Keystone LB-5

The Keystone LB-5 was the first of the series of twin-engine biplane bombers developed from the single-engined Huff-Daland LB-1 to enter service with the US Army Air Corps. Eventually nearly 200 Keystone bombers in seven main variants would enter service, and they were the standard American bomber during of early 1930s.

The LB-5 had been developed as the Huff-Daland XLB-5, but on 8 March 1927 the company had been renamed as the Keystone Aircraft Corporation, thus the change in designation to the Keystone LB-5. Keystone itself would soon be purchased by the Wright Aeronautical Corporation, and become involved in the merger that produced Curtiss-Wright.

Ten LB-5 service test aircraft were ordered, and were delivered to the Air Corps during 1927. They were very similar to the XLB-5, but had a triple vertical tail instead of the single tail of the prototype. Like the XLB-5 they had two twin-gun positions – one in the nose and one in the rear fuselage, with a fifth gun position in a fuselage tunnel. The bombardier’s position was in the chin.

The LB-5 was a very conservative design, showing little improvement on aircraft of the early 1920s, but at the time the Army Air Corps' leadership was equally conservative, and was not yet ready to purchase the all-metal monoplanes that were rapidly becoming standard. As a result Keystone would receive a series of orders for barely modified versions of the LB-5, the last of which would still be in use on some over-seas stations as late as 1939.

The ten LB-5s were followed by twenty-five LB-5As which were given the first 1928 serial numbers. These were very similar to the LB-5, but replaced the triple tail of the earlier aircraft with a twin vertical tail design. The LB-5 was the last entry in the series to be powered by inline V-engines – all later aircraft used radials, but would otherwise be very similar to the LB-5.

In September 1928, soon after entering service nine of the LB-5As took part in a cross-continental movement, from Langley Field to Los Angeles to take part in the National Air Races. The trip out was badly affected by the weather, and took six days, but provided the Army Air Corps with valuable experience of operating over long distances.


LB-5 and LB-5A


Two Liberty V-1650-3


420hp each






44ft 8in


16ft 10in

Gross Weight


Maximum Speed

107 mph at sea level




435 miles


Five 0.30in machine guns

Bomb load


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How to cite this article: Rickard, J (8 October 2008), Keystone LB-5 ,

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