The B29 raids on Osaka.

[syscom3]

Has anyone seen this?

Summer Heat in Early June

The First Raid in March Osaka was first struck by the Boeing B-29 Superfortress very heavy bombers on the night of 13-14 March 1945. Osaka was the third urban area attacked with incendiary weapons …

osakakushu.wordpress.com

 

[wokelly]

First time. But quite enjoyed reading it. Thanks for posting.

 

[Thumpalumpacus]

Interesting to see high-level ("21,000 ft") attacks being pursued even after the spring-time decision to do low-level incendiary attacks as is usually recorded.

 

[Shinpachi]

Our common knowledge often seems to be your discovery though vice versa.
Nice find, sys

 

[wokelly]

Interesting to see high-level ("21,000 ft") attacks being pursued even after the spring-time decision to do low-level incendiary attacks as is usually recorded.

Were the 21,000 ft attacks not all daylight attacks? It looked like the one night attack in June was at low level (6 to 9,000 ft), and then the daylight attacks that followed were all at 20,000+ ft. I would guess it must have been related to the flak defences and Japanese fighters. Defenses were weaker at low night so lower level attacks was possible. At daylight they had to fly higher, especially to avoid the flak.

 

[Peter Gunn]

Were the 21,000 ft attacks not all daylight attacks? It looked like the one night attack in June was at low level (6 to 9,000 ft), and then the daylight attacks that followed were all at 20,000+ ft. I would guess it must have been related to the flak defences and Japanese fighters. Defenses were weaker at low night so lower level attacks was possible. At daylight they had to fly higher, especially to avoid the flak.

Fair question, I consulted my uncles diary which is not a chronological document, more of a stream of consciousness kind of thing. But what I could glean from it (he was in the 315th on Guam which started ops in ~June '45) altitude varied from ~10k up to 18k altitude, all at night as far as I can discern. The lowest reference I could find was 10,100ft and the highest was 18,600ft for bombing altitudes.

Just remember that's not an official document, just what he recorded after missions in his personal diary.

 

[Thumpalumpacus]

Were the 21,000 ft attacks not all daylight attacks? It looked like the one night attack in June was at low level (6 to 9,000 ft), and then the daylight attacks that followed were all at 20,000+ ft. I would guess it must have been related to the flak defences and Japanese fighters. Defenses were weaker at low night so lower level attacks was possible. At daylight they had to fly higher, especially to avoid the flak.

Right, but my point was just that so much of the literature focuses on LeMay's decision in February that seeing even daylight high-level attacks in April and later is interesting.

 

[EwenS]

The night / day mission split per month from March, when the first night missions were flown were as follows:-

Mar - 9/3 = 12
Apr - 12 /70 = 82
May - 13/41 =54
Jun - 25/28 =53
Jul - 58/7
Aug - 20/7

In March there were 3 Bomb Wings available (73rd, 313th & 314th). In April they were joined by the 58th BW which moved over from the CBI to join the B-29 force on the Marianas. The 315th BW then flew its first mission on the night of 26/27 June.

The 313th BW specialised in dropping mines as part of Operation Starvation which commenced on the night of 27/28 March. These missions are included in the above figures

Operation Starvation - Wikipedia

en.m.wikipedia.org

The 315th BW were equipped with the stripped down B-29B fitted with the AN/APQ -7 Eagle radar. Due to the long bomb run required (70 miles) they tended to fly when the weather was poor. Their targets were oil related.

In April & May many missions were flown in daylight against the airfields on Kyushu & Shikoku as part of the support for Operation Iceberg, the invasion of Okinawa, with each airfield target allocated its own mission number but with each attack co-ordinated as part of a larger operation on that day. So for example on 17 April 118 aircraft from 3 BW undertook 6 daytime missions against airfields on Kyushu.

The first escorted mission was to Tokyo on 7th April with P-51D from the 15th & 21st FG based on Iwo Jima. They were joined by the P-51D equipped 506th FG in May and the P-47N equipped 414th FG in July. These units flew 51 VLR missions but very few were B-29 escort missions due the change in B-29 tactics to night missions and significant reduction in Japanese interception efforts in July as they husbanded their aircraft for the invasion of the Homeland. Most of the missions undertaken were fighter sweeps.

VLR History: VLR History, 506th fighter Group, 457 Fighter Squadron, 458 Fighter Squadron, 462 Fighter Squadron Iwo To Japan

506th fighter Group 457 Fighter Squadron 458 Fighter Squadron 462 Fighter Squadron Iwo to Japan are available area.

www.506thfightergroup.org

 

[GrauGeist]

The Jet Stream also changes it's path over Japan, moving northward during spring/summer, too.

This would allow for better bomber operations at higher altitudes versus the colder months.

 

[wokelly]

Right, but my point was just that so much of the literature focuses on LeMay's decision in February that seeing even daylight high-level attacks in April and later is interesting.

Yeah fair enough. I know little about the USAAF raids on Japan, so the descriptions of the daylight raids did seem rather at odds with my perception of the low altitude night raids. Some of the raids looked like a mix of area and precision attacks, with part of the force trying to hit specific works while the rest were trying to burn down part of the city. It made me realize how little I have read on this bombing campaign.

 

[33k in the air]

According to the XXI Bomber Command Monthly Activity Report covering March 1945 (p.10):

During the month the Command performed five night incendiary attacks from 5000 to 8000 feet against Japanese urban areas, two night demolition attacks from 6500 to 8000 feet, two daylight demolition attacks from about 16,000 feet, one high-altitude daylight attack, and two special missions.


According to the XXI Bomber Command Monthly Activity Report covering June 1945 (p.3):

                             Missions  Sorties     Tons
Strategic Targets (Daylight)    24       1412      7861
Strategic Targets (Night)        2         71       438
Urban Areas (Daylight)           4       2096     12006
Urban Areas (Night)             11       1521      9974
Mining (Night)                  12        367      2081
Miscellaneous Sorties            -        227         -
-------------------------------------------------------
Total                            -       5624     32360

The Monthly Activity Reports, along with other documents including the Tactical Mission Reports, can be found at the Japan Air Raids.org website.

 

[Thumpalumpacus]

Yeah fair enough. I know little about the USAAF raids on Japan, so the descriptions of the daylight raids did seem rather at odds with my perception of the low altitude night raids. Some of the raids looked like a mix of area and precision attacks, with part of the force trying to hit specific works while the rest were trying to burn down part of the city. It made me realize how little I have read on this bombing campaign.

One of the reasons I love this forum so is that I learn so much. You're helping that along with this discussion. I know that even in the area missions they were working in many cases to destroy specific neighborhoods that were perhaps rich with subcontractors or housed critical locations, but as in Europe with the 8th, if the bombs hit houses instead, there wasn't much handwringing. So it's entirely possible you're right, that some missions were "dual-purpose", as it were.

I do need to read in depth on this. Right now I'm still digging into Nimitz's leadership and decision processes (just finished Symonds, currently reading Hone), but I think I know what topic I'll read up on next.

 

[Sabrejet]

deleted

 

[33k in the air]

The Tactical Mission Report for the 1 June 1945 raid on Osaka is not available at the website mentioned, but the previous mission is (#186). That mission was on 29 May 1945 and conducted against the Yokohama urban industrial area, with a planned bombing altitude of 18,000 feet. It is offered as an example of a higher altitude incendiary mission. Excerpt below.


Strategy and Plan of Attack: Because of the increased number of losses sustained by this Command in the previous two low-level incendiary attacks, it was decided that a change in the plan of attack would be necessary. A high-altitude formation attack was planned for this mission. The plan called for the groups to cross a time control point on the coast of Japan at 4-minute intervals, allowing approximately 1-minute intervals between squadrons. The mean points of impact were to be hit in rotation in an attempt to give the crews an opportunity to get at least one visual synchronous drop on each point before the smoke should become excessive. Each Wing was assigned a specific mean point of impact instead of assigning a group from each Wing, as was planned in a similar attack on North Nagoya. It was decided that the downwind mean point of impact was to be attacked first, on a downwind run, in order to take advantage of the prevailing winds. (p.4)


The bomb loads varied by unit. The ordnance types carried:

E-28 aimable incendiary clusters (each containing 38 x 6-lb AN-M69 incendiary bombs) — 500-lb class, 350 lbs actual weight
E-36 aimable incendiary clusters (each containing 38 x 6-lb AN-M69 incendiary bombs) — 500-lb class, 360 lbs actual weight
E-46 aimable incendiary clusters (each containing 38 x 6-lb AN-M69 incendiary bombs) — 500-lb class, 425 lbs actual weight
AN-M17A1 aimable incendiary clusters (each containing 110 x 4-lb AN-M50 incendiary bombs) — 500-lb class, 465 lbs actual weight
AN-M47A2 incendiary bombs — 100-lb class, 70 lbs actual weight

Aimable clusters fell as a complete unit until reaching a predetermined altitude (typically about 5,000 feet), at which point they broke open and scattered their contents. By falling as a complete unit, it allowed the cluster to be aimed like a regular bomb, and the low altitude at which the contents were scattered resulted in a tighter concentration.

The average flight rime for this operation ranged from 13h 54m to 15h 14m; the distance flown from 2,672 nautical miles to 2,828 nautical miles. The average fuel consumed ranged from 5,910 gallons to 6,323 gallons, with aircraft landing with an average of 691 to 922 gallons remaining. The average gallons used per mile ranged from 2.09 to 2.25.

The average bomb load weight carried ranged from 9,930 to 13,090 lbs, and the average gross takeoff weight ranged from 135,087 to 135,944 lbs.

 

[Thumpalumpacus]

The Tactical Mission Report for the 1 June 1945 raid on Osaka is not available at the website mentioned, but the previous mission is (#186). That mission was on 29 May 1945 and conducted against the Yokohama urban industrial area, with a planned bombing altitude of 18,000 feet. It is offered as an example of a higher altitude incendiary mission. Excerpt below.


Strategy and Plan of Attack: Because of the increased number of losses sustained by this Command in the previous two low-level incendiary attacks, it was decided that a change in the plan of attack would be necessary. A high-altitude formation attack was planned for this mission. The plan called for the groups to cross a time control point on the coast of Japan at 4-minute intervals, allowing approximately 1-minute intervals between squadrons. The mean points of impact were to be hit in rotation in an attempt to give the crews an opportunity to get at least one visual synchronous drop on each point before the smoke should become excessive. Each Wing was assigned a specific mean point of impact instead of assigning a group from each Wing, as was planned in a similar attack on North Nagoya. It was decided that the downwind mean point of impact was to be attacked first, on a downwind run, in order to take advantage of the prevailing winds. (p.4)


The bomb loads varied by unit. The ordnance types carried:

E-28 aimable incendiary clusters (each containing 38 x 6-lb AN-M69 incendiary bombs) — 500-lb class, 350 lbs actual weight
E-36 aimable incendiary clusters (each containing 38 x 6-lb AN-M69 incendiary bombs) — 500-lb class, 360 lbs actual weight
E-46 aimable incendiary clusters (each containing 38 x 6-lb AN-M69 incendiary bombs) — 500-lb class, 425 lbs actual weight
AN-M17A1 aimable incendiary clusters (each containing 110 x 4-lb AN-M50 incendiary bombs) — 500-lb class, 465 lbs actual weight
AN-M47A2 incendiary bombs — 100-lb class, 70 lbs actual weight

Aimable clusters fell as a complete unit until reaching a predetermined altitude (typically about 5,000 feet), at which point they broke open and scattered their contents. By falling as a complete unit, it allowed the cluster to be aimed like a regular bomb, and the low altitude at which the contents were scattered resulted in a tighter concentration.

The average flight rime for this operation ranged from 13h 54m to 15h 14m; the distance flown from 2,672 nautical miles to 2,828 nautical miles. The average fuel consumed ranged from 5,910 gallons to 6,323 gallons, with aircraft landing with an average of 691 to 922 gallons remaining. The average gallons used per mile ranged from 2.09 to 2.25.

The average bomb load weight carried ranged from 9,930 to 13,090 lbs, and the average gross takeoff weight ranged from 135,087 to 135,944 lbs.

Your posts are always packed with good info. Thanks again.

 

[Peter Gunn]

The 315th BW were equipped with the stripped down B-29B fitted with the AN/APQ -7 Eagle radar. Due to the long bomb run required (70 miles) they tended to fly when the weather was poor. Their targets were oil related.

Just as an aside, I read in my uncles diary of a "training" mission to bomb Truk at night where they ran into some hellacious thunderheads with nasty hail. The AN/APQ-7 "wing" under the Superfort got pretty dinged up apparently and on the bomb run wasn't giving a good image. He mentions the radar operator increasing intensity and that helped quite a bit but not as sharp as normal.

When they got back to Guam it seems they were amazed that the AN/APQ-7 worked at all as the radar antennae wing was so badly damaged they had to junk it and replace it with a new one. He doesn't specify if they saved the internals but I imagine they did as the radar was working, just not very well. It seems the ship itself had some evident hail damage as well.

As I said, just a little anecdote from one guy's experience.

 

[Reluctant Poster]

The night / day mission split per month from March, when the first night missions were flown were as follows:-

Mar - 9/3 = 12
Apr - 12 /70 = 82
May - 13/41 =54
Jun - 25/28 =53
Jul - 58/7
Aug - 20/7

In March there were 3 Bomb Wings available (73rd, 313th & 314th). In April they were joined by the 58th BW which moved over from the CBI to join the B-29 force on the Marianas. The 315th BW then flew its first mission on the night of 26/27 June.

The 313th BW specialised in dropping mines as part of Operation Starvation which commenced on the night of 27/28 March. These missions are included in the above figures

Operation Starvation - Wikipedia

en.m.wikipedia.org

The 315th BW were equipped with the stripped down B-29B fitted with the AN/APQ -7 Eagle radar. Due to the long bomb run required (70 miles) they tended to fly when the weather was poor. Their targets were oil related.

In April & May many missions were flown in daylight against the airfields on Kyushu & Shikoku as part of the support for Operation Iceberg, the invasion of Okinawa, with each airfield target allocated its own mission number but with each attack co-ordinated as part of a larger operation on that day. So for example on 17 April 118 aircraft from 3 BW undertook 6 daytime missions against airfields on Kyushu.

The first escorted mission was to Tokyo on 7th April with P-51D from the 15th & 21st FG based on Iwo Jima. They were joined by the P-51D equipped 506th FG in May and the P-47N equipped 414th FG in July. These units flew 51 VLR missions but very few were B-29 escort missions due the change in B-29 tactics to night missions and significant reduction in Japanese interception efforts in July as they husbanded their aircraft for the invasion of the Homeland. Most of the missions undertaken were fighter sweeps.

VLR History: VLR History, 506th fighter Group, 457 Fighter Squadron, 458 Fighter Squadron, 462 Fighter Squadron Iwo To Japan

506th fighter Group 457 Fighter Squadron 458 Fighter Squadron 462 Fighter Squadron Iwo to Japan are available area.

www.506thfightergroup.org

I have posted this previously

The paper this is taken from is attached

 

[GreenKnight121]

Strategy and Plan of Attack: Because of the increased number of losses sustained by this Command in the previous two low-level incendiary attacks, it was decided that a change in the plan of attack would be necessary.

Back in the 1970s I read a book of WW2 aircrew stories, and one was written by a crewman on the B-29 night missions, and something he said was possibly pertinent to the statement of "increased losses requiring higher altitude".

He related how if you weren't one of the first set of bombers, that the updrafts from the fires would toss the B-29 around like a single-engine trainer in a thunderstorm... he commented on seeing some lose control and crash purely from the updrafts, and of finding his aircraft upside-down over 2,000 feet higher than it had been a few seconds earlier.

 

[yosimitesam]

Were the 21,000 ft attacks not all daylight attacks? It looked like the one night attack in June was at low level (6 to 9,000 ft), and then the daylight attacks that followed were all at 20,000+ ft. I would guess it must have been related to the flak defences and Japanese fighters. Defenses were weaker at low night so lower level attacks was possible. At daylight they had to fly higher, especially to avoid the flak.

During WWII there existed (among all warring nations) something of a "Flak gap" between 5,000-10,000ft. That is, the 37mm,40mm AA guns could use aimed fire at targets up to about 5,000ft, but beyond that the normal dispersion of the projectiles made aimed fire pretty much useless from these guns. Even though these guns' projectiles could probably reach 10,000-15,000 feet, the dispersion made aimed firing at these heights useless. The self-destruct fuses on these shells would also destroy these shells below these heights, in most circumstances. For the big flak guns (88mm/90mm/120mm, etc), the mechanical-computer predictors plus the large inertia of the guns (slow "tracking rate") would make them almost useless below about 10,000 feet for aircraft moving at 250+ MPH or so. They couldn't get off enough accurately tracked/aimed shots below that altitude to really be a threat to aircraft. So you have a gap in the 5,000-10,000 feet range which neither type of AA could handle very well. This is why the altitudes for B-29 night bombing were chosen. Japan had very few heavy flak guns with radar tracking and predicting; they relied on optical ranging/tracking in the daytime for these guns. Even if a B-29 were caught in a searchlight at these altitudes it would be difficult to attack it with accurate fire from either type of AA gun. In the daytime B-29 raids, the 20,000+ bombing altitudes eliminated the light flak as a real threat. Since heavy flak accuracy decreases about 50% for every 5,000 ft above 15,000 ft (due to dispersion), the daytime bombing altitudes were (almost) always 20,000+ ft.

The Germans recognized the "gap" and before the war developed the 5.0cm Flak 41 to fill this gap. Only a few of the guns were produced (less than 100) and were never a success, due to technical problems. Another interesting use of the self-destruct times in the light flak guns was their occasional use as "timed" shots somewhat like heavy flak. When an enemy formation was at the right slant distance corresponding to the time-of-flight of the self-destruct fuse, they would fire their light flak (in a multi-gun barrage) so that the light flak shells would explode (self-destruct) in the "general area" of the incoming aircraft. In the few reports I read where this tactic was used, the pilots all described the barrage of numerous exploading light flak projectiles as "very unnerving."

 

[Reluctant Poster]

During WWII there existed (among all warring nations) something of a "Flak gap" between 5,000-10,000ft. That is, the 37mm,40mm AA guns could use aimed fire at targets up to about 5,000ft, but beyond that the normal dispersion of the projectiles made aimed fire pretty much useless from these guns. Even though these guns' projectiles could probably reach 10,000-15,000 feet, the dispersion made aimed firing at these heights useless. The self-destruct fuses on these shells would also destroy these shells below these heights, in most circumstances. For the big flak guns (88mm/90mm/120mm, etc), the mechanical-computer predictors plus the large inertia of the guns (slow "tracking rate") would make them almost useless below about 10,000 feet for aircraft moving at 250+ MPH or so. They couldn't get off enough accurately tracked/aimed shots below that altitude to really be a threat to aircraft. So you have a gap in the 5,000-10,000 feet range which neither type of AA could handle very well. This is why the altitudes for B-29 night bombing were chosen. Japan had very few heavy flak guns with radar tracking and predicting; they relied on optical ranging/tracking in the daytime for these guns. Even if a B-29 were caught in a searchlight at these altitudes it would be difficult to attack it with accurate fire from either type of AA gun. In the daytime B-29 raids, the 20,000+ bombing altitudes eliminated the light flak as a real threat. Since heavy flak accuracy decreases about 50% for every 5,000 ft above 15,000 ft (due to dispersion), the daytime bombing altitudes were (almost) always 20,000+ ft.

The Germans recognized the "gap" and before the war developed the 5.0cm Flak 41 to fill this gap. Only a few of the guns were produced (less than 100) and were never a success, due to technical problems. Another interesting use of the self-destruct times in the light flak guns was their occasional use as "timed" shots somewhat like heavy flak. When an enemy formation was at the right slant distance corresponding to the time-of-flight of the self-destruct fuse, they would fire their light flak (in a multi-gun barrage) so that the light flak shells would explode (self-destruct) in the "general area" of the incoming aircraft. In the few reports I read where this tactic was used, the pilots all described the barrage of numerous exploading light flak projectiles as "very unnerving."

This excerpt from (attached)

gives a somewhat lower limit for Japanese heavy Flak stating its maximum effectiveness is at 7,500 feet.