How to program the CBU?

[VR Flight Guy in PJ Pants]

Checked the manual. May be missed a few points.

How to change the activation height/time of CBU?

[SloppyDog]

From the A/G armament page: Press M for Menu, then at the bottom you'll press A/G Load, then STEP until CBU-*7 or -97 appear, select it, select the station where it is loaded, fuse.

The video below explains how, from the 7:50 mark.

 

 

[VR Flight Guy in PJ Pants]

My question was: how to set the time or height of canister release once I have selected either option. Anyway will watch GR's video.  Thank you.

[609_Relentov]

I just finished a kneeboard for CBUs, and I’m not at my PC so I’ll just paste that section here

• Set CBU-97 fuse parameters: Right MFD, PB-11 until "M2", then "ARMT" (PB-2), then "A/G LOAD" (PB-7)
• Select "STEP" (PB-10) until vou see CBU-97, then select (PB-4)
• Select all stations at the top loaded with CBU-97 (from PB-16 to PB-20)
• Select "FUZE" (PB-7)
• Select "SEL FUZE" (PB-4), until "F ZU39" is selected
• Select burst time (PB-2/PB-3) or burst height (PB-13/PB-14), as desired
• Select "ENTER" (PB-10) to save fuze parameters to memory

 

[Recluse]

A good trick I learned in one of the videos is to cycle through the available TIME fuzing choices until it disappears, then you can use burst height only. Or so it seems. Worked well for me when I tried it.

 

Note: using CBU-97 I never did see the SPIN option.

[vctpil]

I tried different settings with differents CBUs, but the result is always the same, the bomb disperse always at the lowest altitude. This result in bomblets concentrated at the same point.

Anybody have the same problem ?

[609_Relentov]

2 hours ago, vctpil said:

I tried different settings with differents CBUs, but the result is always the same, the bomb disperse always at the lowest altitude. This result in bomblets concentrated at the same point.

Anybody have the same problem ?

Make sure you have set both the fuse options (see my post above, e.g. set burst height) as well as the delivery options where you choose HEIGHT;  here’s another excerpt from one of my kneeboards:

• Set CBU-97 delivery parameters: Right MFD, PB-11 until "M2", then "ARMT" (PB-2), then "A/G" (PB-3); Select desired progrem, e.g. "PROG 1" (PB-5), then:
• Select all stations with 1 or more CBU-97s (one of PB-16 - PB-20)
• Select "CDIP" (PB-6) or "AUTO" (PB-7), for CCIP or auto delivery mode
• Select 1) "1/STA" (PB-6), 2) "STEP" (PB-7), 3) "RP SGL» (PB-8), or 4) "RP MPL" (PB-9), for 1) one weapon simultaneously from each selected station per pickle button press, 2) one weapon separately from each selected station, per pickle button press, 3) string of weapons separately from each selected station as long as pickle button pressed, and 4) string of weapons simultaneous from each selected station as long as pickle button pressed
• Select "TIME" (PB-6) or "HEIGHT" (PB-7) for canister burst time or height

After setting both, I get expected burst and dispersal.

Edited July 3, 2023 by 609_Relentov

[jaylw314]

3 hours ago, Recluse said:

A good trick I learned in one of the videos is to cycle through the available TIME fuzing choices until it disappears, then you can use burst height only. Or so it seems. Worked well for me when I tried it.

 

Note: using CBU-97 I never did see the SPIN option.

SPIN is for the CBU-87 only AFAIK.  The CBU-97 just sheds the cannister and drops the 4 submunitions at the programmed HEIGHT, then the submunitions do their own pre-programmed dance.  For the submunitions, parachute height, rocket motors, spin rates and release of the pucks aren't adjustable.  As such, I don't think HEIGHT makes a massive amount of difference with CBU-97's dispersal.  You can't edit anything about the submunitions parameters AFAIK.  

Edited July 3, 2023 by jaylw314

[Recluse]

12 minutes ago, jaylw314 said:

SPIN is for the CBU-87 only AFAIK.  The CBU-97 just sheds the cannister and drops the 4 submunitions at the programmed HEIGHT, then the submunitions do their own pre-programmed dance.  As such, I don't think HEIGHT makes a massive amount of difference with CBU-97's dispersal.  You can't edit anything about the submunitions parameters AFAIK.  

Thanks for the info!! 

I was going by this image in the manual which seemed to show a SPIN parameter on the CBU-97

 

 

 

Mainly a Hornet/Harrier driver so the CBU-97 is a shiny new toy with much greater capability than the Mk.20 or CBU-99.  The MIRAGE 2000 Belouga's are similarly better than the Rockeye/CBU-99 but a bit more difficult to deliver accurately, though ACCURATE and CLUSTER BOMB should not necessarily need to be uttered together.  Have had a little experience with the A-10C CBU-97/103/105 but have barely flown the Warthog.

 

Edited July 3, 2023 by Recluse

[vctpil]

I made some other tests, and it works.

It seems that selecting again any CBU make the time/height setting to reset to minimum. Maybe the system works like in reality.

[jaylw314]

On 7/3/2023 at 9:45 AM, Recluse said:

Thanks for the info!! 

I was going by this image in the manual which seemed to show a SPIN parameter on the CBU-97

At least in the Warthog, you can set the SPIN parameter in the CBU-97/105, it just doesn't do anything.  I suppose they may have been debating whether to allow that or not in the PACS 

[609_Relentov]

8 hours ago, vctpil said:

I made some other tests, and it works.

It seems that selecting again any CBU make the time/height setting to reset to minimum. Maybe the system works like in reality.

Yep, that's why it's best to set up all of the delivery parameters for a given program (i.e. PROG x), including selecting the appropriate stations, etc. (see my post above).  As you noted, as soon as you select a station it resets everything for the given program you are in, and you have to program it all in again.

[vctpil]

Even with PROG, I quite sure there is something wrong with the CBUs.

I tried differents settings of time and height, set on the ground or in the air, the results are inconsistent. 80 of the time, the CBU deploy at the very minimum height or time.

Track attached.

Test F-15E CBU.trk

Edited July 5, 2023 by vctpil

[claysanger]

I’m having similar problems — no combination of fuzing / programming options seems to yield anything for me with the CBU-87 but a low altitude, high density burst of bomblets. 
 

I’ll keep experimenting but I’m gonna wager the 87s are buggy enough at the moment that any Konami Code like programming button presses that so make it behave itself are a lucky workaround and not intended design.  
 

I think the only suggestion above I haven’t tried yet is to cycle the TIME parameter in the A/G Load fuse page all the way through before setting your burst HEIGHT and proceeding to A/G programming. 
 

If it works I’ll be a happy camper though. 

[claysanger]

On 7/3/2023 at 8:22 AM, vctpil said:

I tried different settings with differents CBUs, but the result is always the same, the bomb disperse always at the lowest altitude. This result in bomblets concentrated at the same point.

Anybody have the same problem ?

Me too. At least with the CBU-87. Can’t seem to get any result other than minimum burst height no matter what fuzing/programming options I set. 

[claysanger]

Huh. This brings up a “shower thought” type question. The HEIGHT parameter on a CBU-87/97 or Mk20…..

Anybody know what sensor mechanism that is determined by?

1) Baro Altimeter in the bomb? 
 

2) Radio/Radar Altimeter in the bomb? (Seems unlikely in that era of CBUs but not impossible)

3) Baro/Radar Altimeter data passed from the aircraft to the bomb? And the bomb does some math / trigonometry to calculate a burst height? (Sounds more advanced than it would be if that’s the case, well within the capability of weapon programming and guidance electronics of the 20th Century).  

4) Magic Video Game Math?

5) Other?

I guess I’ve never thought about HOW CBU burst height fuzing works based on sensors before. 

[OG84]

3 hours ago, claysanger said:

Huh. This brings up a “shower thought” type question. The HEIGHT parameter on a CBU-87/97 or Mk20…..

Anybody know what sensor mechanism that is determined by?

From what I found on google, it should be a FZU-39/B radar proximity sensor (fuze).

So it seems like it has a small radar for determining when to dispense.

But what my shower type of question would be, how is that setting transfered to the bomb in dcs. Seems like in reality it is set directly on the bomb/fuse itself, outside by some ground crew. So no clue if changing this in the PACS ingame is actually changing the setting on the bomb itself. I assume same applies to the spin parameter which is probably manually adjusting some fins at the tail of the bomb. Probably values entered in PACS are just used for calculating the correct trajectory and drag and setting up the bomb has to be done by ground crew.
But I could be wrong as I don't have any insights in any of those things 

Edited July 6, 2023 by OG84

[jaylw314]

3 hours ago, claysanger said:

I’m having similar problems — no combination of fuzing / programming options seems to yield anything for me with the CBU-87 but a low altitude, high density burst of bomblets. 
 

I’ll keep experimenting but I’m gonna wager the 87s are buggy enough at the moment that any Konami Code like programming button presses that so make it behave itself are a lucky workaround and not intended design.  
 

I think the only suggestion above I haven’t tried yet is to cycle the TIME parameter in the A/G Load fuse page all the way through before setting your burst HEIGHT and proceeding to A/G programming. 
 

If it works I’ll be a happy camper though. 

As mentioned above, SPIN should affect CBU-87's but I haven't messed around with them yet.  Did you increase that parameter as well?  It could be none of the are working right now

[claysanger]

On 7/6/2023 at 10:52 AM, jaylw314 said:

As mentioned above, SPIN should affect CBU-87's but I haven't messed around with them yet.  Did you increase that parameter as well?  It could be none of the are working right now

Yeah, I tried the SPIN parameters as well -- running those up or down on the 87's doesn't seem to change their burst effect any at the moment.

PS: And after forgetting to hit ENTER about 50% of the time to save those settings in the A/G Load sub-page, I also started remembering to do that as well. If your selected parameters don't transfer to the A/G PACS page for your CBU stations, then that's a tell-tale sign you've forgotten to save the setting in the A/G Load sub-menu.

Both result in the same thing --- no change to the terminal performance of the CBU-87s

 

[jaylw314]

1 hour ago, claysanger said:

Yeah, I tried the SPIN parameters as well -- running those up or down on the 87's doesn't seem to change their burst effect any at the moment.

PS: And after forgetting to hit ENTER about 50% of the time to save those settings in the A/G Load sub-page, I also started remembering to do that as well. If your selected parameters don't transfer to the A/G PACS page for your CBU stations, then that's a tell-tale sign you've forgotten to save the setting in the A/G Load sub-menu.

Both result in the same thing --- no change to the terminal performance of the CBU-87s

 

Guess it's not quite working yet, then.  Not that CBU-87's are terribly effective against anything other than infantry and trucks, so you're not missing too much

[claysanger]

1 hour ago, jaylw314 said:

Guess it's not quite working yet, then.  Not that CBU-87's are terribly effective against anything other than infantry and trucks, so you're not missing too much

Yeah looks that way for now. Mk20’s seem to be behaving about the same — but I didn’t do as much testing with them. I could be mistaken. CBU-97s however seem to be mostly performing as expected. So. There is that for now