On 20 July 1917 the Bavarian Motor Works (Bayerische Motoren Werke) was registered, intent on producing the Max Friz redesign of the Karl Rapp six cylinder aircraft engine, denoted the BMW IIIa. The engine was used in the Fokker D.VII fighter plane. The rotating propellor trademark was registered at the Imperial Patents Office on 5 October 1917.
The Bavarian Aircraft Works (Bayerische Flugzeug Werke - formerly Otto Works) was the other part of the company, and was incorporated on 5 June 1922. The old Bavarian Aircraft Works site is still the site for Plant 1 of BMW AG.
Interestingly, Max Friz, the designer of the BMW IIIa aircraft engine, was also the father of the BMW boxer motorcycle.