The PA-25 Pawnee is an

agricultural aircraft An agricultural aircraft is an aircraft that has been built or converted for agricultural use – usually aerial application of pesticides (crop dusting) or fertilizer (aerial topdressing); in these roles, they are referred to as "crop duste ...

produced by

Piper Aircraft Piper Aircraft, Inc. is a manufacturer of general aviation aircraft, located at the Vero Beach Regional Airport in Vero Beach, Florida, United States and owned since 2009 by the Government of Brunei. Throughout much of the mid-to-late 20th cent ...

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.

Design and development

Most agricultural aircraft before 1949 were converted military aircraft and it was in that year that Fred Weick, based at

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, designed a dedicated agricultural aircraft: the AG-1. The AG-1 first flew on 1 December 1950.Peperell/Smith 1987, pp.113-120 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 a distributor for dust and seeds. A few weeks later, Piper sponsored

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 the fuselage with struts. It had a

conventional landing gear Conventional landing gear, or tailwheel-type landing gear, is an aircraft Landing gear, undercarriage consisting of two main wheels forward of the Center of gravity of an aircraft, center of gravity and a small wheel or skid to support the tail ...

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 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 Lock Haven is a city in, and the county seat of, Clinton County, in the U.S. state of Pennsylvania. Located near the confluence of the West Branch Susquehanna River and Bald Eagle Creek, it is the principal city of the Lock Haven Micropolitan ...

, 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, 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

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recommended to

that 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 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 A jump seat (sometimes spelled jumpseat) is an auxiliary seat in an automobile, train or aircraft, typically folding or spring-loaded to collapse out of the way when not used. The term originated in the United States c. 1860 for a movable car ...

fitted in the hopper to assist with operations at remote stations.Macdonald 1964, p. 137 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 the responsibility of the new owners.Piper Service Spares Letter No. 413, May 8, 1988 In 2019, Australia's

Civil Aviation Safety Authority The Civil Aviation Safety Authority (CASA) is an Australian statutory authority responsible for the regulation and safety oversight of Australia's civil aviation. CASA was formed on 6 July 1995 under the ''Civil Aviation Act 1988'' when the Civil ...

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 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.

Variants

;AG-3 :Prototype built at

. ;PA-25-150 Pawnee :Initial production version fitted with a

Lycoming O-320 The Lycoming O-320 is a large family of naturally aspirated, air-cooled, flat four engine, horizontally-opposed four-cylinder, direct-drive engines produced by Lycoming Engines. Introduced in 1953, it is commonly used on light aircraft such a ...

engine. Payload of powders or liquids.Taylor 1962, p. 264. ;PA-25-235 Pawnee B :Fitted with a Lycoming O-540-B2B5 six-cylinder engine. The Pawnee B featured a larger hopper and an increased payload of . ;PA-25-235 and PA-25-260 Pawnee C :The Pawnee C was an upgraded version of the 'B' model and was available with a 235hp or a 260hp high compression version of the O-540 engine and either a fixed pitch or constant speed propeller. The fuselage of the Pawnee C featured a quickly detachable 'turtledeck' panel to ease the rinsing out of spilt corrosive agents from the fuselage structure and to facilitate servicing and inspection of components housed in the rear section of the fuselage. ;PA-25-235 and PA-25-260 Pawnee D :The Pawnee D was also powered by a Lycoming O-540 of 260hp but featured fuel tanks fitted in the outer wings and metal covered ailerons and flaps. From 1980 it was known as the PA-25-235 Pawnee. ;eTug :A modified PA-25 powered by a General Motors LS automotive engine driving a three-bladed propeller. Other differences include a belted

propeller speed reduction unit A propeller speed reduction unit is a Transmission (mechanics), gearbox or a belt and pulley device used to reduce the output revolutions per minute (rpm) from the higher input rpm of the powerplant.Gunston 2006, p. 82. This allows the use of sm ...

. ;Laviasa PA-25 Puelche 235 : Improved version of Pawnee built by Latino Americana de Aviación in Argentina. Powered by Textron Lycoming O-540-B2C5.Jackson 2008, p. 2 ;Laviasa PA-25 Puelche 260 : Powered by O-540-G2A5 engine. ;Laviasa Puelche Trainer : Two seat trainer version of Puelche 235 with side-by-side seating.

Accidents and incidents

*9 August 1974 a crop-spraying Pawnee was involved in a fatal mid-air collision in Norfolk, UK with a

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McDonnell Douglas F-4M Phantom FGR.2.

Specifications (PA-25-235 Pawnee B)

Piper Pawnee VH-SSO conducting a landing at the Bacchus Marsh ALA

Notes

Bibliography

* * * Green, William. ''Aircraft Handbook''. London. Macdonald & Co. (Publishers) Ltd., 1964. * *Peperell, Roger and Smith, Colin. ''Piper Aircraft and their forerunners'' Tonbridge, Kent, England

Air-Britain Air-Britain, traditionally sub-titled 'The International Association of Aviation Enthusiasts', is a non-profit aviation society founded in July 1948. As from 2015, it is constituted as a British charitable trust and book publisher. History Air-Br ...

1987. * Taylor, John W. R. ''Jane's All the World's Aircraft 1962–63''. London: Sampson Low, Marston & Company, Ltd., 1962. *

External links

PA-25 Pawnee fliegerszene.de
{{Piper

Pawnee Pawnee initially refers to a Native American people and its language: * Pawnee people * Pawnee language Pawnee is also the name of several places in the United States: * Pawnee, Illinois * Pawnee, Kansas * Pawnee, Missouri * Pawnee City, Nebraska * ...

Single-engined tractor aircraft Low-wing aircraft 1950s United States agricultural aircraft Glider tugs Aircraft first flown in 1957 Aircraft with fixed conventional landing gear Single-engined piston aircraft