Military Wiki
Role Light bomber
National origin United States
Manufacturer Keystone Aircraft
First flight ca. December 1927
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 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 water-cooled 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.


  • XLB-3 - original version with Allison VG-1410 air-cooled inverted V-12 engines (1 built)
    • XLB-3A - version with Pratt & Whitney R-1340 radial engines (1 converted from XLB-3)

Specifications (XLB-3A)

Data from Jane's Encyclopedia of Aviation[1]

General characteristics

  • Crew: Five - pilot, copilot, bombardier, two gunners
  • Length: 45 ft 0 in (13.72 m)
  • Wingspan: 67 ft 0 in (20.42 m)
  • Height: 16 ft 10 in (5.13 m)
  • Wing area: 105.8 ft2 (1,038 m2)
  • Empty weight: 6,065 lb (2,756 kg)
  • Gross weight: 11,682 lb (5,310 kg)
  • Powerplant: 2 × Pratt & Whitney R-1340, 410 hp (305 kW) each


  • Maximum speed: 116 mph (186 km/h)
  • Range: 544 miles (870 km)
  • Service ceiling: 11,210 ft (3,400 m)
  • Rate of climb: 550 ft/min (2.8 m/s)


  • 2 × trainable .303 in (7.7 mm) Lewis guns in open position in nose
  • 2 × trainable .303 in (7.7 mm) Lewis guns in open dorsal position
  • 1 × trainable .303 in (7.7 mm) Lewis gun in ventral hatch
  • 2,205 lb (1,000 kg) of bombs
  • References

    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.

    This page uses Creative Commons Licensed content from Wikipedia (view authors).