My wife's grandfather was a bombardier in the lead plane of the Bloody 100th Heavy Bomb Group, 8th Air Force, in the days shortly after D-day, until the end of the war. His B-17 was the first of nearly 1000 in the larger raids, and they were accompanied by over 500 fighters.
My question is, if you were some farmer out in your field, and you saw the first plane going overhead, how long would it be until the last one passed? I have not been able to find this online. I would think it would be truly frightening to hear the rumble of radial engines as the "aluminum overcast" passed overhead.
Thanks!
That is a difficult question to answer for a couple of reasons. On any particular day, multiple targets would be attacked using multiple routes meaning that it would be uncommon for a full "1000 bomber" raid to take place; In addition, some raids were staged so that there would be multiple waves of bombers attacking targets to enhance disruption and damage to the targeted city.
However, if you consider that the bomb groups were stacked both horizontally and vertically to maximise their defensive firepower, formations would have passed overhead relatively quickly. To give a time frame would be speculation and that just leads to errors.
(The RAF would use a "bomber stream" (i.e. no real formation) and pass a thousand bombers over a target in less than an hour, sometimes shorter, depending on the ability of the master bomber to hang around over the target, although that is getting off topic)