Bomb-Question (Mk82, GBU-12)

[Wali763]

Hi. 

Just asking to check, if Im doing something wrong.

Usually Im dropping bombs, freefall or laserguided alike,  in CCRP-mode.

Before doing so I set the SPI with the TGP and put the SPI to the closer edge of the target, so not to set the SPI behind the target.

When using the Mk82, I tend to get excellent results with CCRP, much better then with CCIP. With CCRP I use some 2500-3000ft above the target and as long I get the bipper right on the ASL upon release, in most cases get a perfect hit.

The strange thing for me is, that GBU-12s only hit the target, if the time-to-impact-counter on the left of the HUD is 15s or higher. I usually try to have 18s and then it works fine. But when I release the GBU-12 at say 13s (which is still higher than the ~2500ft used for the Mk82), I will probably get a miss. Im usually fireing the laser right before release. Only if Im very high, I wait until 15-18s TTI to fire the laser. If doing auto-laser I choose 15s.

But using CCIP with freefall-bombs, I very often miss the target even though I only release the bomb when the bipper slips exactly over the target. Also CCIP and laserguides bombs need some hight and if released too low, Ill will get a miss.

Overall, its strange to me and thus Im doing this post, that the most inaccurate way (freefall bombs in CCRP) renders better results than CCIP and if used too low (but way higher then on CCRP with freefall bombs) even better results than laserguided bombs. 

Am I doing something wrong? 

[Yurgon]

We'd need to see a few short tracks to make any definitive statement.

2 hours ago, Wali763 said:

The strange thing for me is, that GBU-12s only hit the target, if the time-to-impact-counter on the left of the HUD is 15s or higher.

It sounds like that's on the edge of the envelope. In CCRP, the bomb will start to fall on a ballistic trajectory, meaning the seeker can't pick up the laser reflection right away. When you do a high altitude drop and switch to the F6 camera, you can see the exact moment the bomb picks up the laser and starts to guide. From low altitude drops, there's a risk that the seeker takes too long to pick up the laser reflection and by that time the bomb might no longer be able to guide to the target.

2 hours ago, Wali763 said:

But using CCIP with freefall-bombs, I very often miss the target even though I only release the bomb when the bipper slips exactly over the target.

Only a track can tell what's happening there. I agree that a well executed CCIP release with pipper on target should be fairly accurate. On the other hand, maybe it's not CCIP that's too inaccurate - maybe it's CCRP with dumb bombs that's too accurate?

3 hours ago, Wali763 said:

Also CCIP and laserguides bombs need some hight and if released too low, Ill will get a miss.

Interesting. The seeker should pick up the laser spot right away. But maybe the bomb needs a little time to stabilize before it starts guiding? Or it just can stabilize fast enough and is still in the phase of overcorrecting and thus misses the target? Or maybe there's a seeker activation delay after release? Maybe someone with more knowledge can chime in.

[ASAP]

2 hours ago, Wali763 said:

Am I doing something wrong? 

The results you talked about sound reasonable and accurate. There's a lot to breakdown here:

2 hours ago, Wali763 said:

put the SPI to the closer edge of the target, so not to set the SPI behind the target.

Perfect. Put your SPI at the base of the target, missing short is generally better than missing long because bomb impact angles and fragmentation patterns.
 

 

2 hours ago, Wali763 said:

When using the Mk82, I tend to get excellent results with CCRP, much better then with CCIP. With CCRP I use some 2500-3000ft above the target and as long I get the bipper right on the ASL upon release, in most cases get a perfect hit.

CCRP is very accurate even from much higher up. The ballistics of a conical fin MK-82 are very well understood and the computer does an excellent job of putting a dumb bomb right where you want it. The limiting factor in a level CCRP delivery is YOU being able to get the pipper right on the ASL. Of course, the winds blow. The jet has its own wind table that you shouldn't (but can) mess with. Its possible they will push the bomb off the target especially if there is elevated terrain making the wind whip around and unusual velocities and angles through the bombs flight path, but in general the jet does a great job of calculating winds into the release parameters.

3 hours ago, Wali763 said:

The strange thing for me is, that GBU-12s only hit the target, if the time-to-impact-counter on the left of the HUD is 15s or higher. I usually try to have 18s and then it works fine. But when I release the GBU-12 at say 13s (which is still higher than the ~2500ft used for the Mk82), I will probably get a miss. Im usually fireing the laser right before release. Only if Im very high, I wait until 15-18s TTI to fire the laser. If doing auto-laser I choose 15s.

IRL there is a minimum guide time for the GBU-12 to be able to hit its target which drives a minimum altitude you can release the bomb. Also the lower you get the more you have to deal with things like podium effect. If you drop the bomb in one spot and then fly over the target, 15 seconds later the laser might be pointed at the back side of the target where the bomb can't see the laser spot. The issue is not as pronounced up high as it is down low.

3 hours ago, Wali763 said:

But using CCIP with freefall-bombs, I very often miss the target even though I only release the bomb when the bipper slips exactly over the target. Also CCIP and laserguides bombs need some hight and if released too low, Ill will get a miss.

Just like with your SPI, pickle at the base of the target. Factor in your reaction time between when you think "Time to pickle" and when the button is actually depressed. If you continually miss long, pickle shorter of the target. CCIP diving deliveries require some skill and know how to do correctly. Unfortunately there isn't anything official teaching you how to do that in DCS. There are some good videos out there that attempt to explain it. IRL any diving delivery is flown with specific parameters. Its not as simple as tipping in and killing something. You would do a specific delivery like a 30 degree dive bomb or a 45 degree high altitude dive bomb for instance. Those each have a very specific base altitude and offset, and then you roll in and point at a specific aim off distance from the target, and set the target at a "Initial Target Placement" in the HUD. You'd also set your desired release cue over the target, which is based on your desired time of fall which is also set by the delivery you are trying to do. All that is to say that CCIP deliveries are complicated and need to be practiced and you don't have the required data you need to do it correctly, so missing isn't surprising, and I wouldn't stress too much about it.

3 hours ago, Wali763 said:

Overall, its strange to me and thus Im doing this post, that the most inaccurate way (freefall bombs in CCRP) renders better results than CCIP and if used too low (but way higher then on CCRP with freefall bombs) even better results than laserguided bombs.

CCRP is way more accurate than your average DCS user doing diving dumb bomb deliveries because CCIP is difficult to do correctly. As far as laser guided bomb accuracy, there are some nuances that might be causing issues trying to use them down low. Without seeing you actually use them I can't speak to why they are less accurate. The GBU-12 if unguided or not guided properly is draggy and I would expect it to fall short.

[Wali763]

Thx for your answers, they really help.

Since I cannot mark both as solution I went for the second, very long answer. Sorry Yurgon!  

I think I need to practice CCIP more and update my knowledge about it too.

CCRP deliveries of 82s just are just so accurate, that I thought this has to be wrong. But probably its just me, making CCIP too inaccurate.

@Yurgon: I follow my GBUs quite often in F6-camera and know what your talking about with the point, the bomb picks up the laser. Have to monitor that more closly in the future though.

@ASAP: yes, my GBUs, when released too low, tend to land short. First they tend to dive rather steep and and when they pick up the laser, they cant reach the target any more...

Anyway, thanks for your insightful answers!

 

Edited August 30, 2024 by Wali763

[ASAP]

5 hours ago, Wali763 said:

@ASAP: yes, my GBUs, when released too low, tend to land short. First they tend to dive rather steep and and when they pick up the laser, they cant reach the target any more...

I'm not sure how much of a difference it will make, but here is something you can try. in the DSMS profile for the GBU-12 change one of the options from OPT to BAL (I unfortunately can't remember the name of the option, but it should be fairly obvious because its the only one set to OPT). Opt makes the bomb release at the ideal spot to find the laser, BAL (short for ballistic) makes the bomb release at the best ballistic trajectory to hit the target. See if that helps with it falling short at all. 

Additionally. If you are down low I recommend turning the laser on just prior to pickling and leaving it on until the bomb hits. Delay lasing would probably cause more issues than its worth.

[Yurgon]

5 hours ago, Wali763 said:

Since I cannot mark both as solution I went for the second, very long answer.

Definitely the more comprehensive answer!

What I find a bit odd - and it happens every now and then - is when people are given a perfect answer, they respond "Thank you" and then mark that "Thank you" as the solution. To each their own, I guess...

5 hours ago, Wali763 said:

yes, my GBUs, when released too low, tend to land short.

Interesting! I tend to believe that the A-10's IFFCC drops LGBs a bit long to give them more energy than a purely ballistic trajectory. However I've also heard that they might be dropped a bit short to allow the laser more time to "see the basket" of the laser illumination. Looks like it's the latter.

4 minutes ago, ASAP said:

in the DSMS profile for the GBU-12 change one of the options from OPT to BAL (I unfortunately can't remember the name of the option, but it should be fairly obvious because its the only one set to OPT)

Isn't that the "ORP" solution, the "Optimal Release Point"?

(I half cheated. Typed it, and then confirmed it in the DCS manual ).

[ASAP]

2 hours ago, Yurgon said:

Isn't that the "ORP" solution, the "Optimal Release Point"?

Yup, that sounds right. Thanks! Thats what I get for going purely off memory

 

2 hours ago, Yurgon said:

tend to believe that the A-10's IFFCC drops LGBs a bit long to give them more energy than a purely ballistic trajectory. However I've also heard that they might be dropped a bit short to allow the laser more time to "see the basket" of the laser illumination. Looks like it's the latter.

The IFFCC is either going to release it at the ORP or the ballistic release point based on what you tell it to do in the profile. Neither of those are going to try and give the bomb more energy. The ballistic release point will try and drop it so that it has exactly as much energy as it needs to get to the target assuming the finds are streamlined.  I remember reading somewhere that under most, but not all, circumstances the ORP is further out from the target because.... reasons... I think ORP is trying to maximize the bombs chances to see the laser spot, but I might be wrong about that. In either case, the reason the bomb tends to fall short is because of the design of the guidance logic and the tail fins full-deflection "bang-bang" guidance the bomb bleeds energy and is prone to falling short if not employed correctly.

[Yurgon]

1 hour ago, ASAP said:

Neither of those are going to try and give the bomb more energy.

Since it seems neither of us is sure what exactly is optimized in the ORP solution, I retain that it's possible this might refer to the bomb's ballistic properties, and how the bang-bang guidance is certainly not improving upon the trajectory.

I think I tested BAL and ORP with a dozen or so drops in DCS after a similar discussion and couldn't find a conclusive pattern of either of these falling consistently longer or shorter than the other. Barring input from real life pilots, I guess it remains guesswork.

[Dragan]

I sometimes set the auto laser for the GBU-12 to 12 seconds and also sometimes drop it from 11,000 feet, I have never had a problem with missing the target.I place the TGP directly on the target, as for the Mk-82 bombs, I also use the TGP until I find the target, after that I follow the target while diving and prepare to shoot with my own sight without any adjustments,All this is possible and interesting even in a dangerous environment..

[Wali763]

Late reply, sry. Didnt have time to test things recently.

Kind of inconclusive for me. BAL seems to do better, if released too low over ORP, but not much. ORP tends to fall short. Simple solution: drop it much higher, which would be the right way to do anyway I guess.

Still CCRP seems impressivly accurate (on Mk82s) and CCIP in my case does need more practice.

@Dragan the 12s was meant for the TTI counter on the left of the HUD not lase-time. If you release high enough (say 20s on TTI-counter) 12s of lasetime for sure will be enough

[jaylw314]

1 hour ago, Wali763 said:

Late reply, sry. Didnt have time to test things recently.

Kind of inconclusive for me. BAL seems to do better, if released too low over ORP, but not much. ORP tends to fall short. Simple solution: drop it much higher, which would be the right way to do anyway I guess.

Still CCRP seems impressivly accurate (on Mk82s) and CCIP in my case does need more practice.

@Dragan the 12s was meant for the TTI counter on the left of the HUD not lase-time. If you release high enough (say 20s on TTI-counter) 12s of lasetime for sure will be enough

Still no track or video means no way to give you feedback on technique