The Argus 50 hp aircraft engine, from 1909 was a four-cylinder, water cooled inline engine built by the German Argus Motoren company.

[1][2] It had a bore of 124 mm (4.88 in) and a stroke of 130 mm (5.12 in) and produced about 45–55 hp (34–41 kW) at 1200–1300 rpm[3][4] and was produced in two variants, with the valves and camshaft on the right[3] or on the left side[5] respectively.

[5] The coolant was circulated by a centrifugal water pump which was installed on the carburettor side and driven from the camshaft gear.

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.

There was no oil pump installed and the lubrication was done solely by splash.