How to use ground weapons?

[ldnz]

I tried this on Nevada and saw similar. I was trying to zero the altimeter (for Groom Lake QFE) and found that my bombs were miles out and I go NOLA warnings. Also using pre-desig when set with altimeter far from QNH I noticed the desig symbol altitude is wrong. Had A for laser on the hud, but it seems almost like only barometric altitude is being used (in a dive so probably too steep for radar?) not laser range

[AeriaGloria]

1 hour ago, ldnz said:

I tried this on Nevada and saw similar. I was trying to zero the altimeter (for Groom Lake QFE) and found that my bombs were miles out and I go NOLA warnings. Also using pre-desig when set with altimeter far from QNH I noticed the desig symbol altitude is wrong. Had A for laser on the hud, but it seems almost like only barometric altitude is being used (in a dive so probably too steep for radar?) not laser range

It shouldn’t care about altitude setting, the only methods of air to ground ranging are laser and radar altitude, it does. It use radar. 
 

Understand once the laser is activated (dive of 10 degrees) it stays on for 30 seconds no matter what. And will afterwards stay off for 32 seconds no matter what. 

[SlipHavoc]

1 hour ago, ldnz said:

...it seems almost like only barometric altitude is being used (in a dive so probably too steep for radar?) not laser range

 

19 minutes ago, AeriaGloria said:

It shouldn’t care about altitude setting, the only methods of air to ground ranging are laser and radar altitude, it does. It use radar. 

I think I can confirm it's using the baro altitude for ranging, or something at least: If you dive at the target, laser on (symbol on HUD), then Active Pause and turn the pressure adjustment knob on your altimeter, the range indicated on the scale on the left side of the HUD moves as you turn the knob.

I tested in ISA conditions (1013 hPa), and had to turn the pressure knob to about 1007 hPa to get the range scale to match what I calculated with trigonometry based on altitude and map distance.  But on the other hand, I had to turn the pressure knob to about 1045 hPa to get the pipper to match where the bombs actually fall.  (Active Pause is incredibly useful for figuring all this out.)

Some assumptions I'm making:

1. The slant range itself should only come from the laser; that should measure the straight-line distance from your plane directly to the ground under the pipper, which is the slant range.  That should not be affected by the altimeter setting or anything else.  And I'm assuming the HUD scale should be showing the slant range.
2. However, the weapon ballistics, which means how the weapon flies through the air and where it will actually impact, should depend on the baro altitude, as that is a measurement of air density, which will affect the flight path, and hence where the pipper should be drawn on the HUD.

So it does feel like something should happen when I turn the altimeter pressure knob, as that will make the system think I'm in thicker or thinner air and that the weapon will fly in a different arc.  It seems like there has to be some cross-communication between these systems, because drawing the pipper in the right place on the HUD needs both the slant range and the baro altitude, and as the baro altitude changes, that moves the pipper, which should move the point the laser is shooting at, which will change the slant range, which will also move the pipper.

I assume that programming all of this so it actually works, draws the pipper in the right spot for all the different weapon types, and does so within whatever tiny fraction of the minimum-spec CPU slice they're budgeted for, is a huge pain in the butt.  Kind of amazing that it works as well as it does!

Edited 8 hours ago by SlipHavoc

[AeriaGloria]

1 hour ago, SlipHavoc said:

 

I think I can confirm it's using the baro altitude for ranging, or something at least: If you dive at the target, laser on (symbol on HUD), then Active Pause and turn the pressure adjustment knob on your altimeter, the range indicated on the scale on the left side of the HUD moves as you turn the knob.

I tested in ISA conditions (1013 hPa), and had to turn the pressure knob to about 1007 hPa to get the range scale to match what I calculated with trigonometry based on altitude and map distance.  But on the other hand, I had to turn the pressure knob to about 1045 hPa to get the pipper to match where the bombs actually fall.  (Active Pause is incredibly useful for figuring all this out.)

Some assumptions I'm making:

1. The slant range itself should only come from the laser; that should measure the straight-line distance from your plane directly to the ground under the pipper, which is the slant range.  That should not be affected by the altimeter setting or anything else.  And I'm assuming the HUD scale should be showing the slant range.
2. However, the weapon ballistics, which means how the weapon flies through the air and where it will actually impact, should depend on the baro altitude, as that is a measurement of air density, which will affect the flight path, and hence where the pipper should be drawn on the HUD.

So it does feel like something should happen when I turn the altimeter pressure knob, as that will make the system think I'm in thicker or thinner air and that the weapon will fly in a different arc.  It seems like there has to be some cross-communication between these systems, because drawing the pipper in the right place on the HUD needs both the slant range and the baro altitude, and as the baro altitude changes, that moves the pipper, which should move the point the laser is shooting at, which will change the slant range, which will also move the pipper.

I assume that programming all of this so it actually works, draws the pipper in the right spot for all the different weapon types, and does so within whatever tiny fraction of the minimum-spec CPU slice they're budgeted for, is a huge pain in the butt.  Kind of amazing that it works as well as it does!

Yeah just wierd your baro alt is changing range 

[The Gryphon]

2 hours ago, SlipHavoc said:

 

 

So it does feel like something should happen when I turn the altimeter pressure knob, as that will make the system think I'm in thicker or thinner air and that the weapon will fly in a different arc. 

Thats how Viggen works, it uses barometric settings for weapon deployments, how the MIG functions I dont know. But they are both cold-war jets, perhaps it was common back then?

[AeriaGloria]

I was also confused why Wags set target hieggt in his AG video. 

[Esac_mirmidon]

Some official clarification about the last patch if includes those fixes for air to ground accuracy or not would help.

Bombs falling short are still an issue.