Military Wiki
Role Patrol flying boat
National origin United States of America
Manufacturer Boeing
First flight 1925
Primary user United States Navy
Number built 1

The Boeing XPB (company Model 50) was an American twin-engined biplane long-range patrol flying boat of the 1920s. A single example was built for the United States Navy.

Design and development

In September 1924, the Naval Aircraft Factory was tasked with designing a long-range twin-engined flying boat, capable of flying the 2,400 mi (3,860 km) between San Francisco and Hawaii. The initial design was carried out by Isaac Laddon, an employee of Consolidated Aircraft, and then passed to Boeing for detailed design and construction. The new flying boat, the Boeing Model 50, was a two-bay biplane of very streamlined design for flying boats of the time. The wings were of metal construction, with wooden wingtips and leading edges. The fuselage had a metal lower part, with the upper half made of laminated wooden frames with a wood veneer covering. Two 800 hp (600 kW) Packard 2A-2500 V12 engines driving four-bladed propellers were mounted in tandem between the wings above the fuselage.[1]

Operational history

Boeing XPB-1

The Boeing Model 50, designated XPB-1 by the US Navy, made its maiden flight in August 1925.[2] It was intended to use it to lead a pair of Naval Aircraft Factory PN-9s in an attempt to fly to Hawaii on 31 August 1925, but engine trouble led to its participation in the flight being cancelled.[3][4] In 1928, the aircraft was modified by the Naval Aircraft Factory, its Packard engines were replaced by two 800 hp (600 kW) geared Pratt & Whitney R-1860 Hornet radial engines, leading to the new designation XPB-2.[5]

Specifications (XPB-1)

Data from Boeing Aircraft since 1916[6]

General characteristics

  • Crew: 5
  • Length: 59 ft 4.5 in (18.098 m)
  • Wingspan: 87 ft 6 in (26.67 m)
  • Height: 20 ft 10 in (6.35 m)
  • Wing area: 1,801 sq ft (167.3 m2)
  • Airfoil: Clark Y[1]
  • Empty weight: 11,551 lb (5,239 kg)
  • Gross weight: 26,882 lb (12,193 kg)
  • Powerplant: 2 × Packard 2A-2500 liquid-cooled V12 engine, 800 hp (600 kW) each


  • Maximum speed: 97 kn; 180 km/h (112 mph)
  • Cruise speed: 82 kn; 151 km/h (94 mph)
  • Service ceiling: 9,000 ft (2,700 m)
  • Rate of climb: 4,000 ft/min (20 m/s)


  • Guns: 3× .30 in machine guns
  • Bombs: 4,000 lb (1,800 kg)

See also

  • List of seaplanes and amphibious aircraft


  1. 1.0 1.1 Bowers 1989, p. 73.
  2. Yenne 2005, p. 15.
  3. "Boeing C to Z, and hyphenates". Aerofiles. Retrieved 18 June 2010.
  4. "San Francisco-Honolulu Flight Fails". Flight, 10 September 1925, p. 579.
  5. Bowers 1989, pp. 73–74.
  6. Bowers 1989, p. 75.

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