correct as-is GBU-38 not releasing

[Mav87th]

Tried a mission yesterday and the day before. On both occasions i my GBU-38 did not come of the rail.

 

I was confused about if i did everything right, watched a video tutorial, and redid the mission - still not coming off the rails.

1. Set up all weapons as usual, CCRP, GBU-38 (set to CCRP in the profile as well)
2. Had a stp in the target area - slewed TGP to that
3. found the target and did point lock on that and created a SPI (visually confirmed that the SPI was here)
4. Master arm on, Laser on etc. (profile for GBU set to auto lase as well - i know its a GPS bomb, but anyway)
5. Fly straight and level for a minute or two and check the weapon readiness in DSMS
6. Wiggle the wings and your GBU-38's go back to RDY, but then again after 30 seconds back to ALN RDY
7. Waiting for the launch marker to be within launch parameters of the DLZ and centered etc.
8. pickle and hold the button all they way until the marker was out of DLZ and no bomb had come off the rails.

You can repeat 5-6 many times and its the same result. And its not going to help with more violent maneuvers. It's my guess this is the source of my inaccuracies when dropping these GPS guided bombs.

Can one of you confirm this does work - cus i have no idea right now what i did wrong or if it is a bug

Edited January 3, 2023 by Mav87th
Updated the replication process with steps 5 and 6

[QuiGon]

21 minutes ago, Mav87th said:

Tried a mission yesterday and the day before. On both occasions i my GBU-38 did not come of the rail.

I was confused about if i did everything right, watched a video tutorial, and redid the mission - still not coming off the rails.

• Set up all weapons as usual, CCRP, GBU-38 (set to CCRP in the profile as well)
• Had a stp in the target area - slewed TGP to that
• found the target and did point lock on that and created a SPI (visually confirmed that the SPI was here)
• Master arm on, Laser on etc. (profile for GBU set to auto lase as well - i know its a GPS bomb, but anyway)
• waiting for the launch marker to be within launch parameters of the DLZ and centered etc.
• pickle and hold the button all they way until the marker was out of DLZ and no bomb had come off the rails.

Can one of you confirm this does work - cus i have no idea right now what i did wrong or if it is a bug

I just dropped some GBU-38s yesterday and they worked just fine. Your procedure seems fine to me too (although it has some unecessary steps which I scratched out in the quote ), so I'm not sure what's wrong on your side.

If you could provide a track file of such an unsuccessful attempt, that would probably help to figure out what's wrong

Edited December 23, 2022 by QuiGon

[Mav87th]

Hmm funny i just came home from work, and redid the mission, except i just powered up the jet and instead of flying to the target area, took the jet 8 nm from the base and did an attack on that. Worked beautifully this time. Exact same steps.....must have been doing something wrong yesterday

[ASAP]

Glad you resolved your problem! Something I wanted to clear up based on what you said in the OP. I only bring this up because it is commonly misunderstood with this jet. For the record, you never “created a SPI”. The jet had a SPI the whole time, presumably your steerpoint. You switched the SPI from one sensors point, your steerpoint, to a different sensor point, the TGPs line of sight. I’m not sure what you mean by saying you visually verified the SPI location, it’s whatever is the center of your crosshairs in the TGP screen. If you slew your pod the SPI location shifts as well.

Unless the target is moving there is no reason you’d need to put the pod in point track.

And I highly recommend that if you are dropping a bomb with TGP SPI that you have the laser on when you hit the pickle. That gives the bomb the most accurate coordinates. After the bombs released you can turn the laser off of course. The bomb doesn't care about the laser 

[TheGhostOfDefi]

Did you fly straight for a brief period of time? If so maybe your alignment degraded? (Not quiet shure if the 38 have this too) the gyros need movement before use otherwise they claim to be degraded because the gyros in the weapons don’t give a signal (because the isn’t any to give)… A common problem with the guided CBU. 

[Yurgon]

25 minutes ago, TheGhostOfDefi said:

Did you fly straight for a brief period of time? If so maybe your alignment degraded? (Not quiet shure if the 38 have this too)

Hey that's a very good point! Yeah, the GBU-38 definitely has this problem as well. When the alignment status as shown in the DSMS changes away from RDY (could be ALN UNS or ALN RDY depending on the weapon in question - both of these are bad!), the jet won't allow them to be dropped. This can happen after roughly 5 minutes of straight and level flight, and can be remedied by wiggling the wings or flying a turn of 90 or so degrees.

1 hour ago, ASAP said:

The jet had a SPI the whole time, presumably your steerpoint.

Absolutely! It often feels as if most DCS players don't understand this until years into flying the A-10C (I'm guilty as charged myself ).

The manual still calls the TMS Forward Long action "Make SPI", which is apparently what pilots find in the real Dash One, but in the context of DCS and without an Instructor telling us how the system works, I find this to be a very misleading way to explain that function, or at least it is very easy to get it wrong. Even just "Set SPI" would be way better, and I prefer "Set SPI Generator".

[jaylw314]

4 hours ago, Yurgon said:

The manual still calls the TMS Forward Long action "Make SPI", which is apparently what pilots find in the real Dash One, but in the context of DCS and without an Instructor telling us how the system works, I find this to be a very misleading way to explain that function, or at least it is very easy to get it wrong. Even just "Set SPI" would be way better, and I prefer "Set SPI Generator".

Not to beat a dead horse, but emphasizing what SPI stands for as the "Sensor Pointer of Interest" might suffice  

[Mav87th]

On 12/23/2022 at 5:00 PM, ASAP said:

Glad you resolved your problem! Something I wanted to clear up based on what you said in the OP. I only bring this up because it is commonly misunderstood with this jet. For the record, you never “created a SPI”. The jet had a SPI the whole time, presumably your steerpoint. You switched the SPI from one sensors point, your steerpoint, to a different sensor point, the TGPs line of sight. I’m not sure what you mean by saying you visually verified the SPI location, it’s whatever is the center of your crosshairs in the TGP screen. If you slew your pod the SPI location shifts as well.

Unless the target is moving there is no reason you’d need to put the pod in point track.

And I highly recommend that if you are dropping a bomb with TGP SPI that you have the laser on when you hit the pickle. That gives the bomb the most accurate coordinates. After the bombs released you can turn the laser off of course. The bomb doesn't care about the laser 

Thanks ASAP

Yea create is a bad word used in lack of a better in the moment. But yes moved SPI from steer point to TGP designated point.

I visually confirmed by raising up in my seat looking over the HUD using the helmet sight where you can see the "wedding cake?" on the SPI

 

@TheGhostOfDefithat is very interesting - i had no idea, and VERY likely what could have been going on as i flew more or less straight and level from IP towards target steer point and only had to maneuver very slightly to align bomb fall line.

[Mav87th]

@Yurgon and @TheGhostOfDefi I retested this and they go from RDY to "ALN RDY" in roughly 30 seconds. That seems a bit fast???

When wiggling the wings they go back to RDY, but then again after 30 seconds back to ALN RDY. 

[Yurgon]

3 hours ago, Mav87th said:

@Yurgon and @TheGhostOfDefi I retested this and they go from RDY to "ALN RDY" in roughly 30 seconds. That seems a bit fast???

That seems really fast indeed. I think 5 minutes used to be the norm, with players sometimes reporting values as low as 2 minutes. 30 seconds, though, that seems too fast as far as I can tell. Does it take longer when you wiggle the wings more strongly or when you fly a turn of at least 90 degrees?

[Mav87th]

Nope it seems to be pretty much the same no matter what i do. 

[ASAP]

From talking to the pilots I know the bombs reverting back to ALN RDY is not real world behavior. I was told they never "fall asleep" from flying straight and level like the game simulates. Unless something is wrong with the bomb or the GPS on the jet it should just be RDY in flight. I'm curious what EDs A-10 SMEs say about this issue.

[Mav87th]

@Yurgon and @NineLine is this something you could look into at some point?

[Mav87th]

On 12/29/2022 at 9:23 PM, ASAP said:

I'm curious what EDs A-10 SMEs say about this issue.

So whom do we need to drag into the thread

[Yurgon]

On 12/29/2022 at 8:11 PM, Mav87th said:

Nope it seems to be pretty much the same no matter what i do. 

I finally ran a quick test with an air-started A-10C II.

Initially, the bombs remained "RDY" for 12 minutes of flying straight and level, then they went "ALN RDY". After enough of a wing rock or enough of a heading change to get them back to RDY, this status only lasted somewhere between 30 and 90 seconds or thereabouts, then they went back to "ALN RDY".

However, after flying a 90° heading change and then back to my original heading (with roughly 60° Angle of Bank), they stayed RDY for another 7 or so minutes. So it would appear that they degrade a lot slower after strong heading changes and faster after small heading changes.

I can't tell whether or not that's realistic; going by what ASAP wrote, it seems this is not realistic.

However, I think it's been like this for a long time in DCS. Without somewhat compelling evidence that this is actually wrong, I don't think ED are going to invest resources in changing this behavior. So if anyone can generate a non-classified source (if in doubt regarding classification, you should definitely PM ED team members rather than posting something publicly, even if it's a link to a document that's already on the Internet), that would be fantastic.

In the meantime, it's always a good idea to plan for at least a 90° heading change shortly before reaching pre-planned targets that are to be served with IAMs (JDAM, WCMD), especially when the ingress is a long straight line. May not be realistic, but it's a valid workaround in DCS.

[ASAP]

Interesting. Did your FOM change from D5/B1 at any point while doing that test and did it correlate to the GBUs status change

[Yurgon]

14 hours ago, ASAP said:

Did your FOM change from D5/B1 at any point while doing that test and did it correlate to the GBUs status change

I didn't actually look at it before, but thanks to fast forward, I quickly ran another test; see for yourself.

So no, the jet's FOM remains D5/B1; as far as I'm aware, the degraded status only refers to the weapons themselves, and both a heading change as well as rocking the wings will "transfer" the jet's IMU alignment data onto these weapons in order to update their INS data.

Interestingly enough, this time I packed both JDAMs and WCMDs and in this short test, all these weapons switched from "RDY" to "ALN RDY"/"ALN DEG" at the exact same time, so it seems JDAMs and WCMDs use the same underlying code in this regard, at least in DCS.

Edited January 9, 2023 by Yurgon
"null" WTF?

[Mav87th]

Would it have any influence in the A-10C II at what time of the alignment phase of the jet, that the weapon is loaded...?

i.e. if the weapon is loaded in dsms before alignment is complete vs. if the weapon is loaded via dsms after alignment is fully complete

 

Not going to link it, but there is a JDAM manual in pdf form out there on the internet

[Yurgon]

12 minutes ago, Mav87th said:

Would it have any influence in the A-10C II at what time of the alignment phase of the jet, that the weapon is loaded...?

Not that I'm aware of in DCS. IRL, I have no idea.

[ASAP]

That wouldn’t impact any of this stuff. 
 

Generally though the alignment is completed before the CICU/MFCDs gets turned on and before you do a LOAD ALL from your DTC.  The bomb actually starts doing its BITs as soon as the station it’s mounted on powers on