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Two questions about CBUs


Razor18

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Hi Guys,

 

1. When telling my flight to "Engage with..." and I want them to drop CBU-87 or -97, which type should I say: "Guided bomb", or "Unguided bomb"? And if you have CBU-103 or 105 WCMD?

 

2. Increasing HOF (and spin RPM too) increases the coverage area of the CBU-87 - fine, the higher opening, and the more spin, pure physics. But if we talk CBU-97, it will scatter the parachute hanging BLU-108s basically the same time sequence. Very minor difference in coverage comes from the velocity of the WCMD eighter, so for me, HOF for CBU-97/105 doesn't seem to make much if any difference, the scattered BLU-108s will fly out and deploy their parachutes in whichever HOF, and then we can say wind will also not scatter them any more under the parachutes, because they all will be moved the same way by the wind (if there is wind) together, like "dust cloud particles" floating down. Watching them from vertically above, the area will be all the same whether it bursts at 3000" or 300". Only difference by HOF will be the time between BLU/parachutes deployment and ground explosions. Wiki also says "The 40 Skeets scan an area of 1,500 by 500 feet (460 m × 150 m)", and never mentiones any dependance on HOF. If I'm wrong, can somebody please correct me with some explanation? :huh:

 

Thanks


Edited by Razor18
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1) i think u should ask for unguided bombs if u want them to use 87,97 and ask for guided bombs if u want them to use 103,105 wcmd. after all latter ones do have a guidance system. I used these commands before and they do work but i ve never checked for the munition that was used. Never had a doubt about it i guess.

 

2)Well i only meddled with HOF when using cbu s. In my experience you get the best results if you set the hof between 1200-1800. more than 1800 generally gets drifted too much cos of the wind and cannot kill as much as 1200-1800 range. less then 1200 cannot cover much ground cos of the low altitude and again cannot kill as much as 1200-1800 range.

long story short, i use 1200 if they are staying close to each other or there is only 1 small or medium sized convoy and i use 1800 if they are stretched , scattered, too many in numbers or more than 2 parallel convoys. The reason im telling you all this is i ve never changed anything but HoF when i use cbus. Everytime i change the HoF the kill count changes too.

 

In my limited knowledge of the cbus, i know these little bomblets with infrared sensors scan in a spiral cone below them. So like the radar beam on a fighter, cos of the scanning beams conical shape, it should cover more or less area depending on the distance between the surface area and the sensor.

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Talking of CBU's has anyone else noticed a graphic downgrade when the weapon explodes?

 

I dropped one on a load of trucks yesterday, but the only thing I saw were the trucks blowing up, not the big cloud of sub munitions exploding around the target I used to see.

 

Is this a known bug?

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Talking of CBU's has anyone else noticed a graphic downgrade when the weapon explodes?

 

I dropped one on a load of trucks yesterday, but the only thing I saw were the trucks blowing up, not the big cloud of sub munitions exploding around the target I used to see.

 

Is this a known bug?

 

i can see the submunitions with parachutes if i watch the cbu s fall on F6 camera but right after the sub munitions being deployed camera stays centered on the cbu s explosion point. I cant center it on sub munitions.

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2)Well i only meddled with HOF when using cbu s. In my experience you get the best results if you set the hof between 1200-1800. (...)

 

Well, the informations you wrote are plenty and very helpful, but my question is still open about "whether and physically how HOF has any influence to coverage area size"... :thumbup::music_whistling:

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Talking of CBU's has anyone else noticed a graphic downgrade when the weapon explodes?

 

I dropped one on a load of trucks yesterday, but the only thing I saw were the trucks blowing up, not the big cloud of sub munitions exploding around the target I used to see.

 

Is this a known bug?

 

The visuals were toned down a few months/a year ago to lessen the strain on the hardware. It's not a bug.

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Only difference by HOF will be the time between BLU/parachutes deployment and ground explosions.

 

I recently took a closer look at the CBUs and what you describe is exactly what I witnessed about the CBU-97 and CBU-105.

 

If that's really the case, IMO the lowest possible setting would make the most sense to limit the targets' reaction time and minimize wind drift of the BLU-108 submunitions. Except that with a HOF of 300 feet, my CBU-97 didn't hit anything, so I'm guessing that's actually too low for the submunitions to fire.

 

In essence, I currently think 500 feet would be the only useful HOF for CBU-97 and CBU-105 unless very specific terrain features dictate another setting.

 

But it would be great if someone else could confirm these observations.

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I recently took a closer look at the CBUs and what you describe is exactly what I witnessed about the CBU-97 and CBU-105.

 

If that's really the case, IMO the lowest possible setting would make the most sense to limit the targets' reaction time and minimize wind drift of the BLU-108 submunitions. Except that with a HOF of 300 feet, my CBU-97 didn't hit anything, so I'm guessing that's actually too low for the submunitions to fire.

 

In essence, I currently think 500 feet would be the only useful HOF for CBU-97 and CBU-105 unless very specific terrain features dictate another setting.

 

But it would be great if someone else could confirm these observations.

 

Yeah, 300 feet had no effect for me too. Thanks for confirming my suspicion.

 

A consequent question would be if (depending on HOF and accurate wind datas) the computer also offsets the aiming point ("end of freefall") based on the wind drift for the time between BLU-108 parachute deployment and Skeets starting going off. So whether finally the wind blows the chutes overhead of target, especially after a higher HOF, resulting in longer descent? With accurate wind datas it would not be more difficult to calculate, than wind corrected "end of freefall" position.

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A consequent question would be if (depending on HOF and accurate wind datas) the computer also offsets the aiming point ("end of freefall") based on the wind drift [...]

 

Great question!

 

And does the WCMD account for the submunitions' HOF?

 

Currently I have no clue, need to test that when I find the time. ;)

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Yeah, 300 feet had no effect for me too. Thanks for confirming my suspicion.

 

A consequent question would be if (depending on HOF and accurate wind datas) the computer also offsets the aiming point ("end of freefall") based on the wind drift for the time between BLU-108 parachute deployment and Skeets starting going off. So whether finally the wind blows the chutes overhead of target, especially after a higher HOF, resulting in longer descent? With accurate wind datas it would not be more difficult to calculate, than wind corrected "end of freefall" position.

 

i tried that after i saw a wind correction thread on this forum. i entered 6 layers of wind data and tried it with both 105 and 97. I dunno if i screwed up something else but it didnt work. Wind data only adjusts explosion point of the cbu, doesnt do anything about the sub munitions.

 

Well, the informations you wrote are plenty and very helpful, but my question is still open about "whether and physically how HOF has any influence to coverage area size"... :thumbup::music_whistling:

 

dunno if you read what i wrote but here it is again:

 

"The reason im telling you all this is i ve never changed anything but HoF when i use cbus. Everytime i change the HoF the kill count changes too. <== ( this means it actually affects the coverage area cos i practiced different HoF settings on the same enemy groups)

 

In my limited knowledge of the cbus, i know these little bomblets with infrared sensors scan in a spiral cone below them. So like the radar beam on a fighter, cos of the scanning beams conical shape, it should cover more or less area depending on the distance between the surface area and the sensor."

 

for the second part of my answer maybe i didnt explain myself clear enough lemme re-phrase it. Because of the bomblets infrared sensors scan pattern which is the spherical cone shape as shown in the image below

2000px-Steradian_cone_and_cap.svg.png

If you increase (r-h) value which is our HoF, you will get an enlarged coverage area.

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dunno if you read what i wrote but here it is again: [...]

 

Your explanation is nice, but for all I know it doesn't have much to do with how CBU-97s operate. :music_whistling:

 

The 476th have some great info about these weapons, and there are several paragraphs that, I believe, do answer the questions. Highly recommended read!

 

476th vFG Weapon Fact Sheet 5:CBU-97 SFW

 

I'd love to quote the whole thing, but the most relevant parts should be these:

 

While HOF does not alter the effective area of the CBU-97 as it does with the CBU-87 it is still very important. With the CBU-97 HOF controls only the altitude at which the canisters open and begin dispensing the BLU-108/B submunitions, the submunitions themselves ALWAYS function the same way and disperse their skeets from the same altitude. Therefore HOF only real effect is on the time the BLU-108s will decent on their parachutes before they activate their rocket motors and spin up to deploy the skeets, and as the this always occurs at around 200 ft. AGL, it can have a large impact on the time to impact and the accuracy of the weapon (especially in high winds).

 

BTW, they also recommend the lowest practical HOF but suggest 700 to 900 ft (contrary to my previous 500 ft. suggestion).

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Your explanation is nice, but for all I know it doesn't have much to do with how CBU-97s operate. :music_whistling:

 

The 476th have some great info about these weapons, and there are several paragraphs that, I believe, do answer the questions. Highly recommended read!

 

476th vFG Weapon Fact Sheet 5:CBU-97 SFW

 

I'd love to quote the whole thing, but the most relevant parts should be these:

 

 

 

BTW, they also recommend the lowest practical HOF but suggest 700 to 900 ft (contrary to my previous 500 ft. suggestion).

Yes in my experience 700ft HOF can be quite devastating to convoys and grouped armour.

This is especially true in low level attacks in steep mountainous terrain where you may deploying them from relatively low altitudes in a valley. :-)


Edited by Boomer_QLD
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i tried that after i saw a wind correction thread on this forum. i entered 6 layers of wind data and tried it with both 105 and 97. I dunno if i screwed up something else but it didnt work. Wind data only adjusts explosion point of the cbu, doesnt do anything about the sub munitions.

 

dunno if you read what i wrote but here it is again:

 

"The reason im telling you all this is i ve never changed anything but HoF when i use cbus. Everytime i change the HoF the kill count changes too. <== ( this means it actually affects the coverage area cos i practiced different HoF settings on the same enemy groups)

 

In my limited knowledge of the cbus, i know these little bomblets with infrared sensors scan in a spiral cone below them. So like the radar beam on a fighter, cos of the scanning beams conical shape, it should cover more or less area depending on the distance between the surface area and the sensor."

 

for the second part of my answer maybe i didnt explain myself clear enough lemme re-phrase it. Because of the bomblets infrared sensors scan pattern which is the spherical cone shape as shown in the image below

 

If you increase (r-h) value which is our HoF, you will get an enlarged coverage area.

 

I read and understand what you wrote, and from Yurgon's answer now you probably also understand what I wrote. ;) Changing HOF has no effect on the size of coverage area of the BLUs, only in a way that descending under parachute after an increased HOF gives more time for the wind to blow the group of BLUs off dead center of target area. That's most likely the reason why you have different kill numbers with altering HOF, some of the Skeeter drifted off target, and couldn't find anything below. But the area size the BLUs (!) COULD cover does not change with HOF, neither does it after chute deployment, all the way down. Your cone analogy is OK for individual Skeets, but they do not change their altitude of detonation (appr. 200 feet) anyway. Surely, first they climb back up a tiny bit after parachute release for sure, but that's very small, and got nothing to do with HOF. :)


Edited by Razor18
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