reported GBU-24 Max Range Issue

[Sl1ck]

Hi guys,

Try dropping a GBU-24 from high altitude, high speed at max range.

Bomb never catches sight of the laser (on from launch) and never makes it to target.

Regards

[rob10]

A track would allow people to give you better answers.

My first bet (based on high altitude and maximum range) would be that you're beyond the 8 nm slant range on the laser.  In DCS the laser acts more like a light saber, and it ends at 8 nm and if that's mid air (rather than hitting the target) there is no reflection for the bomb track in on.

[Sl1ck]

Track files attached

F16 and FA18 tested

35000ft M0.9

GBU-24 DLZ Max range is at 18NM in my test, Bomb has no chance.

Same exact test in the FA-18 max ranges at around 9-/10NM works as you would expect.


Also I don't believe your statement regarding laser slant range limit stands true, In my second track named laser test I active paused at 15nm (within the DLZ but right at the upper limit of the bomb actually getting there) You'll see the bombs do indeed pick up the laser, so beyond the 8nm you mentioned.

I'm sure they're not infinite, but my problem I'm illuding to is mostly to do with the DLZ being massively inaccurate.

 

GBU24 Laser test.trk GBU24.trk

[Tholozor]

Lasers in DCS have a finite distance where the end of the beam terminates at around 8.2nm, so it'll pick up the end of the beam mid-air.

Edited October 30, 2022 by Tholozor

[Sl1ck]

That doesn't explain the issue regarding the DLZ giving a max range cue at 18+NM
 

That also doesn't explain how with my aircraft stationary at 15nm the bomb made the target. 

[Ignition]

As others said, laser in DCS is around 8nm. The bomb will pick the laser up to the 8nm and then it will turn around.

The bomb may have energy to reach the target beyond 8nm. The target may be iluminated from other source.

[Sl1ck]

Chaps, Watch the attached track file. 

My aircraft is stationary at 15NM and the GBU makes it all that way. And there is no other laser source.

My problem isn't regarding lasers, if there is a limit then so be it, though it doesn't seem like there is.

My problem is that the F16 reckons you could get a GBU24 to a target at 18+NM according to the DLZ at 35000 and 0.9M, Therefore there is something not right in the coding.

GBU24 15NM.trk

Edited October 31, 2022 by Sl1ck

[NineLine]

Based on the info we have, this is correct. The F-16 knows just what the weapon is capable of and shows based on that. So based on the info we have this is correct as is. Thanks.

[Ignition]

3 hours ago, Sl1ck said:

My problem is that the F16 reckons you could get a GBU24 to a target at 18+NM according to the DLZ at 35000 and 0.9M, Therefore there is something not right in the coding.

 

The bomb can reach the target at that distance, there's no problem with that.

[Sl1ck]

12 hours ago, Ignition said:

The bomb can reach the target at that distance, there's no problem with that.

Show me

12 hours ago, NineLine said:

Based on the info we have, this is correct. The F-16 knows just what the weapon is capable of and shows based on that. So based on the info we have this is correct as is. Thanks.

Dear NineLine, Please see attached track files.

Given the previous replies regarding the maximum distance of the laser, I figured I'd try a JTAC Lasing the target for me.

Again the GBU24 has no hope at the max distance, the GBU 12 behaves as expected as a baseline. (unless the bomb itself has a maximum distance it can see the laser) but then again how can it hope to achieve 18+NM in either case.

Tried JTAC ONLY and both F16 + JTAC Lasing.



Unless there are new features coming to the GBU24 to making it somehow glide further before homing in on the beacon, then I don't quite understand the use of the DLZ.

GBU24 VS GBU12 JTAC ONLY + F16 LASE.trk GBU24 VS GBU12 JTAC ONLY.trk

[Ignition]

You say the 24has no energy to reach the target at maximum range? That may be a bug. For what I saw when I used it, the bomb doesn't fly ballistic (it has an autopilot).

I will test it later.

As a side note I never drop a bomb or shoot a missile at maximum range, always at around 80%. Also I believe the DLZ desn't take into account the wind.

Edited November 1, 2022 by Ignition

[=52d= Skip]

Another great example of a valid report being answered with anecdotal/ unrelated guesswork or ignorance.
If the "F-16 knows just what the weapon is capable of and shows based on that" then why is the Bomb not reaching it´s Target?

We have either a faulty DLZ, a wrong FM for the GBU, or a combination of those. What we don´t have is "correct as-is".

Using the OP´s setting (M0.9 @ 35k ft) the max I could get was 12nm with a TTI still being calculated. Starting at 13nm the TTI wasn´t calculated anymore and the bomb did fall short.

The keen observer may also notice that the TOF isn´t working and a pair was dropping, even tho (default) single was showing.

 

 

[Sl1ck]

1 hour ago, =52d= Skip said:

Another great example of a valid report being answered with anecdotal/ unrelated guesswork or ignorance.
If the "F-16 knows just what the weapon is capable of and shows based on that" then why is the Bomb not reaching it´s Target?

We have either a faulty DLZ, a wrong FM for the GBU, or a combination of those. What we don´t have is "correct as-is".

Using the OP´s setting (M0.9 @ 35k ft) the max I could get was 12nm with a TTI still being calculated. Starting at 13nm the TTI wasn´t calculated anymore and the bomb did fall short.

The keen observer may also notice that the TOF isn´t working and a pair was dropping, even tho (default) single was showing.

 

 

Thanks for your video contribution. My track files show a similar story. In future I will make a video, I don't think people actually bother to watch track files.

I could get a splash from just over 15NM but the bomb is very much heading into the ocean before grabbing the laser at the very last moment and pitching up to glide in very slowly at low level to the target, as opposed to a more optimal / normal trajectory.
 

[NineLine]

1 hour ago, =52d= Skip said:

Another great example of a valid report being answered with anecdotal/ unrelated guesswork or ignorance.
If the "F-16 knows just what the weapon is capable of and shows based on that" then why is the Bomb not reaching it´s Target?

We have either a faulty DLZ, a wrong FM for the GBU, or a combination of those. What we don´t have is "correct as-is".

Using the OP´s setting (M0.9 @ 35k ft) the max I could get was 12nm with a TTI still being calculated. Starting at 13nm the TTI wasn´t calculated anymore and the bomb did fall short.

The keen observer may also notice that the TOF isn´t working and a pair was dropping, even tho (default) single was showing.

 

 

First, please keep your responses mature and constructive, if you are confused what I mean:
"a valid report being answered with anecdotal/ unrelated guesswork or ignorance."
Is not mature or constructive. 

Based on information from the team the answer is as was explained before, it's not about the DLZ, it's about the laser range. The DLZ does not account for laser range. You need to drop no more than 8 nm slant range away.

If you have valid documented evidence proving otherwise, and it is legal to share and post, please do. If you are unsure, send us a PM.

[Tholozor]

2 hours ago, =52d= Skip 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.

At the ranges you're dropping from in this example, self-designation would be impossible given the limited laser range in DCS, and would be better suited for designation by an offboard source.

[Sl1ck]

8 hours ago, 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.

At the ranges you're dropping from in this example, self-designation would be impossible given the limited laser range in DCS, and would be better suited for designation by an offboard source.

Look at my track files. tried using a local JTAC that Auto-lased the target. As well as my ownship + JTAC Still did not work from max range in the DLZ.

It's as if laser spot can't be seen from so far away by the bomb, OR the autopilot part is not working properly.

 

9 hours ago, NineLine said:

First, please keep your responses mature and constructive, if you are confused what I mean:
"a valid report being answered with anecdotal/ unrelated guesswork or ignorance."
Is not mature or constructive. 

Based on information from the team the answer is as was explained before, it's not about the DLZ, it's about the laser range. The DLZ does not account for laser range. You need to drop no more than 8 nm slant range away.

If you have valid documented evidence proving otherwise, and it is legal to share and post, please do. If you are unsure, send us a PM.

 If based on the documentation you have, the DLZ is correct, then how is the bomb intended to be used at max range, given our ownship lasing distance limit?

As mentioned before I tried a JTAC that lased the target continuously, but the bomb was still not able to make it to target. Please see track files uploaded previously.

[BIGNEWY]

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

[Sl1ck]

1 hour ago, 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

That's understood,

So with the Bomb not able to see the laser beyond 8nm and the requirement to designate immediately after release, where and how do we use the bomb when the DLZ is giving us a max range of 18/19NM?

Are we missing something?

Regards

 

[BIGNEWY]

There needs to be a lased target at release, until we see evidence stating other wise it is correct. 

[maxTRX]

To me it looks like a kinematics issue.  First, I noticed a different release profile that GBU24 flies when dropped from a Viper compared to a Hornet.  I only fly Hornets but watched the first part of the vid posted above by Skip.  When dropped from a Viper, the bomb seems to fly a 'normal' separation phase, without any pitch-ups that we see in the Hornet's case.

Here's my test result for the Hornet:

The first drop - target at 10k ft.,  the bomb released from 42k ft.  The initial bomb's pitch-up was brief, followed by a nose down toward the laser spot.  To be honest, I'm not sure whether the bomb's max range was calculated correctly or not, but from this altitude the bomb has a lot of energy to play with to reach the target. The bomb's nose was pointed downward all the way down.  After covering 9nm (horizontal), it hit the target.

The second drop - same tgt. at 10k,  release from 15k.   The pitch-up was horrendous and caused the a/s to drop a lot.  The bomb had 7nm to cover and I could tell right away it wasn't going to make it.   It fell short by a lot.  It was doing 200kts just before impacting the ground.

The third drop - target at sea level,  release from 5k ft.  The bomb pitched up but it only had 3.5nm to go, so the nose had to point down toward the laser spot quickly. The target was hit.

So... it seems to me like some sort of miscalculation related to altitude...

BTW, similar issue related to target elevation and gun accuracy (after using a GPS weapon) has just been fixed by ED.  At the sea level there was no issue. At higher elevations, the gun was shooting 4,5 deg. high.  Nice to see this fixed.

 

[Sl1ck]

5 hours ago, BIGNEWY said:

There needs to be a lased target at release, until we see evidence stating other wise it is correct. 

How is the GBU24 going to reach it's target at 19NM from 35000 M.9 which is the max range according to the DLZ programming, if it can't see the laser spot from the JTAC till 8nm away.

GBU24 VS GBU12 JTAC + F16 LASE.trk

[NineLine]

1 hour ago, Sl1ck said:

How is the GBU24 going to reach it's target at 19NM from 35000 M.9 which is the max range according to the DLZ programming, if it can't see the laser spot from the JTAC till 8nm away.

GBU24 VS GBU12 JTAC + F16 LASE.trk 340.54 kB · 1 download

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

[Arctic Fox]

8 hours ago, BIGNEWY said:

There needs to be a lased target at release, until we see evidence stating other wise it is correct. 

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.

Edited November 3, 2022 by Arctic Fox

[Hulkbust44]

10 hours ago, BIGNEWY said:

There needs to be a lased target at release, until we see evidence stating other wise it is correct. 

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.)

[Tholozor]

1 hour 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.)

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

Edited November 3, 2022 by Tholozor