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Ratio of uxb

MINENAZ16

Well-Known Member
Ordnance approved
Hello,

I heard a lot about the percentage of unexploded bombs, but does anyone know (from official reports) the ratio of US (for example 500lb GP) unexploded bombs after a standard bombing (I know this ratio could vary due to weather, soil type, fuzes...)

Regards
 
US EOD rule of thumb has for decades been 10%. You can make many arguments, but generally I believe that is pretty accurate. I've seen many claims of fuzing designed to eliminate duds, and while I realize that you may limit, Murphys Law is never cheated.

I spent four years at White Sands Missile Range (WSMR) as an EOD Team Leader, working R&D tests every day, weekends and holidays included. Much of that included many of the newest systems of the day and all of the improvements you could imagine. Among R&D we also conducted Lot acceptance testing of many submunition systems including MLRS, ATACMs, Lance, MK 118 Rockeyes, BLU-97 etc. These tests were tightly controlled as systems were deployed into specially prepared long term test areas called WITS (Weapon Impact Test Site). The WITS were leveled, graded, marked in 100' squares so that every detail of impact patterns and effects could be detailed. They were a circular area 2 miles in diameter, we had nine of them on WSMR.

As part of the Lot acceptance testing for MLRS we would fire three full up six-packs, one at ambient temperatures, one heated (hot box) and one refrigerated (cold box). The heated and refrigerated six packs would be moved directly form the climate chambers at the launch point onto the launcher and fired immediately. Each six pack was done separately, and depending upon data recovery and clearance efforts it could be up to two weeks or more between firings. After the firing we would map the impact patterns of the six rockets from the air (helicopter), then move in on foot and clear grid by grid, identifying duds and their locations. Once the duds were identified and mapped we would detonate all duds, and the data collection people would move in for crater counts, motor, fuze and skin section locations, motor nozzle examination etc.

This gave an excellent view of the difference that temperature alone could make on dud count. Noting that this was firing into a perfect impact area, which was re-graded after each firing and returned to condition, an ambient six pack (644 submunitions per rocket) would average between 175-250 duds. Hot would drop to 150-200. Cold would run around 250-400. Keep in mind that during my tenure there we averaged one six pack a week, for over 4 years, so we were pretty confident on our observations and could predict fairly well what our workload was going to be from a given firing.

As you noted, other environmental conditions also affect things significantly. A pattern missing the impact area (rare, but shit happens) would result in impact into soft sand, high grass, snow, etc. All had significant results on dud rate, generally pushing it up higher and higher. This was mirrored with other systems described above and also noted in patterns observed in the Gulf War.

So individual systems vary, impact in different environmental conditions vary, but when you average it out is all seems to come back to about 10%, regardless of improvements or technology. Once it gets to the field the field wins.
 
An interesting question and a very detailed and comprehensive answer based on your experience. Thank you for taking the time to write the post, it made for an informative read.
Best Weasel.
 
It is my understanding all those dud MRLS submunitions caused Allied forces a great amount of grief when occupying Iraqi positions that had been bombarded. I wonder how many millions of duds are still buried in the WWI battlefields of France?
 
Yes, France has enormous quantities, but the farmers in Belgium unearth UXO every time they plow their fields.
 
It is my understanding all those dud MRLS submunitions caused Allied forces a great amount of grief when occupying Iraqi positions that had been bombarded. I wonder how many millions of duds are still buried in the WWI battlefields of France?

Steve, it wasn't just MLRS in DS that gave us the Willie's. A lot of Rockeyes, Beluga's, etc. were used. It was like they were clearing out the bunkers of all the old stuff. Responded to several positions hit by Rockeyes and nearly got left at a site in the middle of nowhere when we ID'd them and the '46 pilots freaked and pulled an immediate DiDi. My worst was finding a 5" Zuni HE warhead in the middle of a depression in Kahafji near a de-salinization plant and major road. Something told me I didn't want to move it, so we got the info and blew it in place (BIP'd) it. Got in to the pubs later and found out the base fuze was a MIG (magnetic induction generator). Made a nice pond in the Sa'abka (sp?).
 
It was fascinating to see the results of many of the munitions when they left the test area and actually encountered the real world. Someplace I have a photo of something I would have sworn was not possible, I may have posted it previously. A MK116 Rockeye which hit a high power line, and stuck in the line. A million to one shot, and to actually penetrate and stick - but I guess more than a million were probably dropped, so maybe not that rare.
 
Jeff, like you, I saw some odd hits/duds with the MK116. A pod opened near the aforementioned 5" and there were a bunch of them sticking in the asphalt like lawn darts. Some creamed in, but there were several intact.
 
The Journal Vol. 156, No. 1 of June 1947 of the Institution of Mechanical Engineers gives the following percentage of UXO's of German bombs dropped on the UK.

Greetings - Antoon


IMG_4162.jpg
 
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Did they give any information on how they came up with those figures? It would be interesting to know how they calculated it then, and based off what data.
 
The writer of the article was H.J. Cough, former chairman of the Unexploded Bomb Committee during WW-2 in the UK. So I think he was close to the actual information in that time.
The article gives also the following information:
By the end of 1945 more than 50,000 high-explosive enemy bombs of 50 kg or over had been dealt with in Great Britain alone. The total number of high-explosive bombs dropped is not accurately known. Table 2. (see previous post)
taken from census figures collected during the most active period of enemy raiding, shows that about 8 per cent failed to explode; during the sporadic raids of 1943 and 1944, an average figure of 20 per cent was approached.
 
Hallo,
about 10% is also the figure I read in german EOD reports of WW2. But, nearly every day, since 1945, more duds are unearthed. So, the percentage is rising all the time. A test, like that described above, where you can account for every single round, is something completely different from field-use.
Bellifortis.
 
The percentage is not rising if you do not know the numbers dropped. You never had a percentage to begin with. A test will always be different from the field, but it gives a baseline for understanding, something to build on and estimate from. The minute that you say you do not accurately know the number dropped however, you have nothing but guesswork. There has to be some basis for the estimated percentage. If you know how many were dropped you can then look at how many you've found and even estimate how many more you may find - based on data.
 
Hallo,
you are right with that @US-Subs,
I do not know how the germans came to that average 10% figure for allied duds. For german bombs in WW2 about the same average dud rate is reported. Between 7% to as high as 15%. The dud rate increased steadily from summer to winter. Many of the problems were found to have resulted from bad storage in the field of fuzed bombs, so that moisture could enter into the fuze. The allied mechanical fuzes had other problems.
regards,
Bellifortis.
 
"The article gives also the following information:
By the end of 1945 more than 50,000 high-explosive enemy bombs of 50 kg or over had been dealt with in Great Britain alone. The total number of high-explosive bombs dropped is not accurately known. Table 2."

The key word appears to "dealt" implying that action was taken. These figures would thus include "nuisance bombs" (Delayed Action) of which both the British and Germans both used in quite high percentage. These can't be classed as malfunctions.

The figures don't state when the bombs that were dealt with, were dropped. During WWII British Bomb Disposal was inudated with unexploded bombs and the only way to cope was to prioritise the incidents. A lot of low priority incidents were put aside for a very considerable time.

TimG
 
I think the mistake made here is that a spent motor from a cargo rocket is misidentified for a complete rocktet with a HE warhead sticking into the ground. I've seen the remark/question pass on the Dutch ammo collectors site about this subject too.
The types of 300 mm rockets mostly used by the sowjets are the cluster ammunition and the thermobaric, both seperating the engine from the warhead.
It's also quite a confusing text with the picture; and unexploded tail section... which appears to contain cluster bombs.... I know the average russian ammo factory worker likes his wodka even on monday morning, but I assume that even in Russia a tail section containing cluster bombs would not make it through quality control.
Counting in these spent motors as duds will make the number of duds rise fast.
 

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There are a couple of articles saying the Russians are experiencing up to 60% malfunction rates on some of their ordnance fired in Ukraine.

https://www.yahoo.com/news/many-60-russias-missile-strikes-114321086.html

I think the mistake made here is that a spent motor from a cargo rocket is misidentified for a complete rocktet with a HE warhead sticking into the ground. I've seen the remark/question pass on the Dutch ammo collectors site about this subject too.
The types of 300 mm rockets mostly used by the sowjets are the cluster ammunition and the thermobaric, both seperating the engine from the warhead.
It's also quite a confusing text with the picture; and unexploded tail section... which appears to contain cluster bombs.... I know the average russian ammo factory worker likes his wodka even on monday morning, but I assume that even in Russia a tail section containing cluster bombs would not make it through quality control.
Counting in these spent motors as duds will make the number of duds rise fast.


The article mixes up two different things. The US official would seem to be talking about guided weapons launched by complex weapon systems. For example the 9M79 and 9M723 series of ballistic missiles and cruise missiles such as the 3M-14 series, Kh-55 and Kh-101. The article then goes on to talk about an entirely different class of munitions, which it equates as being the same as those above.

The rocket motor bodies seen are mostly from the 220 mm unguided rockets of the 9K57 Uragan system, or the 300 mm guided rockets of the 9K58 Smerch system, along with 122 mm rockets from a multitude of different systems. Of the 11 common 220 mm rockets, only one is fitted with a unitary (HE-frag) warhead, all the others are dispensers (submunitions, mines, smoke, etc.). For the 25 known combat guided rockets of the Smerch, only two carry unitary warheads. Of the rest 18 are again dispensers, whilst five are separable unitary. I've not gone through all the 40 odd 122 mm models yet, but there's a more even mix of unitary and dispensers.

The rocket motor bodies seen are commonly not duds, but are just what's left of a rocket that was originally fitted with a dispenser or a separable unitary warhead. Once the payload has been dispensed/released, the rocket motor body, which is commonly still attached to the outer warhead assembly, continues to fly a ballistic trajectory until it strikes the ground. It is this rocket motor body, or combined rocket motor body/outer warhead assembly that is seen stuck in the ground.

Of course even unitary warhead equipped rockets/guided rockets, still have a rocket motor body attached to them and this will be found at or near the impact site, though they are generally in a far worse condition.

Many 'failed' bombs I've seen have been parts of crashes, shot down aircraft, likely dropped at the wrong height, or not fuzed correctly. I've not seen many that were obviously true duds (the fuzing system truly failed).

Even guided missile bodies of 9M79 and 9M723 series of ballistic missiles equipped dispensers warheads have been reported as duds. This is again incorrect. When the warhead operates and dispenses its payload, the now unstable remnant missile tumbles to the ground. The spent missile bodies, to those who are ignorant, are classed as duds. Unitary ballistic missiles, which either function correctly or have failed, will simply bury what's left on them in a steaming crater.

The final class I can think of are cruise missiles that have either been shot down, or have attacked a higher altitude target (radio tower, building etc.). Unless it's got obvious fragmentation or impact strikes on it from an external (not internal) source, then it's unlikely to have been shot down. If it had previously hit a high-level target, what is left will carry on relatively unimpeded until it impacts with the ground. If it buried itself into the ground and the warhead hasn't functioned, then the fuzing has failed, or wasn't fully armed at impact (many only fully arm when near their intended target).
 
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