The Epic of Flight is a 23 volume series (no master index) about the history of aviation. There are specific volumes dedicated to different types of aircraft and aviators.
I haven't seen any of these yet personally, but it is one of the series I hope to get ahold of soon. Anyone out there have them and want to pass on a review? I have seen alternate copies of these books floating around on e-Bay with a brown leatherette cover. I don't know if that is a different printing of this series, though; about 99% of the volumes you see have the blue covers.