I don't think the German's asked the Allies how far away the could be before they got spotted.
I don't think we should be thinking too hard about this, nor should be try and disseminate any 'findings' or ask others to provide data on the range.
Part of the *fun* of approaching the targets is not knowing, and the risk of how far to push it.
Otherwise, we might as well just dumb it right down with a visibility / detection meter.
/smh
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