Viability of tossing CBUs?
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Found some discussion about it, but nothing that really covers what I have in mind.
How viable would it be to toss (using whatever mode is best suited) CBUs from behind a mountain without exposing myself by going over the top of the mountain, or just briefly? If I have a high burst altitude (6000-7500 feet), will I experience problems lofting the CBUs high enough, and if I do, can I count on the bomblets falling on the designated target?
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With CBUs it might be an issue staying behind a mountain, unless that mountain is a few thousand feet tall. I’ve noticed with CCRP lofts you have to maintain nose-up for an excruciatingly long time period before the bombs come off the rail. You could try switching to MAN mode when the toss anticipation cue appears, pull up and release instantly. It works well with JDAMs, maybe not so well with CBUs (when do we get CBU-103/105s?).
According to WDP, the minimum release height for a toss seems to be 3500 feet. I would still consider it effective even if you are exposed above the mountain for a brief period. Release and duck behind the mountain.
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Toss works for CBU, but jinro makes good points about it’s application.
Burst Altitude of 6000 - 7500, I would expect to create dispersion problems. I.e. the bomblets will be so dispersed as to be ineffective. Conventional wisdom seems to be 2000 - 3000 ft to balance dispersion against concentration.
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Re dispersion I’m talking about e.g. lofting 4-8 CBUs and opening at an altitude of 6000-7500. I’ve had quite good results from just a pair with CCIP using that height, but that might of course have to do with the steep dive and high speed I suppose.
What trajectory can I expect of the CBUs by the time they burst? The concern I have apart from being able to gather enough energy to toss them is that they will end up with a relatively flat trajectory at 6000-7500, and thus throw the bomblets long of the target.
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Re dispersion I’m talking about e.g. lofting 4-8 CBUs and opening at an altitude of 6000-7500. I’ve had quite good results from just a pair with CCIP using that height,….
:hmmm: …. I’ll have to try that. Kind of surprising/counter-intuitive. Wonder if it’s some of modeling effect?
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Well, as I said I’ve only really done that in quite high speed dive bombings, so I suppose IRL the bomblets ought to have less ability to spread out once the CBU bursts. It’s also been pairs, so it’s twice the regular amount as well.
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Well, as I said I’ve only really done that in quite high speed dive bombings, so I suppose IRL the bomblets ought to have less ability to spread out once the CBU bursts. It’s also been pairs, so it’s twice the regular amount as well.
OK, I think I mis-read the part about lofting. Just to clarify, in the High Altitude Dive Bomb …. is the ‘Burst Altitude’ 6000 - 7500 feet or is that the release altitude?
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For dive bombing, yes, that is the burst altitude I tend to use for one pair of CBU-87s.
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For dive bombing, yes, that is the burst altitude I tend to use for one pair of CBU-87s.
I haven’t done much (any?) High Altitude Dive Bombing. I’ll give it a shot. Thanks.
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why don’t try it and tell us what happen?
It’s a bit gammy. BA settings are built into the bomb. irl, the BA in the SMS is for FCC calculation and the pilot can’t change the BA on the fuse. The CBU-97SFW can be released a 200ft and rocket motor will thrust it to BA.
I tried lofting over mountains in F4AF. The issue I had was when the CBU was released below BA. The code was porked and the CBU would burst as the bomb when up thru BA and not on the way down.
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…. It’s a bit gammy. BA settings are built into the bomb. irl, the BA in the SMS is for FCC calculation and the pilot can’t change the BA on the fuse. …
I had read some posts on this not too long ago. In RL, can the BA be set to various altitudes prior to take-off? What I mean is, can a pilot direct the crew to set BA at, say 2000 feet …. then, maybe the next mission with the same weapon, direct the crew to set the BA at, say, 1200 feet?
Assuming the BA is ‘user selectable’ (pre-set before flight), what is a real-world useful range for BA … min to max?
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r/l max is max. At some altitude the footprint doesn’t get any bigger. Just gives the wind more effect on the bomblets.
Max would be for personal and light vehicles. Min would be for armor were the bomblet/s would have to contact the tank.
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don’t release just one as you will lose significant control of the a/c…pairs yes!
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FZU-39 on SUU-64A is A-K (I skipped) 300, 500, 700, 900, 1200, 1500, 1800, 2200, 2600, 3000’. It’s set before hand, probably with a screw slot or thumb wheel (something physical).
For target application you’d consult the JMEM but the critical factor is bomblet density. Eddie said that soft target is 5-7 per 1000 sq ft and hard target 10 (roughly). Considering 202 BLU-97A per can it takes 2-4 cans to reach such high densities for even a small(ish) area. Page ate my earlier math but if you do the calcs 808 bomblets (4 cans) could theoretically do high density for 80,000 sq ft or a 320’ diameter circle (surprisingly close to 100m diameter). That’s tiny compared to what the dispensed area is capable of at max RPM and HOF. The 476th vFG table shows the limits being 40x40’ at RPM-0 HOF-300 to a massive 4100x3500’ at RPM-2500 HOF-3000.
I don’t know what RPM BMS aims to simulate but unless you’re a B-52 carrying more cans than a supermarket, you’re going to be releasing 2-4 with max overlap at HOF no more than 1,000’… in the anti-armor mission.
One thing you have to be careful of in BMS is that if you loft CBUs with proximity release you must release above the HOF plane. If you release below the HOF plane the canisters will dud (unrealistic). Otherwise there is no limitation on lofting. IRL you want to make sure to deconfict the weapon with any terrain, jets, Santa Claus, etc. after the ~2-3s AD time but before arriving above the target. Also the radio prox senses in a wide “bubble” which triggers based on proximity and not slant range which might affect your footprint.
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r/l max is max. At some altitude the footprint doesn’t get any bigger. Just gives the wind more effect on the bomblets.
Max would be for personal and light vehicles. Min would be for armor were the bomblet/s would have to contact the tank.
Sorry, I meant what is: what is a general min BA setting in feet and what is general max BA setting in feet? . I think that’s what Frederf posted here:
FZU-39 on SUU-64A is A-K (I skipped) 300, 500, 700, 900, 1200, 1500, 1800, 2200, 2600, 3000’. It’s set before hand, probably with a screw slot or thumb wheel (something physical). ….
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Sorry, I meant what is: what is a general min BA setting in feet and what is general max BA setting in feet? . I think that’s what Frederf posted here:
It would have to do with the CBU design. Different CBU use different BA settings. There are docs for different types of CBUs and target types.
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Don’t post them unless they can be found in quantity in the public domain!
-Babite -
According an UXO-CBU study the CEM spreads over an area “120x200’ to 400x800’ .” Obviously the CEM is capable of footprints larger and smaller than this so perhaps this gives a hint as to footprints used operationally. Another hint is a “required 60’ overlap” in patterns which also suggests footprints of that size order. One can work backward from footprint tables to discover what settings to make.
In the end this is a BMS weapon in a BMS environment with BMS results. Only testing is going to provide meaningful feedback as to what densities are required for acceptably high Pk against various targets.
