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| The Long-Running T53 |
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| Army's decision to shut down its Stratford, Connecticut engine factory closes a chapter in the history of the original turbine helicopter engine, the Lycoming (now AlliedSignal) T53. Sometime in 1997, after existing contracts are completed, the factory that built Sikorsky flying boats, Vought Corsair fighters, Curtiss-Wright radial engines and more than 19,000 T53s, is scheduled to close. Some 1,800 people will be looking for work; however, the venerable T53, that first ran forty years ago, is expected to keep on running, maybe until the year 2020. Over the past four decades, the pioneering T53 powerplant, conceived by the renowned German jet-engine designer, Dr. Anselm Franz, has earned a re putation for reliability and maintainability in number of celebrated single-engine, rotary-wing aircraft-from the Bell Huey and Cobra to the new Kaman KMAX utility helicopter. The T53 also has powered a variety of other significant vertical-lift aircraft, including the Bell XV-15 (the tilt-wing predecessor of the Bell/Boeing V-22 Osprey), the Canadair CL-84 tilt-wing, the Doak 16 ducted fan, the Ryan 92 deflected slipstream aircraft and the Vertol 76 tilt-wing. In the Beginning The T53 first achieved notoriety in the Huey during the 1960s. But when the engine was developed in the early 1950s, the concept of using turbines in rotorcraft was a novel idea embraced by only a few forward-thinking people. One of those visionaries was Dr. Anselm Franz, who had developed the Junkers Jumo 004, the engine used in Germany's famous Messerschmitt Me 262 jet fighter. Franz, who emigrated to the United States after World War 11, understood that turbine powerplants are not as heavy as piston engines of comparable power and don't require the cooling systems needed by reciprocating engines. He reasoned that rotorcraft would benefit from a smaller, lighter turbine engine that could be mounted outside the cabin, thus allowing heavier and bulkier payloads to be carried inside. From 1946 through 1950, Dr. Franz worked as a consultant for the U.S. Air Force, using his knowledge of turbines to help American engine manufacturers solve their jet development problems. However, his personal goal was to get a U.S. company to help him develop and produce a small turbine in the 300- to 1,000-hp class. In late 1950 Franz convinced Avco Lycoming President S.B. Withington that his company needed a small turbine engine to complement Lycoming's line of piston powerplants. In January 1951 Franz
began to assemble a team of turbine engineers at Lycoming's Williamsport, Pennsylvania plant. |
Compact, Easily Maintained The T53 was designed to be compact, reliable and easily maintained. For example, the engine-which weighed approximately 500 pounds and was about two feet in diameter and four feet long-employs an axial-centrifugal compressor, which eliminates the need for the fragile blades used in the later stages of a purely axial compressor. The Ly•coming powerplant also pioneered the concept of modularity; the entire hot section can be removed while the rest of the powerplant remains in the aircraft. However, despite the ingenuity of the T53 design, development problems had to be overcome. For example, the original "T cane" vaporizing tubes could not withstand the heat being generated by combustion, so a glass coating was applied to make them more durable. This was one of the earliest applications of ceramics in gas turbine engines. First T 53 Ran in 1954 After the major development problems were solved, the complete T53 ran for the first time in December 1954. The future of the T53 turned out to be bright. On September 27, 1956, the engine made its first flight in a Kaman H OK-1, and several weeks later flew again in Bell's XH-40, the prototype for the popular UH-1 Huey. During the height of the Vietnam War, when Bell was churning out Hueys as fast as possible, Lycoming's Stratford plant produced the equivalent of 300 engines per month. The T53 went on to become the most reliable and successful helicopter engine in military history. Since 1956, 19,000 engines have logged more than forty-six million hours, with the vast majority of them in single-engine aircraft. Through continuous development, the T53's power output has doubled, the fuel efficiency and reliability have been improved-all without an appreciable increase in the engine's size or weight. Earning a Reputation for Reliability As noted earlier, it was in the Huey that the T53 earned its rugged reputation. During the Vietnam War, the engines were often operated under extreme conditions. For example, if a jungle landing area wasn't completely clear of vegetation, pilots would use the main rotor to chop their way through the underbrush as they descended. One T53 that came back to the factory from Vietnam was missing a couple of four-inch bolts. The U.S.-based technicians who disassembled the powerplant found two of the bolts in the third and fourth stage of the compressor, along with a note that read: "This engine flew back from its mission safely. Thought you'd be interested to see what it swallowed." For nearly forty years, the T53 has performed well, and the turboshaft - still holds many world records. New engines continue to be produced for Kaman's KMAX and Bell Alan Roberts contributed this historical feature about the T-53. |
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