Boeing Model 81/XN2B

1st Flight 1928

The Boeing Model 81 was an American training aircraft built 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.

Operating at a much lower rpm than most engines (1000 rpm) it required the use of a large high-pitch propeller.

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.

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.

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.

Specifications

Crew

2

Length

25 ft 8 in (7.82 m)

Wingspan

35 ft 0 in (10.67 m)

Height

11 ft 2 in (3.40 m)

Wing area

259 sq ft (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, 90.3 kn)

Cruise speed

86 mph (138 km/h, 75 kn)

Range

335 mi (539 km, 291 nmi)

Service ceiling

12,000 ft (3,660 m)

Rate of climb

515 ft/min (2.62 m/s).

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