At the end of the above trailer, there's a frame showing other videos, one of which " The Making of .Masters of the Air", is a presentation and discussion featuring the main author, who's book is the primary basis for the screenplay, and a member of the production company.
It is made very clear, both during the discussion / presentation, and during the Q&A session, that the production team, from Hanks / Speilberg down, were adamant that total authenticity must be maintained throughout, be it the key characters, on which the series is based, or the aircraft, airfield and other locations.
To this end, four very large location "plots" have been used, including the former RAF airfield at Abingdon, in Oxfordshire, UK, now an Army camp ( and I believe at least one other airfield also), and a complete re-creation of a German PoW camp - the entire camp, not just a section. The main areas of Thorpe Abbotts airfield have also been re-created, built as sets, including the control tower area, and accommodation areas, with help and advice from the 100th BG Museum at the real Thorpe Abbotts (the series features the 100th Bomb Group).
I also have some photos of one of the fully restored re-fuelling tankers obtained for and used in the series, and it really looks very authentic (can't post the pics due to Copyright).
Although the aerial sequences are all CGI, the art department built two, full-size replicas of B-17s, which "work" in as much as props turn, they can move etc, and the internal details are totally accurate. These are used for "ground scenes", but one was actually suspended from a crane for a landing scene.
I'll admit I'm slightly dubious about the CGI aerial scenes and, although I accept that some very slight inaccuracies are unavoidable in order to bring the "action" to the screen in an understandable manner, I also understand that was has been shown so far are very short clips and it hopefully will look fine in the overall context of the series.
I'm almost finished reading the other book used as part of the basis for the series, "On a Wing and a Prayer", by Harry Crosby, who was Lead navigator of the 100t BG, and, from what I've learned of the series to date, it matches very accurately with his accounts.