Strange GBU balistics

[Biga42]

with the tacview file attached, watch the last GBU launch...

Tacview-20201203-202725-DCS-AV8_10 JDAMS X Sam Site.zip.acmi

[jonsky7]

I haven't watched your tacview recording but I think there is an ED wide issue with GBU JDAM trajectories at the moment, especially releasing them over 20,000ft.

Edited December 6, 2020 by jonsky7

[DmitriKozlowsky]

I experienced odd GBU-54 behavior. Not really it's accuracy, but it's flight profile and attitude. Oddest is that the weapon falling almost straight down onto target, but keeping it's attitude parallel either with ground or attitude of my aircraft at time of release. 

Perhaps this is due to insufficient accuracy of INS/EGI . So I fly with INS in IFA mode.

Perhaps the fuzing option affect trajectory and attitude during flight to target. In IN (instantaneous ) point detonation option, weapon detonates as soon as its nose touches the target or ground, maximizing shock magnitude. Instead of schock being released into ground . So it would make sense of weapon to impact at shallow dive angle with slowest terminal velocity. 

With DL1 & DL2 delay fuzing, weapon should impact with fastest possible velocity to maximize depth of penetration prior to detonation.  So a steep , almost vertical dive angle , is appropriate. 

If guiding onto moving target with laser , then flight to target would be at weapon's corner velocity, where the JDAM strakes and fins have most control over weapon trajectory.

I figure the most accurate delivery procedure is as follows.

On Stores page select laser JDAM. Set release on AUTO, and FUZE as desired other then SAFE. 

Find target with TPOD. TPOD is in point track mode. 

Lase target for 1 second in order to give INS best possible location of target.

Hold down Next Waypoint for .8 of a second , to transfer target data to weapon. 

When in range, release weapon. But do not lase target yet.

When weapon is 10 - 12 seconds from target , lase it , in point track mode. Keep lasing until impact.