Boeing Model 81
Model 81 / XN2B | |
---|---|
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Role | trainer |
National origin | United States |
Manufacturer | Boeing |
Introduction | 1928 |
Primary user | Boeing School |
Number built | 2 |
Developed from | Boeing Model 64 |
![](http://upload.wikimedia.org/wikipedia/commons/thumb/1/19/Boeing_81_closeup_of_125_hp_Fairchild-Caminez_4-cylinder_radial_engine.jpg/220px-Boeing_81_closeup_of_125_hp_Fairchild-Caminez_4-cylinder_radial_engine.jpg)
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]
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
- Boeing School of Aeronautics
Specifications (XN2B)
Data from Bowers, 1989. p. 144
General characteristics
- Crew: 2
Performance
References
![](http://upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/30px-Commons-logo.svg.png)
- ^ A diagram of the 4-cylinder Fairchild-Caminez cam engine
- ^ Bowers, 1989, p. 142
- ^ Bowers, 1989, pp. 144-145
- ^ Bowers, 1989, pp. 142-144
- Bowers, Peter M. Boeing aircraft since 1916. London: Putnam Aeronautical Books, 1989. ISBN 0-85177-804-6