Boeing Model 81

The Boeing Model 81 was an American training aircraft built by Boeing in 1928. The Model 81 was a development of the Model 64. It was powered by a newly developed engine, the 125 hp Fairchild-Caminez 4-cylinder radial engine.[1] Operating at a much lower rpm than most engines (1000 rpm) it required the use of a large high-pitch propeller.[2]

After initial flight tests with the Fairchild-Caminez, the prototype was refitted with a 145 hp Axelson engine, redesignated Model 81A and delivered to the Boeing School of Aeronautics. There, it was re-engined a number of times, first with a 115 hp Axelson engine, redesignated Model 81B. It then received a 165 hp Wright J-6-5, then a 100 hp Kinner K-5 and a redesigned vertical tail. Redesignated Model 81C, it would later be removed from training service, re-engined with an Axelson engine, and used as a classroom trainer.[3]

On 21 June 1928, the second Model 81 built was delivered to the US Navy at Anacostia, Maryland for $8,300, and redesignated Boeing XN2B. Its trial with the Fairchild engine was unsatisfactory, and on 10 January 1929 it was refitted by Wright Aeronautical with a 160 hp Wright J-6-5 engine. Despite increased performance, it was not ordered into production.[4]

Model 81 / XN2B
Boeing 81B with Wright J-6-5 installed (side)
Role trainer
National origin United States
Manufacturer Boeing
Introduction 1928
Primary user Boeing School
Number built 2
Developed from Boeing Model 64
Boeing 81 closeup of 125 hp Fairchild-Caminez 4-cylinder radial engine
Closeup of Boeing 81 showing 125 hp Fairchild-Caminez 4-cylinder radial engine

Variants

81
Original Caminez-engined aircraft
81A
145 hp Axelson engine
81B
115 hp Axelson engine
81C
100 hp Kinner K-5, redesigned tail.
XN2B
US Navy designation.

Operators

 United States
  • Boeing School of Aeronautics

Specifications (XN2B)

Data from Bowers, 1989. p. 144

General characteristics

  • Crew: 2
  • Length: 25 ft 8 in (7.82 m)
  • Wingspan: 35 ft in (10.67 m)
  • Height: 11 ft 2 in (3.40 m)
  • Wing area: 259 ft2 (24.06 m2)
  • Empty weight: 1,652 lb (750 kg)
  • Gross weight: 2,178 lb (988 kg)
  • Powerplant: 1 × Fairchild-Caminez, 125 hp (93 kW)

Performance

  • Maximum speed: 103.9 mph (167 km/h)
  • Cruise speed: 86 mph (138 km/h)
  • Range: 335 miles (539 km)
  • Service ceiling: 12,000 ft (3660 m)
  • Rate of climb: 515 ft/min (2.62 m/s)

References

  1. ^ A diagram of the 4-cylinder Fairchild-Caminez cam engine
  2. ^ Bowers, 1989, p. 142
  3. ^ Bowers, 1989, pp. 144-145
  4. ^ Bowers, 1989, pp. 142-144
  • Bowers, Peter M. Boeing aircraft since 1916. London: Putnam Aeronautical Books, 1989. ISBN 0-85177-804-6
Boeing School of Aeronautics

The Boeing School of Aeronautics was started by Boeing to compete against the Wright brothers' Wright Flying School and Curtiss Flying School in San Diego, California. Founded in 1929 at Oakland Municipal airport, the school started with a staff of 19 and 100 students. It was licensed by the Aeronautical Chamber of Commerce, who had taken over the licensing of aviation schools.By 1937 the school had expanded operations to 41 staff and 500 students. In October 1938 General Arnold brought in the top three aviation school representatives to request they establish an unfunded startup of Civilian Pilot Training Program schools at their own risk. These were Oliver Parks of Parks Air College, C. C. Moseley of the Curtiss-Wright Technical Institute, and Theophilus Lee, Jr., of the Boeing School of Aeronautics; all agreed to start work. This expanded in 1940 to include training of 5000 U.S. Army Mechanics. The school expanded to 14 buildings and 1000 students at its peak in 1942. Commercial pilot training was suspended to customer United Airlines to meet wartime demand in August that year. By 1943 the CPTP contract had expired and Boeing absorbed the school operations into the parent company. The facilities remained under the new name United Air Lines Training Center which continued to train mechanics under a Navy contract until 1945, before closing.

The school operated early Boeing aircraft. These included the Boeing Model 81 and Model 100 pursuit fighter 1928, Boeing Model 203 in 1929. Students would help design, develop, test fly and maintain Boeing aircraft, providing the parent company sales and engineering feedback. Several original aircraft were designed by students and teachers, such as the 1939 Thorp T-5, and T-6.

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