Very small 5-cylinder radial engine for BMW X6 sport and training aircraft. Although this engine, the BMW X, proved successful at several large-scale events in 1930, including that year's round-Europe flight, only a few were built. A successor model, the BMW Xa, was introduced in 1931.
The successor to the BMW X five-cylinder radial engine, with the swept volume increased from 2.2 to 2.9 liters. Power output went up from 50 to 68 hp.