Hello Old Man
French magazine Icare is now publishing a series of articles about the french aviation in august and september 1914.
Issue 193 contains some details about BR.17 aircrafts.
The aircrafts used in august were #11, 26, 28, 30; there are also #48, 49, 50, 51 but these are referred as
U1 types "escadrille 1914" or
affinés (streamlined

) and have a different cowl.
I will email you some pictures.
gilles