Junkers F24, I think. Ping to #19
Yes, the F-24 is a definite match.
German Wikipedia via Google Translate:
First flight: 1928
Quantity: 11
The Junkers F 24 was the single-engine cargo plane modification of the types Junkers G 23 and G 24.
Compared to the G 24, both the passenger compartment was cleared and the luggage compartment and wet cell extended. The wing centerpieces on which the two outer motors of the G 24 hung were removed, which reduced the span. This conversion was made in 1928 for the first time.
First came a 551 kW strong BMW VIU for installation, these aircraft (seven pieces) were given the designation F 24ko.
Further conversions (F 24kau) received the 507 kW paying BMW VIIau, which however was not built in series.
The version F 24kay received a 529 kW Junkers Jumo 4 2-stroke diesel piston engine. This conversion was preceded in 1929 experiments with a Junkers F04 engine. This upgrade was so successful that some of the models that had already been converted from G 24 to F 24 were retrofitted to this engine.
Wing span: approx. 25,98 m
Length: approx. 15.63 m
Top speed: with BMW VIa about 185 km / h, with Jumo 4 about 190 km / h