When it was developed in 1963, the PT6 was the first turboprop engine rated at 450 shaft horsepower, impressing Beechcraft to the point that the company chose to install the engine in their King Air line of turboprop twins. Fast-forward 50 years, and Beechcraft still choose the PT6, although of ever-increasing power ratings, to power their engines.
Before The PT6
Pratt & Whitney began development of the PT6 in the late 1950’s in an attempt to replace the manufacturer’s Wasp radial engines, developed during in the 1930’s. In 1925, Frederick Rentschler, President of Wright Aeronautical, approached his brother, Gordon, and Edward Deeds, who were both on the board of Niles Bement Pond, convincing them that Pratt & Whitney Machine Tool, a subsidiary of Niles, should fund the creation of a new aircraft engine Rentschler and a colleage, George Mead, were developing. The engine was to be a large, air-cooled radial design. The executives at Pratt & Whitney saw an opportunity for growth and lent Rentschler $250,000, the use of the Pratt & Whitney name and space in their building to begin creating the new engine. Rentschler left Wright Aeronautical and took over operations of Pratt & Whitney Aircraft Division, The first of the Wasp series debuted on December 24, 1925, quickly becoming one of the most widely used aircraft engines in the industry due to their superior speed, rate of climb and reliability. Charles Lindbergh and Ameila Earhart both set records in Wasp-powered aircraft.
Wasp to Hornet
With the development of the PT6 still a few decades away, Pratt & Whitney created the next line of radial engines, the Hornet, rated at 525 horsepower. The dependability of both the Wasp and the Hornet made them very popular among commercial aircraft, and as the public use of air travel increased, so did the demand for Pratt & Whitney engines. As it became apparent that the United States would enter World War II, President Franklin D. Roosevelt called on manufacturers to produce 50,000 aircraft a year for military use, requiring Pratt & Whitney to expand its workforce from 3,000 to 40,000. Throughout the war, Pratt & Whitney continued to innovate, until, by the end of the war, their largest engine provided 3,600 horsepower. However, radial engines were slowly being replaced by lighter turboprop engines.
Vision of the PT6
In 1957, Pratt & Whitney saw an opportunity to channel profits from the piston engine spare parts business to the development of smaller gas turbine engines than those currently being manufactured in the United States. The company gathered a team of 12 young engineers after conducting market studies that found there was a need for a 500 shaft horsepower engine that could replace piston engines, such as the Wasp and Hornet. In December 1963, Pratt & Whitney shipped the first of the PT6 series, the PT6A-6, a highly innovative gas turbine representing technology advances that were significant at the time. Because gas turbines have a higher power to weight ratio than piston engines, the PT6 was perfect for aviation engines.
The PT6 has enjoyed a rich and colorful history since it began production in 1963, and Pratt & Whitney is proud to celebrate the 50th anniversary of this timeless aircraft engine. Learn more about the colorful past, pioneers who flew this engine and continuing evolution of an engine ahead of its time. For more information on the PT6 or about aircraft maintenance, contact Covington Aircraft online or by telephone today.