GBU12 missing targets by a few meters

[Meyomyx]

There's a previous thread about this. All my laser guided munitions miss by a similar small amount. Now, as these missions are launched from a carrier, I have a wind component of 20kts at sea level which gives a 43knot wind at 6k. Could this be the explanation? I'm not convinced that it should affect the accuracy to any significant degree .... not consistently causing the same error. I also haven't tried on a different map (or re-creating it from a "fresh" mission map. I can't find a definitive answer but will keep experimenting.

 

[Snakedoc]

I'm quite sure you'll need to compensate your point of aim for wind ;) i.e. upwind

 

 

on top of this I see from your video that your target is moving. That will also affect where your point of aim should be i.e. where the target will be at the time the bomb will impact

[Meyomyx]

... these are laser guided munitions. The pod tracks the target, the weapon will follow the designation whatever the wind/target movement - that's the whole point! :)

[Snakedoc]

not quite ;) if you do some research you'll see what I'm talking about

[Meyomyx]

I will.

 

So I need to make allowances for wind direction and target movement by anticipating where it will impact??!? I don't see any videos of this happening. Point track. Lase. Munition is guided to TGT point .....

[Fri13]

From the munition point of view, it doesn't care is there a sidewind or headwind or no wind. It has only one job, and one job only, proportional navigation to laser spot it sees.

 

And that it does by moving its guidance fins as often as required (old versions went always to max deflection and back, until spot is still. Newer ones has controllable fins so only small adjustments are possible be done.) and then keep spot stationary. So even if there is a wind, the munition targeting system thinks spot is moving and it needs to follow it.

 

There is no difference from its point of view that does spot move, or does itself move. Pilot job is to release bomb kinetically so that it has trajectory that will fly it near the laser spot so it can be detected and it will fall in the area.

 

Common error was that people started lazing too early, and bomb changed as soon as possible its trajectory, and didn't anymore have a lift and fall short or went over.

[Eldur]

What really gets me in that video is that the thing doesn't do the bang bang, but instead acts like a Paveway III which it simply isn't to be fair.

[Dagger71]

I'm quite sure you'll need to compensate your point of aim for wind ;) i.e. upwind

 

 

on top of this I see from your video that your target is moving. That will also affect where your point of aim should be i.e. where the target will be at the time the bomb will impact

 

 

?????

 

 

 

He's using a GBU laser guided missile. If a vehicle is moving you use track mode and the laser will always paint the moving target. You never lead for GBUs.

[Snakedoc]

try this for yourself: ;)

 

I made even a short mission with a track attached where I make on purpose the mistake of not compensating for the wind. I used the A-10C but the concept is the same, I'll try to do one in the F/A-18C also. **update**: F/A-18C mission and track here

 

- Surface wind is 260/30kts, from the direction I set up the aircraft thats straight headwind.

- WYP 1 is co-located with the TGT

- I am lasing exactly over the TGT, but because of the wind the bomb is falling short (downwind of the TGT)

 

To hit the target you need to lase upwind. I can't remember which training mission it was where it was explaining this concept but there is a way to figure out how much "lead" you need to give into the wind; I can't remember it right know, I'll update here if I find it

 

 

**update** See post #25 here

 

found it: Correction for LGB lasing is approx 1ft upwind per knot of wind. Training mission is M.09 from Maple Flag A-10C AFTQ

GBU12 wind test.trk

GBU12 mission wind test.miz

Edited June 6, 2020 by Snakedoc
updated info

[Snakedoc]

?????

 

 

 

He's using a GBU laser guided missile. If a vehicle is moving you use track mode and the laser will always paint the moving target. You never lead for GBUs.

 

technically its a bomb ;) the GBU12 is the laser guided version of the MK82 general purpose bomb, not a missile

 

if you're lasing for a missile (like the LMAV) then its correct, you don't lead for those

[AndyJWest]

If DCS laser-guided munitions of any sort are missing because of wind, it is a bug. A rather unlikely one, I'd think, since I'm sure it would have been reported (and corrected) a long time ago.

[Dagger71]

^^^^^this.

[Dagger71]

technically its a bomb ;) the GBU12 is the laser guided version of the MK82 general purpose bomb, not a missile

 

if you're lasing for a missile (like the LMAV) then its correct, you don't lead for those

 

 

 

 

You cannot lead the laser ahead of a moving target using TGP. not sure what you are getting at.

[Snakedoc]

Same mission file and track but swapped for an F/A-18C instead ;)

 

conditions are as above, surface wind 260/30kts, course 080.

GBU12 mission wind test F18.miz

GBU12 wind test F18.trk

[Dagger71]

dude you set the wind speed at 165 km/hr at 8000 metres and 147 km/hr at 2000 metres!!!! I don't think any weapon in DCS would hit a target in that wind. That is hurricane winds!

 

set your upper winds to more realistic wind speed and retry.

 

You've got

 

90 knots @ 26K

80 knots @ 6600

60 knots @ 1600

then 31 knots at 33 feet

Edited June 5, 2020 by Dagger71

[QuiGon]

You cannot lead the laser ahead of a moving target using TGP. not sure what you are getting at.

Of course you can! Just keep the laser in front of the vehicle. Why should that not be possible?! :huh:

[Dagger71]

Of course you can! Just keep the laser in front of the vehicle. Why should that not be possible?! :huh:

 

 

in point track? please show me a track of you doing this.

[Snakedoc]

dude you set the wind speed at 165 km/hr at 8000 feet!!!!

 

I set the surface wind at 260/30kts, what you see in the mission brief is 8000mts.

the winds I set are

 

surface 256/30kts

1600ft 256/64kts (this is auto set by the mission editor)

6600ft 286/80kts

26000ft 308/90kts

 

of course I set a strong wind to showcase the concept

[Dagger71]

I set the surface wind at 260/30kts, what you see in the mission brief is 8000mts.

the winds I set are

 

surface 256/30kts

1600ft 256/64kts (this is auto set by the mission editor)

6600ft 286/80kts

26000ft 308/90kts

 

of course I set a strong wind to showcase the concept

 

 

Why are you setting winds at 80-90 knots. That is completely unrealistic. Hurricane winds, regardless of the ground level.

 

 

 

Change the winds to realistic settings and it won't miss.

 

 

 

 

Be realistic here, that is not showing anything. no weapon in DCS can be launched in hurricane winds.

[AndyJWest]

To determine whether the wind is what causes the miss* in the OP's video, it needs to be tried again with no wind.

 

* Frankly, I'm not sure I would call that a miss anyway. It destroys the target. I don't know what the real-world GBU12 expected margin of error is, but I'd be surprised if a metre or so was problematic. The Mk 82 is a blast/fragmentation weapon, and you don't need to hit the target dead on with it.

[Dagger71]

Now to get back to the OP, it should not be missing by that much, and just realized this is an F18 post! So is the GBU in F18 more susceptible by wind? Shouldn't be in the winds you claim.

 

Got mixed up when Alby posted an A10C track. The GBUs in A10C are almost foolproof (might miss if alt is too low or you set the wind speeds to unrealistic setting).

Edited June 5, 2020 by Dagger71

[Meyomyx]

The winds in my mission aren't very much .... and I'm not saying that the wind is causing the problem - merely wondering why the munitions are consistently missing the targets by a few meters.

 

As for introducing lead for wind or a moving target, it strikes me as nonsense. That's the whole point of laser guided munitions - they fall to the point designated by the laser, whatever the wind.

 

The other factor that could cause a problem is if there is a mismatch between the spot height of the designated point and the target information. This is certainly an issue with dumb munitions and the Gulf map. If you set a target in the mission editor, the altitude in the aircraft is a couple of hundred feet out. Unless you correct the waypoint heights manually (specifically the TGT waypoint), the munitions miss the target by a proportionate amount. With a target in high terrain (Lar for example), this can be quite significant.

 

For me, everything is consistently missing the aim point by about 20 feet. I'll keep experimenting

[Dagger71]

yeah you definitely do not lead with a GBU, that's complete nonsense.

 

With the F18 I don't drop too many GBUs but when I did, they usually don't miss like that. Now I have not tried with the new TGP updates, so its possible there is some sort of bug.

[Meyomyx]

To determine whether the wind is what causes the miss* in the OP's video, it needs to be tried again with no wind.

 

* Frankly, I'm not sure I would call that a miss anyway. It destroys the target. I don't know what the real-world GBU12 expected margin of error is, but I'd be surprised if a metre or so was problematic. The Mk 82 is a blast/fragmentation weapon, and you don't need to hit the target dead on with it.

 

Agreed. This one did the job. However, many merely cause some damage - whereas a while back I was getting a very high success rate with the munitions hitting the target as designated. Not sure what has changed! I'll work it out! :)

[Snakedoc]

yeah you definitely do not lead with a GBU, that's complete nonsense.

 

With the F18 I don't drop too many GBUs but when I did, they usually don't miss like that. Now I have not tried with the new TGP updates, so its possible there is some sort of bug.

 

If what you experience is not what you expect it doesn't make it a bug

 

 

 

 

minute 1:21

 

 

This is taken from Mission 9 of the AFTQ campaign for the A-10C

 

Correction for LGB lasing is approx 1ft upwind per knot of wind

 

 

Why are you setting winds at 80-90 knots. That is completely unrealistic. Hurricane winds, regardless of the ground level.

 

Change the winds to realistic settings and it won't miss.

 

Be realistic here, that is not showing anything. no weapon in DCS can be launched in hurricane winds.

 

 

Have a look at some real world wind charts before calling it "unrealistic and nonsense".

 

While not common, high winds at lower altitude do exists and they are directly correlated to surface wind (wind will be veering or backing as altitude increase depending if you're on the northern or southern hemisphere, and it will increase in intensity as your altitude increases)

 

A simple google search will shine some light on the subject if you're keen to discover it

 

 

dude you set the wind speed at 165 km/hr at 8000 metres and 147 km/hr at 2000 metres!!!! I don't think any weapon in DCS would hit a target in that wind....

 

 

I did hit the target on my second pass when aiming upwind. If you look at my F18 track you can see it yourself ;)

Edited June 7, 2020 by Snakedoc
fixed youtube link