Boeing Model 40

The History of the Boeing 40

One of the early effective uses of aircraft outside the military realm was for mail delivery. Until now, mail has arrived by rail or other land-based means.

Some aircraft designs are specifically designed for mail delivery services, usually designed for good speed and inherently strong transport capacity. That's exactly what Boeing did with its Model 40, which first flew on July 20, 1925, and introduced the product in July 1927.

About 80 examples of this type were eventually built, serving several shipping lines at the time, including Boeing Air Transport.

The aircraft was originally developed to meet the new requirements of the United States Postal Service (USPS). So far, the service is based on de Havilland DH, UK. 4 biplanes that appeared during the First World War (1914-1918) in 1917. Nearly 6,300 two-seat biplane light bombers were produced, most of which (including Liberty engines) came from American factories.

This line later affected later aircraft, such as the DH-9 described elsewhere on this page.

To facilitate development and production, the same Liberty engines used in the wartime version of the aircraft will be used in the new mail plane. The biplane wing arrangement was retained, and the tail was in a traditional single-wing configuration. The single-seater open-air cockpit is located aft and under the upper wing.

The landing gear is fixed and movable on all three legs. The exposed Liberty V12 radial engine was mounted in the nose and drove a two-bladed propeller. Steel pipes, aluminum, wood and fabrics are used in the general structure of aircraft. The original aircraft had a 1,000-pound cargo capacity.

The final design was the Boeing "Type 40". After acquiring the Boeing prototype, the USPS turned to the rival Douglas M-Series.

However, the Contract Air Mail Act of 1925 opened up two fronts in the postal service approach, the eastern and western regions, and Boeing sought to secure its aircraft for the latter routes. This included revising the Type 40 to a "Type 40A" to create a more attractive product, and one of the key changes was the introduction of a lighter Pratt & Whitney "Wasp" 425-horsepower radial engine. An interesting addition is the installation of a two-person cabin between the upper and lower wing members, each with a hinged car-style access door and viewing window.

On the cargo side, the plane upped its carrying capacity to 1,200 pounds of mail.

Purchased 25 Type 40A aircraft, some of which ended up with 525 hp Pratt & Whitney "Hornet" engines for increased performance. This resulted in the Type 40B-2 variant, which was essentially a redesigned Type 40A aircraft. From the outset, the Type 40B-4 designation identified a new production aircraft with Hornet engines.

The 40B model line is followed by the "40C model line" with cabin space for 4 people.

Outside the US, the Type 40 is considered part of the Honduran Air Force service and a pair is known to have been delivered to New Zealand. Boeing Canada added some of its 40H-4 aircraft to total production inventory.

The capabilities of this wartime biplane (specifically the Model 40A) include a top speed of 128 mph, a cruising speed of 105 mph, a range of up to 650 miles, a service ceiling of 14,500 feet, and - climb from 770 feet per minute .

Specification

Basic

Production

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Dimensions

Weight

Performance

Performance

Armor

Changes