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Keystone XLB-3A.jpg
Role Light bomber
National origin United States
Manufacturer Keystone Aircraft
First flight ca. December 1927
Primary user United States Army Air Corps
Number built 1

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 (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.


Specifications (XLB-3A)

Data from Jane's Encyclopedia of Aviation[1]

General characteristics





  1. ^ Taylor 1989, p. 559.


  • 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.