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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.
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.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.
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.
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
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.
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.
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.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.
I have posted this previouslyThe 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
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
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".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.
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.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.
This excerpt from (attached)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."