Crop Dusting Aircraft

Crop Dusting Aircraft - Geo-fencing — a virtual GPS-defined perimeter for a real-world geographic area — along with electronic fencing, "poles in the ground around the perimeter of a field with some electronics," will contain the Ag Cormorant within the boundaries of the area

it sprays, Yoeli explains. Software yet to be created may also be used. Confining the AG Cormorant is vital because it eliminates the regulation and management needed to allow drones to fly in airspace between fields as manned aircraft do, Yoeli says.

Crop Dusting Aircraft

"We think this is a limitation that will exist for all unmanned agricultural aircraft." Jim Hirsch is the president of Olney, Texas-based Air Tractor, the world's leading producer of aerial application planes. He told me that his firm's newest model, the AT-1002, will carry even more, up to 3,875 liters, once it completes FAA certification.

Size Matters

"He had a passion, and he had a mission," says Kristin Edwards, Leland Snow's daughter and a vice president at Air Tractor. "He never wanted to just get a job at some aviation company and work nine to five."

For his part, in order to stay in business, Snow was eventually compelled to incorporate and take on partners. "He did have some financial failures," says Snow's daughter, Kristin Edwards. "Initially, he didn't really pay attention to the business side of things.

I think he finally realized then that making money is also important." The self-made, single-minded visionary was now obliged to consult multiple partners before making decisions in a company he himself had founded. Tensions arose almost immediately.

In 1965, realizing their relationship was dysfunctional beyond repair, Snow and his partners arranged to sell Snow Aeronautical to Rockwell-Standard. The deal included hiring Snow as vice president and general manager of the newly established Olney division of Rockwell Aero Commander.

It’s Just Business

"Another thing Leland introduced was sealing the cockpit," says Kornegay. "In the Stearmans, the Grumman Ag Cats, and other older planes, your feet were sitting on rails and there was no floor in the cockpit. Any migrating dust or chemicals accumulated in the cockpit, and pilots would end up covered with it.”

Alterations Snow made to the S-2 configuration were: "Basically the very first example of what we're all still flying today," says Kornegay. "You've got a powerful engine up front, then the hopper, and then the pilot behind it all, safe inside a sealed cockpit."

FAA certification of the S-2 required static load tests of critical structure. Since Snow lacked advanced testing methods in his modest Harlingen shop, he improvised his own DIY protocol: He stacked 280 50-pound bags of insecticide atop the S-2 wingspan, tip-to-tip, applying 14,000 pounds of stress to the wing structure

—the equivalent of 4.2 Gs in flight. A few rivets popped as the wing flexed, but the structure survived. Snow likewise applied the bag method to the horizontal stabilizer and the elevators. Aerial application accelerated after World War II, spurred by the development of a variety of insecticides, fungicides and herbicides and a swift increase in the average size of farms.

Crop-Dusting Was An Often Hazardous Occupation Until A Maverick Entrepreneur And Pilot Designed The Right Airplanes For The Job

Hopper size steadily increased to accommodate larger dry and wet loads — all the way up to the 3,028-liter hopper found on today's piloted Air Tractor 802 planes. The U.S. The State Department describes the regime as "an informal political understanding among states that seeks to limit the proliferation of missiles and missile technology."

Thirty-five countries adhere to the understanding, but the State Department says the regime "is not a treaty and does not impose any legally binding obligations on partners." In an era when astronauts were striving to reach the moon, Snow blazed a lower-altitude frontier: agricultural aircraft, more commonly known as crop-dusters.

A precise, efficient flight path eight feet above the crop canopy was Snow's consuming interest and lifetime endeavour. Nevertheless, Yoeli says the Missile Technology Control Regime "places severe limits on the export of unmanned aircraft that can carry more than 500 Kg for more than 300 kilometers."

The restriction may be lifted in the future, he predicts, "but for now it's an export-limiting factor." The average flight lasts about 20 minutes per aircraft and the planes return to the landing strip. Nixholm says his AT-602s can refuel and take on more chemicals in three to five minutes.

About International Student

Yoeli estimates that the Ag Cormorant can be refilled in 20 seconds. Over a five-hour span, Nixholm's planes will average 20 loads each. Carrying less than a quarter of the load the AT-602 carries, an Ag Cormorant would have to haul and apply more than 80 loads to achieve the same output.

In "less than 90 seconds" the planes are over the cranberry or blueberry bogs, says Curt Nixholm, the company's co-owner. Pilots descend and manually turn on their spray booms as they pass the perimeters at a little over 209 kph.

Yoeli says Ag Cormorant will fly at 111 kph over fields and slower for application to orchards. A light bar mounted ahead of the AT-602's cockpit using data supplied by the airplane's GPS helps pilots line up for the parallel lines they will fly across the bogs.

Their spray booms are calibrated prior to flights with pressures and nozzles adjusted to spray chemicals at the droplet size and rates called for on fungicide labels — usually 38 liters per half hectare — a rate that would rapidly empty the 500-liter Ag Cormorant.

Early Experiments

While still focused on traditional aerial application planes, Air Tractor has made a foray into unmanned aircraft, Hirsch says. In May 2016, Air Tractor acquired Hangar 78 UAV, maker of the Yield Defender, a small autonomous quadcopter fitted with an infrared camera to shoot photos and videos of crops.

But Hirsch notes that certification for large unmanned aerial application aircraft capable of carrying loads comparable to manned ag aircraft in the U.S. is "out of sight now, maybe 10 years away or more." "Each new model was a growth variant," Hirsch says of the Air Tractor fleet.

"Each offered some improvement: a bigger hopper, different aerodynamics, a new powerplant." Today, while the big Air Tractor 802 (derived from a larger model built for fighting fires) comes close in sales, Hirsch says, "the 502 still remains the most popular agricultural airplane in the world—period.

It's the right size. It fits more operations." The starring role on the big screen has led to a more permanent celebrity: the National Air and Space Museum's recent acquisition of an Air Tractor AT-400A—on display at the Museum's Steven F. Udvar-Hazy Center—donated by Texas ag pilot Rusty

Quantum Leap

Lindeman. "Rusty flew the plane on promo tours for the Dusty movies," says Dorothy Cochrane, curator of the general aviation collection. "The aircraft's operational and film history made it an ideal representative of agricultural aviation." We're glad you have enjoyed complimentary access to the Aerospace America digital edition.

If you would like to continue reading our publication you will need to join AIAA or subscribe. Please follow one of the steps below. During this time, thousands of surplus trainer aircraft manufactured during World War II were available for as little as $250.

Combat pilots who had learned to fly with the Boeing-Stearman Model 75 and the Piper J-3 Cub were now flying modified versions of these airplanes over America's farm fields. When a wing sheared off in a later high-speed dive test (the defect was traced to a misplaced decimal point in wing-stress calculations), Snow had to bail out and the S-2 prototype was destroyed.

Local Harlingen banks got nervous and cut off financing. With about 1,800 of the more than 2,600 Ag Cats manufactured between 1959 and 1980 still in use today, worldwide—plus the best pilot safety record in ag aviation—the statistics speak for themselves.

Cost And Safety

Yet Pat Kornegay, who flew both Ag Cats and Air Tractors, feels any rivalry with Snow's designs was ultimately a non-event. "As we became more focused on operational efficiency and spray-pattern quality, the contest was conclusively over," he asserts.

While Leland Snow advanced the low-wing monoplane, the Grumman Aircraft Engineering Corporation, famed for legendary World War II fighters, instead doubled back into biplane design. Grumman's concept, the Ag Cat, was based on a rugged, over-built airframe integrated into the biplane platform to form a highly durable, safe agricultural aircraft.

The skill of ag pilots, averaging 19 years of experience according to the National Agricultural Aviation Association, allows them to spray accurately, minimizing drift — a byproduct of the aerodynamic vortices (swirling air) generated by the wingtips, propellers and rotors of ag aircraft and

helicopters. Drift can result in damage to crops, wildlife and humans adjacent to fields being sprayed. Consequently U.S.-based aerial applicators are monitored for violations by the Environmental Protection Agency. Yamaha's RMAX remotely piloted helicopter is the largest unmanned aerial application aircraft flying in the U.S., although significantly smaller than the Ag Cormorant.

The First Aerial Application Wasn’t From A Plane

Brad Anderson, unmanned systems division manager for Yamaha Precision Agriculture, leads a three-person team, operating 10 RMAX helicopters under special FAA waivers in Napa, California. Yamaha's waivers exempt the RMAX from FAA airworthiness requirements, exempt it from the requirement that the remote pilot have a commercial pilot's license as ag pilots do and allows it to fly at its 64-kilogram weight.

Since 2016 Anderson's team has worked with a small group of vineyards, spraying fungicide for mildew prevention on wine grape crops. "It's the last frontier in aviation," Leland Snow told an interviewer in 1966. "You do your own flying.

And you don't have to answer to anyone except a farmer if you goof on a job. The ag pilot has more freedom than anyone else in the air." In the U.S., aerial application drones "are generally small currently and have very limited capability" says Steven Thomson, engineering programs and projects leader for the National Institute of Food and Agriculture, part of the U.S.

Department of Agriculture. With a background in aerial application of crop protection materials as well as unmanned aerial systems, he views drones as "supplemental" to manned aircraft in the near to midterm. However, the north central Texas town of Olney was soliciting new industry to boost the local economy.

Grumman Ag Cat

Snow met with the chamber of commerce and prominent businessmen. Funding was arranged to relocate Snow Aeronautical to Olney and continue production in a vacant hangar at the airport. Leland's manufacturing tools were transferred from Harlingen north in a convoy of cattle trucks aromatic with cow manure.

Two flatbeds carried a pair of unfinished S-2B fuselages, displayed on Main Street for Olney citizens to ogle. Certain locals expressed doubts about this youthful entrepreneur wearing the worn leather flight jacket. In season, aerial application begins before dawn with Downstown's aircraft flying to an 823-meter gravel runway in the middle of the bogs.

There, pesticide-licensed ground crews mix fungicide to strictly enforced proportions. When the aircraft arrives, fungicide is pumped from mixing tanks into the hopper/tanks immediately in front of the Air Tractor's cockpit. Simultaneously, a farm foreman gives the pilots computer thumb drives containing GPS coordinates for the bogs they will spray.

The pilots insert the drives into GPS units in the aircraft and take off. Measuring 3.5 meters long (with rotor) and 1 meter tall, the RMAX is powered by a 2-cylinder gasoline engine. It carries a 16-liter payload.

Robotic Aerial Application

Anderson tells me over 2,000 are at work in Japan. "Forty percent of rice paddies are sprayed now by a Yamaha remotely piloted helicopter," Anderson says. But he adds that drone regulation and the aviation and agriculture environment are different in Japan.

Air traffic is far less dense and the rice paddies are smaller than America's farm fields. Furthermore, the Japan Civil Aviation Bureau does not require certification of the RMAX. Over a 60-year career, Snow conceived 30 original designs of agricultural aircraft, beginning in the 1950s with the Snow Aeronautical S-2, the first purpose-built ag-plane manufactured for commercial sale.

He fast-tracked research and development of agricultural aircraft and standardized build quality. He tirelessly upgraded new models with improved efficiency and increased safety. In 1970, Snow founded Air Tractor, the Olney, Texas-based company that now dominates the global market for agricultural aviation.

For 18 months, Snow put in 10-hour days, six days a week, designing the first Air Tractor, designated the AT-300. His initial goals were simple: make it light and keep costs low. Working by himself, he generated over 600 drawings and 700 pages of engineering reports required for certification.

M- Dromader

While flying a Cub, Snow noted inherent shortcomings in its performance. "I very quickly became aware of the fact that an airplane designed specifically for agricultural work was badly needed," he wrote in his 2008 autobiography, Putting Dreams to Flight.

The Stearman biplanes, in his view, were also sorely lacking. "With these thoughts in mind," he recalled, "I began laying lines in my spare time for the design of my first airplane, the Snow S-1." "No preliminary engineering calculations were done," Snow wrote of the S-1 prototype in his autobiography.

"I merely operated on the premise that, since it looked just like a big model airplane, I'd proceed accordingly." Fundamentals of the wood-and-fabric structure include a non-tapered wing directly attached to the base of the fuselage for superior strength, plus a more elevated pilot's seat for a wider-angle perspective.

First test flights of the S-1 occurred in 1953, and the Federal Aviation Administration issued Snow an experimental license. In some concepts, rotorcraft drones would rise vertically from the perimeters of the fields they treat, spraying in precise patterns feet above crops, never venturing far from the remote pilots or automated support systems that accompany them.

Ag Pilots Are In High Demand

With no pilot aboard, drone makers say their aircraft are safer than manned aerial applicators. They also claim that drones can be more cost-effective and productive. Rockwell management then intervened with bad news. To consolidate aircraft production, the Olney factory would be shut down and manufacturing relocated to an Aero Commander facility in Georgia.

Rather than leave Texas and accept a demotion and pay cut, Snow opted to resign in March 1970. Since production of the S-2 began in 1958, the Olney factory had rolled out 523 agricultural aircraft, including 100 Thrushes.

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Prior experience had convinced Snow that a proposal for this expensive new model would draw a lukewarm response from Rockwell at best. "In view of this," Snow wrote in his autobiography, "the simplest solution seemed to be not to tell them about it."

Rockwell Thrush Commander

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