investigating GBU-24 Max Range Issue

[ito21]

5 hours ago, NineLine said:

It wont, it needs the laser to guide, if you drop it too soon and without any laser, then its pretty much a jettison of the weapon. If the bomb detects laser energy and is then drop, but loses it after, then it might follow a ballistic trajectory to the target, but the chance of hitting would be slim.

For a successful GBU-24 engagement, be sure to check that slant rate to the target is no more than 8nm at pickle

So if it needs constant lasing how do you employ it when doing a loft style attack? Like other LGBs in that type of attack you would need to delay the lase so it doesn't try correcting too early and fail to reach the target. I guess my request is to double check with your SMEs on the subject cause from the sounds of it, it sounds like a misunderstanding of how the weapon works.

[JCofDI]

Wags' videos on the GBU-24 advertised an increased standoff range for both the Hornet and the Viper. From the May 28, 2022 Viper GBU-24 video: `the GBU-24 also uses a 2,000 lbs. class warhead, but it has a much more advanced autopilot and larger control surfaces that allow a greater standoff range of greater than 11 miles.`

If the DCS laser range limitation is ~8 miles - how should we best go about achieving this greater standoff range - or has the standoff range understanding changed since these videos?

Also, I know it's unlikely but I feel the need to ask - are you able to provide a public reference which suggests the GBU-24 needs a laser track at the point of launch?

Lastly, the only thing I could find in the patch notes around this report indicates it might be related to this line: `Fixed: Code for the GBU-24 is incorrect.` 
Could you clarify any specifics around what this correction was if it does relate to this topic?

[Fromthedeep]

On 11/2/2022 at 12:46 AM, Tholozor said:

Part of the problem I see here is that the target is being lased too late. The 24's autopilot needs to see the laser for the entirety of its flight in order to maximize its range for the most energy-efficient profile.

 

There's a lot of confusion regarding the GBU-24. When dropped above the break (so above 15000), it bumps up then follows a ballistic trajectory until acquisition then it trajectory shapes using a g-bias guidance scheme, which is essentially going to put the path slightly above a pure ballistic profile and result in steeper impact angles. 

The publically documentation very clearly differentiates between the midcourse and the post acquisition guidance phases, which clearly indicates that there is no absolute need for the laser to be acquired prior to release. On top of that, there are different scan patterns that the seeker will utilize depending on the flight profile. If the seeker were to acquire the laser spot prior to release, why would it need to scan for it using either conscan or bar scan patterns? 

Keep in mind that delay lase vs continuous lase is a relatively simple decision matrix for PW2, for PW3, it depends on the particular attack as each target and each attack will have different specifics. Continuous lase also doesn't necessarily mean that the seeker will acquire the laser prior to release, it could simply mean that you can turn on auto lase prior to pickle and let the bomb pick it up as soon as possible once it gets in range because delay lase is not necessary. 

 

On the other hand, it's possible that you're doing a specific attack where delay lasing is necessary because you have very stringent impact velocity and impact angle requirements against a hardened target. In that situation, lasing too early could lead to a shallow profile and decreased penetration while lasing too late could lead to the bomb never acquiring the laser spot in the first place and flying off to God knows where. The point here is that delay lase vs continuous lase is a consideration when employing against hardened targets. If you have no stringent parameters to follow, the bomb will fly around in the appropriate profile and if everything works out fine, acquire the laser. 

[CaptPickguard]

8 hours ago, Tholozor said:

Isn't bang-bang guidance only for PW2 though? My understanding was that PW3 used PN.

 

I believe so, however I think Hulk's comment was more about LGBs in general than just the GBU-24. You definitely do not need to lase immediately when employing these weapons.

11 hours ago, Arctic Fox said:

I'm not sure where you got this idea. The GBU-24 is specifically designed for long glide and low altitude loft employment where its different autopilot profiles can bring its seeker into view of the laser spot well after release. If you need a source, the Air War College document "Precision Guided Weapons Training and Employment" (available publicly on the DTIC archive here) outlines the different guidance profiles used by the autopilot in different release parameters (I believe these are now known "Mode 1" profiles, newer versions of the bomb have several modes that can be configured within the guidance unit). It makes it very clear that the bomb has mid-course and terminal guidance stages, with the latter activating on detection of the laser spot well after release. For example:

GBU-24's proportional navigation capability means it can be employed without a delayed laser without worrying about energy losses, but I have never seen anything indicating it has to be.

 

This is a great find and I think clears up some of the confusion around what PW3's improved guidance entails. By no means does it look like it requires a laser off the rail. If anything it seems like PW3 has more flexibility in this respect.

[Falconeer]

13 hours ago, Hulkbust44 said:

No, that's wrong. Any SME could tell you that. Two words: "Bang, Bang" 

(-24 is different guidance, but lasing at release is still just stupid.)

GBU-24 doesn't Bang-Bang, it can steer proportional, unlike Paveway II

Edited November 3, 2022 by Falconeer

[oldcrusty]

Well, I did some follow up tests of the bomb's trajectory with laser out of the picture (in the Hornet).  First, I tried to use manual lasing by boxing 'TRIG'. That didn't work.  The laser works only on auto cycle as long as it's enabled.  So, I disabled the laser.

The same, altitude related issue can be observed.  At sea level, the bomb flies a 'flat' trajectory, way past the target and impacts the ground nose down, at a moderate angle with sufficient energy. Cool!    Tested both, MAN and SL release.

With the target at 10k ft. elevation and release alt of 15k ft.,  the bomb flies an efficient trajectory, goes nose down, never stalls and impacts short (by a mile or so).  Either the max range release cue or the bomb's ballistics is wrong... or both, hehe.

Another question I would have for the SMEs is:  What's up with the lasing timer?   I know the the entire 'auto' cycle for GBU24 is long (2min?) but... is it just non-stop lasing throughout the whole cycle?   In the Hornet we can see the LTD/R flashing long after the impact, sometimes for a minute or so.  I usually shut the damn thing off manually.  Why waste the laser and attract every sensor in the neighborhood.   I know there is a lot more to GBU24 deployment then we currently have but at least the basics should be implemented correctly.

 

[Hulkbust44]

22 hours ago, Tholozor said:

Isn't bang-bang guidance only for PW2 though? My understanding was that PW3 used PN.

 

"-24 is different guidance"

10 hours ago, Falconeer said:

GBU-24 doesn't Bang-Bang, it can steer proportional, unlike Paveway II

 

Yes, I said it was different guidance... My point being that regardless, lasing at release is not what you want for any Paveway.

Edited November 4, 2022 by Hulkbust44

[KlarSnow]

14 hours ago, oldcrusty said:

With the target at 10k ft. elevation and release alt of 15k ft.,  the bomb flies an efficient trajectory, goes nose down, never stalls and impacts short (by a mile or so).  Either the max range release cue or the bomb's ballistics is wrong... or both, hehe.

The GBU-24 does not fly a ballistic path once released, it will trajectory shape no matter the altitude released at and is very unlikely to hit the target if left without a laser. This is very different to a PW2 bomb which will fall essentially ballistically if it never sees a laser spot. 
 

That being said delay lasing is in fact a required tactic for low level attacks. If you continuous lase from release, the bomb is highly likely to fall short or your range will be reduced, especially if you loft it. Once it sees the laser the bomb will attempt to go direct at whatever angle it sees the laser at. This can result in you cutting the loft short of you have the laser on too soon. Max range at low altitude would be timing the laser to go on as the bomb is starting to pitch over from its loft. Anything earlier will result in a shorter bomb. 

[Fromthedeep]

17 minutes ago, KlarSnow said:

The GBU-24 does not fly a ballistic path once released, it will trajectory shape no matter the altitude released at and is very unlikely to hit the target if left without a laser. This is very different to a PW2 bomb which will fall essentially ballistically if it never sees a laser spot. 

The DTIC document says it flies ballistically above 15 000. Is that incorrect?

[KlarSnow]

...After the bump up... that at a minimum is going to make it miss the ballistic release short.

 

And no the bump up is not usually included in LARs for this, it all assumes you are lasing it and is giving you an idea of when you can get it to your target, not where it will ballistically fall and hit it.

Edited November 4, 2022 by KlarSnow

[VFA41_Lion]

On 11/2/2022 at 10:27 AM, BIGNEWY said:

Hi 

It does not matter if it is a JTAC designating, the bomb cannot detect the laser outside of about 8 nm, the target must be laser designated right at GBU-24 release, unlike Paveway II bombs that you can delay designate.

thanks

with all due respect, both the USAF information page and Wags in the GBU-24 tutorial video have both stated the range of the GBU-24 exceeds 11 nautical miles. This directly contradicts your statement.

[oldcrusty]

3 hours ago, KlarSnow said:

...After the bump up... that at a minimum is going to make it miss the ballistic release short.

 

And no the bump up is not usually included in LARs for this, it all assumes you are lasing it and is giving you an idea of when you can get it to your target, not where it will ballistically fall and hit it.

 

In my tests I was basically just trying to figure out why there was no issue dropping the bomb on targets at sea level, even at max range, from any altitude, but with the targets at higher elevations (8, 10k ft.), the LAR was not accurate, even in SL mode the bomb would run out of steam when dropped from 5k feet or less above target.

Well, I think I need to go back to Hornet's bug forum. This issue has been reported already not that long ago, with tracks provided (not by me).  It seems like the Viper's stew of problems reported in this thread by OP is a bit different. 

[Chris935]

7 minutes ago, oldcrusty said:

In my tests I was basically just trying to figure out why there was no issue dropping the bomb on targets at sea level, even at max range, from any altitude, but with the targets at higher elevations (8, 10k ft.), the LAR was not accurate, even in SL mode the bomb would run out of steam when dropped from 5k feet or less above target.

Different bombs from a different aircraft, but this sounds very similar to the report I've made here, may be of interest if they have a common underlying cause:

Chris

 

[Sl1ck]

My original post has nothing to do with what you're talking about. Though there may also be a problem regarding target elevation, I'm not sure, it's a little more fundamental at this point.

My scenario was M0.9, 35000ft, target at Sea level. Pretty straight forward situation.

DLZ gives 18/19NM max range.

Bomb never ever makes it.

F16 Lasing and JTAC lasing the target the whole time.

My question is, how and why is the DLZ saying to launch at 18/19NM if it can't achieve that, and if it is supposed to be able to make it, what's missing. 

Please see attached track files for the 10th time.

GBU24 VS GBU12 JTAC + F16 LASE.trk

[NineLine]

On 11/4/2022 at 1:20 AM, KlarSnow said:

The GBU-24 does not fly a ballistic path once released, it will trajectory shape no matter the altitude released at and is very unlikely to hit the target if left without a laser. This is very different to a PW2 bomb which will fall essentially ballistically if it never sees a laser spot. 
 

That being said delay lasing is in fact a required tactic for low level attacks. If you continuous lase from release, the bomb is highly likely to fall short or your range will be reduced, especially if you loft it. Once it sees the laser the bomb will attempt to go direct at whatever angle it sees the laser at. This can result in you cutting the loft short of you have the laser on too soon. Max range at low altitude would be timing the laser to go on as the bomb is starting to pitch over from its loft. Anything earlier will result in a shorter bomb. 

Thanks, we are going to take a look at this aspect.

[Moonshine]

Any news on this? seeing the topic still has the "correct as is" tag, yet the last comment and the info @KlarSnow brought up suggests otherwise...

[SmeagleGoneWild]

I would also like to know if any progress has been made. 

[backspace340]

I'm a bit confused about the laser range limitations. I understand own-ship lazing having an 8nm range as simulating the laser getting weaker the further away it is, and so a weak reflection becomes visible when 8nm away from the laser source. But if the JTAC is, say, 1nm away from the target won't that laser reflection be comparitvely much stronger when viewed at 8nm than the one lased from the ownship? I. E. The laser beam and reflection's only travelling 9nm instead of 16nm? So shouldn't we be able to see JTAC designations from much further than we can see our own designations if the JTAC is closer to the target (assuming equal laser power)?

[Hobel]

vor 10 Stunden schrieb backspace340:

I'm a bit confused about the laser range limitations. I understand own-ship lazing having an 8nm range as simulating the laser getting weaker the further away it is, and so a weak reflection becomes visible when 8nm away from the laser source. But if the JTAC is, say, 1nm away from the target won't that laser reflection be comparitvely much stronger when viewed at 8nm than the one lased from the ownship? I. E. The laser beam and reflection's only travelling 9nm instead of 16nm? So shouldn't we be able to see JTAC designations from much further than we can see our own designations if the JTAC is closer to the target (assuming equal laser power)?

In general, aircraft lasers in DCS are no longer limited to 8 nm.

In my last test I was able to laser up to 14-16 nm.

[RPY Variable]

This bomb should fly almost horizontal when dropped at speed. In DCS it is just a normal GBU with a slightly attenuated parabolic trajectory. If you want to have a more or less decent distance you need to drop, let's say, mach 1.2 35.000, and it almost goes on a 45° dive to the target, which goes against the essence of this bomb. In DCS it has a glide ratio of 2.5 or less, which is ridiculously low if you compare it with this video and common sense.

Note that the bomb drops like a normal bomb, then the autopilot kicks gliding with a much more shallow angle. Int not going to make a CFD study of the bomb, but 2/2.5glide ratio (, when dropped at 500kn, seems way too low. 

[RPY Variable]

I just remember I made a post about this problem in 2019, 5 years ago. I hope by next time... 2029/2030 we have a working gbu-24... I don't want to be that "that guy" but come on man, it can't be that difficult.
It is the most capable A/G weapon of the F-14, F-16, F-18 (in 80's 90's scenarios) it should have some priority.

 

[=BoB= David]

10 hours ago, RPY Variable said:

I just remember I made a post about this problem in 2019, 5 years ago. I hope by next time... 2029/2030 we have a working gbu-24... I don't want to be that "that guy" but come on man, it can't be that difficult.
It is the most capable A/G weapon of the F-14, F-16, F-18 (in 80's 90's scenarios) it should have some priority.

 

+1, definitely, I posted something about 24s back in time also, but well... Priority is somewhere else it seems.. If there is even some "priority"...