Air Warfare fiction seems to be quite rare. On my bookselves I found only the following.
On the Great War, 'The Mustering of the Hawks' and 'The Professionals', both by John Harris published 1972 and 1973 respectively (my copies are later editions from Arrow and Puffin). There were a few more on WW2 subjects.
John Beede: 'Rear Gunner' first published 1965 (my copy from Tandem). About Bomber Cmd.
James Campbell: 'Maximum Effort' (again Bomber Cmd) 1957 (my copy Futura).
Spencer Dunmore: 'Final Approach' (about B17s) 1976 (my copy Pan).
Frederick E Smith: '633 Squadron' (and 4 sequels).
Elleston Trevor: 'Squadron Airborne' (about the Battle of Britain) 1955 (Great Pan).
Frankly, none of the above (except perhaps the first 633 Sqn book) is an especially distinguished novel.
Although not strictly a war book, you might enjoy Frederick Forsyth's short story 'The Shepherd' set in the late 1940s (or possibly early 1950s). Anyway, it is set around a flight in a Vampire.
Finally, I met an author at RIAT today who has just published the first of what he hopes will be a series of aviation-centred novels (to follows the naval examples of CS Forrester, Patrick O'Brian etc). The book is called 'The Aviator's Apprentice' (or 'Will Turner's Flight Logs: Part One') by Chris Davey. It looks quite promising, but I have not read it so I can't give you a positive recommendation yet. However, Mr Davey has certainly researched his subject thoroughly. The book is published by the US company Lucky Press and is available on application from The Turner Logs Co, PO Box 72, Hertford, SG14 3HY for £12.95 (incl P&P).
Moving away from fiction, you mentioned Cecil Lewis's 'Sagittarius Rising'. I think this is far and away the best aviation book to emerge from the Great War. There are plenty of other autobiographies and historical books which draw on personal accounts covering all periods from 1914 to the recent Balkans conflicts. Why go for fiction when you could read the real thing?
If none of the above appeals, you could always try Biggles (I think there are nearly 100 of them) or write one yourself!