CBU-99/Mk.20 Height of Burst option

[arkasha_s_mishkoi]

I noticed that cbu and rockeye will always burst at 1500ft, and HT option makes no sense. Is it still WIP or i'm doing something wrong?

[DZShizzam]

If I am not mistaken, HOF or HT is an option that can be changed by the pilot only on newer model CBUs such as the 87, 97, 103, and 105.

 

CBU-99 and Rockeye HOF is set on the ground, so you cannot change this in cockpit.

[Hog_No32]

WIP. Even though Wags in a not too recent video showcased that HT function has been developed, that code never made it into any update so far.

[Raz_Specter]

WIP. Even though Wags in a not too recent video showcased that HT function has been developed, that code never made it into any update so far.

 

 

The HOF function is indeed in the sim and working, i haven't tested the dispersal height yet so cannot comment but its certainly there in the Weapons DDI, its under MFUZ and then select YT and once the screen goes back to the main view HT appears at the bottom.

 

 

 

Cheers Specter

Edited August 2, 2018 by Raz_Specter

[arkasha_s_mishkoi]

Of course i know about it and i'm talking about this function.

Try to release a bomb with different HT (500, 1500, 3000) and you will see that bomb always burst at 1500.

[mvsgas]

I noticed that cbu and rockeye will always burst at 1500ft, and HT option makes no sense. Is it still WIP or i'm doing something wrong?

It is WIP, what make no since of the HT option

 

HOF is set on the ground, so you cannot change this in cockpit.

This is true for all CBU AFAIK IRL, since we can't go to the ground, normally we set this in the pit in DCS.

Edited August 9, 2018 by mvsgas
1.16

[Eldur]

WIP. Even though Wags in a not too recent video showcased that HT function has been developed, that code never made it into any update so far.

 

I might just quote him. "Let's set it to 1500 for now." That's exactly the Height of Burst these bombs have dropped from the Hornet, regardless of the setting on the DDI. Most probably WIP.

The same bomb (Mk. 20) though dropped from a Harrier has either a 4s burst delay (PR) or 1.2s burst delay (OP), totally independent of altitude.

[Trainzak]

What's the difference between CBU-99 and Rockeye? They are both retarded and seem to work the same...

[Raven (Elysian Angel)]

What's the difference between CBU-99 and Rockeye? They are both retarded and seem to work the same...

The Mk20 Rockeye is designed as an anti-tank cluster bomb, whereas the CBU-99 is meant to be used against light vehicles and infantry.

[CHSStarKiller]

Hey guys just so you know, there are many options for HOF and they are set on the ground, dictated by the days load plan, these functions are on CBU's with a(n) FMU-140/B Fuze on it. HOF can be set to 3, 5, 7, 9, 12, 15, 18, 22, 26, and 30 [x100ft]. This was always a huge problem with A/C such as the S-3 as the pilots never really understood HOF and would often release them well above their intended altitudes or to low usually resulting in a big water splash. These shortcomings have kind of fazed their use in the Navy out although Marines will still usually load them. With the use of the JSOW now, HOF really isn't important as its all a 1760 program

 

Now I haven't played with CBU's in this game yet for some reason. Maybe i'll put that old Ordie expertise in the pit for a few.

 

 

You guys can search for the NWP 3-22.5FA28A/B/C/D (A1-F18AC-TAC-300) if you want more of a pilots TAC guide.

Edited August 10, 2018 by CHSStarKiller
Additions

[Frederf]

Rockeye I Mark 12

 

significantly different than

 

Rockeye II Mark 20 Mod 0, 1, 2, 3, 4, 5...

CBU-99 and CBU-99A

CBU-100 and CBU-100A

which are all very very similar. The differences are the dispenser improvements, thermal protection coating, bomblet fuze model, and even just reclassifying from the older naming scheme to the new one.

 

The biggest operational variable of the Rockeye II-type weapons is the fuzing of the dispenser which can be the Mark 339 mechanical time fuze or the FMU-140 radio proximity device. The most likely model to be used with F/A-18 is CBU-99A because it is thermally protected and has the FMU-140 fuze.

 

Both are wire-armed devices with a primary and secondary wire arming function. The primary wire alone initiates the primary time function while pulling of both primary and secondary wire initiates the option time function. While the times for each mode are preset by the factory at 1.2 and 4.0 seconds, each can be set within the range 1.2 to 100 seconds by armament crew.

 

FMU-140 is likewise controlled by primary and secondary wires. The primary wire initiates normal operation while the secondary additional wire causes the dispenser to override normal operation and dispense at 1.2 seconds. In primary operation the dispenser needs to meet the following criteria to function:

1. Decreasing altitude

2. Arming time elapsed (1, 2, 4, 6, 8, 10)

3. Proximity distance reached (300-3000')

Arming times and proximity distances are set from a handful of options on the face plate by armament crew.

 

F/A-18 may only be told which model of fuze is used by WIP but not the particular settings for time and distance. This must be faithfully entered by the pilot to the weapon settings of the cockpit display to match the characteristics of the loaded weapon for correct aiming. SMP code only differs between non-thermally protected "03" for Mk 20 Mod 12, CBU-100 displaying on DDI as "RE" for RockEye and code "02" for Mk 20 Mod 9 or 11, CBU-99 displaying "RET" for RockEye Thermally protected. The thermal protection adds a small amount of weight ~15 lbs and may have slightly more drag.

Edited August 10, 2018 by Frederf

[Trainzak]

The Mk20 Rockeye is designed as an anti-tank cluster bomb, whereas the CBU-99 is meant to be used against light vehicles and infantry.

 

But is it already correctly implemented? They both burst into the same Mk-118 bomblets...

[gekoiq]

They are functionally identical, both anti-armor weapons. They use the same bomblets, the only difference, as the guy above said, is different dispensers and fuzing. In game they are interchangeable.

[BoneDust]

They seem to be relatively ineffective on T72 etc

[Cik]

it's a HEAT warhead, not frag.

 

 

 

the reason they aren't effective is just because explosives in DCS are anemic. they should probably massacre at least light armor, and put more than scratches on heavier armor.

 

 

why even have this class of weapon if it doesn't do anything (IRL)? looking at DCS you'd think anything that isn't a maverick is 100% worthless against anything with armor <20mm thick.

[KPenn5]

it's a HEAT warhead, not frag.

 

 

 

the reason they aren't effective is just because explosives in DCS are anemic. they should probably massacre at least light armor, and put more than scratches on heavier armor.

 

 

why even have this class of weapon if it doesn't do anything (IRL)? looking at DCS you'd think anything that isn't a maverick is 100% worthless against anything with armor <20mm thick.

 

That is no lie. Since the A-10, anything other than a maverick is pointless, well many a LGB. With the bug, I have killed a Tugunska with a MK83, but definitely wasn’t a “tank”. I’ve found the cluster bombs pretty much useless, usually using a mix of rockets and iron bombs right now.

[Nealius]

Just a quick Q since you guys seem to have dropped a lot of CBUs/Rockeyes recently: Has anyone here had the casing burst immediately after drop?

 

A few weeks ago I was filming a quick video scene and needed empty racks, so I dropped 4 Rockeyes straight and level at a couple thousand feet just to dispose of them. Looked out the canopy and saw them burst immediately after leaving the rail, with the bomblets raining down a few thousand feet. I unfortunately deleted the track during post-update folder cleaning.

[Frederf]

You might have pulled option wire which dispenses 1.2 seconds after release. Only pull the primary if you want the FMU-140 to do radio function based on height.

 

 

Also be aware that F-5E CBU which looks to have FMU-140 fuze by visual inspection does not and instead is timed by Mk 339.

[Nealius]

Option wire? Is that a setting through the Stores page?

[Eldur]

Rockeye I Mark 12

 

[...]

 

Great information there. This is something I expected to get told when asking what the difference between the Mk. 20 and the CBU-99 is where ED likes to leave us completely in the dark. But even the lot of information doesn't quite much answer that question completely. I get this right the CBU-99 basically is the thermal protected one which is a tad heavier and slightly draggier than the Mk. 20? What is the thermal protection for actually?

 

Also, do I get this right that the HoB function on the stores page is not able to select the actual HoB since it has to be set on the fuze itself? That would mean the setting most probably just has an effect on the CCIP/AUTO calculation to take into account the different drag characteristics of the bomblets compared to the canister, because there basically must be a reason for the setting's option being there.

 

Setting the HoB would be something for the kneeboard then, as well as setting up the R/S mode of the rocket pods...

[Frederf]

Thermal protection is to prevent/delay weapons for detonating in a ship or land-based fire either on an airplane or more likely in the stowage area. Aircraft carriers are deadly serious about weapon fire protection. You won't find a Mk 83 type bomb without the coating on a CVN, ever (nowadays).

 

 

Height of function for FMU-140 is set on the unit by hand. Yes, DDI value is for airplane knowledge only.

 

 

 

Yes of course the CCIP or CCRP math breaks the trajectory into two parts pre and post dispense and patches them together. If you tell it the HOF is 2000' and it's really 500' then it's going to assume weapon spends more time in the slippery flatter trajectory and will travel beyond the predicted aim point. You should see the CCIP pipper jump around as you cycle through program modes which are set at different assumed HOF.

[mr_mojo97]

Ok, guys n gals, I can't get my rockeyes to burst, I've set everything like in the DCS tutorial, the bomb releases but doesn't open. I've tried every height but the pod just hits the deck. This happens in both CCIP and Auto modes. Any ideas? Cheers

 

 

Radar alt switch set

 

1. Mfuze

2. VT

3. Set height

4. Pickle when CCIP cross is over target

Cluster..trk

AG practice.miz

Edited February 7, 2019 by mr_mojo97

[fencible]

Rockeyes work great....

 

I tried Rockeyes in a home-made test mission - I carried two HARMS and 4 Rockeyes to attack a SAM 6 site set up near Batumi. I took out the radar with a HARM when it locked me, and then dropped 2 rocks on the circle of armoured missile carriers from ~5000ft. I had set the burst height (VT) to 900 feet. I was then staggered when not only the two vehicles I targeted in the CCIP drops were destroyed, but nearly all of the vehicles in the area. The rockeyes were VERY effective against lightly armoured vehicles, and covered a much wider area of dispersement than I had anticipated.

[Sabaton]

VT has to be set at 1500 feet ?

[mr_mojo97]

I added the mission and a track to my first message if anyone could a check please.

 

 

Sabaton, I've tried all heights