Bombing solution seems to use Barometric Altitude only

[ldnz]

In opt mode, a2g, in a dive with a good steady solution bombs appear to always fall short. In active pause, the only thing that appears to affect the indicated slant range is the altimeter setting, laser makes no difference.

It appears that radar altimeter and laser aren't being used for slant range calculation, only baro alt.

Unsure, but in previous mission in mountainous terrain I found a2g cannon with laser (I think, but altimeter would have been no use) to be pinpoint accurate, so possibly just not right with bombs.  

LastMissionTrack.trk

[AeriaGloria]

I have a feeling this has to do with the target altitude in DTC. I couldn’t understand the way Wags explained it exactly what this was changing, and it seemed to be for every waypoint 

[NineLine]

It's quite simple. For accurate ground attack, it helps for the aircraft to know the exact target altitude. If there is a difference in elevation of the aircraft altimeter and the target elevation, that can throw off calculations. The Target Point DTC function simply sets this elevation, just as Wags explained.

[ldnz]

Thanks, but which part of the calculation? Just density? Right now it appears only barometric altitude is used in the slant range calculation, not laser

[Esac_mirmidon]

And we should set barometric altitude to QFE or QNH for the Mig-29 regarding ground attack?

[AvroLanc]

18 minutes ago, Esac_mirmidon said:

And we should set barometric altitude to QFE or QNH for the Mig-29 regarding ground attack?

Set QNH for ground atttck presumably, otherwise there would be no need for setting a target point elevation. This also assumes that, by design, you must ensure the target is co-located as closely as possible with your current Waypoint. 
 

[IvanK]

5 hours ago, NineLine said:

It's quite simple. For accurate ground attack, it helps for the aircraft to know the exact target altitude. If there is a difference in elevation of the aircraft altimeter and the target elevation, that can throw off calculations. The Target Point DTC function simply sets this elevation, just as Wags explained.

But ....based on the limited documentation out there I believe IRL you cannot actually set a target elevation preflight into the INS/WCS. Though the DTC allows it and the DTC capability is being used to neatly simulate data entry by the ground crew on the ground , IRL there just isn't provision for any altitude entry into the system. Happy to be corrected here.

I guess if there is documentation that shows that Baro ranging can be used (and the methodogy) then that would settle the issue ... just haven't seen that in the Docs I can source. So to me the only ranging options are Laser or Radalt.

Though I guess changing the QNH to a dodgy value (aka target area QFE) might work ?? assuming baro ranging is even used 

Edited 20 hours ago by IvanK

[AeriaGloria]

As far as I know, per combat employment manual, all slant ranging is done by either laser or radar altimeter elevation method ( like Mi-24) 

[IvanK]

Found this in the Alan R. Wise version of the manual Page 131:

"The input of ballistic data for the aerial bombs is carried out before flight from the monitor centre by the ground crew setting the wafer switches (coded input) to positions corresponding to the code of aerial bombs used. Depending on the conditions of combat use and the bombing mode, additional information about the target vertical separation relative to the departure airfield and the selected drop angle of aerial bombs in toss bombing is entered from the input monitor panel"

So my take on that is that certainly for toss bombing on a pre planned target the system knows the difference in height between the departure airfield and the pre planned target... a +- DeltaH. Now whether that has any input in the other bombing modes in OPT who knows. More info required as to exactly how this works.

Edited 18 hours ago by IvanK

[ldnz]

Interesting, that makes sense for toss bombing

[IvanK]

11 hours ago, ldnz said:

Interesting

If you are using Baro alt  for your refrence.