B-17 Bombing Accuracy During Training
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- เผยแพร่เมื่อ 26 ก.ค. 2022
- The intent of this part 5 video is to discuss WWII B-17’s bomb accuracy, during training, and discuss the phrase myth, “Pickle Barrel Bombing”.
B-17 Bombing 7 part Series:
B-17 Part 1 (Bombing Introduction): • B-17 Bomber, Aerial Bo...
B-17 Part 2 (Fuses, shackles): • B-17 Bombing, Fuzes, S...
B-17 Part 3 (Norden Integration): • The Norden Bombsight B...
B-17 Part 4 (Ballistics Math): • B-17 Bombing Ballistic...
B-17 Part 5 (Training Accuracy): • B-17 Bombing Accuracy ...
B-17 Part 6 (Combat Accuracy): • B-17 Combat Bombing Ac...
B-17 Part 7 (Norden Bombsight): • WWII B-17 Combat Bombi... - วิทยาศาสตร์และเทคโนโลยี
This video says correctly that bombs tended to fall a little short of the target on training runs. It incorrectly states that there was no explanation available.
Bombs fell short due to an initial oversight by USAAF systems staff. It is due to the fact that the Norden bombsight is calibrated to send its release signal at the instant the computed release angle equals the aiming angle the sight calculates after the bombardier sets the trail distance for his bomb type. However, the bombs are not released from where the sight is, they are released from the bomb bay 20 feet or more behind the sight. You'll find the error more or less corresponds to the distance between the bomb bay bomb attach point and the bombsight for each aircraft type.
This error was documented in the Bombardier's Information File given to each bombardier.
The USAAF could have corrected the error through amending the calibration procedure for the bombsight, however this would mean the bombsights would not be interchangeable between aircraft types (B-17, B-25 etc).
In any case, bombing doesn't mean any one aircraft drops one bomb. What the USAAF usually did was called "train bombing". This has nothing to do with blowing up railway trains, it means each aircraft dropped a train of bombs - that is, a number of bombs released at a controlled interval between each bomb - set by a device called an "intervalometer". The Norden (or Sperry) bombsight did not signal a bomb drop directly - it sent a start signal to the intervalometer.
For example, say the target is a factory 400 feet long, and the blast radius is 30 feet (the case for the usual 500 Lb GP bomb). The bombardier would aim at the leading edge of the factory, having already set the trail 50 feet short and the intervalometer to drop 12 bombs at intervals of 50 feet of aircraft travel, so that the blasts overlap, 2 bombs fall short, and 2 fall late, thus covering random bombing error. In this context, bombing a bit short due to the bomb bay set-back is neither here not there.
Another amazing video, I love the detail included here. The US bombing work in Europe was cutting edge technology and the bomber crews, technicians and strategists were fighting a completely new type of warfare. Many other channels concentrate on the human dimension of the US bomber forces, and quite rightly so, the men in these crews were amazing, but it is great to see technical data and the science behind it too.
Great content and info in all your videos, keep killing it
Thanks you for the videos on your channel. It's great stuff, and I have recommended your channel to others interested in WWII-era aircraft.
Thanks also for making the documents you use in the videos available for download. It's tremendously helpful for those of us who don't have access to in-person historical archives to do research and have to rely on only what's been digitized and put online.
Much appreciated!
Brilliant video series! Thank you
Maybe you could do a video on the other guns like the waist turrets or nose turrets of the G varient of the B-17, But still Great Videos!
Excellent! Informative, interesting and surprising
The photo @6:40 does not show the city of Munster (nor the city of Münster). Rather, it shows the city of Freiburg, Germany, with the Freiburg Minster (or: “Freiburger Münster”) at the center.
Excellent work. We appreciate these vids very much. Hard data on B-17s!! Who knew?
RIP Pops! B-17 Radio Man, Gunner crew member.
WWII US Bombers, can you please answer this: The Norden used by the USAAF went through 6 upgrades during their participation in the War. Most of these upgrades were to enable better performance at progressively higher altitudes and greater airspeeds - eg changes in angular range, increase in sighting telescope power, so that the diameter of a target seen by the bombardier was the same at 22,0000 feet was the same at it originally was at 12,000 feet. Which bombsight version was used in the training runs you've described?
Note: It is typical in military training to use earlier versions of equipment withdrawn from combat service, freeing up the improved models for use where it counts. However, in 1944, the Norden was being made in quantity by several manufacturers, not just the Norden company itself. Presumably using the upgraded sights improved accuracy in practice - that was the whole idea of the changes.
One thing I have read was that under some conditions, bombs could actually go supersonic during the descent. This threw off their aerodynamics in ways not taken into account by the bombsights.
James, where did you read that? It must be very special circumstances indeed. Drag is proportional to the square of the speed, until the speed gets close to the speed of sound, whereupon it increases dramatically . Hence bombs dropped from high altitude increase in speed until the speed of sound is approached but do not exceed it. Note that 1) drag is proportional to air density, and 2) the speed of sound increases with air density and thus is greatest at ground level. Over a certain altitude, bomb terminal speed is always closely the same, and always less than the speed of sound.
WWII US Bombers has produced another video which is excellent and gives actual bomb speed data..
@@keithammleter3824 I honestly don't recall where I saw it. It was years ago. As I recall, it was only heavier bombs, and only under specific circumstances. I'm no expert on aerodynamics, so I just took it at face value.
Now that I think about it, I wonder if it was similar to the way P-38s without dive brakes could have problems when airflow over the wings and control surfaces approached trans sonic speeds.
@@jamescameron2490 : Have a look at WWII US Bombers' excellent video on bomb ballistics and see what you think. I suspect it will give you greater confidence that the USAAF did in fact know what they were doing.
I have a copy of the Bombardier's Information File that the USAAF gave to every bombardier. It is very extensive, and fully covers the sources of error in using the Norden. Its says nothing about errors due to uncertainty in bomb aerodynamics - which is not proof of course - but does indicate that such errors were not worth mentioning i.e., negligible. So I conclude that bombs in some peculiar circumstance falling at supersonic speed is quite unlikely.
@@keithammleter3824 of course, if they didn't know it could be a problem, it wouldn't have made it into the file. An "unknown unknown", so to speak. Like how it took a while to figure out why P-38s could get locked into a dive.
@@jamescameron2490 : Yep - one cannot know what one doesn't know. But it is difficult to see how it could happen unexpectedly. Weather really only occurs at low altitude.
Damage to bomb tailfins could only slow it down and/or send it off course. Bombardiers were supposed to check the condition of bombs, including tailfins, as part of their pre-takeoff checklist.
Currently watching this whilst eating pickles. I'm not kidding.
Is The pickle barrel statement like the Titanic myth of being unsinkable. Or was it really advertised as such?.
Could the bombs impact tended to be to the right be because the bombs spun to the right (?) and would tend to to drift to the right? Just a thought.
Might be a silly question; Would any effect be seen in bomb accuracy from the motion of the earth while the bombs were falling? I recall that duration of fall was given in a previous video, but cannot remember the time given. Just a thought.
Hence the density of bombing. Coat the area with Mk64's and at least some will have the desired effect, sorry about the others hitting your school...
Shotgun effect.
I've been explaining to people for a while that calling the Norden bombsight inaccurate is like saying the M16 rifle is inaccurate because every time the trigger's pulled on one in combat an enemy soldier doesn't drop dead, if enemy soldiers would be cooperative enough to sit up and not throw grenades at you and shoot at you then you'd undoubtedly get a much higher kill rate per bullet.
If the bombardier has to bomb through smoke from smoke pots the Germans lit that's not the fault of the Norden bombsight, if the navigator flies them to the wrong target that's not the fault of the Norden bombsight, if the bombardier doesn't even use it because he switched to radar bombing due to no visibility that's not the fault of the Norden bombsight, if the Germans camouflaged the target and set up a decoy that got bombed that's not the fault of the Norden bombsight.
400 foot error at the realistic speeds and altitudes they bombed at is pretty impressive, and a lot more accurate than the "average bomb didn't even hit within 1,000 ft" claims people always attribute to the Norden bombsight because their math factors in wrong targets getting bombed and any other factors like that, it really was an accurate system for the 1940's.
I'd really like to see what the pattern would look like starting from the + (aiming point) for a B17 box dropping twelve bombs per plane as was the typical load out on a mission, using the lead bombardier/toggle method they used.
That'd be interesting.
Duke, your rifle analogy - very well put, and spot on.
@@keithammleter3824
It really was an accurate system, especially when you consider that it was the 1940's and no one had ever bombed from those altitudes and speeds.
People want to look at the total number of bombs dropped and compare those to the number that actually hit the target and blame the difference entirely on the Norden bombsight, it's far more complicated than that.
They should try looking at the missions where the navigator flew them to the right target, it wasn't obscured by smoke from smoke pots or the British bombing the same target the night before, no cloud cover etc etc, and the lead bombardier got it right and everyone else toggled their bombs correctly, something like that shows the true accuracy of the system.
More often than people believe there were missions where when given the chance the Norden bombsight more than proved how accurate it was when they absolutely plastered the targets.
Those would be some quite large barrels
It's inevitable that the inputs given to the Norden bomb sight had some margin of error. Altimeters and airspeed indicators are never 100% accurate. If faulty data is fed into the bomb sight, then the drop point will also have an error even if the sight is working perfectly.
Do you intend to compare the accuracy of the bombers other than those of the American Norton Bomb Sight?
The USAAF also used large numbers of the earlier Sperry bombsight but found the Norden (derived from the Sperry) clearly superior. The Germans used a Zeis- manufactured bombsight (the Lotfernrohr) that worked on the same general principle as the Sperry and Norden sights, but was simpler and less accurate. Except for a few special instances, The British did not attempt accurate bombing of strategic targets, and instead just bombed wide urban areas willy-nilly. Thus they did not employ a bombsight in any way comparable.
@@keithammleter3824 Thanks. Of course, the British mostly did night bombing. Neither sight would have been of much use then.
The intent of this video is to make me calm and at peace with the world.
Why does every TH-cam video keep on about this pickle barrel claim? It was just a throw-away statement by a Norden executive to the popular press. It is the same sort of thing as me saying "Gee, it's so hot today I could melt." No sensible and same person would think I was claiming I was actually at risk of melting. They would merely thing I was claiming it is pretty hot outside - like maybe a few degrees warmer than the climate average for the season.
Similarly, no sensible person would have actually taken any notice of the pickle barrel claim. It was irrelevant anyway - the sole customer was the USAAF and they knew perfectly well just how well the Norden sight performed.
The Norden bombsight essentially computes an angle. The accuracy of that angle is what was claimed in official service and operating manuals.
How about this bombing strategy theory - any validity to it ? Feed back welcomed.
Bombing would have been much more effective tactically and much more humane if all the bombs had been laid with varying long-time delayed fuses. The damage resulting physical damage would be more or less the same, it would have made the area covered by bombs un-usable or extremely inefficient since the explosions & places would be un-predictable, making the area psychologically 'verboten' to all intents and purposes.
Michael - that's what each side actually did. American GP bombs had a timer that was typically set to random times between instant and 24 hours. But both Britain and Germany set op and employed specialist bomb disposal teams that knew how to render bombs not yet exploded safe - at considerable personal risk. This lead to the employment of anti-tampering devices and the devising of means to render safe the anti-tampering devices. Some German bombs were timed by clockwork mechanisms - that's the origin of bombs supposedly ticking in movies. American bombs were timed by slow chemical reactions.
@@keithammleter3824 Don't know what percentage of bombs used were time-delayed but the tactic proposed here would be in the order of 100%.
@@michaelleblanc7283 I don't know the percentage either, but the main intention documented in US reports was to frustrate the German efforts at repairs. It often wasn't very successful at that. After the elimination of good German fighter pilots and the shortage of aviation fuel curtailing German fighter plane operations, the USAAF and RAF bombed pretty much every day anyway. Before that happened, the Germans proved pretty adept at quickly putting wrecked factories back in operation. They had huge more or less slave/compelled workforces to clear away rubble and put things right. It is recorded by the US Strategic Bombing Survey that the Germans could deploy up to 300,000 or more to repair a large oil refinery. If a few things went bang during the work, that didn't bother Hitler any.
620’ 😁
British 617 squadron says;
"Hold my beer........"
".... while I lose 8 of 19 planes."
@@grizwoldphantasia5005
Dam busters maybe, but the real precision bombing of 617 was Tall boys and Grand slams also designed by Barnes Wallis.
The losses weren't so great, as they had fighter escorts at that time.
At 12,000lbs and 22,000lbs a B-17 couldn't even carry one.
High altitude bombing with dumb bombs was questionable for everyone. When the U.S. turned attention to Japan high altitude bombing was so inefficient that B-29s were ordered to fly low altitude bomb runs and take more fighter losses.
@@darrellkimmel2646 The Tall Boys and Grand Slams had the advantage of not needing as much accuracy, and they still depended on dropping many of them to hope that one would be close enough. The problem with high altitude bombing accuracy is inherent in the altitude and speed itself; no bomb sight was any better than any other, nor bomb release mechanism, nor anything else.
The Lancaster might have had a 10% advantage over the B-17, as the B-17 had over the B-24, or might have been 10% worse; I do not know, but I'd bet a paycheck it wasn't twice as stable a bombing platform.
The sheer weight of those bombs might have made them more stable pr predictable, but again, that's not the planes or crew.
The huge attacking forces of daylight mass bombing also meant that bombs spread out simply because the planes dropping them were spread out.
There really was no significant difference in planes, crews, or anything else.
@@darrellkimmel2646
First off the Lancaster's that carried those bombs were highly modified to be able to carry them, the statement "The B17 couldn't even carry them" is you implying that the B17 couldn't carry that much weight but the Lancaster could just load one up which is total hogwash, the reality of it is that they just didn't modify any B17's to carry them, so what?
The fact is the B17 could carry it's maximum bomb load of 20,000 lbs by simply installing the wing racks, loading them and then loading the internal load of the bomb bay to it's maximum of 13,000 lbs, not 4,000 lbs which is a figure that gets thrown around by the idiot creators of TH-cam videos about bombers who use Wikipedia as a source and then misinterpret the information they list about the B17's bomb carrying capacity's instead of doing the research and using actual records and information from the bombers manufacturer.
Also when the B17 carried it's maximum bomb load of 20,000 lbs aside from simply adding the wing racks and loading it up to full capacity in it's bomb bay it also got to keep all of it's defensive guns unlike the Lancaster that not only lost the few ineffective defensive guns it had to lighten it up enough to carry the equal amount of weight that a fully loaded B17 could the Lancaster also needed to be highly modified to be able to carry those bombs, since the floor that divided the bomb bay from the rest of the fuselage had to be removed to fit the bomb in it, along with removing the bomb bay doors because the bomb had to hang out of it's belly into the aerodynamics creating additional drag and decreasing it's range even more, the internal structure had to be reworked with braces added all over the place because the floor that had to be removed was an integral part of the structure.
If the B17 had been modified to carry those bombs it would have flown higher and faster doing it with it's turbo charged engine's than the Lancaster could have with it's single stage supercharger version of the Merlin engine.
But at the end of the day they didn't bother to modify the B17 to carry those bombs because as the record shows they amounted to nothing more than gimmicks that had no effect on the war, if they'd have been half as effective as your nonsense claims they'd have not only modified B17's to carry them they'd have started producing a new variant of the B17 and every other bomber made to carry them and shortened the war by a year.
You've got nonsense claims, which is typical when it comes to people talking about the Lancaster's capabilities, all over this channels videos that are nothing more than supposition compared to the facts presented in this channels videos, facts from credibl sources like official records and information from the manufacturer of the aircraft.
All you've got that's typical of what you've been upchucking all over the place is things like "I'll bet..." and "There's no way...", and it's because you're butt hurt by the actual facts about the USAAF's record when it comes to bombing accuracy compared to everyone else's, so without any proof you make nonsense claims like "Nobody's bomb sight was any better than anyone else's" when in fact the proof is presented right here in his video's, but you'll troll around through his videos making BS statements like "Subtract half the wingspan and it sounds like dreaming to me", whatever that claim was supposed to mean.
All you have is shade is you're trying to throw on facts out of sheer butt hurt, it's laughable, absolutely laughable.
Oh, and by the way, "Mark Felton said..." isn't credible either, he never seems to list any sources for his claims, only a bunch of malarkey designed to get butt hurt people to click on his videos so he can make money drying up their tears for them.
It’s not a myth, it’s that pickle barrels are too small!
"pickle"