Wind model for Weapons delivery computations

[Notso]

For the Mods or anyone else in the "know"....... What sort of "Wind Model", if any, do DCS aircraft like the Hornet, A-10 and F-16, etc. have for computing weapons releases in both CCIP and CCRP/Auto? The several recent threads on GBU-12s missing and the discussion of winds got me wondering how winds are modeled in DCS.

 

Typically IRL, most tactical combat jets that I'm aware of have a wind model of some sort that will attempt to calculate the wind from the release altitude down to the surface. The most basic method would be the jet's bombing computer would calculate a "standard" wind model using the winds the on-board INS/GPS sees at release altitude and then interpolates or decays the winds down to the surface using a basic algorithm and set of assumptions such as the wind would decrease X knots per 1000 ft. This would then continually adjust the release point based on the winds it sees at that specific altitude at that given moment. For instance, if the winds at release altitude were 090 degs@40kts, the bombing computer would create a calculation such that it assumes the winds are steady at 090 degs but reduce the wind strength say down to 5 kts at the surface and therefore adjust the release spot accordingly. The obviously flaw with this is that IRL, winds are rarely that constant in both direction and magnitude. Hence why an unguided MK-82 dropped in an auto/CCRP delivery from 20K would be unlikely to shack the target. However, in most cases it would be "good enough" to get an LGB into the basket for it to be able to guide with enough energy to hit the target and achieve desired weapons effects unless there was a significant wind shear and/or big change in wind speed from release to the surface.

 

The more advanced wind models would allow the aircraft to "capture" the winds as it climbed or descended through the air mass. But again that would assume that the winds are captured in the target area soon before release. This would be the most accurate wind model as it would account for "non-standard" wind speeds but more importantly account for wind shear which is common at different altitudes. However in many cases, it's simply impractical to dive down to 500 AGL and then climb back up again to 20K in a high threat target area to deliver a Level release GBU-12.

 

So the common middle ground method is for the pilot to manually inputs winds at various altitudes based off of "best guess" weather forecasts or even from observation. For instance if the jet's computer at current altitude says the winds are 090/40, but the pilot can see smoke on the ground moving from north to south at a slow pace, then he/she might program the manual wind model to account for that wind shear.

 

So that was a long winded way to ask - what wind models (if any) does DCS use for the various jet's bombing calculations? Are they accurately modeled? If not, I wonder if some of the reports of GBU-12s missing are due to inaccurate wind calculations and the bomb is not able to make it to the target.

 

Edit to add: BTW - Wind models are critical for CCIP bombing as well, as part of the Continuously Computed Impact Point calculations is wind. However it tends to be less of a factor in CCIP bombing as you are typically at lower altitudes doing dive deliveries with shorter TOF's than medium or high Altitude Auto/CCRP bombing profiles.

Edited December 15, 2019 by Notso

[maxTRX]

I should probably stay out of "in the know" threads but what the heck... for GBU's and other guided munitions... no explanation needed (still the release envelope is effected by wind)

 

For the dumb bombs... your ground track and speed are probably the most significant factors for FCR calculations and yea... can't be perfect, the misses still happen for various reasons.

[Notso]

I should probably stay out of "in the know" threads but what the heck... for GBU's and other guided munitions... no explanation needed (still the release envelope is effected by wind)

 

For the dumb bombs... your ground track and speed are probably the most significant factors for FCR calculations and yea... can't be perfect, the misses still happen for various reasons.

 

I'm not exactly sure what you're trying to say. What do you mean by "no explanation needed"??

[Harlikwin]

For the harrier its explained pretty well in the tac-man.

 

Basically for inertial bombing mode, the INS calculates wind drift based on the ins drift rate. But I'm pretty sure its only for the altitude you are actually at.

 

What makes the harrier cool, is that the ARBS can basically do the same thing but much more accurately, since its getting angular rate change date between the plane and the target. It can hit moving targets using the same effect. Again, not perfect from higher altitudes since it would obviously use the drift data from where you were at.

 

Also, it would make sense that TPOD's would be able to work like the ARBS system in the Harrier.

 

This is not actually modeled in the Harrier currently though, for either one.

[Notso]

I'm sorta assuming that DCS likely uses the "release altitude only" wind model for most of the modules. If that's the case, it would be interesting to know then if the DCS wind model calculations interpolates the wind to the surface or if its using ONLY the full value release altitude wind and nothing else. If the latter, that might explain a lot of the GBU-12 misses being reported in other threads. All the practice I've done so far with GBU-10 and 12 attacks have all be fairly light winds - and both continuous and delay lase seem to work fine. If you throw in a hefty headwind or crosswind and the wind model is incorrect, that could easily cause a miss. That would be true even with continuous lase but even more so with Delay lase if the target is out of the seeker FOV when the laser is turned on because the bomb release solution put it out of the ballistic basket.

 

@Wags or anyone on the ED team - can you please jump in here and offer some insights on how winds are modeled in the various bombing computers. Are they accurate to the jet or still WIP? Thanks.

[SharpeXB]

There are wind directions given for A-10C missions and a method of entering them into the CDU

 

[Notso]

There are wind directions given for A-10C missions and a method of entering them into the CDU

 

 

Ah ha, very cool. Thanks. So its a manually entered profile like I described above. Does the LASTE have the ability to capture winds, or only through manual entry? What if the winds are not entered into the profile. What does the A-10C use to calculate weapons releases?

 

It would be interesting to see what the F-16 and F/A-18 have as well.

Edited December 16, 2019 by Notso

[SharpeXB]

Ah ha, very cool. Thanks. So its a manually entered profile like I described above. Does the LASTE have the ability to capture winds, or only through manual entry? What if the winds are not entered into the profile. What does the A-10C use to calculate weapons releases?

 

It would be interesting to see what the F-16 and F/A-18 have as well.

I believe you have to enter it manually. But since you’re mostly using guided bombs unless the winds were really bad I don’t know how much it affects. If you don’t enter anything you’ll still probably hit the target. In theory all the free fall munitions are affected by wind including precision guided ones. So it’s nice to do.

[Worrazen]

Wouldn't all the weapon physics have to be adjusted for the new weather engine? I guess the new weather engine might modify how wind and pyhsics then work, wouldn't it. Those weapons, and the aircraft themselfs probably would need some kind of changes to interact properly with the new weather, if that has any relation at all, IDK.

[Harlikwin]

I think the current ballistic model probably just uses winds/speeds out of the mission editor where you can specify the weather.

 

I.e.

20k 50kts brg 279

15k 15 kts brg 180

5k 10kts brg 160

 

or whatever it actually is, but I do remember there are "bands"

 

As for different planes having compensation, the A10C is the only one that I'm aware of that does it. And it does have to be entered manually IIRC.

 

I don't think IRL they would use some "auto" system, because if you calculate winds as you ascend to altitude you can't assume they will be same hundreds of miles away. At best you'd get met report and some ground wind info from JTACS/FO's.

 

So INS drift or ARBS drift based on altitude is probably as good as it gets.

[Mars Exulte]

If you don't have a way to get the information, you can't use it to adjust for anything short of a ''guess''. Dumb bombs and CCIP are area attacks, even if targeted areas. You are not going to put a dumb bomb on the hood of a jeep consistently no matter how much you ''guess'' at values. That's what PGMs are for.

 

DCS models wind effects on weaponry at least to an extent. As for compensating for it during CCIP, you don't beyond ''guessing''.

[Tiramisu]

I remember my own thread: https://forums.eagle.ru/showthread.php?t=253663

Basically, if your weaponsystem does not support wind corrections, then you should attack along the wind direction and use ripple mode.

[Harlikwin]

I remember my own thread: https://forums.eagle.ru/showthread.php?t=253663

Basically, if your weaponsystem does not support wind corrections, then you should attack along the wind direction and use ripple mode.

 

Yeah, but the harrier should have wind correction (2 forms of it even), though you are totally right in the sense that if you want to minimize wind effects that's exactly what you would do.

[Tiramisu]

How is that function for the wind correction called in the Harrier? I have not found anything in the documentation, yet.

[Harlikwin]

How is that function for the wind correction called in the Harrier? I have not found anything in the documentation, yet.

 

Thats cuz it doesn't exist in the Razbam version. (yet. maybe someday, maybe never, it is razbam after all)

 

For high altitude bombing it uses INS drift to compute wind speed and uses that for CCRP drops.

 

When using the DMT (And presumably tpod). It tracks the angle rate change to the target from the aircraft to compute "wind speed" (which is also moving target speed).

[Tiramisu]

That sounds extremly cool. I hope there is a wishlist thread for that in the Harrier forum. :(

[Harlikwin]

That sounds extremly cool. I hope there is a wishlist thread for that in the Harrier forum. :(

 

I keep asking.

 

That and the harrier dive toss mode is also not implemented.

[Terrorban]

I'm sure RAZBAM will just say "If ED develops it, we will add it". They said that about pretty much every other major jet feature people have asked them to implement.