High Altitude LGB GBU-24 /B /HE 4.34U3 Results
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Issue RESOLVED go to POST #8 to see what’s now working for me.
I’ve done a bunch of testing with GBU-24 /B /HE today because most of the time I get hit after hit, but starting yesterday I had 3 missions in a row where maybe 3 out of 15 went ballistic. Now in each case I verified TGP code at loadout and in DED matched (plus I got a few hits so I 100% confident not a TGP code issue). I verified laser firing (flashing L) and terminal guidance (targeting range prefix T goes to solid L during terminal guidance). Tried different release mach .7ish to .94ish, etc.
I never saw where the misses landed (I assume very long). So I tried a whole bunch of other things including resorting to RTFM and I couldn’t figure it out. Tried manually laser range finding before dropping, tried consent dropping as per dumb bomb. Tried dropping after drop cue rebounded back up the drop line (so not at max staple but within the staple by a second or two). Then I thought, what if it has to do with altitude?
Started at Angels 28 = miss. Angels 22 hit.
MSL 25,200 miss, MSL 24,020 hit.
My running theory is now that GBU-24s (and probably all GBUs) will never hit when released above 25,000.
Does anyone know if I am right or wrong and if right this is a feature or a bug in 4.34U3? I searched the forums but didn’t find an answer.
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I remember someone saying that all lasing should be done from 14kft. It’s probably weather-dependent, but ultimately, the laser will, at some point, attenuate enough for the bomb to fail to guide on it.
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As per our TOP, we’re releasing and lasing GBU-24s up to FL300 with no problem. We could probably do it even higher, but with our jets, we have relatively low thrust values, making 30,000ft and above rather hard (to not say near-impossible) with 2000 Lbs bombs.
You just have to keep in mind that unlike Paveway IIs, the nose (and thus sensor) is fixed on Paveway IIIs, and you have to slightly adjust your release parameters to make sure the laser can actually be spotted by the bomb. -
You just have to keep in mind that unlike Paveway IIs, the nose (and thus sensor) is fixed on Paveway IIIs, and you have to slightly adjust your release parameters to make sure the laser can actually be spotted by the bomb.
Adjust the release parameters how exactly? Mach? Attitude?
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Some more data:
| Mach | Altitude | Result | |.82 | 26,170 | Hit | |.82 | 23,390 | Miss | |.81 | 27,790 | Miss | |.87 | 27,590 | Miss | |.94 | 28,250 | Miss |
So much to my surprise 1 worked above 25k, yet 4 missed. All these drops were at level flight (I guess maybe a slight climb or descent + or - 1 degree at most).
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Another data set to ponder:
| Mach | Altitude | Result | |.9 | 24,060 | Hit | |.94 | 24,240 | Hit | |.81 | 24,010 | Miss | 30d roll right |.81 | 23,900 | Miss | 10d roll left |.91 | 23,960 | Miss | 20d roll right
Okay so this is getting NOT fun lol. I’m just baffled. Flying pretty much level. Steady as a rock and getting the range solid L and the flashing L the whole way down and I have lock at release and all the way down. There is something wrong or I’m short on information here.
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For PIV, you should lase mostly all the way long. I personnally manually lase after the drop (for a nominal drop, if you drop on climbing, it will not be the same things).
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For PIV, you should lase mostly all the way long. I personnally manually lase after the drop (for a nominal drop, if you drop on climbing, it will not be the same things).
Thanks Amraam!
I will edit the first post to link to this post.
I don’t know what PIV means.
I adjusted the lase time to 45 seconds so I would get lase all the way from Angels 30 and got 5 hits in a row! So that seems to solve it. I’m going with a rough rule of thumb of 1.5 seconds of time per 1000 ft AGL in the event the pilot wants to lase all the way down. That’s rough math based on the 30k drops I was making.
Here is what I found in the manuals.
In the training manual at pg 96:
By default it’s 16 seconds, but you can set it to a realistic setting of 10 seconds for Paveway II bombs now, as the code has been much improved in 4.34. For Paveway III bombs you can manually lase earlier, especially for moving targets.
In the -1
at pg 142:
During LGB delivery the laser is designed to fire automatically for terminal guidance at the pre-defined time from bomb impact that is set on the laser DED page; the laser will keep firing until 2 seconds after the expected impact time.
at pg 156:
Laser Ranging - In order to know if your laser fire is valid you can fire and check if you see valid ranging (L will appear next to the range on the Sniper page). None valid ranging mean that the fired laser doesn’t have enough energy to illuminate the spot; that can happen because of range (the laser has limited range) or weather (clouds obscuring the LOS). In such cases the fired laser can’t be used to guide LGBs or be tracked by LST.
at pg 158:
In the first example, we will be hitting a nuclear plant with 2 GBU-10s rippled in pairs from 22,000 ft and we have precise lat/longs for the target entered into our STPT 5. We have our LASR page set to start automatically lasing the target 20 seconds prior to impact.
So some comments about the manuals. There are clues in there that are suggesting you need to alter your lasing depending on the release parameters, but it’s just hints basically. I am not seeing a discussion on Paveway II vs Paveway III. Most the other ordinance is highly detailed going into variants and release parameters but I am not seeing this for LGBs. Maybe I am missing it?
I am not seeing a discussion on why a pilot would not want to lase all the way down and what the release parameters would be at different given altitudes so that your LGBs don’t drift too far long before the laser is fired.
My guess is (based upon the above quotes) is that the devs spent some time recently working on the guidance code but didn’t get that translated over to the manual very well as to what constitutes effective release and guidance parameters for LGBs for 4.34.
I’m not complaining, just trying to figure this out and help.
So my suggestion is that the LGB section in the -1 get some love as to the different LG bombs (like seen for the Mavericks section) and the training mission simply point to an updated LGB section (especially as to setting the laser time).
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What I have been told from a RL Viper Pilot. Always lase right after pickle until impact.
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Depending on how you release the LGB, you can decrease the effective range of the weapon doing this…
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Always… as in any flavor of LGB?
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What I have been told from a RL Viper Pilot. Always lase right after pickle until impact.
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I would think the only reason you would not is because the enemy might be able to track your aircraft if you are lasing? If so, you would want to minimize lasing time, but that begs the question for us BMSers – what is the minimal time of lasing given the time of flight of the bomb (or whatever are the pertinent variables to consider). It certainly is counterproductive to miss and frustrating because you might not realize (like myself) why you are sometimes missing and sometimes hitting.
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What I have been told from a RL Viper Pilot. Always lase right after pickle until impact.
True for PIII (GBU-24) … not true for PII (GBU-10/12 …)
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Depending on how you release the LGB, you can decrease the effective range of the weapon doing this…
I suppose you could aim short of where you wanted to eventually lase and pickle the bomb off, then move the pointer further out a mile and then lase, but boy you’d want to have the math down on that trick.
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I suppose you could aim short of where you wanted to eventually lase and pickle the bomb off, then move the pointer further out a mile and then lase, but boy you’d want to have the math down on that trick.
That doesn’t work either…unless you’re leading a mover. What you do every time you move the spot is force the weapon to maneuver - which only bleeds it’s energy, and will probably make it hit short. Same can be said for sparkle from release to impact - that may not be the optimum energy trajectory for the bomb to fly to…will vary by bomb, seeker, altitude, fusing, etc., like Dee-Jay points out.
Some LGBs also have more than one guide mode…mixing the wrong sparkle technique with the wrong mode and/or fusing can also wreck your delivery.
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My experience with LGB is quite extensive, but I confess it’s more centred around the GBU-12.
That’s also the case in the training mission.When these weapons are used correctly in BMS, there’s hardly a miss.
We do single release from hi alt, from low alt, lofting them and we do buddy lasing and when we miss it’s 99% our faults
The possible reasons is bad laser code, laser not armed, SPI issue, tracking the wrong target on the CCRP cues and expecting to strike another target.
Laser firing time is hardly the issue but we most of the time use 12 seconds for GBU-12. When we do buddy lasing, we use 15 seconds lasing time.Also, when we miss, we don’t feel the need to question the system. We question us and our procedures. We also do not expect bombs to have a 100% hit rate and we can live with missing the target.
My overal experience with GBU in 4.34 is that it works pretty well if you follow the published procedures, with the correct weapon related to that procedure.
Granted since the manual author use less the GBU-24 and alike, the procedure and our manual testing might not be as extensive as with the GBU-12.From there, it’s pretty expected AFAIK that the further away you are when you lase, the less energy reach the target, clouds obstruction, respect of the ballistic CCRP cues first, switchology are all parameters that will influence the hit rate which should never be 100% IMHO.
Last note regarding the manuals. All these chapters were created for 4.33 and checked but not fully rewritten with 4.34. As they were tested OK, and since there was no notification of behaviour changes, the succesful tests of what’s written in the manual were enough to ensure the manuals were still correct.
Since then, also remember we had 3 consecutive updates which are normally bugfixes only but that’s the visible part of the iceberg and manuals are not rewritten for such lower updates. So there’s a slight possibility of a mismatch induced here as well (from my experience changelogs are not always enough to check that, but it’s a start)Considering all of the above, If you guys can point out specific shortcomings in the manuals, I will make sure they are updated for the next round.
the best thing to ensure it happens is to use the relevant topic in the Documentation forum once you’re positive the manuals are outdated. These are the main topics I track for manual updates.
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@Red:
Also, when we miss, we don’t feel the need to question the system. We question us and our procedures. We also do not expect bombs to have a 100% hit rate and we can live with missing the target.
Boom!
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@Red:
Considering all of the above, If you guys can point out specific shortcomings in the manuals, I will make sure they are updated for the next round.
the best thing to ensure it happens is to use the relevant topic in the Documentation forum once you’re positive the manuals are outdated. These are the main topics I track for manual updates.
ThanksIn the case of the Printed Training Manual it would be great to make note of the Chapter/Page of any changes so they can be noted also please.
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That’s a bit off topic Icer and to be honest we thought about that but it’s impossible to implement.
between 4.33 and 4.34 for instance, there are only a few pages that were left untouched. sometimes it’s a spelling correction, sometimes it’s a minor detail that’s not valid, sometimes it’s a new paragraph.
your solution is only easy in case of new chapters, but our updates go way beyond that actually. Very minor details are worked on throughout all the documents.Believe me initially when I update manuals, I write in red to ease up the corrections tracking.
And I can tell you the implications of one minor change induce red in many different paragraphs and chapters and pther manuals.
So in the end you would need to reprint the whole thing anyway -
So…after doing some looking around, one of the different things about the GBU-24 is that it’s CCU is designed for the weapon to be LOFTED - it’s a GBU-24 LLLGB (Low Level Laser guided Bomb), and this may be why people are having problems with it if it is modeled true to life and people are using is incorrectly. It needs to be tossed into a basket, and sparkle turned on once the weapon apexes and starts downhill - if you mis-manage that you WILL hit short because you will drive the weapon off-schedule by not allowing it to apex.
This also means that the weapon likes to be released FAST, i.e.; with lots of energy - a GBU-24 manages it’s energy in a far different manner than a GBU-12, and will actually “fly” to an extent. AND there are two varieties of GBU-24 (dunno is BMS models them both) one uses bang-bang guidance and the other employs proportional guidance; the first is more sensitive to laser management, the second is less so. And it’s the proportional CCU that allows the weapon to “fly”. If BMS hasn’t captured all of this (but I would think it has) then it’s an improvement to the weapon modeling that could be looked into.