50 hp aircraft engine from 1911 was a four-cylinder, water cooled inline engine built by the German Gustav Otto Flugmaschinenwerke.

[2][3] The cylinders were cast separately from iron and then machined.

They were grouped together to a single block, joined at their cooling jackets by means of flanges and bolts.

There were two side valves per cylinder, which were operated from the camshaft, which was located on the left side of the engine block and driven from the crankshaft by spur gears.

A single spark plug per cylinder was mounted above the inlet valve, with the magneto located at the control side of the engine, driven from the crankshaft via an intermediate spur gear.