B-29 high altitude accuracy

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The 8th Air Force report on bombing accuracy Sep - Dec 1944 has a section on the effect of altitude.

Percentage of bombs within 500ft and 1000ft of the aiming point in good visibility (B17 only):

Altitude - 500ft - 1000ft
Upto 12,000 - 31.7% - 66.6%
12,000-14,900 - 25.7% - 60.2%
15,000-17,900 - 22.7% - 55.7%
18,000-20,900 - 17.5% - 44.8%
21,000-23,900 - 14.2% - 37.3%
24,000 and up - 12.6% - 31.7%

The figures for B-24s show a similar pattern, but a bit worse (the B-17 averaged 15% within 500 ft, the B-24 10.2%)
 
Hop, What type of formation were the aircraft in, or were they individual? Clearly if there are 3 x 112ft wing span in a V then they are going to add at least 200ft on their own? Also, what are the release patterns on the bombs ie are these individual releases (one bomb per aircraft) or a trail?

The accuracy below 12000ft gives an indication of how effective the B-25, B-26 and A-20 might have been. Clearly anything within 500ft of a point could be considered on target given the size of the formation and the likely factory or shipyard target.

I would add that these i think are highly, really highly idealized in that weather in most cases in Europe would degrade that by several times.
 
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The figures are for all 8th AF attacks in 1944 that were carried out in conditions of good visibility. So the formations would be whatever size the 8th were using in 1944.

I would add that these i think are highly, really highly idealized in that weather in most cases in Europe would degrade that by several times.
Click to expand...

Yes, the figures are for good visibility only. At the other end of the scale, in heavy cloud using radar aiming, 0.2% of bombs fell within 1,000ft of the aiming point, and 5.6% within 1 mile. In the period Sep - Dec 1944, 35% of all 8th AF bombing was done using radar aiming through heavy cloud.
 
View attachment Accuracy 43.zipView attachment Accuracy 43.zip
The report referred to is attached below

View attachment Accuracy 44.zip

The Operational Research Section did a number of reports - the only other one I've found as a pdf is from 1943.

View attachment Accuracy 43.zip
 
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Sorry for the repeated posts, I get timed out otherwise.

Note that both the reports above exclude from their numbers "mission failures", in which none of the bombs came within a certain distance of the aiming point, as well as bombs dropped on targets of opportunity, which by definition have no pre-determined aiming point. These two can account for quite a substantial proportion of total bombs, even under visual conditions.

The USSBS did a separate report on bombing accuracy in the ETO, will see if I can find it.
 
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mhuxt said:
Found the USSBS report. It may duplicate some of the above, but anyway...

View attachment 265837
Click to expand...

Your timing is perfect. I am editing a paper for which I needed a number about accuracy.
It's interesting that none of the ETO reports seems to have "overall accuracy." For example, of all the bombs that took off from England, what percentage fell within .5 miles of the designated target? I have seen such numbers in some interim reports from the 20th AF.

Such a total would include the effects of:
  • Mission aborts by individual aircraft, and entire groups.
  • Diversion to secondary targets due to bad weather or other factors.
  • Bad weather when dropping (which has a huge effect in the data you provide)
  • Enemy action before dropping.
As well as all the other problems they document for groups that did get over the designated target, in decent weather.
It would also be interesting to use modern statistics to re-analyze some of this data. It's impressive how far these authors got with no knowledge of techniques like regression analysis.
Thanks again for your very timely post!
 

No worries, glad the info was useful. Have a look especially at pages 18-22 of the 1943 document, in which the analysts describe various measures of presenting the results. If I'm reading it correctly, the "All Missions" measurement describes % of bombs within 1,000 feet and 2,000 feet of pre-assigned aiming points, whatever the weather conditions, altitude etc. Again if I'm reading it correctly, bombs dropped on targets of opportunity will be counted as "misses" by this measure, as they were not targeted onto pre-assigned APs.

It would indeed be neat to re-analyse the data, I was at one time a fervent fan of MiniTab - by now I'd have been dancing about shouting "Data set! Data set!". I don't know how much of the Ops Analysis book you've been able to run through, however even though it was classified by my local library system as being a "History of Mathematics" book, there's remarkably little in the way of actual math in the text. I believe there's rather more at the end of the 1944 report.
 

Thank you. I missed that section. It is indeed almost exactly what I want. There is a slight discrepancy because it is based on a fraction of "all bombs dropped on enemy territory," but since pilots did not return with undropped bombs, the impact of this is small. Mission aborts should not be included, but that is only a few percent of missions launched.
 

Heya,

There is another table which may suit, the very last page of the USSBS ETO accuracy report. It has all the information but fails to provide an overall total:



I double-checked the total tonnage against Davis' spreadsheet of bombing raids (more on that later). Davis has a total of 165,000-odd tons, the report 159,000-odd. As the report excludes three ground support raids (I couldn't determine which three) it seems a very close match. Note that it includes incendiaries and fragmentation bombs - I believe incendiaries were carried by the same bombers which carried HE (again, more on that later.

I pumped it all into a spreadsheet, and multiplied the % of total load by visibility by the % of bombs hitting within the various limits and came up with the following (note the effect of bombs dropped on targets other than the briefed AP, about 11% of the total).

View attachment USAAF Overall Accuracy Late 44.zip

In short, just short of 6% of the total bomb load was dropped within 1,000' feet of the AP during the period in question, slightly more than 6% of the bombs which were actually aimed at pre-determined aiming points.

I'll make some more posts below, more to separate the various issues than to boost my post count.
 
I mentioned there'd be a number of posts...

From the British Bombing Survey Unit, I came up with this:



Edit - download and zoom in, the notations are clearer.

You'll see that in late '44 BC was getting 80% or more of its load within 3 miles of the aiming point (and yes, it was a point, not an urban conglomeration), while the 8th was getting around 70%. I believe this *may* be the origin of the claim that BC by night was generally more accurate than the 8th by day. I've not read enough of the BBSU report to be sure, I'm just the messenger here.

Note that someone in the BBSU has made a serious boo-boo with this USAAF graph - that line corresponds far more closely to attacks under visual conditions than to the USAAF's own assessment of overall accuracy. I've attached it as it at least provides some insight into visual accuracy during periods for which I've not been able to find a pdf report

 
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I've noted above the USAAF was getting around 6% of its load within 1,000' feet of the aiming point. The effect the USAAF raids had on German fuel production is well known: from the USSBS report on oil we get this:



Didn't take a great deal of accuracy to have a decisive effect on fuel production, just volume.
 
Brings me to my own personal axe-grind - the fact that Bomber Command had both the technical means and volume of bomb-lift in 1943 to get its foot on the neck of German fuel production, but failed to do so.

Oil had from the start of the war been identified as a critical system, indeed it was one of the things the ill-starred Pierse was trying to hit. By the time his successor Harris was equipped with Oboe and a large force of heavies, BC could have resumed the attempt, but did not do so. Harris' opposition to "panacea targets" is well known, however when ordered to he had his command pursue objectives about which he himself was ambivalent, for example the Pathfinder Force and the attacks on communications ahead of the invasion.

Much of the oil industry was in the Ruhr, in Oboe range, and the Oboe repeater system (there's my axe, hear it grind...) was capable of extending Oboe accuracy well into the Reich, but neither the technical system nor the target system was pursued.

I believe it's in "The Bombing War" in which Richard Overy builds the argument that, despite technical limitations, the USAAF at least worked out a logical, numerically-based approach to how the bomber could win the war, in stark contrast to BC's consistently wooly claims.

Anyway, there's a tale of how a few Mosquitos, with similar accuracy to the 8th, shut down a couple of the Reich's fuel-production plants in the official RAAF history here:

http://static.awm.gov.au/images/collection/pdf/RCDIG1070709--1-.PDF

And an example of how, even late in the war, the USAAF had to struggle with accuracy here: (I include it only as it's an interesting example of the work of the Operational Research boys, not because I have any particular flag to fly re: daylight accuracy) Abortive attack on the Leuna plant - the H2X operators must have targeted the town, not the plant is my guess

 
Final post for the moment - I apologise if the post immediately above comes across as too preachy. The wife is on a girls' night out and I've had my first beer for a week. MMmmmmmmm that Coopers is a nice drop, but occasionally it, shall we say, alters one's approach to dispassionate posts.
 
Not only the jet stream and wind drift but also in an air perfectly still the air temperature and air density change a lot from ground level to flight level with practically unpredictable gradients. And a variation of air density, with consequent variation of drag from, say 20.000 feet to ground level, implies an error of several hundred feet, if not meters.
 
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mhuxt said:
Didn't take a great deal of accuracy to have a decisive effect on fuel production, just volume.
Click to expand...

Precisely the point I was making in another thread about the possibility of an imaginary, small, Luftwaffe strategic bombing fleet having the ability to cripple the Soviet power system. It is the reason why both allied air forces flew raids with several hundred bombers. To be sure of hitting the intended target or anything meaningful they had to drop a lot of bombs. Both of them did the statistical analyses and both based them on rather optimistic BDAs as the subsequent bombing surveys showed.
Cheers
Steve
 
The RAF certainly seems to have "run the numbers" re: how much would be required to restrict rail movement through France ahead of D-Day. I suppose someone in the RAF must have done similar work re: oil, perhaps one of the Buftons, sadly they couldn't get the point across.
 
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