ANTIQUE ATTIC
First Airliner: the Boeing 40
On April 7, 1924, the Post Office, realizing the need to replace its aging fleet of DeHavilland DH-4s mailplanes, requested proposal for an aircraft based on their specifications: • 400 hp Liberty engine • Cruising speed 95 mph min. • Landing speed of 50 mph or less • Service Ceiling of 15,000 ft. • Payload of 1000 lbs min. • Range of 450 miles min.
Eleven manufacturers submitted their bid for the contract, including the Boeing Airplane Company of Seattle, Washington, and the Douglas Aircraft Copany, of Santa Monica, California. Boeing offered the model 40, a big single place open cockpit biplane, carrying mail and cargo only. The wings had conventional wood spars and ribs, covered with fabric. The fuselage was built of steel tubing for the forward part, while the rest used laminated veneer wood over wood formers. The design performed well compared to the other contenders. However, Douglas was declared the winner of the contest and 50 Douglas M-2 were built for operation on the Air Mail routes.
The only Boeing 40 built, c/n 775, was acquired by the Post Office and put in service on February 10, 1926 on the Cleveland to Chicago route. A later inspection of the airframe warranted its withdrawal from service on June 22, 1926, pending repairs that were never implemented. In Seattle, the design was shelved. In 1925, the Post Office announced that it was going to turn the Air Mail Service over to private contractors. A request for proposal was emitted for the San Francisco to Chicago Route, dubbed Contracted Air Mail Route #18 (CAM-18) in 1926, with open bid period ending on January 15, 1927.
Boeing, convinced by air mail pilot Eddie Hubbard, placed a bid for $ 2.88 per pound of mail carried over the route $1.50 a pound for the first 1000 miles, and 15 cents a pound for each additional hundred mile for mail only while the closest bidder, Western Air Express, asked for $ 4.25 a pound. Boeing was awarded the contract on January 29, 1927. As nobody believed that it could make any money on such a low bid, the Post Office required the company to post a $ 500,000 performance bond. The Boeing 40 concept was dusted off and fitted with steel tube fuselage and a much more efficient Pratt & Whitney 420 hp nine-cylinder R-1340 “Wasp” radial engine and its design revisited to become the Boeing 40A. The 40A was a three-place combination cabin and open cockpit biplane. The forward cabin could accommodate two passengers in pretty tight quarters, while the hatch-covered compartments for the mail and cargo were placed between the pilot’s cockpit and the cabin section (37 cu. ft., limited to 700 lbs), and just behind the engine firewall (25 cu. ft. limited to 500 lbs). Service on the 1,943 miles CAM#18 route from San Francisco to Chicago started on July 1, 1927, each trip taking an average of 22 hours, sometimes with the presence of one or two passengers, paying $ 204 apiece for the privilege of spending their time in a cramped cabin with very basic comfort and questionable safety.
Much to everybody’s surprise, the exploitation of the Air Mail route generated a profit on its first year of operation, Boeing Air Transport having flown 1.5 million miles. At the end of two years, the Boeing 40s had flown 5.5 million miles, carrying 1300 tons of mail and 6000 passengers. Starting in early 1928, the model A was rapidly superseded by the model B, which, basically was the same airframe fitted with a more powerful 525 hp Pratt & Whitney R-1690 “Hornet.” On a rotational basis, the surviving model A’s were flown to the factory in Seattle for the engine exchange, and then, sent back for service on the line. The 40B was retroactively declined in two sub-models, the 40B-2 for service with two passengers, and the B-4, able to accommodate four passengers. The next development of the Boeing 40 was a logical step, the 40C, built for operation on Boeing’s Pacific Coast service, the old Pacific Air Transport route service from San Diego to Seattle (CAM 8). The Boeing 40C was basically a model A sporting an enlarged cabin able to accommodate four passengers. The mail compartment in front of the pilot was converted to seat the extra passengers, limiting its mail and/or cargo load to 500 lbs. Last production model was the 40H-4, version of the 40B-4 built by Boeing’s Canadian factory in Vancouver, British Columbia. Four examples rolled out in 1931-1932, while the last one was never completed. The Boeing 40 was a very important—and often forgotten—step in the history of air transport. It was the first airplane to introduce passenger service along the CAM routes system, opening the door to commercial airline traffic.
Of the 82 Boeing 40 built between 1925 and 1932, two have survived the passing of time, one at the Museum of Science and Industry in Chicago and one at the Henry Ford Museum, in Dearborn, Michigan. However, on February 17, 2008, the type returned to the skies. Tune up next month for the amazing story of the Canyonville mailplane.