DFS/Schleicher Rhönbussard, likely D-6-612 (the dark aircraft in the main photo, top, and in the detail enlargement, bottom), and Schneider Grunau Baby D-6-660 (light coloured aircraft in the rear and in the detail enlargement, centre) of NSFK-Gruppe 6 Breslau (Schlesien).
The Rhönbussard first flew in 1933. It was designed by Hans Jacobs as a small high-performance sailplane. The number of completed aircraft amounted to over 200.
In its original configuration, the Grunau Baby sailplane was designed by Edmund Schneider, together with Wolf Hirth, in Winter 1930/31. Several thousand Babys were built.
Devised in spring of 1937, the aircraft code system (e.g. D-6-660 ) of the NSFK [Nationalsozialistisches Fliegerkorps, i.e., National Socialist Flyers Corps] was implemented by July 25, 1937. The exact date of the photograph and the location are currently unknown to me, however. (Fischer collection)