The PA-25 Pawnee is an agricultural aircraft produced by Piper Aircraft between 1959 and 1981. It remains a widely used aircraft in agricultural spraying and is also used as a tow plane, or tug, for launching gliders or for towing banners. In 1988, the design rights and support responsibility were sold to Latino Americana de Aviación of Argentina.
23-564: Most agricultural aircraft before 1949 were converted military aircraft and it was in that year that Fred Weick , based at Texas A&M University , designed a dedicated agricultural aircraft: the AG-1 . The AG-1 first flew on 1 December 1950. During 1953, Fred Weick was approached by Piper to become a consultant on the agricultural version of the PA-18 , the PA-18A, in particular to design and test
46-582: A Curtiss AT-5A Hawk biplane, featuring a Wright Whirlwind J-5 radial engine, reached an airspeed of 137 miles per hour (220 km/h) equipped with the NACA cowling compared to 118 miles per hour (190 km/h) without it. The idea that the NACA cowling produced thrust through the Meredith effect is fallacious—although in theory the expansion of the air as it was heated by the engine could create some thrust by exiting at high speed, in practice this required
69-406: A classic. It was also at Langley that Weick headed the development of streamlined , low-drag engine cowling technology that was to advance aircraft performance dramatically. The NACA cowling first revolutionized civil air transport by making aircraft faster and more profitable. It also found application on the bombers and fighters of World War II . For this engineering breakthrough, he won
92-506: A distributor for dust and seeds. A few weeks later, Piper sponsored Texas A&M University to design a dedicated agricultural aircraft based on the AG-1 but to use as many PA-18A and PA-22 components as possible. The resulting design, the AG-3, was smaller than the AG-1 and had a steel tube fuselage which was fabric covered. The AG-3 was a single-seat, low-wing monoplane with the wings braced to
115-573: A greater rate of climb, reduced fuel consumption, the elimination of shock cooling (since the LS is water-cooled rather than air-cooled) and a less costly maintenance regime. Data from Jane's All the World's Aircraft 1965–66 General characteristics Performance Related development: Comparable aircraft: Fred Weick Fred Ernest Weick (1899–1993) was an airmail pilot , research engineer , and aircraft designer. Working at
138-620: A spinproof, stallproof, all-safety, dual control light plane that is as easy to fly as the average automobile..." that year's greatest contribution to the scientific advancement of aviation. Weick joined Texas A&M University in 1948. There, he worked on the design and development of the Ag-1 crop duster, and designed the Ag-3, predecessor to the Piper PA-25 Pawnee series. The same basic configuration and design concepts pioneered in
161-437: A symmetric, circular airfoil that is wrapped around the engine. In a normal planar airfoil, like a wing, the difference in airspeeds, and their associated changes in pressure, on the top and bottom surfaces, enhances lift. In the case of the NACA cowl, the ring-shaped airfoil is positioned so this lift effect is forward. This thrust does not fully counter the drag of the cowl but greatly mitigates it. The difference in airspeed on
184-619: Is a type of aerodynamic fairing used to streamline radial engines installed on airplanes . It was developed by Fred Weick of the National Advisory Committee for Aeronautics (NACA) in 1927. It was a major advancement in aerodynamic drag reduction, and paid for its development and installation costs many times over due to the gains in fuel efficiency that it enabled. It won the 1929 Collier Trophy . The NACA cowling enhanced speed through drag reduction while improving engine cooling. The cowling consists of
207-809: The Experimental Aircraft Association Oshkosh airshow for entertainment and lectures. He married Dorothy Church (1900–1991) and they had three children together. Weick died on Thursday, July 8, 1993, in Vero Beach, Florida . In 2002, Fred E. Weick was honored by the Virginia Aeronautical Historical Society, when he was inducted into the Virginia Aviation Hall of Fame for his contributions to aviation and aviation safety. NACA cowling The NACA cowling
230-614: The NACA , he won the 1929 Collier Trophy for his design of the NACA cowling for radial air-cooled engines. Weick's aircraft designs include the Ercoupe , Piper PA-25 Pawnee , and Cherokee . A 1922 graduate of the University of Illinois , he was one of the first university graduates to apply his degree to a career in aeronautics. Weick was also one of the first engineers hired by the original U.S. Air Mail Service . His efforts in
253-752: The "D", the 1980 and 1981 production aircraft were marketed as the Pawnee. The final production aircraft was completed at Lock Haven on 22 March 1981, the last of 5,167 Pawnees. A useful design aspect was the ability to carry a mechanic on a jump seat fitted in the hopper to assist with operations at remote stations. On April 15, 1988, Piper Aircraft, Inc. officially sold the PA-25 series aircraft to Latino Americana de Aviación S.A in Argentina. The sale included all drawings, engineering data, parts inventory, tools, catalogs, and manuals. All support of any nature became
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#1732783802798276-516: The AG-3 was renamed the PA-25 Pawnee. The engine was upgraded to a 150 hp Lycoming O-320-A1A engine. Two pre-production aircraft were built at Vero Beach in 1957 and production started at Lock Haven, Pennsylvania , in May 1959. In 1962, another prototype was built at Vero Beach with a 235 hp Lycoming O-540-B2B5 engine and production aircraft were produced at Lock Haven from 1962. In 1964,
299-618: The Ag-1 can be seen in more modern crop dusters including the Air Tractor AT-802 . In a 1979 interview about general aviation's future past the year 2000, Weick accurately envisioned the continued interest in sport aviation and the practical use of aircraft for medium-range transportation. He mentioned that he had seen gas turbines demonstrated as early as 1922, and that their future use in light aircraft would only be viable with development of cost-efficient materials that could withstand
322-400: The Pawnee B was introduced with a larger hopper and improved dispersal gear. The Pawnee C of 1967 was fitted with oleo shock-absorbers and other improvements; also in 1967, a 260 hp variant was introduced. Early models of the Pawnee had a single fuel tank located between the agricultural hopper and the engine. The National Transportation Safety Board recommended to Piper Aircraft that
345-433: The cylinder heads where it is most needed, as opposed to flowing between the cylinders and crankcase where it does little for cooling. Furthermore, turbulence after the air passes the free-standing cylinders is greatly reduced. The sum of all these effects reduces drag by as much as 60%. The test conclusions resulted in almost every radial-engined aircraft being equipped with this cowling, starting in 1932. The test aircraft,
368-522: The early 1920s to establish emergency fields for night-flying mail pilots addressed a major challenge. Weick worked for the National Advisory Committee for Aeronautics (NACA) at its Langley Aeronautical Laboratory , in Hampton, Virginia beginning in November 1925. He helped design the first wind tunnel devoted to full-scale propeller research and wrote a textbook on propeller design that became
391-400: The early model PA-25's with a fiberglass fuel tank be retrofitted with a rubber fuel cell to minimize the chance of catastrophic failure and fire resulting from a crash. In 1974, the Pawnee D was introduced, with the fuel tanks moved from the fuselage to the wings; the 260 hp variant was also available with either a fixed pitch or constant-speed propeller. Although still the same design as
414-480: The fuselage with struts. It had a conventional landing gear with a tailwheel and was powered by a 135 hp engine. The single seat was placed high in the fuselage to give the best visibility and an 800 lb-capacity hopper was fitted in front of the cockpit. The AG-3 made its maiden flight in November 1954. The aircraft's flying tests were successful and, in 1957, Weick was invited to join Piper at Vero Beach, and
437-452: The heat. He felt future aircraft would not be radically different, but could benefit from safety improvements in controllability. He joined Piper Aircraft in 1957 as director and chief engineer of its development center, remaining there until his retirement at age 70. In addition to the Pawnee, Weick co-designed Piper's Cherokee line of personal and business light aircraft . Weick remained active in general aviation , regularly attending
460-448: The prestigious Collier Trophy for NACA in 1929. The experimental airplane he built in the early 1930s demonstrated Weick's passion for safety. He left NACA in 1936, and joined ERCO's fledgling aircraft team as chief designer. His goal was to make flying as easy and safe as driving the family auto. In addition to the integrated controls for ease of flying, he incorporated the tricycle landing gear that later became standard on most of
483-524: The responsibility of the new owners. In 2019, Australia's Civil Aviation Safety Authority formally approved the issuing to eTugs of Certificates of Airworthiness in the Limited category for the purpose of glider towing. An etug is a PA-25 where the Lycoming engine has been replaced with a General Motors LS automotive engine. The advantages for glider towing, compared to a Lycoming powered PA-25, include
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#1732783802798506-399: The two sides is due not only to the shape of the airfoil, but also the presence of the cylinders on the inside surface, which serves to further slow the airflow. Nevertheless, the total airflow through the cowl is generally greater than it would be with no cowl as the air is sucked through the cowl by the air flowing around it. This has the side-effect of keeping the fast moving air primarily on
529-476: The world's aircraft. Later in the 1930s, Weick improved on that design with the Ercoupe , the two-seat, all-metal, low-wing aircraft that was so easy and safe to fly that many students mastered it in five hours or less. Half of the 6,000 Ercoupes built were still flying at the time of Weick's death. In February 1946, he received the Fawcett Aviation Award "in recognition of his development of
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