Fragments from the explosion: how high to fly?
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There is an extra 27 in one of the charts
OK, I’ll bite! Can someone explain how to use these charts?
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Actually, the inclusion of these two bits of text makes it much more obvious what they are saying
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@Mav-jp said in Fragments from the explosion: how high to fly?:
@Mikyjax said in Fragments from the explosion: how high to fly?:
@Stevie I agree, it looks like the pictures from bms dash 34 are the same warheads. The picture shared by mav JP seems to be the correct ones (I honnestly thought there was more difference in the fragments between those warhead, interesting)
see superimposed pics below
As you can see mk82 and mk84 frag patterns are nearly similars
Which makes sense ballistically. The fragments and explosive velocity would be similar. Mk.84 would have more fragments but the engery of them are going to be similar with the same explosive. It’s like different gauges of shotgun shells if you’re familiar, the pellets are propelled at similar speeds, but different gauges have more pellets. So the fragment cloud is going to be denser with the Mk.84 and slightly further distance. I don’t know about shock wave strength effects though, probably stronger?
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@Snake122 - don’t confuse ballistics with the effect of a static explosion…which is what these represent. Based on experience with the weapon(s) in question, there is no way that a 500 lb warhead will exhibit the same explosive energy as a 2000 lb one. Also, having walked the ranges and picked up chunks of RL MK80 series frag, I can also tell you that the chunks aren’t the same size between the two. I can see the two are different, I just don’t believe they are different enough…
These plots have nothing to do with ballistics - which have to do with sight picture to place the impact where you want it to be. They are the observation of a static destination on the ground, and that is all.
Effects of how the weapon impacts are not depicted (or considered) in these plots. Only position/expectation of frag in seconds post static detonation.
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@CriticalMass - so there are really three charts you have to use:
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the ballistics tables for a manual release of the weapon. This will tell you what mil depression the release will occur at, what range to target and altitude you will be at, and the time of fall for the release.
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the dive recovery chart(s) for your aircraft - there are more than one, based on target G during recovery. This will tell you how far down range you will travel from the time of release to full dive recovery to level flight (usually with a 2 sec reaction time to initiate).
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once the above are known, you plot your down range travel against the bottom axis of the “daisy plot”, and note the time it takes you to get there - then compare that time to the frag envelope post destination (which is time of fall plus your recovery time).
This is why you have to have all of this information for each specific munition…your GWT/speed/dive angle/G limits will factor into the dive recovery and thus the end answer. Most of the time you may just plan to clear top of frag (and/or avoid terrain - dive recovery charts consider terrain avoidance only), unless tactical situation dictates you fly lower.
Back when I was working Harrier we used to drop one of EVERYTHING in the TACMAN during Verification…I was responsible for the weaponeering for every drop series, so I got to do a LOT of this. One of my favorite calculation was to calculate the size of the bomblet pattern on the deck for MK20s released in pairs and bet against my pilot - I’d use the book, he’d use experience. The book was generally right…fun stuff.
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Found this in the BEM pdf page 404 5-88 . Maybe it would apply to debris ?Screenshot_20231221_195549_Adobe Acrobat.jpg
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@phboudreault - the problem with this is that there are no definitions of what the numbers mean, and I can’t force-relate anything in this table into any RL manual I know how to use…let alone what “intact cluster” means…
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Intact cluster would be a cluster that hit the ground intact, i.e. didn’t burst and a high-order detonation. ( https://books.google.com/books?id=omAX-QGXFdMC&pg=PA7 ). This is a worst case scenario for frag hazard.
It should be noted that not all Mark 82s are created equal. Newer warheads have scoring for more consistent frag elements which is more fragments but the big nasty pieces with good ballistic properties more rare. It’s interesting to compare the 1985 Tac Attack table with the 1996 MCH table.
Of course P(hit) threshold is 0.1% which is what is considered acceptable risk. The distances at 1%, 10%, etc. are appropriately closer. The size of your airplane also has an effect. The PH for a B-52 and an F-5 aren’t the same at a given distance.
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@Frederf - the avoidance tables I’ve worked with never contained any reference to Probability of Hit (mil Dispersion, really)- that’s part of the ballistic tables for each munition. They also take into account which platform and software are being employed…which was most of what my job was about at the time - verifying that data against the symbology for a given software Release.
One of the problems with cluster munitions is that in a lot of cases not ALL of the submunitions detonate - in fact, I’m not even sure that in the case of a function fail with a MK20 that any of the submunitions will/do detonate…we never had or considered any estimation of burst for a failed canister, other than that it would fall within our designated Safe area.
Interesting aside - back during the Desert Storm days there was some question as to just how many MK20 (and submunitions) would fail just because they had been sitting in the magazine for so long…so flight after flight of A6s loaded with MERs and as many live MK20s as they could carry dropped them on Range twice a day for a few weeks to gather statistics…you could hear the detonations, and they weren’t as loud as you’d think (but did get your attention)…compared to some of the MK80s and others I’ve personally heard. Worst case having been a FAE - that thing rocked the whole hangar, even though it was miles away!
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Why wouldn’t dive tossing be preferred for low drag bombing?
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@tarball - dive tossing really has more to do with the tactical situation than it does with high/low drag. One case I can think of where one may want to dive-toss is when bombing uphill from low level, onto a bluff for instance. The math tends to fall apart when you are bombing a target at an elevation above your own…but really you’d be closer to lofting in this instance.
Most of the discussion I’ve had with RL pilots re: dive toss is that a dive toss is really a last ditch sort of delivery - where you end up having to pull off target because you are taking fire…but in the last ditch you can eek out a solution on target, but with G on the jet. In general you’d never plan to dive toss - chances of a miss are too great to be reasonably effective.