CBU-97 Accurate Delivery?

[Darkwolf187]

Recently I've been messing with the CBU-97. Hell of a weapon. But I'm having a lot of trouble getting it accurately on target.

 

In CCIP mode, I seem to be unable to launch it entirely. Here's the setup;

 

- CCIP mode, CR is off. Master arm is on, CBU-97 profile selected, SPI is set to desired impact point (not that it matters)

- Altitude 10000 feet MSL, IAS about 220 knots.

- 3 NM out from target on TGP, enter steep dive (35-40 degrees), speedbrakes out to maximum, throttle at minimum.

 

From that setup, the CCIP pipper never comes up from the bottom of the HUD until GCAS is screaming at me to pull up, and when I do so I wind up giving the target a haircut with my wings :)

 

In CCRP mode, I'm able to launch normally. However, I appear to be getting badly affected by wind. I'm dropping the CBU usually from about 6000 MSL, while in a shallow (5 degree) dive at ~200 knots IAS. The guideline is passing through the exact center of the CCRP pipper, and the wings are level at drop. But every time, when I quickly switch to the weapon camera, I see the submunitions all gently floating down to Earth and being pushed a long way off course by the wind.

 

What I'm trying to do is to drop the CBU-97 right in the middle of a whole mass of stationary light vehicles. Should I be putting the impact point slightly upwind, or am I doing it wrong?

[OutOnTheOP]

My first suggestion would just be: use CCRP. It's much easier with the CBU97.

 

However, I can certainly understand how CCIP is desirable in many circumstances (like taking a "snap" shot at a target of opportunity).

 

The problem is that when the bomb reaches it's function altitude and disperses the submunitions, they basically stop in midair and just float under the parachutes- so instead of having a nice parabolic arc trajectory all the way to the ground, the trajectory is a parabolic arc that suddenly stops and drops straight down. This means that the fire control computer calculates the impact point much further back, and therefore it's off the bottom of your HUD.

 

One way to get around this is to lower your function altitude. This will make the bomb follow a ballistic arc for a longer period of it's descent, and therefore the point of impact will be farther "forward". I know a lot of folk around here advocate very high function altitudes for CBU97, on the theory it gives the submunitions wider dispersion, but my experience has been that in DCS they tend to just fall in perfect formation- so higher function altitudes don't really result in more dispersion, just more wind drift.

 

Try 1200 or 900 foot function altitudes and see how that works out for you- though I seem to recall 900 gives a pretty tight grouping of submunitions.

Edited September 6, 2012 by OutOnTheOP

[Razor5-1]

Hi, I would say always drop cluster bombs wings level, CCRP. You can drop them no problem in CCIP but you can end up dropping them below their HOF(height of function).

You can wind correct an iron bomb and the 97 is no exception but even with wind correction the bomblets will be carried away by the wind once they deploy.

I have heard people say that by using wind correction that the bomb will be released upwind and the "chutes" will fly to the target. This has never happened for me, no matter what I change with wind correction.

 

The best thing to do is know the ground wind speed and direction then "aim off" manually with the TGP. This works for me, it's not right 100% of the time but it does get results.

[SmokeyTheLung]

To reinforce the points already made... the lower the HOF the less effect the wind will have on the submunitions. As a rule I set mine to 900 ft, I'd use 700 but in hilly terrain the results seem mixed. 900 is a safe bet.

Also worth noting that higher HOF doesn't actually seem to spread out the submunitions, even though you'd expect it to (the wind will blow them in the appropriate direction, but the remain grouped together in the same pattern) ...At least according to my eyes :) AFAIK this would make anything but the lowest HOF attainable kind of pointless

[KLR Rico]

I've never had much luck with the CBU-97 in regular CCIP either.

 

I use CCRP or CCIP with CR. They do take some practice to get a feel for the "Kentucky windage" you have to apply due to wind drift and how the HOF affects how short the BLU's end up.

[Darkwolf187]

Cheers for the responses. I now understand more about why CCIP acts weirdly with the CBU-97, and it makes sense now I think about it (ie, the trajectory is truncated at the HOF).

 

I don't believe I've been using any wind correction in the settings, I'll mess with that and the HOF and see how it affects the spread. Manually aiming off into the wind with the TGP sounds like it might be a plan to try as well.

 

Looks like I'm going to be dropping a lot of CBU-97's tonight in testing :D

[159th_Viper]

 

From that setup, the CCIP pipper never comes up from the bottom of the HUD until GCAS is screaming at me to pull up, and when I do so I wind up giving the target a haircut with my wings :)

 

Your dive angle is too shallow for the 97. Needs a steeper-than-average dive. Should have no issues CCIP'ing them from 10 000 feet and above.

[KLR Rico]

I'll try a lower HOF, and if spreading is insufficient i'll just increase RPM

 

I don't believe the CBU-97/105's spin, do they?

[marcos]

Recently I've been messing with the CBU-97. Hell of a weapon. But I'm having a lot of trouble getting it accurately on target.

 

In CCIP mode, I seem to be unable to launch it entirely. Here's the setup;

 

- CCIP mode, CR is off. Master arm is on, CBU-97 profile selected, SPI is set to desired impact point (not that it matters)

- Altitude 10000 feet MSL, IAS about 220 knots.

- 3 NM out from target on TGP, enter steep dive (35-40 degrees), speedbrakes out to maximum, throttle at minimum.

 

From that setup, the CCIP pipper never comes up from the bottom of the HUD until GCAS is screaming at me to pull up, and when I do so I wind up giving the target a haircut with my wings :)

 

In CCRP mode, I'm able to launch normally. However, I appear to be getting badly affected by wind. I'm dropping the CBU usually from about 6000 MSL, while in a shallow (5 degree) dive at ~200 knots IAS. The guideline is passing through the exact center of the CCRP pipper, and the wings are level at drop. But every time, when I quickly switch to the weapon camera, I see the submunitions all gently floating down to Earth and being pushed a long way off course by the wind.

 

What I'm trying to do is to drop the CBU-97 right in the middle of a whole mass of stationary light vehicles. Should I be putting the impact point slightly upwind, or am I doing it wrong?

My first suggestion is to go into inventory (INV) on the DSMS and play with the deployment altitude and RPM and make sure the profile specifies a minimum launch altitude above the deployment altitude.

 

I would suggest:

 

PROF

MIN ALT - 1500ft

 

INV

HOF - 1200ft

RPM - 1000

 

It's a good balance between delivery ease, spread and target area saturation. The default min alt and DOF are set to high and yes, it causes problems. Not impossible but not convenient either.

Edited September 6, 2012 by marcos

[159th_Viper]

RPM setting irrelevant for 97/105.

[marcos]

I don't believe the CBU-97/105's spin, do they?

Maybe not, my mistake.

Edited September 6, 2012 by marcos

[marcos]

RPM setting irrelevant for 97/105.

Irrelevant as in not there? Maybe I'm thinking 87/103s, while since I used them.:)

 

In that case ignore the RPM parameter, until you come to 87/103s.

[Invader ZIM]

I actually prefer my HOF settings at 500 to 700 feet for my CBU-97's, but any lower and I found my munitions hit the ground without time to eject their skeets. Most of the time I see a quick target of opportunity and I tend to be at treetop height so making a quick climb and roll over to dive on the target and release a cbu tends to work for me.

 

Added benefit as mentioned above is that the low altitude setting makes the pipper pretty accurate in your hud.

[marcos]

I actually prefer my HOF settings at 500 to 700 feet for my CBU-97's, but any lower and I found my munitions hit the ground without time to eject their skeets. Most of the time I see a quick target of opportunity and I tend to be at treetop height so making a quick climb and roll over to dive on the target and release a cbu tends to work for me.

 

Added benefit as mentioned above is that the low altitude setting makes the pipper pretty accurate in your hud.

Absolutely. It depends on your target. For moving targets, I'd probably use a lower HOF like you suggested, otherwise the lead is difficult to judge. You should really adjust HOF to suit the target.

[Darkwolf187]

Well, I did a bit of experimentation this morning. It seems to me that the wind correction in the LASTE may only make corrections for the complete CBU-97 and not for the submunitions - ie, the ballistics of the weapon change markedly when you hit the HOF, and when using wind correction in LASTE the CBU-97 container appears wind corrected (ie, it breaks open upwind of the target), but then the submunitions float downwind of the target.

 

Running with a lower HOF (I changed to 900 ft instead of the default 1800 ft) doesn't seem to reduce the spread of the skeet hits by much (if any), but it greatly reduces the amount of time the submunitions spend getting blown about by the wind.

 

So, what I'm going to get into the habit of doing now is;

 

- Set HOF to 900 ft by default

- Aim the TGP into the wind slightly

- Use CCRP

 

Thanks for the help :)

[SharpeXB]

I've been using 900' and CCIP CR mode. Since its a cluster bomb the 3/9 setting works fine. Come in just above 900' and avoid getting hit by the deadeye marksmen atop the BMPs and in CR designate the target way out in front of you instead of in a dive.