The CBU 97/105 Effectiveness (lack there of)
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But yes, you’re right that pk is too low, considering it is a line of tanks ~1000ft. They all should get hit at least…, probably soft-killed/unusable… given the weapon and target specs.
Tacview/acmi doesn’t show air-burst, so maybe see BA height?
What is the last recorded bomb altitude… can’t be zer0 ft msl/agl. (shouldn’t be…) -
@jayb Some anecdotal data, if helpful: while flying EMF, I was testing the CBU-87 with loft attacks against a SAM site located on a plateau at about 2600’ MSL. BA values < 2600 produced no spread from the munition. Using a BA around 4000 started to show results, which made me assume that the BA as implemented is in fact MSL, not AGL.
(And—I ask this in total ignorance and happy to be corrected by someone more knowledgeable —wouldn’t that make sense w.r.t. the real thing? It’s a fairly cheap munition with a notoriously high dud rate, so it’s probably set off via some simple barometric trigger, no?)
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@Gadfly that was my thinking too … but if you take one step further – obviously there’s some sort of data-link to update the fusing, based on what you key into the MFD page. it’s possible the avionics could apply the ground-elevation offset, before transmitting BA to the bomb?
could that happen fast enough, reliably enough, for CCIP modes? (and what about MAN release mode?) I have no idea. so, like you I’m inclined to assume it’s MSL, but I can believe AGL if people who know tell me it’s so.
[Edit: wikipedia says it’s “optional FZU-39/B proximity sensor” … which sounds like a little radar-altimeter device]
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@airtex2019 @Gadfly
Tested a little this morning from elevations 200’-6000’ MSL with no difference burst altitudes of 1800’ mostly as @Seifer suggested and then the extreme 3000’ Burst Altitude at both extremes in elevation. Always only two kills even targeting the middle three trucks together that you get in columns. And yes, the simple solution on CBUs is to have a radar altimeter control the burst. -
I would think that it is important to have the radalt active in the jet too. That switch can be overlooked. But I’m with airtex on the BA coming from the jet, likely calculated from active steerpoint
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@Snake122 good thing testing against trucks. The damage can not be messed up from armor values of mbts or ifvs or similar
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@airtex2019 said in The CBU 97/105 Effectiveness (lack there of):
FZU-39/B
[Edit: wikipedia says it’s “optional FZU-39/B proximity sensor” … which sounds like a little radar-altimeter device]yep, seems that’s right.
https://www.bulletpicker.com/pdf/Afghanistan Ordnance ID Guide, Volume 1.pdf#page=236
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@jayb I don’t think the aircraft’s radar altimeter in real life matters. CBU-105 is a bit of a different beast with the data being sent to it, But the non-WCMD CBUs are completely dumb with no data from the aircraft. These are simple stand alone radar altimeters for the burst fuzing.
The other advantage of the trucks is the interval of 3 together before the larger separation distance. The TGP doesn’t like to target the middle one and you kinda have to bump onto it. IMO, all three of these should be taken out but still only 2.
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@Snake122 said in The CBU 97/105 Effectiveness (lack there of):
@jayb I don’t think the aircraft’s radar altimeter in real life matters. CBU-105 is a bit of a different beast with the data being sent to it, But the non-WCMD CBUs are completely dumb with no data from the aircraft. These are simple stand alone radar altimeters for the burst fuzing.
Probably true for real life. But the BMS modelling might require that the Radalt is turned on. We don’t really know until someone with knowledge of how the data and code interact shows up
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@jayb -34 manual page 226 have some insights on this. I dont think its MSl i tested in both near shore and kotan range which is pretty high and observed no change over the covarage.
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@SyntaxErol said in The CBU 97/105 Effectiveness (lack there of):
@jayb -34 manual page 226 have some insights on this. I dont think its MSl i tested in both near shore and kotan range which is pretty high and observed no change over the covarage.
Mav posted a video (for 4.36) about how the SPI altitude can change depending on the sensor - might it be this that causes the discrepancies?
Take a look at
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@CriticalMass well, syatem altitude/range shouldnt effect cbu burst height. Burst height or “altitude” must be a simple radar altimeter onboard the munition, independent of launching aircrafts altitude. The target elevation error may result in bomb falling short or long because of ccrp solution would be wrong but bomb burst is independent of that solution.
Also observed in all shots cbu body landed at exactly where my tgp cross is.
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@SyntaxErol said in The CBU 97/105 Effectiveness (lack there of):
@CriticalMass well, syatem altitude/range shouldnt effect cbu burst height. Burst height or “altitude” must be a simple radar altimeter onboard the munition, independent of launching aircrafts altitude. The target elevation error may result in bomb falling short or long because of ccrp solution would be wrong but bomb burst is independent of that solution.
Also observed in all shots cbu body landed at exactly where my tgp cross is.
Well, I don’t disagree with anything you say, but you seem to be making big assumptions about what the code is or is not doing and possibly conflating RL with a bunch 0s and 1s. for example: “Burst height or “altitude” must be a simple radar altimeter onboard the munition”: I’d be very surprised if the code simulates radars in the weapons themselves.
There may be a number of parameters that influence the “drop” height, the “BA”, the dispersal pattern and many more no doubt: just one of those with an anomalous value (could be random or derived from some other set of values) could cause the observed outcome - other people report good results (different weather? a “glitch” in the underlying terrain mesh? (I’m making this up as I go along )
Anyway, appreciate your thoroughness! Would be good to get a definitive reason for the differences in observed effectiveness.
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The subject will be checked by the dev team later on…
Please stop making assumptions for now…
You don’t have code access… -
@SyntaxErol said in The CBU 97/105 Effectiveness (lack there of):
The frag circle is set at 430 meters (the closest value of reported SFW longitudinal cover area of 460) And while I can get 2 kills consistently when aimpoint is in middle of the group or leading element. The actual Killzone is still a lot smaller than reported coverage area.
For me to understand, 1 bomb would kill 2 tanks? Or was it a group of other vehicles? Could you specify your targets?
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@Tumbler31 yes, 2 is almost always the maximum kill amount. I’ve even switched to dropping on the trucks because sometimes as I said those columns will have those in intervals of 3 close before the larger spacing distance (can’t remember total radius of the trucks, but seems well within published radius). Still only kills 2 trucks despite targeting the center truck and 500-3000 Burst Altitude range.
GBU12 at this point is just as effective with it’s blast radius in my testing, it also almost always results to two kills, even if it is tanks next to each other.
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@Tumbler31 Its a T62 brigade, target point was at first 2 groups of tanks, groups are consisting of 2 tanks (nearly 30 vehicles so 15 groups) in line formation.
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@SyntaxErol No problem.
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@Kavelenko again CBU-87CEM, not 97/105. This is 4.37 or the “good old days”? Armor, motorized infantry, or supply truck column?
It’s missions like that that gets the medals in the logbook, which these days I think not be able to get them with most loadouts is probably a good thing.
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@Snake122 I get even better results with CBU 97s but testing 87s at the moment. Something wrong with CBU 105s but no facts to back that up, just not very successful with them at the moment. Will see what I can do with CBU 105 because I’ve only done a couple missions with them. I have not messed with any data files this is straight out of the box, so I would hold fire with criticizing 97s, and 87s for now, just my opinion.
Latest test with CBU 87s below, will try CBU 105s later I’m pooped.