Page 33 - Volume 14 Number 2

result, the aircraft was conceived strictly on speculation and without any money from the Air Corps, Navy or the federal government.
During the past 85 years, exactly how the design process began in the mind of Lloyd C. Stearman sometime in 1931, and how it was revived in 1933 by engineers Mac Short, J. Jack Clark and Harold W. Zipp, remains somewhat unclear. Apparently, the trio based their design on a rudimentary drawing by Stearman of a modified Model 6 Cloudboy that embodied upgrades to make it appealing to the military.
Led by chief engineer Short, the team made further improvements to the airframe that included a cantilever main landing gear, a fuselage cross section that was similar to that of the sole Model 80 biplane and a new empennage that featured dual trim tabs. In general, it was only an evolutionary, not revolutionary design, but it did represent the company’s latest attempt to create a rugged flying machine aimed specifically at the military’s primary training mission.
Designated as the Model 70, the latest Stearman was both attractive in appearance but tough, too.
The airframe was stressed for +12G and -9G, which allowed for the execution of many aerobatic and combat maneuvers that were standard fare for a fledgling cadet. The trim biplane was powered by a Lycoming R-680 static, air-cooled, nine-cylinder radial engine rated at 210 horsepower swinging a two-blade, ground-adjustable steel propeller.
By the end of 1933 the airplane was completed and underwent a series of ground checks, rigging and engine runs before engineers and company test pilot David “Deed” Levy pronounced the Model 70 ready for its first flight. Levy took the ship into its element on New Year’s Day, 1934, and upon landing proclaimed that the ship exhibited no bad habits and flew well.
The U.S. Army Air Corps and U.S. Navy agreed to test the biplane, and during the next few months test pilots would wring out the Model 70 at Wright Field near Dayton, Ohio, Naval Air Station Anacostia, and at the Navy’s flight training base at Pensacola, Florida. Both Army and Navy aviators liked the Stearman but found fault in its stall behavior, which was too benign. They wanted the stall to be more abrupt, and eventually
FEBRUARY 2020
KING AIR MAGAZINE • 31