Loading dust (insect spray) into plane of agricultural crop spraying outfit. This particular group of flying insect killers follows the seasons from Florida to New Jersey to New York. Planes are usually old (new planes with sufficient carrying capacity are too fast). The front seat is taken out and replaced by the hopper which contains the dust. Spring 1938.
Dust or insecticide is spread by low flying planes onto crops to control various insect pests, 1942.
On August 31, 1921, a surplus World War I Curtiss JN-6H (Jenny), piloted by Lt. John A. Macready, took off from McCook Field near Dayton, Ohio to attack a new enemy – the Catalpa sphinx moth. To the cheers of an enthusiastic group of spectators, Macready dumped a load of powered lead arsenate from a makeshift metal hopper attached to the Jenny's fuselage onto an orchard being defoliated by the insects. A subsequent inspection soon revealed that the pesky moths had been virtually wiped out by the aerial assault and a new practical application for the airplane was born—crop dusting.
As airplane design matured, the business of crop-dustingor “aerial application,” the preferred professional termalso became more sophisticated. Farmers became increasingly aware of, and dependent upon, crop-dusting aircraft to efficiently fertilize their crops and dispense chemical pesticides on destructive pests. One of the major powers in commercial aviation, Delta Airlines, began its long and storied existence in 1920 as “Delta Dusters”a Louisiana crop-dusting company.
The piloting skills required for crop dusting were usually passed along in informal flight sessions, treated as more of an art form than the sophisticated science that it was. Pilots were taught how to fly low, with their wheels almost touching the crops, as a method to reduce “chemical drift”fertilizer or pesticides straying into the wrong areas. Obstacles seemed to await them at every turn. Crop dusters were always clipping their tails on standpipes (tall, tower-like structures used to store water in rural communities), hitting fence posts or pulling up without seeing a string of electric or telephone wiresunseen dangers that often meant injury or death to the pilot.
Flagmen on the ground signaled to the crop-duster pilot with a white flag, indicating which parts of a field had been “dusted” and which still required an aerial application. One of the more hazardous jobs in crop dusting, the flagman risked injury or death from the low-flying airplanes in addition to the insidious hazards of exposure to the chemicals being applied. Flagmen (and crop-duster pilots) often joked that they were immune from mosquito bites following an aerial application of pesticides.
The scores of biplane military trainers developed in the World War II era later turned into an unexpected windfall for the crop-dusting industry. The early days of crop dusting were often hazardous for the pilot because lightweight airplanes with weak frames were modified for use as crop-dustersthis situation changed for the better immediately after the war, when sturdily built surplus aircraft with improved pilot visibility were soon transformed into crop dusters.
The famous Boeing/Stearman Model 75 Kaydet two-seat biplane, developed in the mid-1930s as the primary trainer for both the U.S. Army Air Corps and the U.S. Navy (under their military designations of PT-17 and N2S, respectively), became a mainstay of the post-war crop-duster industry. More than 8,000 Kaydets (and variants) were manufactured in a 10-year span before production ceased in 1945, and thousands were sold as post-war surplus for as little as $250 apiece. The robust Kaydet's fabric-covered control surfaces, common in the 1930s, were usually replaced with a metal skin, more powerful radial engines were installed and a hopper was retrofitted into the front cockpit to contain the crop-dusting load.
Piper's venerable J-3 Cub, in which 80 percent of all United States military pilots during World War II received their initial flight training, was also transformed into another popular post-war crop-duster. The Cub's small size and agility permitted it to be flown from short dirt runways that could not support larger aircraft but, when equipped with more powerful engines, many Cubs could carry 1,000-pound (454-kilogram) crop-dusting loads.
However, it became apparent that an aircraft specifically designed and built for the demanding operations of crop dusting was needed. In cooperation with federal agencies and the light plane industry, a design team at Texas A&M built the first plane specifically intended for agricultural flying in 1950. Known as the Ag-1, it was a low-wing monoplane with a high cockpit for maximum visibility and special features for safety and for resistance to corrosion from chemical payloads. It subsequently became the basis for the Air Tractor crop dusters built by Leland Snow, and for the Piper Pawnee series of agricultural aircraft of the late 1950s. Its general configuration also influenced the design of Cessna’s Ag-Wagon agricultural planes. In the meantime, Grumman's Ag-Cat, a bi-plane design, became the first aircraft designed and marketed by a major aircraft company to meet the requirements of agricultural flying. Schweizer Aircraft took over production of the Ag-Cat under license to Grumman; deliveries began in 1960.
The Piper PA-25 Pawnee was a low-winged monoplane equipped with a 20-cubic-foot (0.6-cubic-meter) capacity hopper that fed a chemical spray distribution system. Piper built the Pawnee with pilots in mind, incorporating such design aspects as a high-seating position to greatly improve visibility and, recognizing the inherent dangers of crop-dusting, reinforcing seat restraints and strengthening the cockpit structure to withstand low-speed crashes.
More than 4,400 Pawnee's were built from 1957 until 1972 when the model was replaced by the greatly improved PA-36 Pawnee Brave. The Pawnee Brave's chemical hopper capacity was increased to 38 cubic feet (about 1 cubic meter) and its airframe was coated with polyurethane to reduce corrosion and “dust traps.” More than 1,000 Pawnee Braves were manufactured before the design was sold in 1981.
Today's modern crop-dusting airplanes, such as the Ayres Turbo-Thrush and the Air Tractor AT-400 Turbo Crop-Duster, are built for shorter takeoffs, higher spraying speeds, and increased chemical capacity to deliver more acres “dusted” per hour of flight time. Instead of a flagman on the ground to signal whether a field had been dusted, modern crop dusters use Global Positioning System satellite technology to track and record their flight paths.
The days of attaching a 50-gallon drum of chemicals to a rickety airplane have faded into history, but the sight of a crop duster roaring low and fast across a field, mere inches above the ground, remains one of aviation's most enduring and thrilling experiences.
Anderson, Mabry I. Low and Slow: An Insider's History of Agricultural Aviation. San Francisco: California Farmer Publishing Company, 1986
Phillips, Edward H. Piper: A Legend Aloft. Eagan, Minn.: Flying Books, 1993
Schweizer, William. The Ageless Ag-Cat: The 40-Year History of the Ag-Cat Agricultural Airplane. Bluffton, S.C.: Rivilo Books, 1995
Durden, Rick, Of Ag-planes, Fire Bombers and Inventions, Avweb.com. http://www.avweb.com/articles/lounge/tpl0034.html
Marshall, Kyle. Flying Low, The Daily Mississippian Online http://dm.olemiss.edu/archives/99/9907/990721/990721ENmarshall.HTML
The National Agricultural Aviation Museum. http://www.msaaa.com/naam.htm
Roach, Susan and Ryland, Janet. Willing to Take a Risk: The Folklore of Cropdusting, Louisiana's Living Traditions. http://www.crt.state.la.us/folklife/creole_art_cropdusting.html