If there’s a certain cachet for being first in a field, there’s also the risk of being outmoded by the second entrant in that field.
The Boeing 247 airliner set a standard when it first flew on Feb. 8, 1933. An obvious replacement for the trimotored airliners then in service, the 247 built upon Boeing’s pioneering aluminum airframe work with the earlier single-engine Monomail transport and twin-engine B-9 bomber.
The 247 was the first American low-wing multi-engine transport. It set the tone for airliners to follow.
It was an all-metal twin that could climb with a full load on one engine. Its retractable landing gear and full cantilever wing with stout bridge-truss style internal construction earned respect.
Boeing’s relationship with United Air Lines meant competing airlines would not have access to 247s right away, as production capacity fed United’s needs.
TWA (originally Transcontinental and Western Air) needed to stay abreast of airliner developments, and queried other aircraft manufacturers about creating a state-of-the-art transport to go head-to-head with United’s Boeing 247s. Even before the first flight of the 247, TWA was aligned with Douglas Aircraft in the design of a modern twin-engine low-wing metal airliner in late 1932.
The initial Douglas product was the DC-1, available to TWA in December 1933. Although only one DC-1 was ever built, it showed promise. Its 12-passenger configuration bested the 247 by two passengers.
And where the 247’s stout wing spars passed through the passenger cabin, necessitating stepping over them to move fore and aft, the DC-1 had no such impediment.
The 247 was built on the cusp of the era when wing flaps gained popularity —and it had none. The DC-1 was an early adopter of split flaps, with the flap hinging from the undersurface of the wing, leaving the upper airfoil surface intact.
During the brief production life of the 247, Boeing introduced some upgrades. Notably, the 247D model boasted a top speed of 200 miles per hour, up from the earlier top speed of 182. The 247D also cruised at 189 mph, faster than older 247s at 155 mph.
New 247Ds employed full NACA cowlings, and controllable pitch propellers. They also had a rearward sloping windscreen and fabric control surfaces.
Some older 247s were upgraded to D-model configuration while retaining their metal control surfaces and forward canted windscreen.
Meanwhile, the sole DC-1 evolved into a 14-passenger airliner that was produced as the slightly lengthened DC-2 for American Airlines. More than 198 DC-2s were built, compared with only 75 Boeing 247s.
Even more telling, the DC-2 was succeeded in 1935 by the larger and essentially redesigned DC-3, which halted production in wartime after 607 DC-3 airliners had been built.
But that was far from the end of the story, as military transport variants like the C-47 and C-53 accounted for a production run in excess of 10,000 aircraft. Thousands more were built under license in the Soviet Union (and hundreds by prewar agreement in Japan).
The groundbreaking Boeing 247 had a positive impact on the future of Boeing. In 1933, the 247 represented a forward-looking amalgam of metal aircraft design tenets as interpreted by Boeing, and incorporating things learned from their earlier Monomail and B-9 designs. The all-new Boeing Model 299 of only two years later carried this design and construction rationale forward as the B-17 Flying Fortress, a mass-produced strategic bomber of significant value in the Second World War victory over the Axis powers.
Historian Peter M. Bowers, whom some will remember as the creator of the Of Wings & Things column, wrote in “Boeing Aircraft Since 1916” that the Model 299 “can be most accurately described as a direct structural and aerodynamic combination of the Model 247 transport and the… XB-15” then in development by Boeing. The Flying Fortress had good aeronautical genes inherited from the pioneering 247.
Placing the wing low allows good visibility upwards and makes the aircraft more maneuverable by reducing pendulum stability. It also puts the wing closer to the ground, generating a more noticeable ground effect thus allowing shorter takeoffs.
My Dad, Bert Zimmerly, had 3 247D’s in 1945 replacing 4 Cessna Airmasters and a Travel Air S6000B for his intrastate airline in Idaho that started in April of 1944. Zimmerly Airlines application to the CAB in 1945 for certification of Empire Airlines became the standard for all applicants for airline certification. I was 12 years old but got a little stick time with my Dad in the 247. Empire Airlines was the second airline certified after WWII. They had a perfect safety record. The history of Zimmerly/Empire can be found in a book by Richard R. Roth, Empire in the sky, The Bert Zimmerly Story.
Low-wing transport seems to be the norm. What are the essential advantages of Low-Wing vs High-Wing?