I wondered whether the final scene in The Memphis Belle where they hurry to extend the gear by hand crank (because their electric system failed) is realistic, but according to this answer the B-17 indeed used a hand crank for manual gear extension.
But why did it (and other aircraft of the era that used similar system) need to manually crank the gear all the way down rather than just pull a latch out and let gravity do the rest, like modern systems generally work?