definately is a bug. It's totally unrealistic that the laser spot floats in midair 8nm from the TGP when it doesn't hit the ground or an object. Though limited range is realistic, since the air does diffuse the light beams by refraction and other optical physicsnesses. Unlimited range would just be realistic in vacuum / space. Imagine it like gun fire, just in much longer distances. At low ranges you still have a clear and crisp laser spot, but at higher ranges it widens up and gets less dense until the point an LST doesn't catch it anymore because it's not concentrated enough anymore. Some ranges that probably are more realistic than the 8nm of DCS are given by silverdevil some posts above.

[Harlikwin]

The issues with any laser designator come down to the following issues.

 

1. How sensitive the detector in the bomb is (i.e. at what range does it pick up spot and start guiding on it)

2. How much power can the laser put on the target at a given range. Laser attenuation and spot size are the major players here.

3. And optical jitter. The lasing platform is not 100% stable, and this obviously gets worse in bad weather. Plus optical effects of the intervening air, though those mostly can be factored into the attenuation/spot size issues.

4. Problems with lazing at ground/target level. I.e. hitting a second nearby target after the first bomb impact is a major problem as dust is kicked up which scatters the laser spot. Or if there is smoke (fire) or Fog obscuring the target, you are basically hosed (thermal will see through that, but the laser won't go through it)

 

Actually based on what I've read 8nm (15km) is probably pretty realistic under alot of real world conditions. Those longer ranges are mostly "under perfect conditions" kinda numbers but it varies alot on which laser you are talking about.

 

In space you still have the problem with spot power decreasing with range. In fact its the major issue with deployment of most real world laser weapons.

 

Alot of those cited factors/problems/shortcomings were what actually led to the development of JDAM's, which of course have their own drawbacks.

Edited August 8, 2019 by Harlikwin

[raelias]

The way I see it, say the range should actually be 8nm and beyong that it's not strong enough to guide, then whatever weapon shoudn't lock it at all beyon this range, not lock the "spot in sapce", or even just lose track if we fly further away

[Harlikwin]

The way I see it, say the range should actually be 8nm and beyong that it's not strong enough to guide, then whatever weapon shoudn't lock it at all beyon this range, not lock the "spot in sapce", or even just lose track if we fly further away

 

Agreed. But it is what it is in game cuz its easier to code it that way at the moment, but I hope it gets fixed.

[fudabidu]

"Easier to code" ... *cough*

 

Right now the TGP is casting a ray of 8 mile length. Where it intersects with the terrain is where your laser spot will be. So there is already code in place to check where that intersect happens.

 

It would be stupidly easy to add an exception to this piece of code: if it doesn't intersect with the terrain, there will be no laser spot (instead of a floating laser spot).

 

Anyone who ever worked with IF, ELSEIF and ELSE could fix this in minutes.

[Aphrodite51503]

Laser is line of sight like uhf radios 

What this means 

It will not travel around the curvature of the earth 

However 

If you can see it from altitude 

Line of sight 

Like your vision 

You should be able to lase the target 

About 11 to 15 miles from altitude 

Probably more if you can zoom like a laser pod allows 

 

It is line of sight and you definitely lase more than 8 miles in good atmospherics

 

 

 

 

 

[Phantom711]

I know this is an old thread, but since it got revived, I wanna add (or amplify) 2 more points:

 

1. The view perspective:

typically, the further away you are, the shallower the angle at which you are looking at the target. At 8NM, even if you were at 48000ft, you were looking at an angle of ~45°. If you take that down to a more realistic altitude of 20000-25000ft, we are looking at someting like 30° (too lazy to calculate that exactly now). Now looking at a target from that angle is more difficult, since it can more easily be obscured by other objects that have a vertical dimension (buildings, trees, hills etc.).

 

2. Laser spot size:

That point had been mentioned before, but it is important to understand, that a laser beam diverges over distance. So at 8NM it will be significantly larger than at its source. 

If you combine that with the above mentioned shallow view angle, you run into another challange which is "spill over": Due to the large laser spot size at that range, some of your laser light "spills over" your actual target and gets reflected from some object behind the target. Now you have 2 laser spots...50/50 chance, that the bomb/missile will choose the right one .

 

Bottom line: The 8NM we have in DCS do not seem too conservative to me.

[Harlikwin]

19 hours ago, Aphrodite51503 said:

Laser is line of sight like uhf radios 

What this means 

It will not travel around the curvature of the earth 

However 

If you can see it from altitude 

Line of sight 

Like your vision 

You should be able to lase the target 

About 11 to 15 miles from altitude 

Probably more if you can zoom like a laser pod allows 

 

It is line of sight and you definitely lase more than 8 miles in good atmospherics

 

 

 

 

 

The part you are missing, are all the things that attenuate a laser signal, moisture, dust etc. and the fact the spot will loose power due to collimation issues. And then the seeker needs to see some minimum signal to guide on so the choice of target and how well its reflecting also matter. So there are multiple variables to how far Mr laser goes and is actually useful for things like GBU guidance. For legacy systems 8nm is a decent guess, more modern systems are better.

 

 

 

[amalahama]

What's really annoying is that laser guided weapons guide towards an imaginary point floating in the air at exactly 8nm  from target when illuminating out of range

[Harlikwin]

3 hours ago, amalahama said:

What's really annoying is that laser guided weapons guide towards an imaginary point floating in the air at exactly 8nm  from target when illuminating out of range

Yeah, that is pretty weak unfortunately. But I don't see ED fixing it anytime soon.