Junkers F 13 F 13bi, ci, di, fi (BMW IV)

Alongside the Junkers L2 and L5 engines of its own manufacture, Junkers offered the F 13 with BMW powerplants, and the second letter -i of the type code marked the 186 kW (250 hp) BMW IV. The sources describe these versions as being the ca to fa airframes with the BMW IV installed in place of the Junkers unit, which places them in the middle of the type's power progression from 160 hp to 570 hp. Offering a second engine supplier mattered commercially: the F 13 was sold to operators on every continent, from South American mail lines to European airlines and to several air forces, and the ability to fit whatever engine an operator could support locally was part of what kept the aircraft in service for so long. No separate operational history is documented for the -i versions; they are censused here to complete the engine census of the type.