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The difference between aiming is because of the need to stay in formation, if every aircraft starts moving to line up with the target the formation will break and the collision risk goes way up. The solution became leader does a "full" sighting, the immediate formation drops when the leader does, the nearby formations drop when their leader's sight says correct range. Repeat depending on the raid size. The nearby formations will up their risks of collision or hitting the slipstreams of the leaders if they start moving for deflection, that is changing course. The method was more accurate than individual sighting.
I doubt the idea was to certainly miss the target. Remember the diagram is not to scale, we have no idea of the distances between the formations, or the different heights, if the second pair of formations were exactly behind the first at the same altitude they would be badly affected by the slipstream, so they must have been at least at different altitudes. We also do not know whether the bomber course was parallel to the bridge, at right angles or somewhere in between. Then add there were another 30 bombers from a different group in the same airspace.So Able ( the Group Leader and Leader of the first Attacking Unit ) sighted for both range and deflection. The same did Charlie, Leader of the second Attacking Unit, because he flew behind Able and their routes didn't interfere. Baker and Dog, which flew on the right of the previous, sighted only for range, cause sighting for deflection would have caused their collision with the other two boxes.
In this way, if Able and Charlie would have released with precision, Baker and Dog would have for certain missed the target. Probably A and C bombed sligthly off-center on the left to allow B and D to place some bombs on the target and the others on the right of it.
Agreed the entries are confusing.I still don't understand the statement on the report that the AU Leaders sighted at the same time for "range and deflection" ( as in the upper line ) and for "range only" ( as in the line below ). Maybe that sight for "range" is simply redundant . . .
Yes Geoffrey, the "six aircraft front bombing formation", as compared with the "train of boxes" formation, could completely miss the target. See below from 1945 "Air Operations Briefs" : Formations in the Fifteen ".I doubt the idea was to certainly miss the target.
The issue is: was this radar bombing or visually. It's not clear to me from the foregoing posts. The comment "weather poor" does not align with visually identifying the target, but I stand to be corrected. If bombing by H2X, the bombing may have been "highly precise" but at the same time "highly inaccurate"Yes Geoffrey, the "six aircraft front bombing formation", as compared with the "train of boxes" formation, could completely miss the target. See below from 1945 "Air Operations Briefs" : Formations in the Fifteen ".
The Boxes were stacked down with 200 to 300 feet difference in altitude. Each Box in trail was spaced of 500 to 1000 feet.
A bridge was usually attacked with an angle from 30 to 45 degrees.View attachment 719488View attachment 719489
I don't meant that they deliberately miss but that they created a pattern in width just as they created one in lenght with the use of intervallometer: it increased the possibility that the central bombs hit the target, while the first and last obviously failed. Similarly, for 6 nearly paired aircraft attacking, with only the second from left ( the Attacking Unit Leader ) sighting the for range and deflection, I wonder how it was possible for n. 4,5,6 from left to hit the target. I think that the AU Leader aimed a bit left of the target to allow at least n 3 and 4 to hit in the center, while the others probably hit too left and too right. But this is only my opinion.
It wasn't that precise. The bombs themselves had poor ballistic characteristics and could spear off in any number of directions. Making fine adjustments to the left or right of the aim point didn't make a lot of difference in the probability of hitting the target.
Just look at the different angles these bombs are pointing.
View attachment 720299
Incendiaries were particularly bad, having appalling ballistic characteristics:
View attachment 720300
One more and then I'll quit:
View attachment 720301
As others have pointed out the bomb ballistics come into play and the reality of mass produced weapons. When the 509th Composite Group began its training it discovered in the final moments a movement by the bombardier of a couple of inches as he readied to drop made a difference of hundreds of feet to where the bomb landed. The USSBS did a major report on bombing accuracy, noting how errors went up with altitude and size of raid.I didn't mean that they deliberately miss but that they created a pattern in width just as they created one in lenght with the use of intervallometer: it increased the possibility that the central bombs hit the target, while the first and last obviously failed. Similarly, for 6 nearly paired aircraft attacking, with only the second from left ( the Attacking Unit Leader ) sighting the for range and deflection, I wonder how it was possible for n. 4,5,6 from left to hit the target. I think that the AU Leader aimed a bit left of the target to allow at least n 3 and 4 to hit in the center, while the others probably hit too left and too right. But this is only my opinion.
If the group only had 1 PFF aircraft airborne then it was single point of failure, if the H2X set failed or the aircraft had a defect, or was damaged or shot down, then the mission was in trouble. There should have been at least a backup PFF aircraft. Also why have so many PFF aircraft in a group if only 1 was needed on a mission? On 31 March 1945 the strength in groups was 77 PB-17 to 307 B-17 and 176 PB-24 to 690 B-24 or about 1 in 5 were pathfinders.What I know for certain is that, although there were many PFF ships assigned to a Group, only one leaded the Group in a mission. A second ship could be employed if the Group was splitted to attack two different targets, but it was non common.
I understand that, I was after file references. The example given is an AFHRA file, likeAbout B-17 of 15th AF, see for example of this report of 301st PFF. There is only one PFF operator and only one PFF bombardier. The source of all my knowledge are the records of NARA and AFHRA.
That first photo with the B-17s, those bombs are almost certainly 100-lb class based on the number being released, in which case they're either the AN-M30 GP or the AN-M47 incendiary. (The B-17, using cluster adapters, could carry 38 of the GP bombs or 42 of the incendiary.) The two photos with the B-29s, based on the number of bombs being dropped, are again either the 100-lb AN-M30 GP or AN-M47 incendiary, most likely the latter. (Using cluster adapters, the B-29 could carry up to 184 of the incendiary.)
Below is a graph showing the trajectories of various incendiary bombs and clusters, along with a couple of GP bombs for comparison. The notably smaller dispersal area of the aimable cluster using the 4-lb incendiary versus the quick-opening cluster is readily apparent. (Source: Fire Warfare — Incendiaries and Flame Throwers, Summary Technical Report of Division 11, NDRC, Volume 3, p.17)
View attachment 720313
From the same source (p.51), a table showing the results from a formation drop of AN-M47 incendiary bombs.
View attachment 720315
Lastly, from the same source (p.52) a graph plotting the dispersal of incendiary bombs from a single aimable M18 cluster (38 x 6-lb AN-M69).
View attachment 720316
The smaller incendiary bombs were always area weapons, given their light weight resulted in them being easily dispersed.
ETA: the source document can be downloaded from the Bullet Picker website. It's found in the Library section under 'US Government', fourth from the bottom in the list. It can also be found at the Japan Air Raids.org website, under Documents > English Language Documents > Incendiary Weapons.
The A-2 and B-2 boxes (your c and d) cruised to the right but moved into trail for the attack so offset was not necessary. The 449th BG was tasked a different bridge on 23 Sep but did not bomb as both the primary and secondary targets were completely undercast. See the attached attack sheet and formation plan.Thank You Geoffrey.
So Able ( the Group Leader and Leader of the first Attacking Unit ) sighted for both range and deflection. The same did Charlie, Leader of the second Attacking Unit, because he flew behind Able and their routes didn't interfere. Baker and Dog, which flew on the right of the previous, sighted only for range, cause sighting for deflection would have caused their collision with the other two boxes.
In this way, if Able and Charlie would have released with precision, Baker and Dog would have for certain missed the target. Probably A and C bombed sligthly off-center on the left to allow B and D to place some bombs on the target and the others on the right of it.
I still don't understand the statement on the report that the AU Leaders sighted at the same time for "range and deflection" ( as in the upper line ) and for "range only" ( as in the line below ). Maybe that sight for "range" is simply redundant . . .
Depended on the target. The previously attached formation plan has a Mickey Ship (PFF) at A-1-1 and B-1-1. In the formation plan attached here A-1-1, B-1-1, B-2-1, and C-1-1 are all PFF. The names with MN preceding are the "Mickey Navigators" . B-24 Lead ships carried 3 navigators: normal navigator, Mickey navigator and a navigator manning the nose turret to aid with pilotage nav. Later in the war, the deputy leads (A-1-2, etc.) would also be PFF ships on missions where PFF navigation or bombing was likely.What I know for certain is that, although there were many PFF ships assigned to a Group, only one leaded the Group in a mission. A second ship could be employed if the Group was splitted to attack two different targets, but it was non common.
About B-17 of 15th AF, see for example of this report of 301st PFF. There is only one PFF operator and only one PFF bombardier.
The source of all my knowledge are the records of NARA and AFHRA.
Not always and not in this case. The "train of boxes " was not the rule( the longer the train, the happier the FLAK ). In the "6 air front formation" the position of boxes could be the same in cruising and bombing. In the sheet to which my original question referred is clearly said "bombing formation".The A-2 and B-2 boxes (your c and d) cruised to the right but moved into trail for the attack so offset was not necessary. The 449th BG was tasked a different bridge on 23 Sep but did not bomb as both the primary and secondary targets were completely undercast. See the attached attack sheet and formation plan.
Yes, of course. I told that only one PFF leaded the Group and aimed during the bombing run. The spares were inactive unless malfuctions or alternate targets needed their intervention.Consider the possibility the reports in the files are from the PFF aircraft used, as the entire group (including any other PFF aircraft) dropped with it.
Agree with everything you're saying, and smaller, lighter incendiaries are inherently more susceptible to dispersion from higher altitude. However, my general point remains. Even slight damage to the fin structure of a 500lb bomb will impact its trajectory...and there are plenty of images showing bombs being rolled over the ground and other similar practices that are likely to ding the fins. And that's before we consider subtle dimensional differences in the bomb shape itself that may alter its ballistic trajectory.