I did now complete a somewhat larger test run with some interesting results.
Method:
Offline Practice, all arena settings (but protect objects) and object settings set to default.
Complete arena reset between individual runs (= restarting Aces High)
Single bomber, bomb altitudes between 850 and 1000 ft. Delay 0.05. Bomber speeds between 157-186 mph.
All attacks runs commenced from astern. Not a single bomb missed.
Results:
Lancaster, 1000 lb
Salvo 12 = sunk
Salvo 11 = sunk
Salvo 10 = sunk
Salvo 9 = sunk
Salvo 8 = sunk
Salvo 7 = not sunk
B24, 2000 lb
Salvo 4 = not sunk
I did repeat both Lancaster as well as B24 8k drops two times, with same results every run.
This seems to indicate that it's still 8K to sink a CV, not 12.