This is an experimental liquid propellant rocket motor of Cleve H. Shaffer. He carried out his experiments in 1926-1932 on a deserted beach at Fort Barry, Marin County, California, San Francisco Bay, after being given permission to test there by the Army. He may have been the second person in the U.S. to test liquid fuel rockets after Robert H. Goddard.

Shaffer designed and tried various metals, as well as ceramics, for helping to cool the motor, but the details are unknown. Only static tests were carried out and no flights were made. Good results were achieved, but due to a lack interest in his work by the Army and high expenses of the experiments, Shaffer abandoned this activity. The motor was donated in 1961 to the Smithsonian by Shaffer.