The Aeromarine BM-1 was a new mail plane design to meet a request for proposal by the US Postal Service in the 1920s.
[1] The BM-1 was a single place biplane with conventional landing gear and a steerable tail skid.
The aircraft used a dropable main fuel tank between the main gear to meet crashworthiness requirements and a small header tank of 10 gallons in the upper wing.
The wings had optional metal or wood spars with doped aircraft fabric covering.
The engine featured a radiator mounted to the front with a pass-through for the propeller shaft.