Sorry that this is more than 30 years old, but have you tried "Sagitarius Rising" by
Cecil Lewis?
It seems that Lewis and Rhys-Davids were great pals... it also gives you the "straight dope" on
Albert Ball-- you know, that nonsense on him being a "whirling dervish" (recounted in the Red Baron 2 and Red Baron 3D simulation games). If you read Lewis' account, you can appreciate just where and how a myth can start... BTW, it was Lewis who saw Rhys-Davids finish off Voss, as Rhys-Davids didn't actually see the result of his shooting-- read the account, it's all there!