How It's Made - Crop-dusters
Crop dusters are airplanes Specially outfitted for aerial spraying. Farmers use them to seed fields And apply pesticides and fertilizer. The aquaculture industry uses them to feed fish, And emergency crews fly them to spread retardant on forest fires And dispersants on oil spills. Depending on its size, A crop duster can carry up to 2,700 liters Of liquid or dry material. The plane is designed to be able to swoop down low To accurately cover
the target spray area. At the factory, they manually weld Lightweight aircraft-grade steel tubes To construct the frame of the fuselage.
Next they use spring-loaded fasteners To affix aluminum panels to the sides. An anti-rust coating turns the aluminum golden color. All the plane's aluminum parts require this coating, Because many of the chemicals crop dusters carry Are corrosive. The tank that holds those chemicals is called a hopper. The factory molds it out of many layers of fiberglass, Which is deliberately transparent. This enables the pilot to see at a glance Roughly how much chemical remains. Inside each of the plane's wings Is a row of vertical supports called webs. To make each web, they lay a soft aluminum sheet on a mold, Place a rubber mat on top, then load the assembly into a press. A built-in water bag distributes the pressure evenly.
This helps form the aluminum sheet perfectly. Next they soak the web for a half-hour In molten sodium chloride At more than 900 degrees fahrenheit. Then they immediately submerge the web in lukewarm water. This triggers a molecular reaction That hardens the aluminum. Each wing contains 32 webs. Technicians line them up in an assembly fixture In between the wing's horizontal beams called spars. Once they've riveted the webs to the spars,
They cover the structure with aluminum panels Using spring clamps for now. The panels have holes in them To allow regular inspections of the structure inside.
After riveting the panels, Technicians screw covers onto the inspection holes. They also seal the seams between panels with liquid rubber So chemicals can't penetrate. Next they install the engine and the propeller, Which ranges from 750 to 1,400 horsepower. The prop has from three to five aluminum blades. Now the equipment that releases the chemicals from the air. For spraying liquids, they hook up horizontal pipes Lined with spray nozzles
called booms. To apply dry chemicals or disperse seed, The flight crew detaches the booms And installs a large stainless-steel funnel Called a spreader under the plane's belly.
At release time, The pilot opens a door at the bottom of the hopper, Enabling the wind to draw out the contents Through the spreader. To spray liquids, a wind-driven pump Moves the hopper contents to the booms. Technicians now assemble and install The instrumentation panel. To fill the hopper with liquid chemicals, They connect a pump to a valve on the side of the crop duster. For dry chemicals, they just lift the hopper's lid And fill her up.