IZLAR- Jdam

[marzzz]

Hi

I don’t understand the new features for the JDAM

JDAM - (add: IZLAR/ Auto Mode for PP and TOO Mode / dynamic TOF /TOT -PP Cue - In-Zone / TOT cue on HUD/ heading is defined for IZLAR)

Specialy the IZLAR

 

I thought there will have a new cue on the HSI, a cue that indicates the launch zone for the terminal heading target

But nothing ...

is someone can explain to me ?

[Swift.]

They didn't add the izlar stuff, only a very cursory foray into the HUD cues. But nothing proper.

Edited May 30, 2020 by Swiftwin9s

[marzzz]

Ok thanks

Effectively when i am in zone of the terminal heading, an « in zone » appears on the hud and the LAR circle disappears on the HSi

 

On the other hand it seems there is a bug with the heading terminal cue, on the HSI in pp mode

When you enter differents heading ( for exemple 310, 320...)the cue doesnt correlate !

 

And i notice there is no terminal heading cue in too mode

[Swift.]

Yep, terminal stuff is super WIP. And the IZLAR kinda relies on that, so its also super WIP. There is currently no IZLAR cue (trapeziodal shape) on the HSI.

[LastRifleRound]

Yep, terminal stuff is super WIP. And the IZLAR kinda relies on that, so its also super WIP. There is currently no IZLAR cue (trapeziodal shape) on the HSI.

 

IZLAR isn't just for terminsl parameters. When the target is within a 30 degree cone of the nose, a pie like izlar appears even withou term. This represents the actual area you can drop in by the time you get to any point in that area and changes with airspeed and altitude.

 

This differs from the over simplified logic in the JF17 and the IRLARs we have in the Hornet now.

 

Picture the current, circular cues on the HSI. Picture one with no term parameters. The symbology would lead you to believe you could fly to a point 90 degrees to the side and still hit. Of course, by the time you get there, the circle shrinks past your aircraft. In reality, the drop zone is always pie shaped.

 

Tl dr, the IZLAR is the area you could actually drop when you got within range of the target and assumes any heading within a 30 degree cone of the nose and the current altitude and airspeed

[marzzz]

Ok thanks

I hope we will have the pie shaped « trapezoidal shape » soon

[Swift.]

IZLAR isn't just for terminsl parameters. When the target is within a 30 degree cone of the nose, a pie like izlar appears even withou term. This represents the actual area you can drop in by the time you get to any point in that area and changes with airspeed and altitude.

 

This differs from the over simplified logic in the JF17 and the IRLARs we have in the Hornet now.

 

Picture the current, circular cues on the HSI. Picture one with no term parameters. The symbology would lead you to believe you could fly to a point 90 degrees to the side and still hit. Of course, by the time you get there, the circle shrinks past your aircraft. In reality, the drop zone is always pie shaped.

 

Tl dr, the IZLAR is the area you could actually drop when you got within range of the target and assumes any heading within a 30 degree cone of the nose and the current altitude and airspeed

 

'The In-Zone Region indicates the region in which the JDAM weapon, if released, will impact its target and achieve the selected terminal attack parameters'

 

Max range cue = Theoretical maximum range if the weapon is released heading towards the target.

 

IRLAR = Represents the range from the target that a JDAM released under the current flight conditions can still hit the target with greater than 35 degree impact angle and greater than 300kts. Varies with altitude, ground speed and heading.

 

IZLAR = Represents the region in which the JDAM can impact the target and achieve the terminal parameters. Intended to provide release cues to achieve the terminal parameters, even if the current flight conditions are different from the pre planned conditions.

[LastRifleRound]

'The In-Zone Region indicates the region in which the JDAM weapon, if released, will impact its target and achieve the selected terminal attack parameters'

 

Max range cue = Theoretical maximum range if the weapon is released heading towards the target.

 

IRLAR = Represents the range from the target that a JDAM released under the current flight conditions can still hit the target with greater than 35 degree impact angle and greater than 300kts. Varies with altitude, ground speed and heading.

 

IZLAR = Represents the region in which the JDAM can impact the target and achieve the terminal parameters. Intended to provide release cues to achieve the terminal parameters, even if the current flight conditions are different from the pre planned conditions.

 

Yes, this concurs with what I said. Note the IRLAR is heading dependent. IZLAR assumes 30 degrees FOV of term parameter (if any) if 30 degrees nose to target. This why IZLAR won't appear unless those conditions are met. I believe what you quoted should say "bearing" and not "heading". If that is how it's supposed to work (i.e. heading) then the current implementation of IRLAR is wrong, as it is bearing dependent, not heading. See next example for evidence.

 

If you head to a point in the IRLAR circle perpendicular to the target, you will find launch impossible by the time you arrive. This is because the IRLAR was calculated on bearing, which changes more rapidly the closer you are to the target. Note your IZLAR description does not preclude defaults. Nothing you posted is in contra-position to what I posted (not sure if you intended it to be, either. just assumed that since you quoted me).

 

If IRLAR responded to heading instead of bearing, it would be more predictive and more useful, but that is not it's current implementation in DCS, and the documents I have do not say what you cited.