Page 35 - Volume 13 Number 10

The forward cockpit and a small windshield are visible in this photograph taken with the cover panel removed. The three small circles on the side of the fuselage covered parachute-type flares that could be ejected, slowly drifting downward to illuminate a landing area at night. (Courtesy Kansas Aviation Museum)
In 1927 Mac Short, a graduate of the Massachusetts Institute of Technology
with a degree in aeronautical engineering, worked side-by-side with Lloyd Stearman to transform their designs into production aircraft. As with Stearman, Short was a native Kansan and a key figure in the Stearman |Aircraft Company from 1927 until the late 1930s. As chief engineer, he led the team that created the overall design of the Model 80 and Model 81.
(Courtesy Wichita-Sedgewick County Historical Museum)
controllable-pitch propeller that would set it apart from its older
would improve takeoff and climb performance.
The engine was equipped with an Eclipse electric starter and the electrical system included a 15-volt, 15-ampere Eclipse generator with a control box and a master switch in the aft cockpit. An Exide storage battery operated the instrument panel lights in both cockpits. Based on slide rule calculations, Short estimated that the Model 80 would have a maximum speed of 175 mph and a cruising speed of 150 mph. Range would be about 700 statute miles, rate of climb 1,500 feet per minute with a service ceiling of 20,000 feet.
Other specifications included:
= Wingspan: upper panels – 35 feet, lower panels – 27 feet
= Total wing area: 275 square feet
= Empty weight: 2,436 pounds
= Maximum gross weight: 3,500
pounds
= Fuel capacity: 104 gallons
= Stall speed: 58 mph
The Model 80’s basic airframe would be based on the Model 4 series but with a number of changes that
siblings. For example, to increase speed the engineers chose the NACA 4412 airfoil that provided a good cruising speed without sacrificing slow-speed handling and landing characteristics. A new empennage was designed that incorporated an offset rudder tailing edge to help counteract the Wasp Jr.’s torque during takeoff and climb. The fixed, semi-cantilever main landing gear featured only two struts per side and was an advance compared to the braced configuration that had served Stearman airplanes well since 1926.
Throughout the design process Short worked closely with Vette to ensure the Model 80 would be exactly what the customer ordered: “Stearman engineers are collaborating with Vette and have extended themselves in an effort to design a plane not only to meet the special requirements, but to be the last word in comfort, utility and speed.” The aircraft featured dual flight, engine and wheel brake controls in both cockpits as well as a dual set of Pioneer flight and engine instruments. In the aft cockpit only, workers installed Sperry gyroscopic attitude and heading indicators for flying by reference to instruments. As a final touch, Vette ordered a sliding canopy to cover the aft cockpit.
Sparing no expense, Vette also specified installation of a Lear Radioaire receiver set with a frequency range of 235-720 kilo cycles, and one headset. In a time when very few personal aircraft carried radio communication equipment, the Model 80’s airframe was bonded to minimize interference with the radio. A final specification
OCTOBER 2019
KING AIR MAGAZINE • 33