8th Air Force peaked at 40 bomb and 15 fighter groups on 6 June 1944, which includes the 492nd (B-17/24) which was more about training by that time and became Carpetbagger/leaflets, the 489th (B-24) was made non operational in November and sent to USA, leaving 15 fighter to 38 bomber (26 B-17, 12 B-24 after 5 B-24 groups converted to B-17 July to September). The 15th Air Force grew to 21 bomber (6 B-17 and 15 B-24) and 7 and 1/3 fighter groups. The 8th Air Force transitioned its 4 P-38 groups to P-51 July to September 1944, after which it converted 3 of its 4 P-47 groups to P-51, the 15th kept 3 P-38 groups to the end of the war and converted its 2 P-47 groups to P-51 May/June 1944.
Heavy Bomber Effective sorties, USAAF Statistical Digest
| Month | ETO | ETO | ETO | MTO | MTO | MTO |
| Month | Sorties | lost | % lost | Sorties | lost | % lost |
Jan-43 | 220 | 18 | 8.18 | 622 | 11 | 1.77 |
Feb-43 | 313 | 23 | 7.35 | 585 | 6 | 1.03 |
Mar-43 | 823 | 21 | 2.55 | 720 | 2 | 0.28 |
Apr-43 | 349 | 29 | 8.31 | 1,359 | 13 | 0.96 |
May-43 | 1,471 | 69 | 4.69 | 1,890 | 16 | 0.85 |
Jun-43 | 1,268 | 90 | 7.10 | 1,944 | 10 | 0.51 |
Jul-43 | 1,743 | 118 | 6.77 | 2,860 | 30 | 1.05 |
Aug-43 | 1,850 | 117 | 6.32 | 2,097 | 85 | 4.05 |
Sep-43 | 2,457 | 98 | 3.99 | 2,339 | 20 | 0.86 |
Oct-43 | 2,117 | 186 | 8.79 | 1,427 | 37 | 2.59 |
Nov-43 | 2,581 | 95 | 3.68 | 1,069 | 28 | 2.62 |
Dec-43 | 4,937 | 172 | 3.48 | 1,606 | 36 | 2.24 |
Jan-44 | 5,027 | 203 | 4.04 | 3,811 | 54 | 1.42 |
Feb-44 | 7,512 | 271 | 3.61 | 2,380 | 128 | 5.38 |
Mar-44 | 8,773 | 345 | 3.93 | 4,202 | 85 | 2.02 |
Apr-44 | 9,945 | 420 | 4.22 | 8,084 | 194 | 2.40 |
May-44 | 13,975 | 376 | 2.69 | 11,584 | 175 | 1.51 |
Jun-44 | 22,713 | 320 | 1.41 | 10,001 | 196 | 1.96 |
Jul-44 | 18,864 | 352 | 1.87 | 10,825 | 317 | 2.93 |
Aug-44 | 18,964 | 331 | 1.75 | 10,760 | 254 | 2.36 |
Sep-44 | 15,617 | 374 | 2.39 | 8,509 | 94 | 1.10 |
Oct-44 | 17,058 | 177 | 1.04 | 6,037 | 140 | 2.32 |
Nov-44 | 15,245 | 209 | 1.37 | 6,955 | 132 | 1.90 |
Dec-44 | 16,424 | 119 | 0.72 | 7,235 | 205 | 2.83 |
Jan-45 | 14,750 | 314 | 2.13 | 2,918 | 88 | 3.02 |
Feb-45 | 19,933 | 196 | 0.98 | 10,748 | 147 | 1.37 |
Mar-45 | 28,804 | 266 | 0.92 | 12,737 | 149 | 1.17 |
Apr-45 | 18,180 | 190 | 1.05 | 11,771 | 83 | 0.71 |
May-45 | 2,254 | 7 | 0.31 | 36 | 14 | 38.89 |
| Total | 274,167 | 5,506 | 2.01 | 147,111 | 2,749 | 1.87 |
For June 1944 to May 1945 inclusive
8th AF 208,806 effective sorties (76.16% of total wartime), 2,855 heavy bombers lost, including 703 listed as lost to enemy aircraft and 1,764 to flak, 1.37% loss rate
MTO 98,532 attacking sorties (66.98% of total wartime), 1,819 heavy bombers lost, including 303 listed as lost to enemy aircraft and 1,042 to flak, 1.85% loss rate
In November 1943 the 15th Air Force inherited 4 B-17 and 2 B-24 groups from the 12th Air Force, which had in turn inherited B-24 groups from the 9th Air Force in September 1943.
8th Air Force using first mission dates as proof of a unit being operational, the first B-24 group became operational in October 1942, two months after the first B-17 group, and joined 4 operational B-17 groups.
The difficulties of these early days can be well shown by the way the 92nd Bomb Group, which had begun operations in September 1942, ceased operations in October 1942 to be turned into training units, it did not fly operationally again until May 1943. When it came back into the line 1 squadron had the YB-40, the B-17 gunship, for between 1 and 2 months.
There was the draw down for Torch, so by early November 1942 there were 2 B-17 and 2 B-24 groups operational, except the B-24 groups were only 3 squadrons, not 4 like the B-17s. And by mid November 1942 two more B-17 groups were declared operational. In December 1942 one of the B-24 groups left for Africa, returning in late February 1943 but the remaining group was given its fourth squadron.
The 8ths B-24 groups had an interesting 1943, with detachments to the Middle East, of which the Ploesti raid is the most famous. By mid year the 8th had 10 B-17 and 2 B-24 groups operational. The detachments meant that from the end of June to the beginning of September 1943 the 8th flew no B-24 operations while the number of B-17 groups rose to 16. (MTO detachments, 93rd 13 December 1942 to 20 February 1943, then 44th, 93rd, 389th 2 July to 21 August 1943, then 44th, 93rd, 389th again 21 September to 1 October 1943)
Then came the B-24 surge, by the end of 1943 it was 18 B-17 to 7 B-24 groups, by the end of March 1944 it was 20 to 10, and the peak was in June 1944, 21 to 19 in favour of the B-17, in squadron terms it was 83 B-17 to 73 B-24 in the bomber groups thanks to some squadron detachments, or 20.75 to 18.25 in group terms. (492nd being counted as B-24 here)
Around July 1944 the 8th began two processes, one was to convert the 3rd Bombardment Division to all B-17, the other was to regularise the various provisional units it had, like carpetbaggers. So by mid September 1944 the bomber groups were 26 B-17 to 13 B-24, with all groups having 4 squadrons. The 492nd Bomb Group had been turned into the carpetbagger unit.
The 34th, 486th, 487th, 490th and 493rd Bomb Groups were converted from B-24 to B-17 mid July to mid September 1944.
In November 1944 the 489th Bomb Group was sent back to the US, leaving the final ratio as 26 B-17 to 12 B-24.