Messieurs !
Those engines are shown at the Oberschleißheim Historic Aerodrome of the Royal Bavarian Aviator Troops from around 1912;
it is part of the Deutsches Museum, Munich .
The airworthy D.III will be an engine to drive a replica fighter.
It is the museum where "Umlaufmotor" took the frames of Kollomann Mayerhofers beautiful Albatross replica .
Due to museum barriers I couldn't get a better angle of view of the airworthy D.III .