GBU-38 failure to release

[Newbie62]

While running the PGM training for A-10C (original, not II), I encountered failure to release by JDAM.  Actually, I've seen it many times, it seems like JDAMs work only rarely, but this time I decided to save a track and raise a forum topic.  Timestamps refer to the clock, just right of the IFFCC switch.

7:23:07 to 7:23:14: side note: the TGP failed to box the target.  I had to move the target cross around a few times before it finally boxed.  That matters because I've noticed that laser guided bomb delivery seems to be degraded unless the TGP actually boxes the target.  I'm not sure whether this is normal, on either point (having to move the crosshair a few times to get good TGP target lock, and degraded accuracy with loose lock).  Anyway that isn't the subject of this post.  Just a side note.

7:26:24: Hit the first target with a laser guided bomb.  Dead on because I had done the previous trick of shifting the TGP crosshairs until it actually boxed the target.  Also off topic, just a side note.

7:31:04 to 7:31:36 : I had the reticle right on ASL / PBIL most of the time.  The range bar was between min and max.  I pressed and held the weapon release button, and not when the ASL / PBIL strayed from the reticle.  No release.

7:33:36: start of attempt #2, range bar starts to unwind

7:33:49 to 7:34:00: I have the reticle right on ASL / PBIL.  I pressed and held the weapon release button.  No release.

7:36:47 to 7:37:05: attempt #3, same result.

I tried press and hold until release (which never comes), press and hold then release the button after a presumably adequate time, and quick press.  None of them worked...

It's not that JDAMs never work.  I have seen them release before and hit the target, but it seems like 80% of the time, they don't release.

A-10C-Training-PGM - failure to release.trk

[[MA] BigSwede]

The GBU-38 are white in DSMS, they have lost the alignment, happens to me also very often.

When it happens, I usually push my stick hard forward and then back again to a level flight.

Don't know if JDAMS work in real like this or if it's a bugg.

Edited May 19, 2023 by [MA] BigSwede

[Newbie62]

Seems like a bug.  They were aligned fine going into the run, and I had just come out of a turn which from what I read in another thread triggers realignment (or as you mentioned stick hard forward).  In this case, I see what you're talking about.  Had I dropped a moment sooner that would have been the 20% case of what I observed: "It's not that JDAMs never work.  I have seen them release before and hit the target, but it seems like 80% of the time, they don't release."  These two images were five seconds apart.  I read in that other thread that IRL that doesn't happen, they will stay aligned in straight and level flight almost indefinitely.  So bombs losing alignment isn't something that ED should have even simulated...  Or, at least do it realistically...

[Newbie62]

@Flappie since I was introduced to you in the F-15C ILS topic...

[Newbie62]

Anecdotal, but...  B-52s drop JDAMs IRL.  I doubt they're pulling hard g's 30 seconds before they line up their drops just to get the bomb gyros to align.

[Yurgon]

12 hours ago, Newbie62 said:

In this case, I see what you're talking about.  Had I dropped a moment sooner that would have been the 20% case [...]

Just to be clear, when you make sure that your GBU-38 show green weapon stations in DSMS, do they now release correctly for you? Or do they still fail to release?

11 hours ago, Newbie62 said:

Anecdotal, but...  B-52s drop JDAMs IRL.  I doubt they're pulling hard g's 30 seconds before they line up their drops just to get the bomb gyros to align.

I'm sure even B-52 can fly turns of 60 degrees heading change without breaking their wings off...

TBH, I have no idea how JDAMs work IRL, or whether they work differently on different platforms, or whether what we have in the DCS A-10C is realistic. What I can tell you is that it has been like this for a very long time, and most virtual pilots have adopted and made it their personal standard operating procedure to plan a heading change of at least 40 or 50 degrees prior to engaging targets with JDAMs when there are long and straight run-ins.

[Newbie62]

"Just to be clear, when you make sure that your GBU-38 show green weapon stations in DSMS, do they now release correctly for you? Or do they still fail to release?"

I didn't do a statistically significant check, but in one rerun just now in which I replayed the track until run-in, took control just as I was coming into max range, and yes successful release before the bombs went to ALN RDY.  So you definitely hit the nail on the head as to what the issue is.  Question is, should it even be an issue?

"I'm sure even B-52 can fly turns of 60 degrees heading change without breaking their wings off... "

Of course.  Can.  But do they do that at a matter of course just prior to target ingress, just to keep the JDAMs from fucking up?  I doubt it.  Were that the case, JDAM would have been sent back to the drawing board...

"What I can tell you is that it has been like this for a very long time, and most virtual pilots have adopted and made it their personal standard operating procedure to plan a heading change of at least 40 or 50 degrees prior to engaging targets with JDAMs"

Well my heading change was 270 degrees.  Still didn't help, because I straightened out a bit early to line up my run, and in that brief time the bombs went to NOPE mode.  Hard turns and short run-ins sounds like a workaround for something that should have been fixed in the game a long time ago...

Edited May 19, 2023 by Newbie62

[Yurgon]

5 minutes ago, Newbie62 said:

Were that the case, JDAM would have been sent back to the drawing board...

It's often times quite surprising how operating procedures are used to work around shortcomings of technology.

I'm not saying B-52s have to perform heading changes prior to engaging targets with JDAMs - I simply don't know. I'm just saying, if a significant heading change was required in real life operations, crews would plan for exactly that, and the whole thing would be a non-issue.

8 minutes ago, Newbie62 said:

Hard turns and short run-ins sounds like a workaround for something that should have been fixed in the game a long time ago...

If you can provide public, unclassified information in this regard, ED are always eager to improve the product. If you're in doubt about the nature of a source document, it would be best to ask someone via the forum's private message system if it's okay to post excerpts from, or link to, said documents.

9 minutes ago, Newbie62 said:

So you definitely hit the nail on the head as to what the issue is.

It's working okay for you now? Excellent!

[Newbie62]

@Yurgon  Follow-up: I found a JDAM tactical manual from a public source, but apparently public source doesn't satisfy the policy "When posting aircraft, sensor or weapon information more recent than 1980, you must also include the source of the document showing that it is 100% public and verified as not from a classified or non-ITAR controlled source." and I got a strike.  So I will follow up but tread more carefully this time.

ED must be simulating INS alignment quality.  My lazy turn as I built separation from the target wasn't enough to achieve alignment.  The 20 second more aggressive turn for line up in the track I posted was enough to get alignment and the bombs went green just as I straightened out, but it wasn't a quality alignment, which consequently only lasted 45 seconds before the JDAMs went white again in DSMS.  Referring to the observed behavior in DCS, longer lasting non-lazy turns result in a better quality and more lasting alignment.

Bottom line: I stand corrected, and when you said "It's often times quite surprising how operating procedures are used to work around shortcomings of technology" you hit the nail on the head.  Realism .

Edited May 21, 2023 by Newbie62