Boeing 247 Model 247

Boeing brought together in the 247 a set of advances it had been testing on the Monomail mailplanes (Models 200, 221 and 221A) and the B-9 bomber: anodized-aluminium semi-monocoque construction, a fully cantilevered wing and retractable landing gear. To that it added control surface trim tabs, an autopilot and de-icing boots on wing and tailplane. The 247 was faster than the best US fighter of its day, the open-cockpit Boeing P-12 biplane.

A low landing speed of 100 km/h avoided the need for flaps, and pilots learned that at speeds as low as 16 km/h the aircraft could be taxied «tail high» for easier ground handling. With controllable-pitch propellers, the 247 could hold 3,500 m at maximum gross weight on one engine.

The original project was a fourteen-passenger airliner with Pratt & Whitney R-1690 Hornet engines. A preliminary review of the design concept by United Air Lines' pilots forced a redesign into a smaller, less capable configuration with R-1340 Wasp engines. The pilots doubted that many airfields could safely take an eight-ton aircraft, and objected to the Hornets, which detonated on the low-octane fuel then available and vibrated excessively. Pratt & Whitney's chief engineer, George Mead, knew the problem would eventually be solved, but the company's president, Frederick Rentschler, gave in to the airline pilots' demand. The decision opened a rift between Mead and Rentschler.

The windshield of early 247s was raked the opposite way from normal, a solution — also used on other contemporary aircraft — to instrument panel lights reflecting off the glass. The cure was worse: the reversed windshield reflected ground lights instead, especially on landing, and increased drag.

Boeing sold the first sixty 247s to its affiliated airline, Boeing Air Transport, part of the United Aircraft and Transport Corporation, for $3.5 million — $65,000 a unit — an unprecedented order. TWA also wanted the 247, but UATC declined the order; the refusal led TWA president Jack Frye to write the requirements for a new airliner and fund Don Douglas to build the DC-1 prototype. Out of that came the DC-2 and the DC-3.

The 247 entered service on 22 May 1933; a Boeing Air Transport aircraft set a transcontinental record of nineteen and a half hours on its San Francisco to New York inaugural flight, eight hours faster than its predecessors. It was the first of its class into series production, but also the one that exposed its own limits: ten passengers in five rows proved too few against the DC-2 and DC-3, and the main wing spar ran through the cabin, forcing passengers to step over it.