This is a fascinating exhibit at the Polish Aviation Museum, unfortunately preserved without wings. The aircraft was modified to this form from a Siemens-Schuckhert DV.1 123 of which were built around 1918. The DV.1 had a very good performance but arrived too late and in too small numbers to affect the balance of air power in the late stages of WW I. It first flew in the form here in 1926.
The Polish Aviation Museum contains a phenomenal selection of original 1st World War aircraft, unfortunately mostly without wings. From left to right these are Halberstadt CLII, LFG Roland DV1b, DFW CV.C, Aviatik C.III, Albatross C.1, Sopwith F.1 Camel and Albatross H.1 - together an amazing sight.