Fully developed, specialised agricultural aircraft, which to this day form the basis of this type of aviation, appeared in the second half of the 20th century. One of the first was the Texas A&M AG-1, designed by Fred Weick in the late 1940s and first flown in 1950. The designer was known for placing great emphasis on safety.
It was a single-engine, strut-braced low-wing monoplane of all-metal construction. The designer applied solutions that became typical of 2nd generation agricultural aircraft: a fuselage structure enhancing forward visibility and the pilot’s chances of survival in a crash; a low-wing configuration, advantageous in view of the risk of collision with the ground or an obstacle; a chemical tank mounted in the fuselage between the cockpit and the engine firewall (engine–tank–pilot arrangement; in a crash, the pilot was not at risk of being crushed by the tank). On commission from Piper, F. Weick developed a design based on the AG-1, utilising components from the Piper PA-18 and PA-22 aircraft. The aircraft, designated AG-3, became the basis for production of the Piper PA-25 Pawnee. In the D version, another safety feature was introduced: fuel tanks were placed in the wings instead of the fuselage to reduce the risk of fire in a crash.
The PA-25 became one of the most popular agricultural aircraft – over 5,000 were produced. The second American pioneer of specialist agricultural aircraft was Leland Snow, an agricultural aviator and designer. In 1951 he built the S-1 aircraft, on which he performed agricultural aviation services for several years. The experience gained enabled him to design the improved S-2 model. It became the basis for the development of the Ag Commander/Thrush/Thrush Commander line of aircraft, produced by successive companies. Second-generation agricultural aircraft also include the biplane Grumman G-164 Ag-Cat, the IMCO CallAir A-9, the Cessna 188, the British Auster B-8 Agricola, the Australian Yeoman Ya-1 Cropmaster, the Czechoslovak Zlin Z-37 Čmelak (engine–pilot–tank layout), the Argentine Aero Boero 260AG, and the Brazilian Embraer EMB 202 Ipanema. The aircraft mentioned differ in size and payload capacity, but they share a configuration and characteristic silhouette with the “hump” of the reinforced cockpit.
The agricultural aircraft becomes a specialised agricultural machine whose design often remains exclusively a function of agrotechnical requirements and flight safety under agricultural conditions. — F. Borodzik, H. Kamiński, J. Krężałek*
