Keystone XLB-3

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).

Keystone XLB-3A
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

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

  • 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



  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.

External links

Keystone Aircraft

Keystone Aircraft Corporation was an early pioneer in airplane manufacturing. Headquartered in Bristol, Pennsylvania, it was formed as Ogdensburg Aeroway Corp in 1920 by Thomas Huff and Elliot Daland, but its name was quickly changed to Huff-Daland Aero Corp, then to the Huff-Daland Aero Company. The company made a name for itself in agricultural aircraft, and then in the United States Army Air Corps' early bomber aircraft. From 1924, James McDonnell was the chief designer.

In 1926, Huff left the company, and it was soon purchased by Hayden, Stone & Co., who increased capital to $1 million (United States) and renamed it Keystone. In 1928, it merged with Loening and was known as Keystone-Loening. In 1929, it was taken over by Curtiss-Wright. Also in 1929, the Keystone- Loening plant on the East River in New York City was closed by Curtis- Wright and the operation was moved to the Bristol, Pa. Keystone plant. A small band of the top Loening management, design and shop workers (all New Yorkers) did not want to go to Bristol. They instead started their own aircraft company in a small rented shop in Baldwin, NY in Jan. 1930. The principal players were Leroy R. Grumman, Leon "Jake" Swirbul and William Schwendler. Grumman Aircraft went on to stellar heights with some of the top Naval aircraft in Navy history. Grumman also designed and built the Lunar Excursion Module (LEM) that landed US astronauts on the moon. Keystone itself became a manufacturing division of Curtiss-Wright and ceased production in 1932.Lieut. Comdr. Noel Davis and Lieut. Stanton H. Wooster were killed in their Keystone Pathfinder American Legion while conducting a test flight, just days before they were to attempt a trans-Atlantic flight for the Orteig Prize.

Manufacturer designations
Patrol aircraft
Observation aircraft
Scout aircraft
USAAS/USAAC/USAAF/USAF bomber designations, Army/Air Force and Tri-Service systems
Original sequences
Main sequence
Long-range Bomber
Tri-Service sequence


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