Model Variants (Including Prototypes)
MB-1 - Martin Company Designation / Military Designation.
GMB "Glen Martin Bomber" - United States Army Air Service designation for MB-1 series.
GMT "Glenn Martin Transcontinental" - Fitted with fuel tanks for increased range.
GMC "Glen Martin Canon" - Fitted with 1 x 37mm cannon replacing bow-mounted 7.62mm machine gun.
GMP "Glenn Martin Passenger" - Accommodations for up to 10 passengers; redesignated to T-1.
MBT "Martin Bombers - Torpedo" - Torpedo Bomber Variant; used by the United States Navy.
MT "Martin Torpedo" - Used by the United States Navy; based on MB-1 system with wing assembly of MB-2 bombers; redesignated to TM-1.
T-1 - GMP Redesignation
TM-1 - MT Redesignation
MB-1 / NBS-1 - "Improved" MB-1 Model Series