This is basically the only book I've really come across that's dedicated just to WWI aviation as a general history of it. There are some books on specific aircraft (Osprey Aircraft of the Aces), and generally a WWI book will mention them in the vaguest terms, as will (usually) a history of military aviation, although they quite often just start with 1918 when the RAF was formed. Unfortunately, I don't think it's in print. One sec. Yeh, I've just looked on Amazon and the most recent edition they have is 1977. But it's really good. I was totally gripped, and it wasn't just because I love WWI aviation (at least, I don't think it was). I really enjoyed it.
There was more mention of the thrilling exploits of the RNAS in Belgium, though I got the impression that a lot of it came from Churchill's book... There were a lot of references to Churchill too, although to be fair, Churchill was Chief of the Air Ministry or something along those lines, and also as the Minister for the Navy he was involved with the RNAS too.
It was a really good introduction to the air war, with sections on the people involved (the aces), the aircraft, the tactics. However, I don't think it really went deep enough to be completely satisfying. I still want to know more. I saw one or two new books in a bookshop in London on the topic, but they don't seem to have them at the library (with the exception of First Blitz, which is absolutely excellent, but does only cover a limited aspect of the air war). Still, it was an enjoyable book, and the pictures were great because I was trying to put strings on a Sopwith Triplane at the time, and the instructions with the model weren't very good, so I was able to see what it should look like.