Keystone XLB-3

Prototype Biplane Bomber

XLB-3

XLB-3A
Role	Light bomber Type of aircraft
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.

Variants

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 sq ft (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

Performance

Maximum speed: 116 mph (186 km/h, 101 kn)
Range: 544 mi (870 km, 473 nmi)
Service ceiling: 11,210 ft (3,400 m)
Rate of climb: 550 ft/min (2.8 m/s)

Armament

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

Notes

^ Taylor 1989, p. 559.

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.