The LB-5 was an improved version of the XLB-5 used as service test aircraft. The most apparent difference between the two aircraft was the single tail on the XLB-5 and the triple vertical tail on the LB-5. Ten aircraft were ordered by the Air Corps in 1927 and used into the late 1930s, long after they were made obsolete by much more advanced aircraft.
The LB-5 was a very conservative design, not much different from the Martin NBS-1 of the early 1920s. The Air Corps leadership favored the twin-engine biplane bomber, and it would be another five years before a significantly improved bomber would appear in the Martin B-10.
TECHNICAL NOTES: Armament: Five .30-cal. machine guns and 2,312 pounds of bombs Engines: Two Liberty V-1650-3s of 420 hp each Top speed: 107 mph at sea level Service ceiling: 8,000 ft. Range: 435 miles with full bomb load Span: 67 ft. Length: 44 ft. 8 in. Height: 16 ft. 10 in. Weight: 12,155 lbs. gross Crew: Five Serial numbers: 27-335 to 27-344