The thick wing and balanced rudder suggests this is an early Rhonadler. The rudder is similar to that of the prototype and the canopy resembles a Rhonadler 32.
As an aside, I have the impressions that there were more Rhonadler variations than have been documented, including an open cockpit variant,
original 18m prototype Rhonadler had a rudder of an entirely different shape to the later production version and can be seen on p.109 Sailplanes 1920-1945 by Martin Simmons. The trailing edge of the rudder is a continuous curve not unlike the Weihe.
In Hans Jacobs Pionierleben im Flugzeugbau Band 2 by Peyter Ocker, p271, there is another photo of the prototype. P.273 and p276 show different rudders.
The drawings of the pre 1933 rudder, post 1933 and the ridder of the Rhonadler 35, don't look quite right when compared to photos.
Like the open Rhonadler photo !