8th AF bombing

[ObtuseOcelot]

The reason was to determine improvements. When the miss deviation was that large, the cause of the error was something outside the value of comparing successful raids. If you read the USSBS you can see they very much do care, track, and analyze the causes and percentages for raids that fall into the "failed mission" category. They very much did not like missing. You're just only getting a small slice of the data with the above chart, leading to incorrect conclusions.

 

[SaparotRob]

That may not have been the intent at the time, due to the chance of navigation errors resulting in the bombers not even bombing the right city sometimes.

I didn't really read your post thoroughly the first time. My mind read it as .."that may not have been the internet at the time….."
It would have explained bombing the wrong country.

 

[buffnut453]

There was a planned target with a designated IP and aim point. The fact that a formation never found the correct IP and aim point means the planned target wasn't hit. Aside from the statistical side of things, that is operationally significant. The planned target that was missed still needs to be hit, which means a replan for another day, with consequent additional losses of aircraft and crews.

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.

 

[ObtuseOcelot]

There was a planned target with a designated IP and aim point. The fact that a formation never found the correct IP and aim point means the planned target wasn't hit. Aside from the statistical side of things, that is operationally significant. The planned target that was missed still needs to be hit, which means a replan for another day, with consequent additional losses of aircraft and crews.

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.

Hence my point, it was operationally significant and they did track it. You're just not seeing it on the posted chart. It's out of context, specifically applicable to a previous question not your point. You can find "Mission Failure" data out there as well. It isn't posted that way to somehow slant the data.

 

[buffnut453]

Hence my point, it was operationally significant and they did track it. You're just not seeing it on the posted chart. It's out of context, specifically applicable to a previous question not your point. You can find "Mission Failure" data out there as well. It isn't posted that way to somehow slant the data.

But it's fudging the CEP figures. "Mission failure" covers a multitude of issues. If a formation just got plain lost and bombed the wrong target, you can't discount that from your CEP calculations.

This all smacks of trying to make "precision daylight bombing" appear more accurate than it really was.

 

[ObtuseOcelot]

It would be, if that chart existed in isolation. It does not. The USSBS alone is over a thousand pages. Between wartime analysis and other official USG studies it's at least in the tens of thousands. This chart is data analysis that exists within a greater context that is not posted here (because it was specifically answering a different question). Jumping to conclusions about skewing data is incorrect, because other data exists within that context to honestly represent the impact of "mission failure" raids. It's just jumping to conclusions based on only seeing a small slice of the pie.

 

[wuzak]

But it's fudging the CEP figures. "Mission failure" covers a multitude of issues. If a formation just got plain lost and bombed the wrong target, you can't discount that from your CEP calculations.

This all smacks of trying to make "precision daylight bombing" appear more accurate than it really was.

Ignoring bombers that didn't bomb the correct target seems sensible if the goal is to determine the best bomb aiming system.

 

[SaparotRob]

Unless that bomb aiming system is why those bombers hit the wrong target.

 

[pbehn]

I do not know if it would make sense to try to count the bombs dropped on a city 25 miles away, many times when they bombed the wrong target they idid not know what the aim point had actually been. I think it would count more as a matter for statistical probability of finding/not finding the target. If you are not even aiming for the right target how can you apply the CEP to the intended target . . . ?

And in the most unknown of unknowns many things and important people were hit on all sides purely by accident an sometimes by their own people.

 

[buffnut453]

It would be, if that chart existed in isolation. It does not. The USSBS alone is over a thousand pages. Between wartime analysis and other official USG studies it's at least in the tens of thousands. This chart is data analysis that exists within a greater context that is not posted here (because it was specifically answering a different question). Jumping to conclusions about skewing data is incorrect, because other data exists within that context to honestly represent the impact of "mission failure" raids. It's just jumping to conclusions based on only seeing a small slice of the pie.

That greater context may answer some of the issues I've identified but arbitrarily excluding some units/formations from your CEP calculation, for whatever reason, is introducing bias, I'm afraid. What's the cut-off between a formation that's counted for CEP purposes and one that's not counted? One mile? Five miles? Twenty five miles? If all my bombs failed to fall within 1000ft of the target, then that's still a CEP error. Excluding that formation by terming it a "mission failure" makes the calculated CEP figure look better than it actually was.

Now, I'll fully accept that I haven't read all of the USSBS. If you can confirm that the CEP figures are amended to incorporate mission failures, then I'm happy. However, the post in question suggested that such corrections to the CEP calculation weren't made.

 

[drgondog]

That greater context may answer some of the issues I've identified but arbitrarily excluding some units/formations from your CEP calculation, for whatever reason, is introducing bias, I'm afraid. What's the cut-off between a formation that's counted for CEP purposes and one that's not counted? One mile? Five miles? Twenty five miles? If all my bombs failed to fall within 1000ft of the target, then that's still a CEP error. Excluding that formation by terming it a "mission failure" makes the calculated CEP figure look better than it actually was.

Now, I'll fully accept that I haven't read all of the USSBS. If you can confirm that the CEP figures are amended to incorporate mission failures, then I'm happy. However, the post in question suggested that such corrections to the CEP calculation weren't made.

I see both your arguements but CEP based on impacts of the actual attack on (or missed ) the intended target - is a sound basis for discussing CEP statistically.

Bombing a target 25 mi away due to flawed navigation must be entered into a broader category of bombing effectiveness globally.

The questions from either case include
1.) what were visibility conditions? Satisfactory or unable to visually acquire the MPI as biefed?
2.) If visibility deemed acceptable, what circumstances dictated accurate/inaccurate bombing results expected?
3.) If results unsatisfactory despite favorable visibility, what other factors believed to influence lack of desired results? Training/expertise of the bombardier? Undetected cross winds? Faulty bomb aiming unit? Pilot/mechanical failure or interference with Automatic Flight Control system?
4.) If no visibility and bombing by radar, what planned target definition was absent or misinterpreted?
5.) Was lead bomber Mickey system tested and found satisfactory upon return rom mission? Were any previous issues recorded for the equipment?
etc., etc.

 

[GregP]

But it's fudging the CEP figures. "Mission failure" covers a multitude of issues. If a formation just got plain lost and bombed the wrong target, you can't discount that from your CEP calculations.

This all smacks of trying to make "precision daylight bombing" appear more accurate than it really was.

Yes, you can and SHOULD discount that.

CEP SHOULD mean the circular error probable when bombing a target that is in sight using a bomb-aiming device that is properly employed. In other words, when you see the target and try to hit it using your aiming device correctly.

If you get lost or can't see the target, that the result, however far away from intended target, does not contribute to the observed accuracy of the bomb aiming device when it is employed properly.

Of course, it DOES count in the overall accuracy of bombs dropped, but CEP was primarily developed to get an idea of how accurate the bomb aiming device was when employed as designed. It wasn't developed to see how well we bombed overall, even when everything was obscured by clouds. Both are of interest, but randomly-dropped bombs don't tell you anything useful about your bombsight accuracy.

 

[buffnut453]

Yes, you can and SHOULD discount that.

CEP SHOULD mean the circular error probable when bombing a target that is in sight using a bomb-aiming device that is properly employed. In other words, when you see the target and try to hit it using your aiming device correctly.

If you get lost or can't see the target, that the result, however far away from intended target, does not contribute to the observed accuracy of the bomb aiming device when it is employed properly.

Of course, it DOES count in the overall accuracy of bombs dropped, but CEP was primarily developed to get an idea of how accurate the bomb aiming device was when employed as designed. It wasn't developed to see how well we bombed overall, even when everything was obscured by clouds. Both are of interest, but randomly-dropped bombs don't tell you anything useful about your bombsight accuracy.

You're measuring with a micrometer screw gauge and then drawing the line with a fat marker pen. A combat box was typically 500ft deep x 600 ft in altitude x 2500 ft in width. All of those dimensions impact fall of bombs onto the target area. How can CEP be solely about the aiming device when only one aircraft in such a large area was actually aiming at the target? Poor formation keeping will increase the size of the combat box and hence reduce bombing precision and accuracy, and that has nothing to do with the bomb sight.

Evaluating the accuracy of the bomb sight is done during testing which, in the case of the Norden system, led to the "bomb in a pickle barrel" claims (results which couldn't be replicated on operations for a host of reasons). However, the USSBS isn't about evaluating the effectiveness of the bomb sight. It's about assessing the effectiveness of the bombing campaign, which is a broader capability issue rather than a narrow focus on equipment. In modern US parlance, we'd talk about DOTmLPF-P. It's clear that US doctrine for daylight precision bombing changed from 1941 thru 1944, as did training, processes and everything else. You can have the best bomb sight in the world but if your crews can't get to the target reliably then, from a capability perspective, you're not successful.

I still say that discounting the results for formations which achieved less than 5% of bombs within 1000ft of the aim point is skewing the data, particularly given the size of the combat box.

 

[ObtuseOcelot]

As others have added above, you can certainly critique the data methodology but none of what's posted indicates data that was adjusted to push a certain slant.

 

[buffnut453]

As others have added above, you can certainly critique the data methodology but none of what's posted indicates data that was adjusted to push a certain slant.

That's a fair point, although the USSBS was established by the Secretary of War in response to a directive from Roosevelt. It would be truly amazing, indeed exceptional, if a document intended for such levels of national leadership wasn't pushing some kind of agenda. Many of the key participants in USSBS went on to enjoy influential postwar careers related to the development of strategic forces. I'm not saying that the CEP data was, itself, part of the agenda. However, the final deliverable absolutely had an agenda, not least in light of the creation of the USAF in 1947.

 

[pbehn]

Does anyone know how far from the target a bomber is when the bomb run starts using a Norden sight at 25,000ft?

 

[Barrett]

All true but the question 'what could, and frequently be achieved' also had many successes when target MPI designated aiming point was visible to the lead bombardier.

Recognizing that machine shops/tooling or catalytic cracking locations, etc. were on a frequent 'want to take out' list, that 10% CEP may include 10 hits from 150 B-17s very tightly located on the specific target. Also note that at say, Landsberg where a Me factory lay, not only a very large plant existed but a whole lot of 'producution' were on the airfield making a wonderful target on the periphery of the CEP.

Another factor in the ETO totals and averages - weather, undercast - Mickey Nav and bomb aiming was not as good as RAF LR electronic bombing aids.

The Norden, given clear visibility and trained crews delivered many high value results.

And take note that Fat Man dropped by B-29 neutralized CEP as a high value discriminant.

Bill, thank you. I'd just add that 8/15AF fusing was a factor. Impact fuses tended to blow off the roof, sometimes leaving much/most of the equipment intact. Re-strike (had to hyphenate it, damned auto-correct) knowledge came late on both sides of the Channel. In 1940 the Luftwaffe tended to write off a target after the first mission. Sheesh-o-dear.
In researching the 15th AF book I found that Speer feared revisits to the large ball bearing plants, which seldom occurred in timely fashion.

 

[GregP]

You're measuring with a micrometer screw gauge and then drawing the line with a fat marker pen. A combat box was typically 500ft deep x 600 ft in altitude x 2500 ft in width. All of those dimensions impact fall of bombs onto the target area. How can CEP be solely about the aiming device when only one aircraft in such a large area was actually aiming at the target? Poor formation keeping will increase the size of the combat box and hence reduce bombing precision and accuracy, and that has nothing to do with the bomb sight.

Evaluating the accuracy of the bomb sight is done during testing which, in the case of the Norden system, led to the "bomb in a pickle barrel" claims (results which couldn't be replicated on operations for a host of reasons). However, the USSBS isn't about evaluating the effectiveness of the bomb sight. It's about assessing the effectiveness of the bombing campaign, which is a broader capability issue rather than a narrow focus on equipment. In modern US parlance, we'd talk about DOTmLPF-P. It's clear that US doctrine for daylight precision bombing changed from 1941 thru 1944, as did training, processes and everything else. You can have the best bomb sight in the world but if your crews can't get to the target reliably then, from a capability perspective, you're not successful.

I still say that discounting the results for formations which achieved less than 5% of bombs within 1000ft of the aim point is skewing the data, particularly given the size of the combat box.

I'm not doing anything and didn't. I wasn't there.

It's quite simple.

1) You already know the accuracy of the bomb aiming device from testing.
2) When the target is visible and when the bomb aiming device is used properly, measure your CEP from BDA pics.
3) Adjust your formation procedures to make the results better.
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.

Cheers.

 

[ThomasP]

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?

 

[ThomasP]

Admit it, when you read the first line in my post above you though of the Harry Potter movies.