The Keystone XLB-3 (originally built under the Huff-Daland name) was a prototype bomber biplane developed in the United States in the late 1920s. It was a twin-engine development of the single-engine LB-1, brought about by a change in policy by the

United States Army Air Corps The United States Army Air Corps (USAAC) was the aerial warfare service component of the United States Army between 1926 and 1941. After World War I, as early aviation became an increasingly important part of modern warfare, a philosophical r ...

(USAAC).

Design and development

The shift from a nose-mounted engine to engines mounted in nacelles on the lower wing created an opportunity to provide stations for two extra crewmembers: a bombardier and a nose-gunner, bringing the total to five. The LB-1's single tailfin and rudder was augmented by an extra rudder either side of it.

Operational history

A single prototype was constructed, and delivered to the USAAC for evaluation at the end of 1927. Evaluation, however, showed that performance was actually inferior to that of the single-engine LB-1. The decision was taken to change the XLB-3's air-cooled inverted Liberty engines for air-cooled radials, at which point it was redesignated XLB-3A. With performance still unsatisfactory, development was abandoned in favor of a parallel design, the

LB-5 The Keystone LB-5 (originally ordered under the Huff-Daland name) was a bomber aircraft produced in the United States in the late 1920s. Its manufacturer nicknamed it the Pirate, but this name was not officially adopted by the United States Army ...

Variants

* XLB-3 – original version with

Allison VG-1410 The Liberty L-12 is an American water-cooled 45° V-12 aircraft engine displacing and making designed for a high power-to-weight ratio and ease of mass production. It saw wide use in aero applications, and, once marinized, in marine use both ...

air-cooled inverted V-12 engines (1 built) * XLB-3A – version with

Pratt & Whitney R-1340 The Pratt & Whitney R-1340 Wasp is an aircraft engine of the reciprocating type that was widely used in American aircraft from the 1920s onward. It was the Pratt & Whitney aircraft company's first engine, and the first of the famed Wasp series ...

radial engines (1 converted from XLB-3)

Specifications (XLB-3A)

References

Notes

Bibliography

* Taylor, Michael J. H. ''Jane's Encyclopedia of Aviation''. London: Studio Editions, 1989. * ''World Aircraft Information Files''. London: Bright Star Publishing, File 899, Sheet 09.

External links

National Museum of the USAF XLB-3 fact sheet

National Museum of the USAF XLB-3A fact sheet

{{USAF bomber aircraft Biplanes Huff-Daland aircraft Light bombers LB-3 Keystone LB-3 Aircraft first flown in 1927 Twin piston-engined tractor aircraft