Marc Birgikt originally designed what became the 18.Sb as the 1,680 hp 18.R. Earmarked for the Nieuport-Delage ND 450 and ND 650 seaplane racers, the engine was intended for use in the 1929 and 1931 Schneider Trophy contests. Its unusual three-bank W engine gained limited popularity in France and England at this time, mainly for high-performance racing and military aircraft. A military derivative, the 18.Sb, was for a short time the most powerful production engine in existence. Tested for extended periods at 1,680 hp, it was designed to run at 1,000 hp. However, it achieved only limited success, powering a single Amiot 124 experimental plane derived from the Amiot 122 bomber, and Bernard V-4 racer that never flew. Only two American aircraft used the 18.Sb, Ford’s un-built Midel 12-A and a single 14-A experimental tri-motor transport that never flew.
The 18.Sb on display is on long term loan from the National Museum of the Marine Corps.