The Biggles novels might be ostensibly aimed at younger readers, but that's not to say that they are childish in all ways. Capt.W.E. Johns' experiences form the basis for a lot of the anecdotes which appear in early Biggles stories, which makes them semi-autobiographical, and you can learn a lot about the period of WW1 flying in the RFC by 'reading between the lines' in Biggles books. I remember re-reading the bit in 'Biggles learns to fly' some time ago, and it brought a wry smile to my face when I read the bit where he loses sight of the airfield on his first solo circuit and has to land in a nearby field, as I recalled my own first solo flight when I nearly ended up doing the same thing (fortunately in my case I spotted it again). I heartily recommend anyone into aeroplanes reading the early Biggles books, you'll be surprised how enjoyable they are.
Chock