8th AF bombing

ThomasP said:

reductio ad absurdum (maybe )

Assume you are using guided bombs. You wage a campaign using these weapons. During the campaign you drop 100 bombs. All 100 land within 10 ft of the aiming point (assume close enough to have done significant damage to anything at the aiming point).

After the campaign you find that only 50 of the aiming points were at the correct target. When you do your post-campaign analysis of CEP, what do you learn from using the 50 bombs that hit the correct aiming point, and what do you learn from the 50 that hit an incorrect aiming point 10 miles from the target.

If useful for the problem we are discussing we can change the numbers that hit the wrong aiming point to only 40, with the remaining 10 being dropped over open ocean (500 miles away - say we are in the PTO) due to engine failure aborts.

Or make it 9 out of the 10 are dropped over open ocean due to engine failure aborts, and 1 destroyed when the bomber crashes at the end of the runway on TO.

What is your CEP?

What do the CEP results tell you?

Does it make any sense when evaluating other phenomena in the campaign?

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If a weapon is jettisoned because of system failure (engine, fuel, hydraulics etc) then it is not counted as being dropped/launched at the intended target. Same-same for a weather abort with the bombs being jettisoned over a "safe", designated area of the sea. Such circumstances are always classified as mission aborts and are not considered in the CEP. IMHO, a formation that attacks the right target but misses isn't in the same class of mission failure.

In your first example, if the pilot selects the wrong aim point then he/she isn't attacking the right target. The aim point (in modern parlance the Joint Desired Point of Impact) is defined by the targeting process and not randomly selected by the crew mid-mission. If the pilot is tasked on a particular target but misses entirely because of navigational errors, then the weapon missed the desired and tasked target. Period.

The example we're talking about is when a formation attacks the right target but less than 5% of their bombs fall within 1000ft of the target. That's not 5 miles away or over the ocean. Discounting raids that meet this criteria seems really odd to me. Even if the formation attacks the right aim point, the sheer size of the combat box formation means that, at best, 40% of bombs would fall within 1000ft of the target. That's under perfect conditions with every bomber at the same altitude, all bombs falling evenly, and the lead bombardier releasing at the optimal instant. That percentage falls off drastically when we factor in different altitudes of aircraft within the formation, or if there are other errors (the formation is slightly off-track, the wind speed/direction is mis-calculated, or the lead bombardier pickles slightly early or late).

GregP said:

4) You do NOT want to include when the target was obscured or when the bomb aiming device was not working properly or not used properly ... only when everything was good. Then you have a chance to make the impacts better with altered procedures.

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But we're not talking about these circumstances. We're talking about formations attacking the right targets but less than 5% of bombs falling within 1000ft of the aim point. No mention was made of weather or system malfunction. Excluding these missions/formations seems arbitrary to me, and smacks of excluding figures that we don't like in our analysis.

Possibly I misunderstood what you said earlier?

re post#23 "By definition, CEP is the radius within which 50% of the bombs land that are dropped against a planned target. There's no outer limit on the distance from the aim point. If a formation entirely missed the target area, then so be it. It doesn't matter that some of the bombs fell 25 miles away...they can't just be discounted because doing so makes a nonsense of the entire concept of a CEP."

ThomasP said:

Possibly I misunderstood what you said earlier?

re post#23 "By definition, CEP is the radius within which 50% of the bombs land that are dropped against a planned target. There's no outer limit on the distance from the aim point. If a formation entirely missed the target area, then so be it. It doesn't matter that some of the bombs fell 25 miles away...they can't just be discounted because doing so makes a nonsense of the entire concept of a CEP."

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That's just one example. There are plenty of other situations. I went back to the earlier post in this thread which stated that missions were discounted if less than 5% of the bombs fell within 1000ft of the aim point. That's a pretty stringent criteria upon which to entirely discount the CEP metric for the reasons stated in my last post.

Expecto absurdium!

GregP said:

Expecto absurdium!

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Brilliant.
I might just have that engraved on my tombstone. Or the motto of some scam online college I might set up.

Beware the terminology seems to shift at times.

The USSBS accuracy table is using the same data as the 107 page 8th AF Bombing Accuracy report dated 20 April 1945 for the 1 September to 31 December 1944 period which has a lot more details, like altitude, raid size, B-17 versus B-24 etc.

The report says for H2X Gross errors in 10/10 cloud, 42% of all pattern centers were more than 5 miles from target, 35 to 45% of effort had errors of over 5 miles, due to accidental releases or failures to release (The latter was being fixed by radio signalling release), H2X failures, formations crowding or interfering with each other and target misidentification. Lots of clouds means bad weather, including wind drifts more than the bomb sight could handle, lack of H2X sets meant more group attacks instead of squadron attacks.

H2X failure in 45 out of 240 squadrons with errors of more then 5 miles. Overall 16% H2X failure at squadron level. 105 out of 3,025 formations experienced interference from other formations. Misidentifications, on one raid 42 squadrons to Ludwigshafen, 24 bombed Stuttgart thinking it was Ludwigshafen.

Visual raids had good photographic feedback, bad weather raids could take weeks before photographs were available. There had been little improvement of H2X attacks since the first one, there was fairly uniform results across the 8th Air Force. The B-24 flying lower and in smaller formations had an edge.

For lone aircraft 285 test runs using The Oxford Test gave an average circular error of 0.85 miles. Same arrangement using targets in Nottinghamshire February and March 1945 using SCR-584 to assess accuracy 1.25 miles.

October 1943 to January 1944 inclusive, percentage of bombs within 1,000 feet of the Aiming Point, first figure is for all bombs dropped / then less Gross errors or targets with no AP assigned, by bomb wing,

1st 12.6 / 17.6
40th 15.9 / 21.8
41st 30.0 / 33.5
94th 25.5 / 27.2
2nd 13.7 / 20.2
14th 20.3 / 25.8
20th 11.3 / 17.4
4th 32.3 / 39.6
13th 28.6 / 35.6
45th 24.0 / 35.5

April 1944, Mission failure = no bombs within 1,000 feet of aiming point, Gross error = radial error 3,000 feet or more even though some bombs dropped within 1,000 feet of the aiming point. There were no mission failures in April.

1st Division: group attacks 15 out of 148 gross, section attacks 3 out of 20
2nd Division: section attacks 29 out of 197 gross, squadron attacks 5 out of 25
3rd Division: group attacks 29 out of 258 gross, squadron attacks 12 out of 74

September/October 1944 accuracy report, Normal aimings are where the pattern center was within 3,000 feet of the assigned MPI. Targets of Opportunity and gross errors are cases where pattern center was 3000 feet from assigned MPI, except in case of a mission failure. Mission Failure are cases where, due mostly to adverse weather, a negligible degree of accuracy was achieved by the total force assigned to a given target.

2,908 formation attacks, 906 visual, 2,002 Pathfinder. Visual was 753 9-14 aircraft formations, 153 6 aircraft formations. For the 9-14 aircraft formations 727 had intervalometer settings of less than 50 feet resulting in 189 normal attacks, 210 unable to appraise, 57 targets of opportunity and gross errors, 271 mission failures.

Accuracy for 189 normal aimings and 57 gross errors/targets of opportunity 37.6% within 1,000 feet 64.3% within 2,000 feet.

153 Normal Aimings averages for 12-14 aircraft formations: 20% within 500 feet, 48% within 1,000 feet, 83% within 2,000 feet, pattern size 1,800x1,650 feet, errors 650 feet range 620 feet deflection 1,020 circular from 21,000 feet.

34 Normal Aimings averages for 9-10 aircraft formations: 19% within 500 feet, 50% within 1,000 feet, 82% within 2,000 feet, pattern size 1,750x1,500 feet, errors 740 feet range 650 feet deflection 1,120 circular from 22,500 feet. Two 3rd BD 9-10 aircraft formations excluded from the averages for unknown reasons.

I think that phrase came from Harry Potter's Hogwart's School of Wizardry and Witchcraft Basic Magic Primer for Muggles.

I shouldn't have said that ... and that's a direct quote from Hagrid.