Close this search box.

Boeing Model 40

The Boeing Model 40 was a United States mailplane of the 1920s.

It was a single-engined biplane that was widely used for airmail services in the United States in the 1920s and 1930s, especially by airlines that later became part of United Airlines.

It became the first aircraft built by the Boeing company to carry passengers.

The Honduran Air Force used these as transports.


Model 40

Original 1925 design with Liberty engine.

Model 40A

Revised 1927 design for BATC, The aircraft was powered by a Pratt & Whitney Wasp radial engine, plus seating for two passengers in an enclosed cabin.

Model 40B

Model 40As re-engined with a 525 hp (391 kW) Pratt & Whitney Hornet radial piston engine.

19 Model 40A were converted.

Redesignated Model 40B-2.

Model 40B-4

Revised Model 40B with seating for four passengers and other improvements.

Equipped with operable windows, plus seating for four passengers.

Model 40B-4A

One Model 40B used as engine test-bed by Pratt & Whitney.

Model 40H-4

Four Model 40B-4s built by Boeing Canada.

Two aircraft were exported to New Zealand.

Model 40C

Similar to Model 40B-4 but with Pratt & Whitney Wasp engine of Model 40A.

(Ten built, all later converted to Model 40B-4 standard).

Model 40X

Unique special-order machine similar to Model 40C with only two-passenger cabin and extra open cockpit forward of pilot’s cockpit.

Model 40Y

Unique special order machine similar to Model 40X, but with Pratt & Whitney Hornet engine.





Two passengers and 1,200 lb (540 kg) mail


33 ft 2.25 in (10.12 m)


44 ft 2.25 in (13.47 m)


12 ft 3.1 in (3.74 m)

Wing area

547 sq ft (50.82 m2)

Empty weight

3,531 lb (1,605 kg)

Max take-off weight

6,000 lb (2,727 kg)


1 × Pratt & Whitney Wasp,

420 hp (313 kW)


Maximum speed

128 mph (206 km/h, 111 kn)

Cruise speed

105 mph (169 km/h, 91 kn)


650 mi (1,046 km, 565 nmi)

Service ceiling

14,500 ft (4,420 m)

Rate of climb

770 ft/min (3.9 m/s).

Share on facebook